International Rice Research Notes Vol.20 No.3

International Rice Research Notes The International Rice Research Notes (IRRN) expedites communication among scientists concerned with the development of improved technology for rice and rice- based systems.

The IRRN is a mechanism to help scientists keep each other informed of current rice research findings. The concise scientific notes are meant to encourage rice scientists to communicate with one another to obtain details on the research reported.

The IRRN is published quarterly in March, June, September, and December by the International Rice Research Institute; annual subject and variety indexes are also produced.

about research collaboration, and announcements. The IRRN is divided into three sections: notes, news

IRRN production team . . . . . . . . . . . . . Editor: Carolyn Dedolph Assistant editor: Teresita Rola Layout and design: Erlie Putungan Production supervisor: Millet Magsino Editorial assistant: Luisa Gelisan Typesetting: Erlie Putungan

Artwork: Jesus Recuenco Cecilia Gregorio

Juan Lazaro IV

ISSN 0115-0944

2 IRRN 20:3 (September 1995)

Contents September 1995

Genetic resources Search for seedborne endophytic fungi in rice 4

Genetics Genetic variation in chemical composition and digestibility of

Heterosis in chemical composition and digestibility of rice

Allelic relationship among fertility-restoring genes in rice 5

nutrients in rice straw 4

straw 5

Breeding methods Identifying restorers and maintainers for five cytoplasmic male

Androgenesis in rice breeding 6 Using colored-leaf mutants of thermosensitive genic male sterile

sterile lines 6

rice 7

Yield potential Correlation and path analysis of rice grain yield under alkali stress

conditions 8

Grain quality Milling characters of raw and parboiled popular rice cultivars 8 Induction of mutants with low amylose content in endosperm

Gan Wan Xian 19: high-yielding indica rice variety with improved

Physical, milling, chemical, and cooking characters of some rice

using a chemical mutagen, N-methyl-N-nitrosourea 9

grain quality 10

cultivars in Tamil Nadu, India 10

Pest resistance—diseases Genetic diversity in Xanthomonas oryzae pv. oryzicola 12

Integrated germplasm Improvement - irrigated 13 ASD19: a medrum-duration, short- and slender-grained variety for

Tamil Nadu, India 13

Seed technology Mutagenic effectiveness, efficiency of gamma rays, and genetic

parameters of variation in gamma-irradiated upland rice 14

Physiology and plant nutrition Chemical composition and digestibility of urea-treated rice

Effect of root pruning during ripening on grain filling in rice 16 Mineral elements in Australian brown rice 17

Fertilizer management Effects of Sesbania rostrata population, time of harvest, and urea

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straw 16

application rate on lowland rice production 18

Fertilizer management — inorganic sources Band placement of urea solution increases N use efficiency in

transplanted lowland rice 19

Germplasm improvement

Crop and resource management

Transformation of N in soil affected by different sources and methods of N application in a flooded rice ecosystem 20

Effect of substituting sodium for potassium in a lowland double- rice cropping system 20

Fertilizer management — organic sources Algicides in Azolla germplasm management 21

lntegrated pest management — diseases Occurrence of teleomorph of Fusarium graminearum Schwabe,

Rice hull ash applied to soil reduces leaf blast Incidence 23

lntegrated pest management — insects Effect of some fungicides on Metarrhizium sp. Sorok: an

Evaluation of rice, maize, and 56 ricefield weeds as hosts of

Biology of the maize orange leafhopper Cicadulina bipunctata

Suitability of ricefield plants to planthopper Nisia carolinesis

Feasibility of hybridization between Nephotettix virescens

the causal agent of rice scab, in India 23

entomopathogen on insect pests of rice and pulses 24

planthopper Peregrinus maidis (Ashmead) 25

(Melichar) on rice and maize 26

Fennah 27

(Distant) and Nephotettix nigropictus (Motsch.) in rice 28

lntegrated pest management — weeds Rice off-types in Central Luzon, Philippines 28

Economic analysis Farmer participation and cost effectiveness of bulk fertilizer

purchasing scheme in Sri Lanka 29

DNA fingerprinting of Xanthomonas oryzae pv. oryzae using

Use of molecular analysis in selecting spreader row components IS1112-based polymerase chain reaction 30

for blast screening nursery 31

IRRI and UK intensify research collaboration 32 Genetic engineering of rice for sheath blight resistance 33 IRRI library reinvigorates rice literature collection in

Rockefeller Foundation supports China-IRRI collaboration 33 Training on rice germplasm collecting in Vietnam 33

Cambodia 33

IRRI positions announced 34 Biotechnologia Habana '95 34 2nd lnternational Symposium on Systems Approaches for

IRRI group training courses for 1995 35 Rice dateline 35 New IRRI publications 36 New publication 36 Rice literature update reprint service 36 Call for news 36 IRRI address 36

Agricultural Development 35

IRRN 20:3 (September 1995) 3

Research methodology

Announcements

Germplasm improvement

Search for seedborne endophytic fungi in rice G. C. M. Latch, AgResearch, Palmerston North, New Zealand; and D. A. Vaughan, National lnstitute of Agrobiological Resources, Kannondai 2-1-2, Tsukuba, lbaraki 305, Japan

A search was made for Acremonium spp. endophytes in the seeds of Oryza and related species. These endophytes occur in a symbiotic relationship with many grasses where they assist in the growth and persistence of their host. They are beneficial because the chemicals they produce make the grass more tolerant of drought, produce more tillers and seed, and enhance resistance to some pests and diseases. Infected grasses are symptom- less and transmission of the fungus is only through mycelium in the seed. Usually all seeds from an infected plant contain mycelium.

The benefits could be considerable if such a fungus was present in rice. Seeds in the IRRI germplasm collection from

20 species of Oryza and 5 species in related genera collected from 31 countries were examined for the presence of endophyte mycelium. Seeds of O. glaberrima, O. glumaepatula, O. rhizomatis, and O. schlechteri were not available for testing. Seeds were softened by soaking overnight in 5% sodium hydroxide, then washed in water. and boiled for 2 min in Garner’s solution (50 ml lactic acid, 0.325 g aniline blue, 100 ml water). Seeds were then deglumed, squashed on a microscope slide, mounted in aniline blue, and examined with a microscope for the presence of endophyte mycelium. Single seeds from 20 to 100 plants were examined where possible, but for a few species, only 5-10 seeds were available. The species examined and the countries from where the seeds were collected are listed (see table). None were infected with endophyte mycelium.

related genera are infected with Acremonium endophytes. However, the possibility that some species may contain this endophyte cannot be ruled out entirely.

It is unlikely that species of rice and

Species examined for the presence of Acre- monium endophytes.

Species Country of origin

Oryza alta Brazil, India O. australiensis Australia O. barthii Guinea, Mali,

Sierra Leone O. brachyantha Mali, Sierra Leone O. eichingeri Sri Lanka O. grandiglumis Brazil O. granulata India, Malaysia, Nepal O. latifolia Costa Rica, Guatemala O. longiglumis Indonesia O. longistaminata Benin, Côte d' Ivoire,

Nigeria, Sierra Leone O. malampuzhaensis India O. meridionalis Australia O. meyeriana Malaysia O. minuta Philippines O. nivara Bangladesh, Cambodia,

India, Myanmar, Sri

Thailand Lanka, Taiwan-China,

Thailand

Ghana, India, Kenya, Nigeria, Tanzania, Zaire

O. officinalis Malaysia, Myanmar,

O. punctata Cameroon, Chad,

O. ridleyi Thailand O. rufipogon Bangladesh, China,

India, Malaysia, Papua

China, Thailand New Guinea, Taiwan-

Malaysia, Taiwan-China O. sativa Bangladesh, India,

Chikusichloa sp. Japan Hygroryza aristata Sri Lanka Leersia perrieri Madagascar L. tisseranti Guinea Rhynchoryza subulata Argentina

~ ~~~

Genetic variation in chemical Table 1. Rice varieties grouped according to nylon bag organic matter digestibility where A =

Table 2. Chemical composition (g/kg dry matter) and digestibility of nutrients (%) in rice straw.

composition and digestibility NBOMD group Group A Group B Group C of nutrients in rice straw

1988-89. a high, B = medium, and C = low. 1988-89.

M. Singh, Animal Science Department, and H. P. Singh, Plant Breeding Department, College of Agriculture, Govind Ballabh Pant

UPR79-123 IR8 Pradesh, lndia Pant Dhan 6 Sarju 52 University, Pantnagar 263145, Uttar Narendra 118 Ratna

The chemical composition and nylon bag Jaya VPR83-34 organic matter digestibility (NBOMD) were determined for 24 straw samples from 21 varieties (Table 1). Twelve were Govind grown in an agronomic trial in 1988 and 12 in a plant breeding trial in 1989. Sita, Pant Dhan 4, and Saket 4 were used in NBOMD where A = high, B = medium, both years. All varieties were hand- and C = low (Table 2). from 443 to 548 g/kg. A averaged 530; harvested at 6-7 cm above the ground. After 72 h of incubation in fistulated B, 501; and C, 453. Chemical Varieties were grouped according to their rumens of cattle, the NBOMD varied composition in B and C was similar, so

Nutrient

Saket 4 (2) Narendra 2 Sita (2) IET8580 Pant Dhan 4 (2) VL 8

A B C High Medium Low

IET9362 Chemical composition NDF 692 729 728 Hemicellulose 231 251 250 Cellulose 298 324 309 Crude protein 54 48 46

Digestibility 45

Hemicellulose 52 52 45 Cellulose 48 48 42

46 44 39

Manhar IR24

IET8111 IET8110 UPR-80-120 Organic matter 53 50

a Figures are average values.

4 IRRN 20:3 (September 1995)

Genetics

42.0 4.9

The straw of 15 F 1 crosses and that of their 10 parents were collected from a rice breeding experiment. The chemical composition and nylon bag (72-h) dry matter digestibility (NBDMD) were determined for each (see table).

Crossing two varieties resulted in a hybrid with higher NBDMD than that of the parents, except for Narendra 118/Pant Dhan 6. Eliminating the cross with negative heterosis (Narendra 118/Pant Dhan 6) from heritability (h 2 ) estimation by regression gave h 2 values of 0.86 for NBDMD and 0.82 for nylon bag organic matter digestibility (NBOMD).

The crude protein (CP) content in most hybrids was greater than that of both or one of the parents. Both Narendra 118 and Pant Dhan 6 had

the difference in NBOMD was because

digestibility ( r = 0.7) and CP content the difference in NBOMD could only be components of NDF. higher NDF ( r = 0.9) and cellulose conditions in the same soil, implying that cellulose and hemicellulose, the two NBOMD in A was attributed to the were grown under the same agronomic contributed by higher digestibility of (NDF) contents for A. The higher indicating no year effect. The varieties degraded faster than in C. This was crude protein (CP), and lower cell wall varieties was similar during both years, the neutral detergent fiber (NDF) in B neutral detergent solubles (NDS), higher The NBOMD of the three common

perhaps due to a combination of higher contained more CP. The difference between A and B was ( r = 0.66). Varieties with lower NDF because of their genetic makeup.

Heterosis in chemical composition and digestibility of rice straw M. Singh and A. K. Gupta, Animal Science Department, Govind Ballabh Pant University of Agriculture and Technology (GBPUAT), Pantnagar, 263145, Uttar Pradesh, India; and H. P. Singh, Plant Breeding Department, GBPUAT

Chemical composition (%) and NBDMD (%) of rice straw from different parents and hybrids.

Parents Hybrids

CP NDF NBDMD CP NDF NBDMD NBOMD

IR58 a 4.2 70.1 47.1

IET7566 4.6 66.4 46.3 4.9 69.5 49.9 51.0 ab IET7613 4.7 68.6 49.9 5.4 68.2 54.6 55.7 c

UPRH39 5.6 71.3 46.9 5.4 67.3 50.2 51.4 ab Pant Dhan 6 5.3 69.3 49.3 5.8 67.6 53.8 54.8 c

UPR85-32 3.5 73.7 65.2 51.7 52.9 b

UPR83-169 5.1 66.2 49.0 6.5 65.8 54.5 55.6 c

UPR82-43 3.6 72.1 41.2 5.3 66.9 49.8 51.1 ab Narendra 118 a 5.1 69.2 48.0

UPR85-32 3.5 73.7 42.0 6.0 67.7 50.7 51.8 b IET7566 4.6 66.4 46.3 6.5 66.5 52.2 53.4 bc

Pant Dhan 6 5.3 69.3 49.3 4.7 68.1 47.9 49.0 a IET7613 4.7 68.6 45.9 6.1 70.6 52.0 53.0 bc

IET6223 a 4.4 66.6 45.1 IET7566 4.6 66.4 46.3 5.3 66.7 51.2 52.3 b IET7613 4.7 68.4 45.9 5.7 64.6 50.1 51.2 ab UPRH39 5.6 71.3 46.9 5.4 68.5 49.7 50.9 ab Pant Dhan 6 5.3 69.8 49.3 6.0 69.0 52.2 53.4 bc

a lR58, Narendra 118, and IET6223 were crossed with the varieties grouped below them to produce hybrids.

relatively higher dry matter digestibility The positive correlation between CP and (DMD) and CP, so no further improve- DMD and the simultaneous reduction in ment could be expected in the hybrids. the neutral detergent fiber (NDF) of

Polygenes, the combination of which hybrids are desirable for improving the seem to be identical in these two nutritive value of straw. varieties, may control the CP content.

Allelic relationship among fertility-restoring genes in rice J. Ramalingam, N. Nadarajan, C. Vannia- rajan, and P. Rangasamy, Agricultural Botany Department, Agricultural College and Research Institute, Madurai 625104, Tamil Nadu, India

We studied the allelism for the restoring gene(s) present in purified testers received from IRRI. The five testers, IR24 (T 1 ), IR54742-22-19-3 (T 2 ), IR29723-143-3-2-1 (T 3 ), IR9761-19-1 (T 4 ), and ARC11353 (T 5 ), were tested for

Segregation pattern of pollen and spikelet fertilities in test cross F 1 progenies. Tamil Nadu, India. 1992-93.

Total plants Pollen fertility a Spikelet fertility b

Test cross observed (no.) Fertile Sterile Fertile Sterile

V20 A (T 1 × T 2 ) V20 A (T 1 × T 3 ) V20 A (T 1 × T 4 ) V20 A (T 1 × T 5 ) V20 A (T 2 × T 3 ) V20 A (T 2 × T 4 ) V20 A (T 2 × T 5 ) V20 A (T 3 × T 4 ) V20 A (T 3 × T 5 ) V20 A (T 4 × T 5 )

200 200 200 200 200 200 200 200 200 200

169 31 200 175 25 200 165 35 200 168 32 178 22 200 161 39

169 31 200 174 26 200 167 33 200 166 34 178 22 200 163 37

a Pollen fertility = fertility > 60%, sterility = 0%. b Spikelet fertility = fertility > 80%, sterility = 0%.

IRRN 20:3 (September 1995) 5

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Identifying restorers and maintainers for five cyto- plasmic male sterile lines F. U. Zaman, M. J. Abraham, A. R. Sadananda, F. Mohammad, and Y. Raj, Genetics Division, Indian Agricultural Research Institute, New Delhi 110012, India

Two new cytoplasmic male sterile (CMS) lines, Pusa 3 A and Pusa 5 A, were developed. Pusa 3 A has in its background high-yielding Basmati variety Pusa Basmati 1. Pusa 5 A has the aromatic, non-Basmati line Pusa 150. These lines, along with IR58025A, PMS2 A, and PMS3 A, which possess CMS wild abortive cytoplasm, were used to make test crosses. During the 1994 wet season, 326 hybrids and their respective parents were evaluated to identify effective restorers and maintainers for the CMS lines. Each genotype was trans- planted in 3-m rows at 20- × 20-cm spacing. Standard agronomic practices were followed.

Five plants from each genotype were randomly selected and used for analyzing pollen and spikelet fertility. Anthers from upper, middle, and lower portions

their restoration and inheritance patterns during 1992-93 rabi season (Sep-Jan). All were found to be effective restorers and inherited digenically.

the genes, these five testers were crossed in all possible combinations, excluding reciprocals. The F 1 generation of 10 R × R combinations was raised along with cytoplasmic male sterile line V20 A; A × (R × R) crosses were made. These

To determine the relationship among

10 test cross F 1 progenies (A × (R × R)) were raised at 20- × 19-cm spacing during 1993 kharif season (Jun-Sep). Each combination had 10 rows with 20 plants per row. Their pollen and spikelet fertilities were scored (see table).

The restorer lines differed in their gene action. The test cross progenies from T 1 × T 3 , T 1 × T 5 , T 3 × T 5 , and T 2 × T 4 did not yield any sterile progeny. These lines have identical R alleles

between them while remaining crosses showed segregation, indicating the alleles differed among their parents. These results suggest that the five restorer lines can be divided into group 1 = T 1 , T 3 , and T 5 and group 2 = T 2 and T 4 , which possess different pairs of R genes. A suitable combination of any two of the pairs seems to restore fertility in male sterile lines.

CMS line Restorers (no.) Restorers Maintainers (no.)

Restorers and maintainers for five CMS lines. New Delhi, India. 1994.

Maintainers

lR58025 A 36 PRR3, PRR5, PRR7, PRR8, PRR11, 7 TC7-2-1-92-39, TC11-3, TC23, PRR12, PRR16, PRR22, PRR23,

PRR42, PRR43, PRR44, PRR74, P615-K-271, P615-4-1 PRR79, PRR82, PRR98, PRR99, PRR100, PRR101, PRR102, PRR103,

PRR25, PRR34, PRR35, PRR38, TC25-41, P615-K-61,

PRR104, PRR105, PRR107, PRR112, PRR113, PRR114, PRR115, PRR116, PRR117, PRR118, PRR119

PMS3 A 13 PRR2, PRR8, PRR10, PRR24, PRR33, 4 PRR45, PRR47, PRR55, PRR83, PRR84, PRR85, PRR87, PRR89

PMS2 A 4 PRR3, PRR5, PRR44, PRR85 3

Pusa 3 A 6 PRR69* a , PRR70*, PRR71*, PRR90, 5 PRR94, PRR95

Pusa 5 A 2 PRR57, PRR91 2

Total 61 21

P615-K-160, RCPL 1-87-4, PP94-429, PP94-432

ADT2008-2-7-1, P1191-3, P1192-2

TC4-721, TC7-3-1 TCll-7-3-4-1, TC120, HKR91-410

P615-K-61, P615-K-172

a * = Basmati restorers.

of half emerged panicles were col- Three potential Basmati restorers were lected and squashed in 2.2% I-KI stain identified for Pusa 3 A. The frequency of to observe pollen fertility. Cultivars restorers (19%) was higher than that of with up to 1 % pollen and spikelet maintainers (6%) (see table). fertility were classified as perfect We are using the potential restorers to maintainers, those with 60-100% develop new hybrids with improved quality pollen and 80-100% spikelet fertility characteristics. Some perfect maintainers as potential restorers, and the rest as with good agronomic traits are being partial restorers. converted into new CMS lines.

Androgenesis in rice breeding N. Mandal, Chinsurah Rice Research Centre, Hooghly 71 21 02, India; S. Sinha and S. Gupta, Botany Department, Bose Institute, Calcutta 700009, India

Plant regeneration efficiency from anther culture of F 1 cross Pankaj × O. rufipogon has been improved using He2 + NAA + Kin 0.5 + ABA 2 mg/liter + 5% maltose as

the callus induction medium (see table). Our objective was to transfer the submergence tolerance from the wild species O. rufipogon Griff. to the O. sativa variety Pankaj.

We used modified MS (NAA 0.5 + Kin 2 mg/liter + 3% sucrose) medium for plant regeneration. Several chlorophyll- deficient plants (albino, xantha, viridis, albo-viridis, virido-albina, virido-xantha,

and striata) and green plants that have different ploidy numbers were obtained. Among the regenerated plants, 73.3% were double haploids. These lines were grown in the field, where 74.8% survived. We examined 696 androgenic lines for differ- ent qualitative and quantitative characters. Statistical analysis revealed that the characters within one line were relatively uniform and stably heritable. Among

6 IRRN 20:3 (September 1995)

Breeding methods

Effect of basal medium and other supplements on androgenesis of rice. a

Treatment a Basal medium Callus Calli giving Plant regeneration induction (%) green plants b (%) efficiency (%)

A N6 6.8 7.9 53.7 He32 8.5 10.8 91.8

B N6 6.4 He2 8.3

9.5 13.0

60.8 107.9

a A = Basal medium + NAA + Kin 0.5 mg/liter + 5% sucrose. B = Basal medium + NAA + Kin 0.5 + ABA 2 mg/liter + 5% maltose. b Calli were regenerated on MS + NAA 0.5 + Kin 2 mg/liter + 3% sucrose.

different lines, broad genetic surviving after another 10 d of sub- recombinations occurred. mergence were recorded. Compared with

In the next season, 4-wk-old seedlings Pankaj, only PR324 is a high-yielding from each line were submerged in a (4.0-4.4 t/ha), submergence-tolerant type glasshouse tank for 8 d to select with a lower rate of photorespiration

Scheme for eliminating contaminated seed in hybrid rice derived from colored-leaf TGMS lines.

- submergence-tolerant types. Starch from

content coincided with a marked increase 14.1%; milling percentage, 73%; and submergence. The decrease in starch quality is high: protein, 8.6%; amylose, the internodes rapidly disappeared upon (P = 0.01) and wide adaptability. Grain

in amylolytic activity (21.4 EU). Plants length:breadth, 3.5.

Using colored-leaf mutants of plants to be discarded at the seedling thermosensitive genic male stage. To test the effectiveness of this

sterile rice system, colored-leaf mutants were induced directly in TGMS line 2177S.

Shu Qingyao, Xia Yingwu, and Liu Quifu, Institute of Agricultural Sciences, Zhejiang Agricultural University, Hangzhou 310029, People's Republic of China

We set up a marker-assisted system to eliminate seed contamination that results from incomplete male sterility of thermosensitive genic male sterile (TGMS) lines in a two-line hybrid seed production system (see figure). Chloro- phyll-deficient leaves (chlorina, albino) were used as markers to determine the

In July 1991, dry seeds (13 % water content) of 2177S were treated with 60 Co gamma rays at a dose of 300 Gy. They were sown, transplanted, and grown to maturity. A few seeds of each M1 plant were harvested to make M2 progenies. Various non-green seedlings were detected and isolated from these prog- enies; only a few grew to maturity.

Thirteen heritable colored-leaf mutation lines (M6-7) were developed through successive selection and identifi-

Leaf color transition and morphoagronomic characters of the mutants and 2177S.

Leaf color of Morphoagronomic characters Group Mutant

Seedling Plant Plant Panicle Grains/ Fertility 1,000-grain Growth height length panicle (%) weight duration

20 °C 30 °C (cm) (cm) (no.) (g) (d)

cation. Mutation lines were grouped according to their color transition during growth (see table).

Group I included five yellow-leafed mutants, for which leaves remain yellow or yellowish from seedling to maturity stages. Group II had eight yellow- or albinotic-leafed mutants in which the first 3-4 seedling leaves are albinotic or yellow before the 4th or 5th leaf extends, then the leaves turn greenish while in the seed bed, and finally a normal green at maturity (see table).

leaves when the mutants were crossed with 2177S or any other variety with normal leaves, suggesting that a recessive gene(s) controls all of the mutations. The leaf color segregation ratio of normal green to mutated color in each F 1 popula- tion between the mutants and 2177S was fitted well to a 3-1 ratio, indicating that a single recessive gene controlled all these mutations. Allelic tests of these mutation lines showed that W1 and W17 were controlled by an allelic gene, and so were W3, W5, and W11 . Nine nonallelic loci are involved with the 13 mutation lines.

The mutant lines and 2177S were

All of the F 1 plants had normal green

I W3 Cream Yellowish Yellow 79.0 19.8 102.7 55.9 27.8 138 crossed with the conventional line TEC. W5 Cream Yellowish Yellow 83.8 21.9 109.2 61.3 27.2 W11 Cream Yellowish Yellow 74.9 20.2 97.2 50.3

27.7 W12 Cream Yellowish Yellow 76.1 18.8 82.2 58.1 26.0 127

these F 1 plants were recorded and The morphoagronomic characters of

W18 Yellowish Yellow Yellow 67.4 18.3 71.7 53.5 26.4 117 analyzed. No significant differences II W1 Albinotic Yellowish Green 79.0 19.8 77.5 58.6 25.9 126 were detected among them for plant

W17 Albinotic Yellowish Green 79.3 19.6 91.6 51.7 27.2 123 W4 Yellow Albinotic Green 76.6 20.4 101.8 44.8 27.6 121

height, panicles per plant, panicle length, grains per panicle, and yield per plant (P W24 Albinotic Albinotic Green 76.5 18.9 87.8 58.9 27.0 121

W25 Albinotic Albinotic Green 74.8 19.6 111.2 46.4 26.1 122 W27 Albinotic Albinotic Green 76.3 20.0 105.2

= 0.05) (data not shown). This suggests

W29 Yellow Yellow Green 63.8 17.3 64.6 58.4 24.5 123 W33 Yellow Yellow Green 65.5 17.7 66.8 33.4 25.5 126

27.0 122 that these co1ored-1eaf mutants can be used as markers for eliminating seed

Check 2177S Green Green Green 75.3 19.3 84.4 47.1 27.0 120 contamination in two-line hybrid rice.

IRRN 20:3 (September 1995) 7

141

125

More than half of the rice consumed in India is parboiled; in Tamil Nadu State it exceeds 85%. Raw and parboiled rices have different qualities. We investigated the differences in some milling characters between raw and parboiled rices in 15 popular cultivars.

Nine short-duration (10.5- 120 d) cultivars were grown in 1992 kuruvai

season (Jun-Jul sowings) and six me- dium-duration (125-140 d) cultivars in 1992 thaladi season (Sep-Oct sowings). A recommended package of practices was followed for a transplanted lowland crop. Seeds were collected from replicated trials, cleaned, and dried to 14% moisture content. Samples were drawn 1 mo after harvest. One half was

S. Arumugachamy, S. Giridharan, A. P. M. K. Soundararaj, P. Vivekanandan, S. Antho- niraj, and T. M. Thiyagarajan, Tamil Nadu Rice Research Institute (TNRRI), Aduthurai 612101, lndia

Milling characters of raw and parboiled popular rice cultivars

We studied direct and indirect associa- tions of yield components with grain yield in 27 short-duration rice genotypes to identify suitable criteria for effective selection of genotypes under alkaline stress condition.

The experiment was laid out at CRS in a randomized block design during 1993 wet season (rabi) with three replications. The soil was clay loam with pH 8.6, EC

A. Ramalingam, N. Sivasamy, S. Subra- manlan, and K. Koodalingam, Cotton Research Station (CRS), Srivilliputtur 626125, lndia

Correlation and path analysis of rice grain yield under alkali stress conditions

1.4 dS/m, and 18% exchangeable Na. The soil had low N (109 kg), low P (10.8 kg), and high K (672 kg). The crop received 125-50-50 kg NPK/ha during the season. We transplanted 25-d-old rice seedlings at 20- × 10-cm spacing in 2- × 3-m plots. The genotypes had 105-

Grain yield was positively and from 1.7 to 6.0 t/ha. 115 d durations and grain yield varied

significantly correlated with panicle length ( r = 0.578), grains per panicle ( r = 0.547), 100-grain weight ( r = 0.401), dry matter production ( r = 0.901 ), and straw yield ( r = 0.752) (see table). Straw yield was positively and significantly correlated with plant height ( r = 0.523),

panicle ( r = 0.544), and dry matter

production was significantly and production ( r = 0.858). Dry matter

panicle length ( r = 0.698), grains per

positively correlated with plant height ( r = 0.44), panicle length ( r = 0.692), grains per panicle ( r = 0.600), 100-grain weight ( r = 0.410), and root weight ( r = 0.378).

Path analysis studies indicated that dry matter production had a high direct effect on grain yield (see table). Productive tillers per plant and grains per panicle had low direct effects. For the other traits, the effect was negative. Although panicle length, 100-grain weight, and straw yield had a positive and significant correlation with grain yield, they did not exhibit direct effect on grain yield. These characters had an indirect effect on grain yield, mainly through dry matter production.

Dry matter production seems to be the most reliable character for effective selection of genotypes under alkali stress conditions.

Coefficients of correlation and path analysisa showing direct and indirect effects of yield components on grain yield under alkali stress condition. Srivilliputtur, India. 1993.

Plant Panicle Productive Grains/ 100-grain Root Dry matter Straw Grain Variable height length tillers/plant panicle weight weight production yield yield

Panicle height rg b 0.574** –0.303 0.306 0.184 0.255 0.440* 0.523** 0.263 P c –0.059 –0.014 –0.029 0.015 –0.006 –0.072 0.545 –0.118

Panicle length rg –0.089 0.647** 0.139 0.298 0.692** 0.698** 0.578** P –0.034 –0.024 –0,009 0.032 –0.005 –0.084 0.857 –0.157

Productive rg 0.024 –0.215 0.180 –0.137 –0.018 –0.091 tillers/plant P 0.018 0.002 0.097 0.001 0.007 –0.051 –0.169 0.004

Grains/panicle rg –0.188 0.352 0.600** 0.544** 0.547** P –0.018 –0.016 0.002 0.050 0.006 –0.099 0.743 –0.122

100-grain rg –0.127 0.410* 0.291 0.401* weight P –0.011 –0.003 –0.021 –0.010 –0.032 0.036 0.508 –0.066

Root weight rg 0.378* 0.193 0.161 P –0.015 –0.007 0.017 0.018 0.004 –0.281 0.469 –0.043

Dry matter rg 0.858** 0.901* production P –0.026 –0.017 –0.013 0.030 –0.013 –0.106 1.239 –0.193

Straw yield rg 0.752** P –0.031 –0.017 –0.002 0.027 –0.009 –0.054 1.062 –0.225

a Residual effect = 0.35; underlined figures denote direct effects. * and ** = significant at the 5 and I% level. respectively. b rg =genotypic correlation coefficient. c P = path coefficient.

8 IRRN 20:3 (September 1995)

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parboiled by the double steaming method used in conventional rice mills and dried to 14% and the other half was raw milled. Both samples were dehulled in a labora- tory model Satake rubber roll huller and milled for 30 s in a McGill miller. Milling characters were estimated (see table).

values for brown rice percentage in parboiled rice compared with raw rice because of soaking losses. Brown rice percentage in raw rice ranged from 75.4% for Improved White Ponni to 79.5% for ADT36; in parboiled rice, it ranged from 74.5% for Improved White Ponni to 77.8% for ADT39. Quantity of hull removed in parboiled rice was less than that for raw rice. The hull percent- age was 20.0-23.0% in raw rice and 19.0- 21.8% in parboiled rice. The most hull (23.0%) was removed from Co 45 and Improved White Ponni in raw rice and

All the cultivars had decreasing mean

21.8% from Improved White Ponni in parboiled rice.

Parboiling improved the milling characters in all varieties. Milling recovery ranged from 71.3% for Im- proved White Ponni to 75.7% for ADT39 in raw rice compared with 72.7% for Improved White Ponni to 75.9% for ADT36 in parboiled rice. The physico- chemical structure of the kernel was altered in parboiling, conferring strength to the grains due to gelatinization by double steaming and subsequent drying.

More bran was obtained with raw milling than with parboiling, with 1.1 % in ADT38 and ADT39 and 4.2% in ASD18. This suggests that uniform milling for 30 s for both raw and par- boiled rice is inadequate. Time should vary for uniform polishing. In raw milling, ASDl8, IR64, IR50, and ASD16 yielded 5.0-5.7% bran and IR36 yielded only 3.3%, indicating that cultivars vary

in hardness and resistance of milling. On the contrary, in parboiled rice, bran yield was highest in Co 43 (3.4%) and least in ADT37(1.4%), perhaps because of increased variation in gelatinization for the cultivars, even under similar condi- tions (see table).

Head rice recovery in parboiled rice was much greater than that in raw rice. The head rice recovery of the cultivars under the raw rice treatment was rela- tively lower than their normal averages because of the environmental conditions to which samples were exposed from harvest until analysis. Cultivars, how- ever, may respond differently to head rice recovery because of genetics.

In both raw and parboiled rices, no definite trend was observed in brown rice, total milled rice, head rice, and hull and bran content, suggesting that genetics and the environment largely govern the characters.

Milling characters (%) for raw and parboiled rice of 15 popular cultivars. TNRRI, Aduthurai, India. 1992.

Raw rice Parboiled rice

Brown rice Hull Total milled rice Bran Head rice Brown rice Hull Total milled rice Bran Head rice

IR50 77.7 21.9 72.7 5.0 50.0 76.4 20.5 74.0 2.4 71.0 TKM9 78.1 20.9 73.2 4.6 48.5 76.5 20.4 73.7 2.8 72.8 ADT37 79.0 20.5 75.1 3.9 53.5 77.3 19.4 75.6 1.4 74.5 Co 37 78.4 20.6 74.1 4.0 41.1 77.0 19.2 75.4 1.5 74.6 ADT36 79.5 20.0 74.9 4.5 46.8 77.6 19.0 75.9 1.5 73.8 IR36 79.2 20.2 75.2 3.3 52.5 77.3 19.7 75.3 2.0 74.0 IR64 77.7 22.0 72.4 5.2 46.7 77.0 21.0 73.9 2.8 71.7 ASD16 78.6 21.0 72.8 5.0 45.0 75.9 19.8 74.1 1.8 73.1 ASD18 78.5 20.6 72.6 5.7 46.9 76.9 20.1 75.3 1.6 74.0 ADT39 79.7 20.0 75.7 3.9 51.6 77.8 19.5 75.8 2.8 73.9 IR20 78.2 21.2 73.2 4.8 46.5 76.9 19.5 74.5 2.6 72.8 ADT38 78.4 21.5 74.4 3.9 52.2 77.4 20.5 74.4 2.8 72.8 Co 43 78.0 21.7 73.0 4.8 54.9 76.6 20.2 73.0 3.4 71.5 Co 45 76.5 23.0 71.6 4.7 40.8 76.5 20.7 73.8 2.7 72.2 Improved White Ponni 75.4 23.0 71.3 3.9 47.4 74.5 21.8 72.7 1.8 71.3

X 78.2 21.2 73.5 4.5 48.3 76.8 20.1 74.4 2.7 72.9 SD 1.1 0.9 1.30 0.62 4.06 0.78 0.73 0.93 0.61 1.15

Variety

Induction of mutants with low amylose content in endosperm using a chemical mutagen, N-methyl-N- nitrosourea K. Ise, Sun Youquan, K. Tomita, and Y. Sunohara, Japan and China Joint Research Program on Rice Genetic Resources, Yunnan Academy of Agricultural Sciences (YAAS), Kunming, Yunnan, People’s Republic of China

With the increasing demand for quality

breeding cultivars with good eating quality.

According to our recent surveys, urban people in Yunnan Province prefer soft-cooked rice with low amylose content. We studied how changes in the environment affect amylose content in the endosperm. An improved japonica cultivar, Hexi 4, was grown in Yunnan Province at five locations with different

rice in China, we are focusing on altitudes (Table 1). Temperature during grain-filling markedly affected amylose content, with temperature below 20 °C enhancing it. Based on this finding, we are selecting elite breeding lines with lower amylose under low temperatures for high-altitude regions.

There are some traditional and improved indica cultivars with low amylose grains that are soft-cooking in Yunnan Province. We do not, however, have such japonica germplasm in the

IRRN 20:3 (September 1995) 9

The Jiang Xi Provincial Seedboard released Gan Wan Xian 19 in 1992. It is a new semidwarf indica rice variety derived from the cross between Hei Shi Tou, a traditional variety, and F4084, a strain from the cross IR2061/Ai Gan Nuo/Ru Wei Tao. It is suitable for late sowing in the double-cropped area of southern China.

Gan Wan Xian 19 is 95-102 cm in height and has strong stems. It matures in 134 d and has high yield potential under good irrigation and management conditions. In regional trials, the average yield was 6.8 t/ha, 11.6% more than that of M112, a local check in southern China. The highest yield obtained was 8.7 t/ha in the Huzhou region of central Jiangxi in 1993.

The variety possesses resistance to blast, bacterial blight, and whitebacked planthopper. It has tolerance for water

Table 1. Amylose content in endosperm of Hexi 4, grown at 5 locations with different altitudes in Yunnan Province, China.

Altitude Average daily Amylose Location (m) temperature content

in July (°C) (%)

Shunghshao 2140 18.6 19.8 Kunming 1916 19.8 18.9 Yuxi 1637 20.9 16.4 Yiliang 1550 21.7 16.4 Huanian 1000 24.3 15.4

Table 2. Amylose content in endosperm of mu- tant lines induced by N-methyl-N-nitrosourea treat- ment in Hexi 4.

Mutant or Origin Amylose cultivar content

(%)

Hexi 4 Yunnan 20.1 94YM01 (dull) Mutant 11.3 94YM02 (waxy) Mutant 1.0 Koshihikari a Japan 16.5 Nipponbare b Japan 21.5

a Most popular variety in Japan, has good eating quality. b Used as standard for eating quality tests in Japan.

YAAS Crop Germplasm Institute. So we tried to induce low-amylose mutants by treating the fertilized eggs of a nonwaxy cultivar, Hexi 4, with N-methyl-N- nitrosourea (Table 2). We obtained two mutants, one of which was waxy and the other with very low amylose or dull endosperm. The mutant lines and Hexi 4 only differed slightly in heading time, plant height, and plant type. These lines are useful for improving the quality of japonica rice cultivated in the high altitudes of the subtropics and tropics.

Gan Wan Xian 19: high- yielding indica rice variety with improved grain quality Yu Chuanyuang, Wan Jianlin, and Gan Shuzhen, Rice Research Institute, Jiang Xi Academy of Agricultural Sciences, Nanchang 330200, China

Table 1. Reaction a of Gan Wan Xian 19 to blast, bacterial blight, and whitebacked planthopper.

Whitebacked Leaf blast Neck blast Bacterial blight planthopper

Province b / institute Rating Reaction c Rating Reaction c Rating Reaction c Rating Reaction c

Zhejiang 5 S 3 MR Yunnan 3 MR 3 MR Hunan 2 MR 0 HR Guandong 5 S 0 HR 3.7 R-MR Jilin 3 MR Jianmu 2.9 H R-R China National – Rice Research Institute

5.7 MR-S 3 R

a Scored using a 0-9 scale for leaf blast, and a 0, 1, 3, 5, 7, 9 scale for neck blast, bacterial blight, and whitebacked planthopper. b Data from the plant protection Institute of each province. b S = susceptible, MR = moderately resistant, R = resistant, HR = highly resistant.

submergence in the areas where floods are frequent (Table 1).

Gan Wan Xian 19 has long, slender, translucent grains with intermediate amylose content, low gelatinization temperature, and soft gel consistency. It won a silver prize for its high quality at the First China Agricultural Product Exposition in October 1992 (Table 2).

in Jiang Xi in 1993 and has been spreading quickly in other parts of southern China.

The variety was grown on 66,000 ha

Table 2. Quality characteristics of Gan Wan Xian 19.1992.

Characteristic Mean

1,000-grain wt (g) Brown rice (%) Milled rice recovery (%) Head rice (%) Kernel length (mm) Length–width ratio Chalky kernel (%) Area with chalkiness (%) Amylose content (%) Alkali spreading value Gel consistency (mm) Protein content of brown

26.0 79.8 73.1 55.3

7.1 3.6 8.0 1.7

21.3 7.0

76.0 rice (%) 8.2

Physical, milling, chemical, Growers, traders, millers, and consumers and cooking characters of prefer different rice cultivars because of

some rice cultivars in Tamil Nadu, India

their grain yield and quality characters. We attempted to catalog certain physical, milling, chemical, and cooking characters

S. Arumugachamy, S. Giridharan, A.P.M.K. in 16 rice cultivars commonly grown in Soundararaj, P. Vivekanandan, and S. Tamil Nadu, India. Anthoniraj, Tamil Nadu Rice Research Nine of these cultivars are short-du- Institute, Aduthurai 612101, India ration (105-120 d), six are medium-

duration (121-140 d), and one is long- duration (more than 145 d). All are recommended for the lowland ecosystem. The short-duration cultivars were grown in 1992 dry season (Jun-Sep), and the medium- and long-duration varieties in 1992-93 wet season (Aug-Feb), following recommended practices. Grain was harvested, cleaned, and dried to 14%

10 IRRN 20:3 (September 1995)

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Physical, milling, chemical, and cooking characters of 16 rice varieties. Tamil Nadu, India. 1992-93.

Variety Duration 1,000- Kernel Kernel Kernel L-B Kernel Kernel Kernel Kernel

(d) grain length breadth thickness ratio length shape length breadth weight (mm) (mm) (mm) after cooking after cooking

(g) (mm) (mm)

IR50 TKM9 ADT37 ADT36 ADT41 ADT42 ASD16 ASD18 IR64 ADT39 ADT38 IR20 Co 43 Co 45 Improved White Ponni CRR1009

X SD CV (%)

105 105 105 110 110 110 110 110 120 125 135 135 135 135 135 155

121.25 3.85 3.18

19.3 6.3 2.0 25.0 5.9 2.7 20.5 5.1 2.7 21.2 6.1 2.3 24.2 8.3 1.9 25.0 6.3 2.3 24.2 5.7 2.6 21.1 6.2 2.2 25.3 7.1 2.1 19.0 5.9 2.3 22.7 6.8 2.2 21.6 6.1 2.3 22.6 6.0 2.4 26.1 7.4 2.3 18.1 5.9 2.1 22.8 5.1 2.7 22.5 6.3 2.3

1.8 0.9 0.5 8.0 14.1 20.8

1.6 3.1 1.8 2.2 1.5 1.9 1.6 2.7 1.6 4.3 1.7 2.7 1.8 2.2 1.6 2.8 1.7 3.7 1.6 2.6 1.7 3.1 1.7 2.6 1.7 2.6 1.8 3.2 1.6 2.8 1.9 1.9 1.7 2.8 0.3 0.8

19.2 28.1

Medium Medium Short Medium Extra long Medium Medium Medium Long Medium Long Medium Medium Long Medium Short

Slender Medium Bold Medium Slender Medium Medium Medium Slender Medium Slender Medium Medium Slender Medium bold

9.5 9.2 8.7

10.3 11.7 10.1

8.1 9.2

10.6 9.2

10.0 9.7 9.5

12.0 10.3

8.5 9.8 1.0

10.3

3.0 3.9 3.7 3.3 2.9 3.5 3.8 3.3 3.3 2.8 3.4 3.4 3.7 3.5 3.3 3.9 3.4 0.6

16.4

Variety Linear Breadth- Elongation Alkali Amylose Water Volume Brown Milling Head rice

elongation wise index digestion (%) uptake expansion rice (%) recovery ratio expansion score a 100 (ml) (%) (%)

IR50 TKM9 ADT37 ADT36 ADT41 ADT42 ASD16 ASD18 IR64 ADT39 ADT38 IR20 Co 43 Co 45

CR1009 Improved White Ponni

X SD CV (%)

1.6 1.6 1.6 1.7 1.5 1.6 1.6 1.6 1.5 1.6 1.5 1.7 1.6 1.7 1.8 1.7 1.6 0.3

18.8

1.4 1.1 3 1.5 1.1 6 1.4 1.2 2 1.3 1.3 2 1.5 1.0 5 1.5 1.1 2 1.4 1.2 2 1.4 1.1 3 1.5 1.0 2 1.4 1.2 3 1.5 1.0 2 1.5 1.1 2 1.5 1.1 3 1.5 1.1 7 1.5 1.2 3 1.5 1.2 3 1.5 1.1 3.1 0.2 0.3 1.2

15.2 24.1 39.1

23.2 28.0 24.8 29.6 16.0 28.8 24.8 22.4 21.2 24.0 24.0 23.2 32.4 23.2 22.4 32.4 25.0

2.0 8.2

220 200 280 200 260 220 180 280 200 200 240 260 200 180 260 280 228.8

5.9 2.6

4.2 3.9 5.0 4.0 4.7 4.1 3.9 5.0 3.9 3.6 4.5 4.6 3.9 3.7 4.6 4.6 4.3 0.7

15.7

74.0 77.6 79.2 79.2 72.8 79.2 78.4 77.2 76.8 80.0 78.4 79.2 78.4 78.4 76.4 76.8 77.6

1.4 1.8

68.0 72.8 70.4 72.8 66.8 76.6 72.0 69.2 72.4 76.0 74.4 76.0 74.0 73.6 72.4 72.4 72.5

1.6 2.3

50.0 48.5 52.4 51.2 53.2 56.8 64.0 47.9 62.0 57.2 64.4 55.6 59.2 46.8 50.4 51.0 54.4

2.4 4.3

a Based on the spreading scale of 1-7.

moisture content. Samples were drawn 1 mo after harvest. The methods described in the Standard evaluation system of rice, Juliano and Perez (1984), Pillaiyar and Mohandass (1981), and the standard procedures recommended for determining cooking qualities by Bhattacharya and Sowbhagya (1972) were used with two replicates (see table).

Kernels of ADT41, an aromatic fine rice, were extra long and slender. Ker- nels of IR64, ADT38, and Co 45 were long and slender, while those of ADT37 and CR1009 were short and bold. IR50

had medium slender kernels and the rest had medium kernel length and shape.

Co 45 and IR64 had the heaviest 1,000-grain weights and Improved White Ponni and ADT39, the lightest.

High mean values for linear elonga- tion ratio and elongation index coupled with low mean values for breadthwise expansion ratio result in longer cooked rice grains with the least breadthwise swelling, giving a good appearance. These characters were favorably com- bined in ADT36, Improved White Ponni, and ADT39 (medium kernel length and

shape) and in ADT37 (short and bold). But the three long slender and one extra long slender genotypes showed similar values for linear elongation and breadthwise expansion ratios (see table).

alkali digestion scores, and the other genotypes had low mean values.

CR1009, Co 43, ADT36, ADT42, TKM9, ADT37, and ASD16 had high amylose content (more than 24%) and ADT41 had a very low content (16%). The others had intermediate amylose content.

Co 45, TKM9, and ADT41 had high

IRRN 20:3 (September 1995) 11

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ASD16 and Co 45 took up the least amount of water; ADT37, ASD18, and CR1009 took up the most. However, ADT37 and ASD18 had the highest values for volume expansion and ADT39 the least. Low water uptake and high volume expansion were noted in ADT42.

Head rice recovery was highest in ADT38 followed by ASD16 and IR64 (more than 60%). It was very low in

Co 45, ASD18, and TKM9 (less than 50%). ADT41 recorded a low percentage of brown rice (72.8%), with other geno- types ranging from 74.0 to 80.0%. Milling and head rice recovery in the genotypes, however, were not proportion- ate to their respective hulling percentages.

The brown rice to milling difference is indicative of the quantity of bran and germ removed from the kernels. It was

highest in ADT37 (8.8%) and lowest in ADT42 (2.6%).

The fewest brokens were in ASD 16 (8.0%) and the most in Co 45 (26.8%). The genotypes studied possessed more variability for gelatinization temperature, Length-breadth ratio, elongation index, and kernel breadth, indicating the possibility of the genetic improvement of these grain quality traits.

Genetic diversity in Xanthomonas oryzae pv. oryzicola A. K. Raymundo and A. Briones, Jr., Institute of Biological Sciences, University of the Philippines Los Baños, Philippines; E. Y. Ardales, IRRI; J. E. Leach, Plant Pathology Department, Kansas State University, Manhattan, Kansas, USA, and T. W. Mew and R. J. Nelson, IRRI

Bacterial leaf streak (BLS), caused by Xanthomonas oryzae pv. oryzicola, is an increasing problem in rice production in tropical and subtropical Asia. Losses can be as high as 17% depending on the cultivar and climatic conditions. In China, BLS has recently become so severe that the pathogen has been placed on the quarantine list of some provinces. Many plots on the IRRI farm and in nearby farmers’ fields have been heavily infected during the past two wet seasons.

Past studies have shown that X. oryzae pv. oryzicola exhibits a wide and contin- uous range of virulence. No clear differ- ential interactions have been established. In this study, we determined the haplo- typic diversity of X. oryzae pv. oryzicola and explored the relationships between haplotype and pathogen aggressiveness. This may be useful in allowing the selection of pathogen strains for screen- ing and characterizing sources of resist- ance to BLS.

We evaluated the genetic diversity of a group of 124 X. oryzae pv. oryzicola strains between 1972 and 1990 from different regions of the Philippines. Diversity was estimated from data obtained by restriction fragment length polymorphism (RFLP) (Fig. 1a) and Pst I

12 IRRN 20:3 (September 1995)

1. a) DNA hybridization profiles obtained using pR41 as the probe. b) DNA banding patterns based on Pst I restriction digestion.

Pest resistance—diseases

2. Phenograms showing the relationships among the different haplotypes for strains of Xanthomonas oryzae pv. oryzicola obtained using a) data and b) Pst l restriction enzyme analysis. a

a Strain designations for representative isolates are shown in parentheses. Stralns were grouped using the unweighted pair group method with arithmetic means (UPGMA). The percentage of times that a particular group was formed by bootstrap analysis is shown on each fork of the phenogram.

restriction endonuclease analyses (Fig. 1 b). For restriction endonuclease analysis, chromosomal DNA isolated from each strain was digested to comple- tion with PsfI. High molecular weight (HMW) bands between 23.1 and 7.1 kb were polymorphic between genomes of

HMW bands ranged from 5 (in BLS280) to 13 (in BLS30). Thirty-six different banding patterns ( Pst I haplotypes) were resolved by Pst I digestion.

was a repetitive DNA sequence contained in plasmid pBluescript that had been isolated from a partial genomic library of X. oryzae pv. oryzicola strain, BLS335. Clone pR41 was suspected to contain a repetitive DNA element based on the intensity of hybridization in colony blots when probed with labeled genomic DNA from X. oryzae pv. oryzicola. The repetitive nature of the pR41 insert was confirmed when the clone hybridized to multiple fragments of Pst I-digested genomic DNA of X. oryzae pv. oryzicola in Southern blots. The DNA sequence of the pR41 insert (459 nucleotides in length) is 44.8% identical to part of the sequence of a IS1112, a mobile, repetitive DNA insertion element cloned from X. oryzae pv. oryzicola. When Southern blots of Pst I-digested DNA from the 124 strains of X. oryzae pv. oryzicola were hybridized with the pR41, 26 different banding patterns (R41 haplotypes) were observed based on 71 total band posi- tions. The genetic diversity of the population of X. oryzae pv. oryzicola

the strains (Fig. 1b). The number of

For RFLP analysis, the probe used

assessed by RFLP was estimated to be 0.92 by Nei and Tajima’s equation. This value is similar to the genetic diversity of a comparable collection of X. oryzae pv. oryzae strains.

The DNA fingerprints of the 26 different R41 and 36 Pst I haplotypes were used to estimate the relatedness among the different haplotypes by cluster analyses (unweighted pair group arithmetic average clustering methods, or UPGMA). The robustness of the phenograms was evaluated using the bootstrap procedure (Fig. 2). The haplotypes that defined both R41 and Pst I did not cluster tightly. Several small clusters of two to three similar haplotypes were seen, but most haploytpes did not belong to clearly defined groups.

X. oryzae pv. oryzicola were inoculated to rice cultivar IR50 and lesion lengths were measured to determine if groups of the pathogen could be discerned based on aggressiveness (as measured by lesion length). A continuous range of lesion lengths was observed. That is, although infection with strains from different haplotypes resulted in lesions of different lengths, there was overlap in lengths of lesions caused by the various haplotypes and no discrete groupings were formed. To determine if haplotypes are differ- entially aggressive to other rice varieties and to identify representative isolates for evaluation of germplasm, we are now inoculating strains representing each of the R41 and Pst I haplotypes to a diverse group of rice varieties.

Strains representing the haplotypes of

ASD19: a medium-duration, short- and slender-grained variety for Tamil Nadu, India W. Wilfred Manuel, T. Sundararn, K. Ganesan, S. Valravan, P. Shanrnuga- sundaram, K. Mohanasundaram, S. Palanisamy, M. Subramanlan, and M. Rangaswamy, Rice Research Station, (RRS), Ambasamudram 627401, Tamil Nadu, India

ASD19 is a derivative of the cross between Lalnakanda and IR30. It is semidwarf (108 cm) and matures in

120-132 d. It is highly suitable for sowing ASD19 possesses moderate resistance in Pishanam season (Oct-Feb) in southern to blast and is tolerant of early drought. districts of Tamil Nadu where IR20 and It has well-exserted panicles with ADT39 are currently being grown. short, slender grains that have a protein

In 240 trials conducted at research content of 9.6% and good cooking stations and in farmers’ fields in Tamil quality. Its milling recovery to total Nadu and around the nation, ASD19 rough rice is 65.5%, 3.8% higher than yielded an average 5.8 t/ha, outperforming that of IR20. Its 1,000-grain weight is all of the checks, including IR20 by

ASD19 was released in January 1995 14.2% (Table 1). 18.3 g.

In fertilizer trials, 100 kg N/ha was for general cultivation in Pishanam found to be the optimum fertilizer dose for season in southern districts of Tamil ASD19 (Table 2). Nadu. (See next page for tables.)

IRRN 20:3 (September 1995) 13

Integrated germplasm improvement—irrigated

Table 1. Grain yield of ASD19. Tamil Nadu, India. 1979-93.

Trial a and year Mean grain yield (t/ha)

ASD19 IR20 ADT39 CO 43 Ponni/White Ponni

RRS, Ambasamudram, 1979-93 5.2 3.8 3.8 4.3 4.4

Multilocation trials at research 4.9 4.3 4.0 5.3 stations, 1981-92 (25) (18) (1) (15)

Adaptive research trials in

(18) (18) (5) (13) (14)

farmers' fields Nellai Kattabomman District, 5.6 5.1 6.8 5.0

1987-90 (49) (48) (10) (49)

Table 2. Fertilizer trial on ASD19. Tamil Nadu, India. 1991-93.

Grain yield (t/ha) N level (kg/ha) 1991 1992 1993 Mean

0 3.4 2.3 4.3 3.3 50 4.6 3.0 4.6 4.1

100 5.4 3.3 4.9 4.5 150 5.0 3.4 5.0 4.5 200 5.9 3.6 5.0 4.8

CD (P= 0.05) 1.5 0.2 0.2 –

Chidambaranar District, 6.9

Kanyakumari District, 1983 4.1

Minikit - Chidambaranar District, 6.3

National trials - Directorate of 4.3

1987-90 (28)

(14)

1988, 1992 (100)

Rice Research, 1987, 1990 (6)

Overall mean 5.8 Trials (no.) 240 Corresponding mean yield of

Increase over checks (%) ASD19

a Figures in parentheses indicate number of trials.

6.0 5.7 6.3

3.6 (28) (10) (28)

(14)

5.0 5.7 5.1

5.7 6.1 5.7

14.2 8.4 11.9

112 26 119 4.4

5.0

13.2

14

Mutagenic effectiveness, efficiency of gamma rays, and genetic parameters of variation in gamma-irradi- ated upland rice S. S. Mehetre, P. A. Patil, S. K. Lad, C. R. Mahajan, and P. M. Dhumal, Botany Section, College of Agriculture, Kolhapur 416004, Maharashtra, India

We studied mutagenic effectiveness, efficiency of gamma rays, and genetic parameters in the M 1 and M 2 generations of eight upland rice varieties (HS17, Basmati 371, Jaya, Kundalika, R24, Ghansal, JS180, and ACK5) that were irradiated with gamma rays.

M 0 generation. The experiment was laid out in a factorial randomized block. Dry seeds of the varieties were irradiated at 10, 20, 30, 40, and 50 kR.

M 1 generation. Irradiated seeds were sown along with unirradiated control seeds during 1992 dry season (kharif). Germination and survival percentages (Table 1) were recorded at 10 and 30 d after sowing. Obser-

14 IRRN 20:3 (September 1995)

vations were recorded for different characters (Tables 1 and 2).

Analysis of variance showed significant varietal differences and variety × dose interactions, indicating that the gamma rays induced variation for days to flowering, days to maturity, and grain yield/plant. Seeds were collected from the primary panicles of all surviving M 1 plants. Seed fertility was recorded. As the radiation dose increased from 10 to 50 kR, both germination and survival percentage (except at 30 kR) and plant height (except at 30 kR) decreased compared with the control (Table 1). Grain fertility decreased in all the doses compared with the control.

Genetic components were com- puted, except for the control, and irradiated varieties and doses were pooled for different characters. Varia- tion ranged from 1.0% (days to matu- rity) to 20.2% (grains/plants). The greatest range of variation was for grains/plant (20.2%), grain yield/plant (18.0%), and tillers/plant (16.6%), indicating greater scope for genetic improvement in these characters. The

extent of genotypic coefficients of variation (GCV) showed that grain yield/plant (48.3) had the highest GCV followed by 1,000-grain weight (28.2), plant height (24.6), and grains/plant (21.6). High GCV values in these characters proved the existence of high genetic variability in gamma ray-induced varieties.

High broad sense heritability estimates were recorded by all the characters except tillers/plant. High genetic advance was observed for grain yield plant (93.3%), 1,000- grain weight (58.6%), and plant height (48.9%). High heritability along with high genetic advance were most useful in predicting the resultant effect for selecting the best individuals.

Grain yield/plant, 1,000-grain weight, and plant height indicated the presence of additive gene action, which is desirable for the selection process in subsequent generations.

M 2 generation. Seeds were collected from the primary panicles

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IRRN REMINDER Multiple submissions. Normally, only one report for a single experiment will be accepted. Two or more items about the same work submitted at the same time will be returned for merging. Submitting at different times multiple notes from the same experiment is highly inappropriate. Detection will result in the rejection of all submissions on that research.

Seed technology

Table 1. Effect of gamma ray doses on germination, survival, plant height, and sterility in M 1 and on chlorophyll mutation frequency, mutagenic efficiency, and effectiveness of gamma rays in M 2 .

Character Treatment

Control 10 kR 20 kR 30 kR 40 kR 50 kR

Mutation frequency on M 1 plant basis (t)

M 1 damage (%) based on Lethality (L) Injury (I) Sterility (S)

Mutagenic effectiveness (t dose kR × 100)

8.2 5.5 5.0 52.9 42.4

6.1 10.6 22.5 46.8 51.6 2.4 1.2 4.0 33.5 26.6

32.5 40.6 50.1 31.2 59.1

82.6 27.8 16.8 132.3 121.7

Mutagenic efficiency based on Lethality (t/L × 100) 134.4 192.7 51.9 22.2 82.2 Injury (t/l × 100) 341.7 458.3 125.0 157.9 159.4 Sterility (t/S × 100) 12.1 13.5 10.0 169.6 71.4

Chlorophyll mutants M 1 plants scored (no.) 579 508 521 395 34 33 Mutants (no.) 44 30 24 21 31 M 2 plants (no.) - 9312 3496 2449 2243 1560 Segregating families (no.) 0 42 29 20 18 14 Mutants/100 M 1 families (no.) - 8.3 5.6 5.1 52.9 42.4 Mutants/100 M 2 plants (no.) 0.5 0.9 1.0 0.9 2.0 Segregation ratio 0.7 0.1 0.1 0.6 0.9

Spectrum of mutants Albina Xantha Striata

90.9 80.0 100 85.7 86.7 9.1 6.7 14.3 6.7

13.3 6.7

Table 2. Genetic parameters for different characters in M 1 generation of gamma-irradiated upland rice. Maharashtra, India. 1992 kharif.

Days to Plant Tillers/ Grains/ 1,000- Grain Source of variation a height plant plant grain yield/

50% Maturity (cm) (no.) (no.) weight plant flowering (g) (g)

Mean 98.3 126.6 99.1 13.4 115.6 19.9 11.1 Range Minimum 75.0 101.0 69.8 9.0 83.0 11.4 2.9

Maximum 122.0 151.0 143.4 18.3 165.5 28.1 23.3 CV (%) 1.3 1.0 6.8 16.6 20.2 4.2 18.0 Variance (G) 152.3 177.5 596.0 3.0 624.8 31.2 28.9

(P) 153.8 179.1 641.0 7.9 1031.0 31.9 32.1 Coefficient of variation

(G) 12.6 10.5 24.6 13.0 21.6 28.2 48.3 (P) 12.6 10.6 25.5 21.1 27.8 28.5 51.8

Heritability (%) (BS) 99.0 99.1 93.0 38.1 60.6 97.9 87.8 Genetic advance 25.3 27.3 48.5 2.2 40.1 11.6 10.4 GA % mean 25.7 21.6 48.9 16.5 34.7 58.6 93.3

a G = genotypic, P = phenotypic, BS = broad sense.

of all surviving M 1 plants and fertility recorded. The M 2 generation was raised during the 1993 wet season in a compact family block. In the M 2 generation, chlorophyll-deficient mutants albina, xantha, and striata were scored (Table 1). Mutation spectrum and mutation frequency were worked out on a M 1 and M 2 plant basis and mutagenic efficiency and effectiveness were estimated. No definite trend was evident in mutagenic effectiveness and efficiency (Table 1). Effectiveness was lowest (16.8%) at 30 kR and highest (132.3%) at 40 kR. Mutagenic efficiency based on lethality, injury, and sterility percentage was lowest at 30 kR followed by 20 kR (except for injury). The highest efficiency based on lethality (192.7%) was recorded at 20 kR on injury (458.3%) at 30 kR, and on sterility (169.6%) at 40 kR.

proportion of mutation in relation to an undesirable effect, such as lethality, sterility, or injury. All doses in this study were equally potent in produ- cing chlorophyll mutations. The proportionate decrease in mutation rate was much higher than the propor- tionate increase in gamma ray dose. The highest effectiveness was re- corded with 40 kR followed by 50 kR; 30 kR was found least effective. It appears from these results that 40 kR is most ideal for inducing mutation in upland rice.

Mutagenic efficiency indicated the

IRRN 20:3 (September 1995) 15

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We evaluated how roots contribute to grain filling when pruned at different times around heading. High-yielding semidwarf cultivar IR58 was transplanted at the beginning of Jul and Aug 1989 (wet season) at IRRI at a density of 50 hills/m 2 . We applied a total of 150 kg N/ha during the entire growing season. A sickle was used to prune, at night, all of the roots (at the base of the hill) for 20 plants in the middle of a 30-m 2 plot. Each pruned hill was lifted once into the

Crop and resource management

air to ensure the plant was completely separated from the ground and then returned to the same place.

Each treated plant-was tied to a stick inserted into the soil beside the hill. This

Chemical composition and

kept the plants erect and avoided disturbances in the canopy structure from affecting grain filling. Roots were pruned at different times before and after heading with three replications. Grain yield and yield components were determined using conventional methods.

The sudden decrease of surface area for water absorption after pruning caused

digestibility of urea-treated rice straw A. R. Atharuddin, M. Singh, Animal Science Department, College of Agriculture, Govind Ballabh Pant University of Agriculture and Technology (GBPUAT), Pantnagar 263145, Uttar Pradesh, India; and H. P. Singh, Plant Breeding Department, GBPUAT

The straw of seven rice cultivars, grown during 1993 under uniform agronomic conditions, were treated with 3%, 4%, or no urea. Their chemical composition (Table 1), nylon bag organic matter digestibility (NBOMD), and nylon bag neutral detergent fiber digestibility (NBNDFD) were determined (Table 2).

The crude protein (CP) content in untreated Basmati 370, Sita, Cauvery, Pant Dhan 6, and Saket 4 was higher than that in Pusa Basmati and Kasturi (Table 1). The ash content in untreated cultivars

Saket 4, Kasturi, and Pant Dhan 6 was more than the mean value of 151 g/kg dry matter (DM). The neutral detergent fiber (NDF) content in the untreated straw varied from 728 to 778 g/kg DM.

content and decreased organic matter (OM) content of straw. Straw with a higher ash content has a lower energy value. The NDF content increased in cultivars Kasturi and Pusa Basmati. whereas in the others it declined when treated with 3% urea and even more with 4% urea. Treating with 3% urea in- creased the CP content to 119 g/kg DM and with 4% to 136 g/kg DM.

from the cultivars differed significantly (Table 2). There was no significant difference between 3 and 4% urea treat- ments. The improvement in digestibility was greater in straw that had lower digestibility prior to urea treatment.

Treating straw with urea increased ash

The NBOMD and NBNDFD of straw

The relationship between NBNDFD of treated straw (Y) and NBNDFD of untreated straw (x) was Y = 788-1.35 x (r2 = 0.76, n = 7) for 3% urea-treated straw and Y = 681-1.15 x (r2 = 0.75, n = 7) for 4% urea-treated straw. This

emphasized that for increased profitabil- ity, rice straw with higher digestibility may be fed to animals without urea treatment.

Effect of root pruning during ripening on grain filling in rice S. S. Akita, C. K. Kim, and F. T. Parao, IRRI

The positive contribution of roots during the ripening phase to grain filling has been suggested in many reports. However, the discussion seems to have been speculative, with higher yield sometimes being observed where most of the roots are black and necrotic at ripening.

Table 1. Differences in chemical composition of straw of cultivars untreated and treated with urea (g/kg DM). Uttar Pradesh, India. 1993.

CP Ash NDF CP

Untreated 3% urea-treated 4% urea-treated Variety

Ash NDF CP Ash NDF

Basmati 370 129 763 54 142 755 113 136 768 140 Pusa Basmati 148 778 46 154 810 106 157 768 125 Sita 142 728 65 159 768 130 157 748 145 Kasturi 161 768 49 165 810 121 164 753 137 Cauvery 158 763 37 Pant Dhan 6 158

162 731 133 151 751 141 752 68 170 747 109 158 727 130

Saket 4 170 737 70 181 738 121 170 723 136 Mean 151 755 61 162 765 119 156 748 136

Table 2. Nylon bag organic matter digestibility (NBOMD) and nylon bag neutral detergent fiber digestibility (NBNDFD) (72h) of rice straw of different cultivars. Uttar Pradesh, India. 1993.

Variety NBOMD (g/kg) NBNDFD (g/kg)

Unit 3% urea-treated 4% urea-treated Unit 3% urea-treated 4% urea-treated

Sita 547 653 680 439 634 615 Pusa Basmati 573 669 698 496 627 652 Kasturi 570 676 669 519 640 606 Pant Dhan 6 596 684 665 507 620 584 Saket 4 584 658 667 493 576 590 Basmati 370 597 645 651 523 579 605 Cauvery 615 663 670 540 588 604

Mean ± SEM 582 ± 8.9 664 CD (P = .01) 36.2 CD (P = .05) 26.4

672 50.3 ± 34.0 605 608 34.0 24.8

16 IRRN 20:3 (September 1995)

Physiology and plant nutrition

Ninety samples of brown rice from popular cultivar Amaroo were collected from commercial crops in the irrigated rice-growing regions of southern Aus- tralia at the end of the 1991-92 season. The samples were analyzed for total N using the Kjeldahl technique and for P, K, Mg, S, Ca, Mn, Na, Al, Zn, Fe, Cu, and Mo using inductively coupled plasma emission spectroscopy.

The range and mean concentrations of each element were summarized from this study and ranges reported in 22 previous studies from Southeast Asia and the USA (Table 1). Many samples in earlier studies were from crops grown under experimental conditions with various nutrient inputs. Mean concentrations of

K. M. Marr, G. D. Batten, and A. B. Blakeney, New South Wales (NSW) Agriculture, Yanco Agricultural Institute, Yanco, NSW 2703, Australia

Effect of root pruning on grain yield of IR58. IRRI, 1989.

Effect of root pruning at various times during ripening on IR58 grain yield and its components. IRRI, 1989.

Grain yield Filled Grain Treatment Time of grains weight

treatment Actual Corrected c (%) (mg) (DAH) a (g/m 2 ) sd b (g/m 2 )

Control (Jul planting) 337 29 337 64 18.7 Roots pruned –5 190 21 217 47 16.6

0 290 15 273 56 17.3 5 350 40 306 62 17.5

10 320 22 324 64 18.0 Control (Aug planting) 426 31 426 71 21.3 Roots pruned –5 355 25 334 62 19.1

0 350 31 389 66 20.9 5 380 19 408 71

10 406 48 364 67 20.4

15 385 35 398 71 19.3 19.9

a Days after heading. b Standard deviatlon. c Corrected yield assuming spikelet number is the same as in the control plot.

leaves to curl slightly the next day. Little wilting, however, was observed on the second day after pruning and none after that.

Both grain weight and ripening percentage decreased in all the treated plots (see table). The reduction in ripening percentage was higher when roots were pruned earlier, the time during which fertilization and initial grain growth occur—and when plants are most sensitive to water imbalance.

Grain yield was reduced markedly when treated before heading and by about 10% when plants were treated at 5 d after heading and later, despite the complete removal of roots (see figure). Active nutrient uptake and the supply of cytokinins from the roots might have been reduced completely because the roots and root zone were removed. Few new roots formed in the pruned plants.

Neither the nutrient uptake nor the supply of plant hormones from the roots

at this growth stage seem to be the major factor for grain filling. The principal contribution of roots to ripening is to supply sufficient water and to support the top of the plant. Grain yield was not so high in the wet weason, so the required nutrients after heading may have been smaller. Similar experiments during the dry season, when yields are higher, would help further elucidate the contribution of roots to grain filling in rice.

Mineral elements in Australian brown rice

Table 1. Comparison of elemental composition of brown rice from Australia and that reported in previous studies (all values on oven-dry weight basis).

Range Element Australian crops (mean)

This study Previous studies a

Nitrogen Phosphorus Potassium Magnesium Sulfur Calcium

Iron Zinc Sodium Manganese

Aluminum Copper Molybdenum

13.7 3.4 2.8 1.3 1.1 0.1

48 23 19 15 15

5 0.8

(g/kg) 11.0 - 17.0 na

2.8 - 3.6 2.0 - 5.0 2.4 - 3.5 0.7 - 3.3 1.2 - 1.5 0.2 - 1.7 0.9 - 1.3 0.3 - 2.2 0.03 - 0.13 0.1 - 0.6

(mg/kg) 29 - 70 2.3 - 42

0 -221 15 - 24

6 - 78 0.6 - 42 1.6 - 15 0 - 2

20 -395 7 - 33 2.3 - 60 0.3 - 30 1.2 - 7 0.3 - 1.2

a Based on data from 22 independent studies in Southeast Asia and the USA.

all mineral nutrients in Australian grain

Some samples had higher Fe, Al, and Cu greater range of P and Na concentrations. Ca, which was at lower concentrations. Grain in the previous studies also had a

nated by these elements during grinding. generally at higher concentrations, and some of these may have been contami- studies, except for Mn, which was from Southeast Asia and the USA, but fell into the ranges found in earlier concentrations than reported for samples

IRRN 20:3 (September 1995) 17

Elements removed by brown rice grain were compared with the concentrations removed by hulls and straw and the resulting nutrient harvest index (Table 2). In an average 10 t/ha crop of Amaroo at 14% moisture, brown grain removed 103 kg N; straw, 61 kg N; and hulls, 3.7 kg. Brown rice removed most of the P (25 kg in an average 10 t/ha rice crop), while straw removed 4.8 kg and hulls removed 0.4 kg, giving a nutrient harvest index of 83%. The amounts of K, Mg, Ca, Zn, and Mo removed by straw exceeded those removed by brown rice; hulls con- tained low concentrations. The propor- tion of Mn, Fe, Na, and Al removed by grain was lower than or equal to that removed by hulls, with straw removing the greatest proportion. Straw and grain removed similar amounts of Cu and S, with much lower concentrations in hulls.

At the rice mill, hulls are separated from the grain, and most are dumped and burned or converted to livestock feed. Rice straw is usually burned after harvest.

inputs for rice in southern NSW. Incor- N, P, and S are the dominant fertilizer

Table 2. Partitioning of mineral elements by an average Amaroo rice crop yielding 10 t/ha (at 14% moisture). a

Element removed Nutrient Element Total nutrients harvest index

In brown In hulls In straw removed (%) b

grain

(kg/ha) Nitrogen 103 3.7 61 167.7 61 Phosphorus 25 0.4 4.8 30.2 83 Potassium 21 9.0 212 242.0 9 Magnesium 10 0.6 14 24.6 41 Sulfur 8 0.4 5.8 14.2 56 Calcium 0.9 1.4 23 25.3 4 Manganese 0.4 0.6 5.8 6.8 6 Sodium 0.2 0.3 27 27.5 1 Aluminum 0.1 0.1 6.2 6.4 2 Iron 0.1 0.1 2.2 2.4 4

Zinc 140 26 259 425 33 Copper 35 2 35 72 49 Molybdenum 6.0 1.4 25 32.4 19

(g/ha)

~~~

a A rice crop yielding 10 t/ha (at 14% moisture) will have an average of 8.4 t grain/ha, 1.6 t hulls/ha. and 11 t straw/ha. The data were calculated using concentrations of minerals on an oven-dry weight basis and multiplying by 7.5, for grain, 1.4 for hulls, and 9.6 for straw (i.e.. yields at 0% moisture).

b Nutrient harvest index = 100 × Amount in grain

Amount in grain, hulls, and straw

porating residues would enhance the tively small amounts because it is recycling rate of all the nutrients studied. predominantly exported in the brown However, P would be supplied in rela- grain.

Effects of Sesbania rostrata population, time of harvest, and urea application rate on lowland rice production D. Nazemi, M. Alwi, and Mukhlis, Banjarbaru Research Institute for Food Crops, P. O. Box 31, Banjarbaru, South Kalimantan, Indonesia

We studied the effects of plant popula- tion and time of harvest of Sesbania rostrata and urea application rate on lowland rice production.

0.16% N, 2.34% organic C, 16.76% ppm P, C-N ratio of 14.62, and 0.48 meq K/100 g.

plot design with three replications during 1991-92 wet season (Oct-Mar). The main plot treatment was S. rostrata population at two levels: 62,500 and 125,000 plants/ha. S. rostrata harvest time was the treatment in the subplot (45 and 60 days after sowing [DAS]),

Soil was silty clay with a pH of 5.7,

The experiment was laid out in a split

Table 1. Effect of plant population and time of harvest on N concentration (%) in plant tissue of S. rostrata. Maros, Indonesia.

Plant population/ha a

62,500 125,000

45 2.45 a 1.88 b 60 1.47 c 1.86 b

Time of harvest (DAS)

a In a column, means followed by the same letter are not significant at the 5% level by DMRT.

and levels of urea application (0, 23, and 46 kg N/ha) were the sub-subplot treat- ments.

S. rostrata seeds were sown in the plot and thinned based on the plant population treatment. S. rostrata was plowed under in preparation for rice planting according to the treatments. Rice cultivar Cisadane was planted a week later. Half of the urea was applied at planting and the rest at panicle initiation. All of the plots were also treated at planting with triple superphosphate at 26.4 kg P/ha and KCl at 41.5 kg K/ha.

Table 2. Effect of S. rostrata plant population, time of harvest, and rate of urea application on rice panicle number, unfilled grains, and grain yield. Maros, Indonesia.

Panicles/hill Unfilled Grain Treatment (no.) grains/ yield

panicle (no.) (t/ha)

S. rostrata population/ha

62,500 122.47 a 15.95 a 5.3 a 125,000 128.61 a 14.47 a 5.6 a

Time of harvest of S. rostrata (DAS)

45 128.70 a 14.56 a 5.4 a 60 122.38 a 15.86 a 5.5 a

Rate of urea application (kg N/ha)

0 115.32 b 17.08 a 4.4 c 23 126.62 a 15.49 b 5.7 b 46 134.68 a 13.06 c 6.4 a

a In a column, means followed by the same letter are not significant at the 5% level by DMRT.

The greatest N content in S. rostrata plant tissue occurred with 62,500 plants/ ha and harvest at 45 DAS (Table 1).

18 IRRN 20:3 (September 1995)

Fertilizer management

The plant population, time of S. rostrata harvest, and their interaction were not significant. The rate of urea application, however, was significant.

The rice crop responded to urea applica- tion. S. rostrata green manure gave the same rice yield as did 46 kg N/ha as urea. Applying urea at 46 kg N/ha could

decrease the unfilled grains/panicle, increase the panicled/hill, and increase grain yield (Table 2).

Band placement of urea solution increases N use efficiency in transplanted lowland rice P. Devasenapathy and S. P. Palaniappan, Agronomy Department, Tamil Nadu Agricultural University (TNAU), Coimbatore 641003, India

Most of the N fertilizer used in rice in Asia is urea. Rice under flooded systems makes poor use of urea because of losses through ammonia volatilization, denitri- fication, leaching, immobilization, and ammonium fixation. Scientists at IRRI modified a technique where urea solution is placed in bands using a two-row, push- type applicator for transplanted lowland rice. Nitrogen use efficiency (NUE) and rice yield were significantly increased using this technique compared

with point placement of urea super- granules (USG).

We evaluated the IRRI applicator for urea solution (see figure) with broadcast prilled urea (PU), neem-coated urea (NCU), and point placement of USG at Agricultural Research Station (ARS), Aliyar Nagar, Tamil Nadu, during 1992- 93, followed by on-farm testing. The experiments were laid out in randomized complete block design with 11 treatments and three replications using varieties IR50 and ADT36.

All growth and yield parameters increased significantly (see table) with band placement of urea solution at 50 kg N/ha in 2 splits compared with applying 100 kg N/ha as PU in a conventional 3-way split. The grain yield increase with band placement was 10% more for IR50 and 25% more for ADT36 than that

with the 3-way PU split. Higher agro- nomic efficiency and apparent recovery of N were obtained with band placement (see table) of urea solution. At 100 kg N/ ha, the optimal growth and yield param- eters also occurred with band placement.

Effect of treatments on yield components, yield, and N use efficiency in rice. ARS, Tamil Nadu, India. 1992-93.

Yield (t/ha) N use efficiency

Agronomic efficiency Apparent Treatment N rate Panicles/m 2 (no.) Grain Straw (kg grain/kg N) recovery (%)

(kg/ha) IR50 ADT36 IR50 ADT36 IR50 ADT36 IR50 ADT36 IR50 ADT36

Control (No N) 0 460 420 3.6 3.8 3.8 4.7

BC a 50% N as basal 100 510 435 4.6 5.4 4.6 5.6 10.3 15.8 18.3 22.8 + 25% N each at 15 and 35 DAT b as PU c

BP d of urea solution 50 600 603 5.1 6.8 6.1 8.3 30.0 59.1 62.1 95.2 at 1/3 N at 15 DAT + 2/3 N at 35 DAT

BP of urea solution 100 615 625 5.2 7.1 6.2 8.4 16.3 32.4 35.3 55.9 at 1/3 N at 15 DAT + 2/3 N at 35 DAT

Point placement of 100 565 550 4.9 6.6 5.2 7.5 13.5 27.5 25.8 42.9 USG e at 7 DAT

BC 50% N as basal as 100 555 495 4.8 6.6 5.0 8.0 12.3 27.3 22.5 40.9 NCU f + 25% N at 15 DAT as NBU g + 25% N at 35 DAT as PU

LSD (0.05) 12 29 0.3 0.7 0.3 0.9 (Not analyzed statistically)

a BC = broadcasting. b DAT = days after transplanting. c PU = prilled urea. d BP = band placement. e USG = urea supergranules. f NCU = neem-coated urea. g neem-blended urea.

IRRN 20:3 (September 1995) 19

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Urea solution applicator.

15 N studies showed that conventional recovery of 15 N improved with band fertilizer management strategy for application of PU resulted in low recov-

50 kg N/ha in 2 splits is an alternate shown). The plant and total (plant + soil) Band placement of urea solution at 6.5 t/ha yield potential. N appeared to have been lost (data not

in 2 splits compared with applying PU. obtaining higher NUE to achieve about a ery and that the major portion of applied placement of urea solution at 50 kg N/ha reducing N losses, increasing yield, and

Transformation of N in soil affected by different sources and methods of N application in a flooded rice ecosystem R. Das, D. K. Das, and B. Das, Agricultural Chemistry and Soil Science Department, Bidhan Chandra Krishi Viswavidyalaya, Mohanpur, West Bengal 741252, India

We investigated the effect of applying 60 kg N/ha through various sources and methods on rice cultivar IET4094 during 1992-93 rabi (wet) and 1993 kharif (dry) seasons at the university’s farm in Kalyani, West Bengal, India.

0.85% organic C, 26.32 C mol (p + )/kg CEC, and 0.993% total N. The experi- ment was laid out in a randomized block design with three replications. Nitrogen was applied according to the schedule in

Soil was a Haplustalf with a pH of 7.9,

the table. We applied 13.34 kg P/ha and 24.89 kg K/ha basally across the entire area at final puddling.

Two to three 25-d-old rice seedlings were transplanted at 25- × 25-cm spacing. Various fractions of N in the soil, includ- ing ammonium-N, nitrate-N (using 10% NaCl solution as an extractant in the ratio of 1:4, soil:solution), hydrolyzable N (HL-N) (6 N HCl), and nonhydrolyzable- N (NHL-N) (acid-nonhydrolysate) were measured, as well as N losses through ammonia volatilization (trapping evolved NH 3 in 0.1 N H 2 SO 4 ) and leaching (soil solution collected by a piezometer with a porous cup). Rice yield was also re- corded.

Applying (NH 4 ) 2 SO 4 basally main- tained a higher concentration of ammo- nium N in the soil than did most treat- ments during kharif. Soil NO 3 -N values

with prilled urea (PU) as a basal applica- tion and PU as a split were similar in both seasons while green manure (GM) + PU resulted in a generally lower soil nitrate N concentration. Use of neem-coated urea applied basally maintained relatively high amounts of both HL-N and NHL-N.

The cumulative N loss through am- monia volatilization in GM + PU was similar to that of PU (split) during both seasons. The N loss through leaching was generally lower with the PU as a split than with the other treatments during both seasons (see table).

We concluded that applying PU as a split and GM + PU are the most efficient fertilization forms of those studied. They resulted in generally higher yields with relatively low N losses to volatilization and leaching.

Transformation of N in submerged soil in relation to yield of rice cultivar IET4094 a . West Bengal, India. 1992-93.

NH 4 + - N (mg/kg) NO 3

- - N (mg/kg) Hydrolyzable-N (mg/kg) Nonhydrolyzable-N (mg/kg) Treatment

Kharif Rabi Kharif Rabi Kharif Rabi Kharif Rabi

Control 2.58 d 2.12 d 0.60 c 0.62 d 595.75 d 634.00 d 140.00 d 120.25 e Prilled urea (basal) 5.34 a 4.27 b 0.89 a 0.89 a 686.25 bc 703.40 b 150.50 c 157.25 d Prilled urea 4.29 b 3.26 c 0.82 ab 0.89 a 687.50 bc 691.00 bc 164.75 a 168.75 a

(1/2 at transplanting + 1/2 at 30 DAT b )

Neem-coated urea 3.86 c 3.85 bc 0.88 a 0.68 cd 701.75 a 738.50 a 160.45 ab 165.75 ab Sulfur-coated urea 3.68 c 3.77 bc 0.81 ab 0.71 bc 691.30 ab 717.25 b 162.50 a 164.25 abc

Green manure c + 4.50 b 4.42 ab 0.75 b 0.72 bc 673.25 c 681.75 c 165.25 a 163.40 bc (NH 4 ) 2 SO 4 5.71 a 4.99 a 0.88 a 0.78 b 684.50 bc 700.75 bc 156.50 b 160.30 de

prilled urea (1:1)

a ln a column, means followed by the same letter are not significantly different (P=0.05) by DMRT. b DAT = days after transplanting. c Green manure = Sesbania rostrata in kharif and Anabaena azollae in rabi.

Effect of substituting sodium for potassium in a lowland double-rice cropping system Wang Jia-yu and Chen Yi, Soil and Fertilizer Research Institute, Zhejiang Academy of Agricultural Sciences, Hangzhou 310021, China

We evaluated the effect of substituting sodium (common salt) for potassium

20 IRRN 20:3 (September 1995)

(muriate of potash) in indica, japonica, 240.15 kg exchangeable Na/ha; Wen-lin and hybrid rices during 1990-91 in three soils with different K-supplying capaci-

loamy clay (Typic Haplaquept) with pH

N/ha, 16.09 kg Olsen P/ha, 219 kg ex- ties. 5.6, 22.0 g organic C/kg, 270 kg available

Soils (top 0-15 cm) were Yu-yao silty- changeable K/ha, 614 kg nonexchange- clay loam (Typic Haplaquept) with pH able K/ha, and 319.47 kg exchangeable 6.2, 13.3 g organic C/kg, 1.83 g total Na/ha; and Shao-Xing loamy clay (Typic N/kg, 19.3 g K/kg, 263 kg available N/ha, Haplaquept) with pH 5.8, 23.3 g organic 20.50 kg Olsen P/ha, 77 kg exchangeable C/kg, 719 kg available N/ha, 6.18 kg K/ha, 493 kg nonexchangeable K/ha, and Olsen P/ha, 137 kg exchangeable K/ha,

Table 1. Yields of three rice types grown with and without K and Na fertilizers. a Zhejiang, China. 1990-

Yield (t/ha)

Treatment 1990 1991

Late rice season Early rice season Late rice season

Hybrid lndica Japonica Hybrid

692 kg nonexchangeable K/ha, and 79.70 kg exchangeable Na/ha.

The field experiments were laid out in a random block design with three replications. K was applied as muriate of potash at 0 (K 0 ), 62.2 (K 50% ), 83.0

..

(K 66% ), and 124.5 (K 100% ) kg/ha. In 1990, Na was applied as common salt at 0 (K 0 ), 62 (Na 33% ), 93 (Na 50% ), and 186 (Na 100% ) kg NaCl/ha (Na was chemically equivalent to K); in 1991, it was applied as 83.3 (Na 33% ), 250 (Na 100% ), and 375 (Na 150% ) kg NaCl/ha (NaCl rates were equal to KCl rates). The crop also received 150 kg N/ha as urea and 19.8 kg P/ha as single superphosphate. Plant samples at full heading and ripening stages were analyzed to determine contents of N (Kjeldahl method), K (H 2 SO 4 -H 2 O 2 digestion-ICP method), Na (1 N HCl extraction-ICP method), SiO 2 (H 2 SO 4 -H 2 O 2 digestion-weighting method), and Cl (Mohr method).

Applying Na up to 250 kg NaCl/ha (Na 100% ) significantly increased grain yield by 4-8% compared with that of the

K 0 (control) 6.7 a 6.0 a 6.7 a 8.7 a K 100% 7.9 e 6.6 d Na 100% 7.0 b 6.3 bc Na 150% 6.1 a 6.8 a K 50% Na 50% 7.4 c 6.4 c

7.6 b 10.2 c 7.0 a 9.4 b

9.4 b 7.3 b 9.9 c 7.4 b 10.0 c K 66% Na 33% 7.6 d 6.1 b

CV (%) 6.1 3.5 4.9 5.9

a ln a column, means followed by the same letters are not significantly different at the 5% level by DMRT. The substitution of Na for K was chemically equivalent in 1990 and equal to the salt rates of NaCl to KCl in 1991.

no K and Na application control. produced with Na application than in The combined application of Na and the control (Table 2). K (K 50% and Na 50% , and K 66% and Applying NaCl did not markedly Na 50% plots) gave almost the same

oversupplying NaCl (Na 150% plot in grain yields as the K 100% plot in the increase rice plants’ uptake of K, and

perhaps because more dry matter was uptake. Na, and Cl contents in rice plants, antagonistic effect between Na and K ing NaCl usually increased N, SiO 2 , rice plants’ K uptake, showing the 1991 late rice crop (Table 1). Apply- 1991 early rice crop) obviously reduced

Table 2. Nutrient uptake of rice a as influenced by applying common salt. b Zhejiang, China. 1990-91.

Nutrient uptake (kg/ha)

N K SiO 2 Na CI Treatment

G S T G S T G S T G S T G S T

1990 late rice season Hybrid rice

K 0 Na 100%

61.4 70.4 131.7 17.9 54.5 72.3 173.4 582.8 756.2 0.5 15.8 16.3 8.3 48.0 56.2 70.5 78.8 149.3 23.0 52.5 75.5 216.2 658.7 874.8 0.6 26.6 27.3 10.1 62.1 72.2

1991 early rice season lndica rice

K 0 92.0 41.3 133.2 28.4 79.2 107.6 176.0 644.6 820.5 0.5 5.6 6.1 8.8 36.5 45.3

Na 100% 99.0 34.8 133.8 28.1 68.1 96.2 236.3 668.3 904.5 0.5 8.5 9.0 10.2 35.5 45.7

Na 150% 89.9 33.3 123.2 25.7 67.2 92.9 117.9 518.0 695.9 0.4 8.0 8.4 11.5 29.3 40.8

a G = grain, S = straw, T = total rice plant. b In 1990 experiment, Na 100% = 186 kg NaCl/ha. In 1991 experiment, Na 100% = 250 kg NaCl/ha, Na 150% = 375 kg NaCl/ha.

Algicides in Azolla lowland rice in parts of Asia and the

germplasm management South Pacific. Azolla cultures are commonly maintained in the vegetative

E. Hall and W. J. Zimmerman, Natural Sciences Department, University of

phase in germplasm collections. Free-

Michigan-Dearborn, Dearborn, Michigan living cyanobacteria and microalgae

48128, USA within the growth medium of the open cultures may contaminate these

The aquatic fern Azolla is cultivated as a accessions. Valuable plants may die green manure for application with from frequent infestations if they are not

periodically washed and transferred. The presence of the Anabaena azollae symbiont complicates eradicating these phototropic contaminants with biocides.

maintenance problem, six Azolla species were tested for tolerance for two Cu +2 - based algicides: copper sulfate and chelated copper (Cutrine-PlusR, Applied

As a possible solution to this

IRRN 20:3 (September 1995) 21

Fertilizer management — organic sources

91.

Biochemists, Inc., Milwaukee, WI, USA). Accessions came from A. micro- phylla (MI-NE KKN3), A. mexicana (ME-UCD 62), A. caroliniana (CA 3007), A. filiculoides (FI 1514), A. pinnata var. imbricata (PI 0509), and A. nicolata (NI 5001).

Several Cu+2 concentrations from 0.1 to > 2.5 ppm of each algicide were added to N-free BG- 11 growth medium. Each Azolla species was tested for viability and growth. Duplicate 14-d experiments were completed in a laboratory under moderate photon flux densities (100-200 µmol/m 2 per s) and temperatures (22-25 °C). Glass beakers (400 ml) containing 250 ml of BG-11 were inoculated with 0.5 g fresh weight (FW) of Azolla. Evaporated water was re- placed as needed. Growth was measured by changes in total chlorophyll and FW.

The effectiveness of both algicides in decreasing the presence of microbial contaminants in growth media was visually apparent at concentrations of > 0.5 ppm Cu+2 Biomass accumulation in all Azolla species was slightly reduced at 0.5 ppm (see figure) and was inhibited more at higher concentrations. Viability thresholds of each species were deter- mined to be near 1.0 ppm, where chlorosis of fronds and decreased relative growth rates of FW were observed (see table). The source of Cu+2 was not a differentiating factor in the results of most growth trials. Accessions did not survive doses of > 2.5 ppm of either

Combined average data for Azolla growth and viability.

algicide. Conversely, applications of stable, signifying a healthy symbiont, and 0.1 ppm produced no visible symptoms the presence of contaminant populations is of stress, and little difference in growth. diminished. A side effect, however, is between the treated and control samples stunted root development. This phenom- in any species (see table). enon was not observed to be harmful to

Amendments of 0.5 ppm Cu +2 to Azolla viability in these experiments and growth medium as either copper sulfate may prove to facilitate maintenance. or a chelated form were concluded to be Freely hanging roots often become tangled, potentially useful if incorporated into the thus complicating cleaning. They are also maintenance programs of Azolla microsites for protists, nematodes, and germplasm collections. Plant growth is phototrophic contaminants.

Growth of six Azolla species in N-free growth medium amended with copper-based algicide. a

1.0 ppm Cu +2 0.5 ppm Cu +2 0.1 ppm Cu +2 No added CU +2

Azolla species Total Chl b FW c Total Chl FW Total Chl FW Total Chl FW

(µmg) (g) (µg) (g) (µg) (g) (µg) (g)

A. microphylla 258.90 0.88 861.08 1.76 786.77 1.86 1043.88 2.15 (3.27) (0.04) (12.34) (0.07) (99.24) (0.14) (74.95) (0.09)

A. nicolata 389.88 0.88 712.79 1.60 818.03 1.54 889.47 1.74 (42.89) (0.06) (34.47) (0.00) (41.09) (0.04) (43.12) (0.07)

A. pinnata var. imbricata 681.25 1.25 989.71 1.99 1258.30 2.02 1269.65 2.08 (213.56) (0.19) (26.39) (0.02) (76.04) (0.05) (48.09) (0.06)

A. caroliniana 227.92 0.73 858.53 1.77 962.71 2.07 1018.42 2.19

A. mexicana 192.13 0.79 704.33 1.62 1086.43 2.26 978.48 2.14 (13.62) (0.02) (114.49) (0.13) (129.46) (0.11) (77.03) (0.09)

A. filiculoides 291.07 0.92 666.78 1.44 877.68 1.67 879.80 1.82 (27.60) (0.03) (132.10) (0.17) (125.62) (0.12) (46.25) (0.06)

(9.34) (0.04) (13.03) (0.03) (111.79) (0.17) (75.35) (0.11)

a Combined data of both chelated copper and copper sulfate; numbers in parentheses represent standard errors of means. b Chl = chlorophyll. c FW = fresh weight.

22 IRRN 20:3 (September 1995)

Occurrence of teleomorph of (RSc). We collected black fungal

rice scab, in India

pathogenicity. Fusarium graminearum fruiting bodies from completely rotted booting with 5-d-old culture to prove

Schwabe, the causal agent of tissue of the uppermost leaf sheaths We compared the conidial state enclosing the panicles of rice variety Leima Phou during November 1993 in pure cultures of F. graminearum and two

(anamorph) of the fungus with those of

N. lboton Singh and R. K. Tombisana Devi, Botany and Plant Pathology Department, College of Agriculture, Central Agricultural University, Iroisemba, lmphal 795001, Manipur, lndia

Fusarium graminearum Schwabe is one of the causal organisms of rice scab

research plots of the College of Agricul- ture and in nearby farmers’ fields (Fig. 1).

Fruiting bodies were separated from the rotted tissues, purified, and placed on potato dextrose agar to isolate the fungus. Leima Phou was inoculated at

1. Black colored fruiting bodies of Gibberella zeae on rotted portions of a flagleaf sheath.

other causal agents of RSc, F. moniliforme and F. avenaceum. We also studied the morphological characteristics of the perfect state (teleomorph) of the fungus from the diseased specimens.

The perithecia are superficial, spherical to ovoid, dark brown, and mostly 60-200 × 60-192 µm in dimen- sion. They have cylindrical to club- shaped asci, often slightly curved with a short stripe, and a thin undifferentiated wall measuring 60-83 × 4-12 µm. They have 8 distichous to obliquely mono- stichous ascospores. Ascospores are hyaline, curved fusoid with rounded ends, with 2-3 septate, measuring 19-28 × 5-8 µm (Fig. 2).

The perithecial characteristics of the fungus were identified as Gibberella zeae (Schw.) Petch, the teleomorph of F. graminearurn, which has been reported in the literature on a range of gramineous hosts except rice. The occurrence of the teleomorph of F. graminearurn on rice constitutes the first report from India.

Rice hull ash applied to soil reduces leaf blast incidence C. T. Kumbhar and A. G. Nevase, Agricultural Research Station (ARS), Mahatma Phule Agricultural University Lonawala, 410401 Maharashtra, India; and N. K. Savant, International Fertilizer Development Center, Muscle Shoals, Alabama 35662, USA

Leaf blast caused by Pyricularia oryzae Cav. is a serious disease that can severely damage rice at the seedling stage. We investigated the effect of applying rice hull ash (RHA) to the soil in the seedbed on the incidence of leaf blast. The pot experiments were conducted in a greenhouse at ARS during the 1992 and 1993 wet seasons. Black to gray RHA (81.0% SiO 2 ), prepared by burning rice hulls in an open field, was amorphous

2. Asci of G. zeae outside the perithecium. The ascospores are diagonally oriented in each ascus. with no peaks observed in X-ray

IRRN 20:3 (September 1995) 23

2. Effect of rice hull ash applied to soil on leaf blast incidence in rice seedlings. a

1992-93.

a scores based on Standard evaluation system for rice, 0-9 scale. b DAS = d after sowing.

severity of the infection for both culti- vars. For Early Kolapi-70, the RHA at 1.0 and 2.0 kg/m 2 was effective in controlling the disease at 30 DAS, with the seedlings still moderately resistant up to 45 DAS. For Chimansal 39, the seedlings treated with 1.0 and 2.0 kg RHA/m 2 were resist- ant to blast up to 45 DAS. The increased resistance to blast could be attributed to the increase in the SiO2 content of the seedlings (Fig. 2) from the RHA.

black or gray RHA at 1.0 kg/m 2 to the seedbed can protect rice seedlings from leaf blast damage without using fungi-

The results demonstrate that applying

evaluation system for rice (0-9 scale) at 30 cides, thus helping to protect the environ- and 45 DAS. ment. (Note: The use of rice hull-fired

Applying RHA to the soil in the stoves, such as the FAO-promoted seedbed had a marked prophylactic effect Vietnamese Lò Trâú or the IRRI-designed on rice blast in the seedlings compared Ipa-Qalan cookstoves, by farmers for with the control where no RHA was domestic cooking can facilitate collection applied (Fig. 2). RHA greatly reduced the of RHA.)

1. X-ray diffraction pattern of rice hull ash.

diffraction (XRD) patterns (Fig. 1). Only the amorphous form of SiO 2 is absorbed by plants. Crystalline SiO 2 , from white or pink RHA, is not available for plant uptake.

The RHA was applied to a sandy loam soil on an area basis at 0.0, 0.5, 1.0, and 2.0 kg/m 2 . The treatments were replicated six times on two highly susceptible rice cultivars: Early Kolapi 70 and Chimansal 39. A conidial suspension of P. oryzae was sprayed on the seedlings at night 15 d after sowing (DAS). The plants’ reactions to blast were scored using the Standard

Effect of some fungicides on Metarrhizium sp. Sorok: an entomopathogen on insect pests of rice and pulses G. Mikunthan, Agricultural Biology Depart- ment, Faculty of Agriculture, University of Jaffna, Sri Lanka

A naturally existing entomophagous fungus, Metarrhizium sp. Sorok, was identified in adult brown planthopper (BPH) Nilaparvata lugens (Stål), and larvae of armyworm Spodoptera litura (F). The insects are important pests of rice and pulses, respectively. Legumes are predominantly cultivated after rice in the dry zone of Sri Lanka. It was ob- served that the fungicides frequently used to control diseases in a rice - pulse cropping system influenced the develop- ment of Metarrhizium sp. A bioassay method was used to understand the effects of commonly used fungicides on the development of Metarrhizium sp.

Effect of fungicide treatments on Metarrhizium sp. a

Treatment

Control 0 7.2 fgh

Propineb 100 7.7 bcd

Concentration (ppm) Mycelial growth of Metarrhizium sp. (cm) b

1000 500 7.3 efg

7.3 efg

Mancozeb 100 7.3 efg 7.4 def 500

1000 6.6 ijk

Cuprous oxide 100 500

7.7 bcd 7.7 bcd

1000 7.8 abc

Metalaxyl and mancozeb 100 500

7.7 bcd 7.6 cde

1000 7.3 efg

Benomyl 100 0.6 n 0.6 n 0.6 n

500 1000

Edifenphos 100 6.8 500 5.4

ij I

1000 4.1 m

Sulfur 100 8.0 ab 500 7.0

1000 6.6 ghi

ijk

Captan 100 500

8.1 a 7.8 abc

1000 7.7 bcd a Mean of four replications. b In a column, means followed by common letters are not significantly different at 5% by DMRT.

24 IRRN 20:3 (September 1995)

eggs were laid on rice and 52 other plant species in the 16 botanical families tested.

Egg survival was determined by splitting the stems of the plants to recover the eggs and incubating them in petri dishes on moist filter paper saturated with a fungistatic agent (M-tegosept). Egg survival was greatest on R. cochin- chinensis (96.9%) followed by P. maxi- mum (95.4%), maize (94.7%), and L. chinensis (89.7%). None of the eggs laid on L. octovalvis were viable.

Nymph adaptation showed highest survival (94.1 %) on maize followed by 88.6% on R. cochinchinensis, 81.7% on P. maximum, and 71.9% on L. chinensis. Developmental periods for nymphs on

the planthopper on rice, maize, and 56 common ricefield weeds as potential hosts.

The test plants were dug in the vegetative stage from the IRRI farm and transplanted into pots. The plants were allowed to recover for 3 wk. A mating pair of P. maidis was introduced onto a potted plant enclosed with a 10-cm- diameter × 72-cm-high mylar cylinder cage pushed into the soil. The eggs laid were counted by dissecting the plants after 5 d of caging.

More eggs per female (72.7) were laid on maize than on Rottboellia cochin- chinensis (56.9), Panicum maximum (19.6), Leptochloa chinensis (15.2), or Ludwigia octovalvis (2.2) (Table 1). No

Evaluation of rice, maize, and 56 ricefield weeds as hosts of planthopper Peregrinus maidis (Ashmead)

Fungicides propineb, mancozeb, cuprous oxide, a metalaxyl and mancozeb mixture, benomyl, edifenphos, sulfur, and captan were studied. For each, solutions containing 100, 500, and 1,000 ppm were prepared using distilled water. Agar media were prepared using 1 ml of each fungicide solution for every 20 ml of potato dextrose agar and poured into sterile petri dishes. The control sample (0 ppm) was made by adding 1 ml of dis- tilled water. Metarrhizium sp. grown in pure cultures were transferred aseptically as agar slugs (6-mm-diameter disks) to the center of each petri dish, replicated four

times in a completely randomized design. Petri dishes were then incubated in the laboratory at 29 ± 2 °C and 76-89% relative humidity. Colony diameters were measured from incubation at 24 h intervals for 5 d. Data were analyzed using Duncan’s multiple range test (see table).

benomyl was most toxic to Metarrhizium sp., limiting growth to 0.6 cm even at the lowest concentration (100 ppm) (see table). Edifenphos inhibited mycelial growth to a lesser degree, while the re- maining six fungicides enhanced

Of the eight fungicides tested,

mycelial growth at some or all concentra- tions.

This experiment clearly indicates the benefits of applying sulfur, captan, cuprous oxide, a metalaxyl and mancozeb mixture, mancozeb, and propineb at low concentrations because they enhanced the development of this entomophagous fungus. Application of benomyl should be limited because of its powerful fungicidal action on Metarrhizium sp. In an inte- grated pest management program for a rice - pulse cropping system, fungicides that minimally affect entomopathogenic fungi should be selected.

J. L. A. Catindig and A. T. Barrion, IRRI; J. A. Litsinger, 1365 Jacobs Place, Dixon CA 95620, USA

In the Philippines, rice is reportedly a host of the maize planthopper Peregrinus maidis, a vector of several viral diseases in the tropics. We compared the oviposition, egg survival (the number of eggs developing to first instar divided by the total eggs laid multiplied by 100), and nymphal survival (the number of first instar developing to last instar divided by the total first instar multipled by 100) of

Table 1. Host plant range of P. maidis. IRRI, 1990-93. a

Host

Poaceae Maize Rottboellia cochinchinensis Panicum maximum Leptochloa chinensis Onagraceae Ludwigia octovalvis

Survival (%) Nymph development Eggs laid period (d) b

(no./female) Egg Nymph

72.7 ± 8.7 a 94.7 ± 3.5 b 94.1 ± 3.8 a 17.2 ± 0.4 a 56.9 ± 5.4 b 96.9 ± 3.2 a 88.6 ± 8.4 b 127.5 ± 0.5 b 19.6 ± 2.2 c 95.4 ± 5.2 b 81.7 ± 8.4 c 17.6 ± 0.9 b 15.2 ± 2.5 d 89.7 ± 8.0 c 71.9 ± 15.7 d 17.6 ± 0.7 b

2.2 ± 0.8 e

Fecundity of surviving females

(no. eggs laid) c

65.3 ± 2.8 a 52.3 ± 3.3 b 17.3 ± 3.8 c

8.7 ± 1.6 d

aValues are means ± standard errors at 95% confidence level. Av of 10 replications. In a column, means followed by a common letter are not significantly different (P < 0.05) by LSD statistical test. Nonhosts: Aizoaceae — Trianthema portulacastrum; Amaranthaceae — Alternanthera sessilis, Amaranthus spinosus; Asteraceae — Ageratum conyzoides, Eclipta prostrata, Synedrella nodiflora, Tridax procumbens, Vernonia cinerea; Capparaceae — Cleome rutidosperma; Commelinaceae — Commelina benghalensis, C. diffusa, Murdannia nudiflora; Convolvulaceae — lpomoea aquatica, I. triloba; Cyperaceae — Cyperus brevifolfus, C. difformis, C. haplan, C. iria, C. kyllingia, C. rotundus, Fimbristylis millacea; Euphorbiaceae — Euphorbia hirta; Fabaceae — Calopogonium mucunoides, Mimosa pudica, Sesbania sesban; Poaceae — Brachiaria distachya, B. mutica, Chloris barbata, Chrysopogon aciculatus, Cynodon dactylon, Dactyloctenium aegyptium, Digitaria ciliaris, D. setigera, Echinochloa colona, E. crus-galli ssp. hispidula, E. glabrescens, Eleusine indica, Eriochloa procera, lmperata cylindrica, lschaemum rugosum, Leersia hexandra, Oryza sativa, Panicum repens, Paspalidium flavidum, Paspalum conjugatum, P. dlstichum, P. scrobiculatum; Pontederiaceae — Monochoria vaginalis; Portulacaceae — Portulaca oleraceae: Rubiaceae — Borreria ocymoides, Hedyotis biflora; Scrophularlaceae — Lindernia anagallis; Sphenocleaceae — Sphenoclea zeylanica. b n = 10. c n = 10.

IRRN 20:3 (September 1995) 25

the four hosts ranged from 17.2 to 17.6 d. Fecundities of the females reared on each host were very similar to those initially tested as ovipositional hosts from adults reared in the stock culture on maize.

The incubation period of the egg stage on maize was 5.2 d (Table 2). Each of the five nymphal stadia lasted 3.2 to 3.8 d for a total developmental period of the egg and nymph of 22.4 d. The adult female lived 11.0 d while the male lived 10.1 d.

Rice is neither an ovipositional nor a developmental host of P. maidis, which develops best on maize, R. cochinchinen- sis, P. maximum, and L. chinensis.

Table 2. Life history of P. maidis on maize in a greenhouse. IRRI, 1993.

X ± sd

Egg incubation period (d) 5.2 ± 0.8

Nymphal stadium (d) I II III IV V

3.8 ± 0.8 3.6 ± 1.0 3.3 ± 1.0 3.2 ± 0.6 3.3 ± 0.5

Total immature developmental period (d) 22.4 ± 4.8

Adult longevity (d) Male Female

10.1 ± 3.3 11.0 ± 4.8

Biology of the maize orange leafhopper Cicadulina bipunctata (Melichar) on rice and maize J. L. A. Catindig and A. T. Barrion, IRRI; J. A. Litsinger, 1365 Jacobs Place, Dixon CA 95620, USA

The leafhopper Cicadulina bipunctata is a vector of rice leaf gall in the Philippines. Plant injury is by removal of leaf tissue and leaf galls. Excessive feeding causes leaf yellowing or wilting. Its biology was compared on rice and maize in a greenhouse with an average ambient temperature of 27.6 ± 1.2 °C and relative humidity of 69.4 ± 4.3%.

Newly emerged adult pairs were obtained from a stock culture and released to oviposit on rice and maize. The mean incubation period was determined from eggs extracted from plants and held on moist filter paper in petri dishes with 1% M-tegosept, a fungistatic agent. Ten neonate nymphs were individually reared on a one-tillered host plant covered with a 6- × 25-cm cylindrical mylar cage with side and top nylon mesh (5 mm) vents. The duration of each instar was recorded from daily observations.

Life history of C. bipunctata a on rice and maize in a greenhouse. IRRI, 1993.

Rice Maize Difference b

x ± sd x ± sd t-test

Egg incubation period (d) 7.5 ± 0.8 7.5 ± 0.5 ns

Nymphal stadium (d) I II II IV V

3.0 ± 0.0 2.5 ± 0.5 3.3 ± 0.8 2.3 ± 0.6 3.5 ± 0.5 2.0 ± 0.0 3.4 ± 1.0 2.1 ± 0.3 3.3 ± 0.9 2.2 ± 0.4

Nymph developmental period (d) 16.5 ± 3.2 11.1 ± 1.8

Adult longevity Male Female

11.0 ± 1.6 11.4 ± 0.8 ns 14.5 ± 0.9 13.9 ± 1.1 ns

Eggs laid (no./female) 15.3 ± 4.5 729.0 ± 34.4 **

a n = 10. b ns = not significant (P > 0.05). ** = highly significant (P < 0.01).

Incubation period of whitish elongated from first to fifth instar. Shorter nymph eggs, normally laid singly on rice and development indicates greater fitness on a maize, averaged 7.5 d on both (see table). plant host. Adult longevity was equal on

Neonate nymphs disperse in search of rice and maize. On both the host plants, food, becoming increasingly mobile with however, females lived longer (14 d) than age. The nymphs passed five nymphal the males (11 d). Fecundity averaged instars in 16.5 d on rice, but the period

observed in 2.5, 2.3, 2.0, 2.1, and 2.2 d period and greater fecundity, but rice can while on maize, five nymphal stadia were to rice because of its shorter nymphal occurred in 3.0, 3.3, 3.5, 3.4, and 3.3 d, bipunctata is more adapted to maize than (11.1 d). On rice, nymphal moltings

We conclude that in the laboratory, C. was significantly shorter on maize 15.3 eggs on rice and 729 eggs on maize.

sustain its development.

26 IRRN 20:3 (September 1995)

IRRN REMINDER News about research collaboration Items accepted: general news and current update items about consortia, networks, country and regional projects, conference and workshop recommenda- tions, and other information of interest to IRRI readers, such as new projects, work plans, memorandums of understanding, and highlights of collaborative projects in progress.

Items not accepted: routine housekeep- ing information for collaborative groups, research notes, new variety releases, work and trip reports, and personal items.

**

Suitability of ricefield plants to planthopper Nisia carolinensis Fennah J. L. A. Catindig and A. T. Barrion, IRRI; J. A. Litsinger, 1365 Jacobs Place, Dixon CA 95620, USA

Nisia carolinensis (= atrovenosa Lethiery), a meenoplid planthopper common in ricefield habitats, is recorded as a minor pest of rice. We studied its ovipositional preference, survival, and developmental biology on rice and 58 ricefield plants common in the Philippines that comprise 16 botanical families: Poaceae (26), Cyperaceae (7), Asteraceae (5), Commelinaceae (3), Fabaceae (3), Amaranthaceae (2), Convolvulaceae (2), Rubiaceae (2), and one each of Aizoaceae, Capparaceae, Euphorbiaceae, Onagraceae, Pontederiaceae, Portulacaceae, Scrophulariaceae, and Sphenocleaceae.

Individual plants in the vegetative stage, collected from the IRRI farm, were potted and enclosed in 10- × 72-cm cylinder mylar film cages with top and side mesh vents pushed into the soil. A mating pair of adult hoppers from a stock culture on purple nutsedge Cyperus rotundus L. was allowed to oviposit and its progeny developed on each potential host (10 pairs per plant species) in the greenhouse. Host suitability was based on the following parameters: egg production per female, egg survival (the number of eggs developing to first instar divided by the total number of eggs laid multiplied by l00), nymphal survival (the number of first instar developing to last instar divided by the total number of first instar multiplied by 100), and nymph development time.

After five days, N. carolinensis females oviposited on only 16 plants from six families: Poaceae (6), Cyperaceae (5), Asteraceae (2), and one each on Commelinaceae, Euphorbiaceae, and Fabaceae. The best ovipositional hosts (no. eggs/female) were C. rotundus L. (44.4) and C. difformis L. (28.1) (Table 1). Seven or less eggs per female were laid on the 14 other ricefield plants: Cyperus iria L. (7.0), C. brevifolius

Table 1. Host plant range of N. carolinensis in a greenhouse. a IRRI, 1990-93.

Host Eggs laid Egg survival Nymphal Nymph Fecundity of

(no./female) (%) survival (%) developmental surviving period (d) b females

(no. eggs laid) c

Cyperaceae Cyperus rotundus 44.4 ± 4.7 a 96.2 ± 4.2 a 83.6 ± 6.8 a 17.0 ± 0.8 a 52.1 ± 3.7 a C. difformis 28.1 ± 5.6 b 91.5 ± 9.8 b 77.6 ± 10.1 b 17.2 ± 1.5 b 30.0 ± 4.4 b

CV (%) 13.30 4.30 5.73 2.09 5.71 LSD (0.05) 0.13 0.16 0.18 0.02 0.04

a Values are means ± standard errors at 95% confidence level. Av of 10 replications. In a column, means followed by a common letter are not significantly different (P < 0.05) by LSD statistical test. Nonhosts: Aizoaceae — Trianthema portulacastrum L.; Amaranthaceae — Alternanthera sessilis (L.) R. Br. ex roem. & Schult.. Amaranthus spinosus L.; Asteraceae — Ageratum conyzoides L., Eclipta prostrata (L.) L., Tridax procumbens L.; Capparaceae — Cleome rutidosperma DC.; Commelinaceae — Commelina benghalensis L., C. diffusa Burm. f.; Convolvulaceae — lpomoea aquatica Forssk., I. triloba L.; Cyperaceae — F. miliacea (L.) Vahl; Fabaceae — Mimosa pudica L., Sesbania sesban (L.) Merr; Onagraceae — Ludwigia octovalvis (Jacq.) Raven; Poaceae — Brachiaria distachya (L.) Stapf, B. mutica (Forssk.) Stapf, Chloris barbata Sw., Cynodon dactylon (L.) Pers., Dactyloctenium aegyptium (L.) Willd., Digitaria ciliaris (Retz.) Koel., D. setigera Roth ex Roem. & Schult., Echinochloa colona (L.) Link, E. crus-galli (L.) P. Beauv. ssp. hispidula (Retz.) Honda, E. glabrescens Munro ex Hook f., Eriochloa procera (Retz.) C. E. Hubb., Leersia hexandra Sw., Leptochloa chinensis (L.) Nees, Oryza sativa L., Panicum maximum Jacq., P. repens L., Paspalum distichum L.. P. scrobiculatum L., Zea mays L.; Pontederiaceae — Portulaca oleracea L.; Rublaceae — Borreria ocymoides (Burm. f.) DC., Hedyotis racemosa Lam.; Scrophulariaceae — Lindernia anagallis (Burm. f.) Pennell; and Sphenocleaceae — Sphenoclea zeylanica Gaertn. b n = 10. c n = 10.

Table 2. Life history of N. carolinensis on C. Among the 16 ovipositional hosts, rotundus in a greenhouse. IRRI, 1993. only two Cyperaceae species allowed egg

x ± sd and nymphal survival: C. rotundus (96.2% and 83.6%) and C. difformis (91.5% and 77.6%) (Table 1). Nymph Egg incubation period (d) 5.4 ± 0.5

Nymphal stadium (d) development time was similar between C. I 3.4 ± 0.5 rotundus (17.0 d) and C. difformis (17.2

IV 3.1 ± 0.5 and 30.0 eggs each, respectively. V 3.7 ± 0.9 rotundus and C. difformis averaged 52.1

II 3.5 ± 0.6 III 3.3 ± 0.5 d). Female fecundity reared on C.

Egg-nymph development period (d) 22.4 ± 3.4 On C. rotundus, nymphs hatched after 5.4 d (Table 2). The planthopper passed

Adult longevity (d) Male 9.4 ± 1.3 Female 12.1 ± 2.0

through five nymphal stadia lasting 3-4 d each. The developmental period from oviposition to last nymphal stadium

IRRN 20:3 (September 1995) 27

(Rottb.) Hassk. (6.9), C. kyllingia Endl. (1.2) (Cyperaceae); Vernonia cenerea (L.) Less. (3.2), Synedrella nodiflora (L.) Gaertn. (1.4), (Asteraceae); Chrysopogon aciculatus (Retz.) Trin (2.5), Eleusine indica (L.) Gaertn. (2.4), Paspalum conjugatum Berg. (0.8), Iscahaemum rugosum Salisb. (0.8), Rottboellia cochinchinensis (Lour.) W.D. (0.5), Imperata cylindrica (L.) Raeuschel (0.3) (Poaceae); Murdannia nudiflora (L.) Brenan (0.7) (Commelinaceae); Euphorbia hirta L. (1.4) (Euphorbiaceae); and Calopogonium mucunoides Desv. (1.2) (Fabaceae).

avearage 22.4 d. Adult feamles usually emerged ahead of the males, and females lived longer (12.1 d) than males (9.4).

The only hosts of N. carolinensis were sedges, thus we could not confirm reports that rice was a host of this ricefield planthopper.

Feasibility of hybridization between Nephotettix virescens (Distant) and Nephotettix nigropictus (Motsch.) in rice A. Ghosh and N. V. Krishnaiah, Directorate of Rice Research, Rajendranagar, Hyderabad 500030, Andhra Pradesh, India

To test the feasibility of interspecific hybridization between Nephotettix virescens (Distant) and Nephotettix nigropictus (Motsch.), green (NVGR) and blue (NVBR) forms of N. virescens were separately reared on TN1 rice plants (R) for six generations. N. nigropictus individuals, originally collected from ricefield bunds, were reared and maintained separately on grass Echinochloa colona (E) (NNGE) and on rice cultivar TN1 (NNGR) for five generations. Attempts were made to hybridize blue (NVBRF) and green (NVGRF) females of N. virescens with green males of N. nigropictus reared on E. colona (NNGEM) separately. Crosses of blue females of N. virescens (NVBRF) and N. nigropictus green males raised on TN1 (NNGRM) were also made. Intraspecific crosses between NVBRF and green N. virescens males (NVGRM) were made to estimate the normal fertility levels between the two forms. Studies were replicated four times. The ability of NNGE, NNGR, NVBR, NVGR, and the interspecific hybrids of NVBRF/

Rice off-types in Central Luzon, Philippines F. F. Fajardo and K. Moody, IRRl

A ricefield survey was conducted every 100 m along the main roads within 10-km radii of PhilRice, Muñoz, Nueva Ecija; Guimba, Nueva Ecija; and Victoria, Tarlac, Philippines, for off-types from 4 Oct to 4 Nov 1993. We surveyed 1,917 fields. Mature panicles were collected from 44 fields and brought to IRRI for further characterization.

The off-types were taller than the cultivated varieties, had different grain

28 IRRN 20:3 (September 1995)

Table 1. Interspecific crosses between N. virescens and N. nigropictus a .

Eggs Nymphs Nymphs Survival Cross b Fertile Infertile emerged surviving to up to adult

(no.) (no.) (no.) adult stage (no.) stage (%)

NVBRF/NNGEM NVGRF/NNGEM NVBRF/NNGRM NVBRM/NNGRF NVBRF/NVGRM

2.2 ± 0.6 3.6 ± 0.7

c

26.0 ± 2.12 54.0 ± 3.81

0.0 0.0

56.5 ± 4.62 48.75 ± 3.54

0.0 0.0

26.5 ± 3.72 20.0 ± 1.66 46.4 ± 14.9

0.0 0.0

46.25 ± 3.25 40.5 ± 1.81

a Mean ± SEM of 4 replications. b NVBRF = N. virescens blue female on rice, NNGEM = N. nigropictus green male on E. colona, NVGRF = N. virescens green female on rice. NNGRM = N. nigropictus green male on rice, NVBRM = N. virescens blue male on rice, NNGRF = N. nigropictus green female on rice, and NVGRM = N. virescens green male on rice. c Observations not recorded.

Table 2. Rice tungro disease transmission by Nephotettix spp. a

Transmitters (%)

strain or hybrids b Nephotettix spp.,

Female Male

NVGR NVBR NNGR NNGE NVBRF/NNGRM NNGRF/NVBRM

33.3 b 66.6 a 11.1 d 23.3 c 34.9 b 28.9 bc

73.3 b 80.0 a 27.2 d 26.6 d 38.1 c 41.0 c

a Mean ± SEM of 3 replications. The values in a column followed by the same letter are not significantly different at P = 0.05 according to LSD method. b NVGR =green N.

NNGR = green N. nigropictus on rice, NNGE = green N. virescens on rice, NVBR = blue N. virescens on rice.

female on rice, NNGRM = N. nigropictus green male on nigropictus on E. colona, NVBRF = N. virescens blue

rice, NNGRF = N. nigropictus green female on rice. and NVBRM = N.virescens blue male on rice.

NNGRM and NNGRF/NVBRM to transmit rice tungro disease (RTD) was also tested in three replications.

between NVBRF or NVGRF and NNGEM, although a few fertile eggs

No nymphs were produced by crosses

were laid, as determined by eyespot development (Table 1). In contrast. crosses between NVBRF and NNGRM produced many nymphs, almost half of which survived to the adult stage. The reciprocal cross between NVBRM and NNGRF also produced a large proportion of nymphs that survived to the adult stage. Thus, the success of interspecific crosses between N. virescens and N. nigropictus appears to depend in part on whether N. nigropictus has been reared on rice.

The individuals of NNGE and NNGR transmitted RTD but less efficiently than did NVBR and NVGR forms. The transmission ability of the interspecific hybrids of NVBRF/NNGRM and NNGRF/NVBRM was of intermediate order (Table 2).

fertility in the F 2 generation of inter- specific hybrids and their ability to transmit RTD.

We are currently studying the level of

characteristics, and tended to lodge. They were separated into two groups based on hull color: straw and black. One hundred and two (5.3%) of the fields were infested with black-hulled off-types while 187 (9.8%) were infested with straw-colored off-types. The highest level of infestation was 30% for the black-hulled off-types in a field 8.4 km from the Victoria Municipal Hall on the Victoria-Tarlac road and 20% for the straw-hulled off-type in a field 1.4 km from the Guimba Municipal Hall on the Guimba-Victoria road. Two hundred and twenty-four panicles were collected. Of

these, 89 were from cultivated rice, 75 from black-hulled off-types, and 60 from straw-colored off-types.

The cultivated varieties had more panicles per plant, less grains per panicle, and narrower and longer grains than the off-types (see figure). Grain weight was similar for the cultivated varieties and the off-types. The grains of the black-hulled off-types were bolder than those of the straw-hulled off-types. Most of the grains were awnless or had short awns. Most awns were observed in the black- hulled off-type grains with 30.4% having awns greater than 2.0 cm in length.

Integrated pest management — weeds

- - - - - - - -

Farmers thought that the off-types had arisen from crosses with other cultivars, by degeneration from continuous use of the same cultivar, and from seed mix- tures.

Competition and possible preharvest shattering of off-types of rice reduce yield and contaminate harvested rice, decreasing both grade and quality. Control is difficult and expensive.

effectiveness of bulk fertilizer purchasing scheme in Sri Lanka M. Wijeratne and I. R. N. Abeydeera, Agricultural Economics Department, Faculty of Agriculture, University of Ruhuna, Kamburupitiya, Sri Lanka

To reduce fertilizer cost in rice production, a bulk fertilizer purchasing scheme (BFPS) was introduced in Hambantota, a major rice-growing district in southern Sri Lanka. This program promoted farmer groups to collectively purchase fertilizer at the wholesale level to avoid the higher retail prices.

We evaluated the degree of farmer participation in the BFPS and the cost effectiveness of the scheme. Sixty farmers were randomly selected and interviewed at the end of 1993-94 maha (wet) season.

About 70% of the farmers continued to buy fertilizer directly from retailers rather than through the scheme. Several factors accounted for this preference. Retailers grant credit that farmers commonly use. Many farmers have deviated from the standard fertilizer recommendation, which made estimating the bulk quantity a difficult task. Farmers typically apply fertilizer in three splits (basal and two topdressings) and prefer to buy small quantities as needed for a particular application. In the BFPS, farmers did not always receive fertilizer in time for application. In some instances, farmer organizations granted

Grain characteristics of cultivated and off-types of rice in Central Luzon, Philippines.

credit to facilitate participation in the

an individual basis, $83.10/ha. The through the BFPS cost $81.40/ha and on loans properly. Fertilizer purchased BFPS, but borrowers did not settle the

difference in cost was not statistically significant by t-test. All of these factors negatively affected participation in the scheme.

IRRN 20:3 (September 1995) 29

IRRN REMINDER Routine research. Reports of screening trials of varieties, fertilizer, cropping methods, and other routine observations using standard methodologies to establish local recommendations are not ordinarily accepted. Examples are single-season, single-trial field experiments. Field trials should be repeated accross more than one season, or in more than one location as appropriate. All experiments should include replications and an internationally known check or control treatment.

Economic analysis Farmer participation and cost

Research methodology DNA fingerprinting of Xanthomonas oryzae pv. oryzae using IS1112 -based polymerase chain reaction M.L.C. George, IRRI; J.E. Leach, Kansas State University, Manhattan, Kansas, USA; and R.J. Nelson, IRRI

Repetitive DNA elements are commonly found in the genomes of various organ- isms. Although the function of these elements is unknown, their conserved nature and dispersed distribution have been exploited to generate DNA finger- prints by detecting unique sequences between the repeats using Southern-based restriction fragment length polymorphism (RFLP) or the polymerase chain reaction (PCR) (Fig. 1a).

number (about 80 copies in some strains), repetitive element isolated from the bacterial blight pathogen, Xanthomonas oryzae pv. oryzae (Xoo). In this study, outwardly facing primers complementary to IS1112 sequences (Fig. 1b) were used to fingerprint the DNA of 71 Xoo strains using PCR and PCR-based restriction analysis.

Amplification was performed in a 25-µl volume containing 50 pmol each of the two opposing primers, 20 ng of genomic DNA, 185 µM each of 4 dNTPs, approximately 2.5 units of Taq polymerase in a standard incubation buffer (Boehringer Mannheim) amended with 10% dimethylsulfoxide (v/v) and 7.5 µl of Tris-HCl (pH 9.5). The reaction mixture was overlaid with one drop of mineral oil, initially denatured for 1 min at 94 °C, and then subjected to 30 cycles of PCR (10 s denaturation at 94 °C, 1 min annealing at 62 °C, and 8 min extension at 65 °C) and a final extension for 8 min at 65 °C using a Perkin Elmer Cetus DNA Thermal Cycler. PCR-based restriction analysis was done by digesting 10 µl of the amplified product with BamHI in a 20-µl volume for at least 1 h. To visualize the DNA fingerprints, 10 µl of the PCR products and 20 µl of the digested products were loaded in a gel containing 0.5% agarose and 0.75%

IS1112 is a relatively high-copy

30 IRRN 20:3 (September 1995)

1. a) Scheme of generating DNA fingerprints using IS1112, a dispersed repetitive element found in Xanthomonas oryzae pv. oryzae, using outwardly directed primers. The RFLP method detects sequences within two restriction sites that flank the repetitive element. PCR detects sequences between the repetitive elements while PCR-based restriction analysis generates additional bands based on the presence of restriction sites within these sequences. b) Sequence of the two primers based on IS1112. The oligonucleotides were designed from each end of IS1112 in opposite orientation such that the 3' ends were directed outward from each copy of the element.

2. Dendrograms constructed with UPGMA using PCR and PCR-based restriciton analysis data from, 71 Xanthomonas oryae pv. oryzae strains. Numbers represent the race designations of strains associated with each grouping. Letters represent the lineage designations of the strains based on IS1112 -based restriction fragment length polymorphism (RFLP). The bootstrap values are noted as numbers on the main branches of the dendrograms. The bootstrap values, indicating the percentage of the 2,000 iterations in which the major groups of strains were formed, reflect the strength of the grouping.

b Primer 1 (JEL 1) 5' CTCAGGTCAGGTCGCC 3' Primer 2 (JEL 2) 5' GCTCTACAATCGTCCGC 3'

Synergel TM (Diversified Biotech, New- ton, MA, USA) and 0.5X Tris-borate buffer. Gels were electrophoresed for 6 h at 125V, stained with ethidium bromide, and then photographed using Polaroid Type 55 film.

The banding pattern of each strain was coded in binary form, 1 representing the presence and 0 the absence of each band. To include more bands in the PCR-based restriction analysis, composite data were generated by pooling the new bands produced by restriction digestion with the undigested bands from PCR.

Dendrograms were generated within the SAHN (sequential, agglomerative,

Use of molecular analysis in selecting spreader row components for blast screening nursery D. H. Chen, R. S. Zeigler, and R. J. Nelson, IRRI

In breeding for blast resistance, screening is usually conducted in blast nurseries in which susceptible rice varieties and lines are used as spreader rows for multiplying pathogen inocula. Diversification of the blast pathogen population in the nursery would help ensure that breeding lines are exposed to as much diversity of pathogen virulence as possible. Selecting and managing spreader rows have been key components in the protocol for blast resistance screening. Spreader row culti- vars are usually chosen based on their wide susceptibility to various local blast isolates or races. Single cultivars are often used for the spreader rows.

genotypes amplified by different culti- vars, we used DNA fingerprinting to analyze subpopulations of Pyricularia grisea infecting individual rice cultivars and lines in two blast nurseries used by IRRI. A diverse set of rice cultivars and lines (n = 38) was selected to serve as a trap nursery for the collection of pathogen isolates. The nursery included lowland and upland rice cultivars with a range of origins and field susceptibilities. The trap nurseries were planted at the IRRI Blast Nursery (IRRI-BN) in Los

To assess the diversity of the pathogen

1 hierarchical, and nested clustering methods) program of NTSYS-pc using the UPGMA (unweighted pair group method, arithmetic averages).

bands in PCR, and 17-47 bands in the composite PCR-based restriction analy- sis, were generated using the IS1112- based primers. The largest DNA frag- ment detected was approximately 7.0 kbp while the smallest was 100 bp. There were 112 and 118 band positions scored in PCR and the composite PCR-based restriction analysis, respectively.

DNA fingerprinting methods are pre-

DNA fingerprints, consisting of 13-35

Dendrograms produced using the two

sented in Figure 2. The groupings defined by the two methods corresponded well with their previously established pathotype and IS1112 -based RFLP groupings. In general, the groupings produced by the two methods at higher levels of similarity had high bootstrap values, but straight PCR was the better method, giving more robust clusters for this set of strains. These results — and the simplicity, speed, and convenience of the PCR — make PCR-based methods highly suitable for analyzing large numbers of samples, allowing for greater efficiency in the study of bacterial blight pathogen populations.

Lineage distribution, genetic diversity, and differentiation of Pyricularia grisea calculated from isolates taken from each host, pooled from three collections. IRRI, Philippines.

Lineage Haplotype Genetic diversity (no.)

Cultivar 1 4 7 14 17 44 45 46 47 48 Lineage Haplotype RAUDPC a

IRAT2 1 0.00 0.00 0.01-0.07 C101A51 3 0.00 0.44 0 b

Tetep 4 0.00 0.64 0-1.47 IRAT13 2 0.00 1.00 0-1.19 IRAT104 2 0.00 1.00 Kinarabao 3777 14 0.08 0.77 0.18-60.25 IR36 20 0.09 0.85 1.59-61.86 IR62 16 0.11 0.78 0.86-38.34 IR50 26 0.12 0.91 10.72-59.83 C101PKT 13 0.18 0.83 16.23-49.49 IR72 19 0.18 0.83 16.23-49.49 OS6 14 0.26 0.88 0.05-62.67 Kinarabao 19430 7 0.27 0.71 0.01-59.01 IAC47 7 0.27 0.76 0-59.83 Carreon 7 0.32 0.79 0.01-0.08 Aichi asahi 14 0.33 0.88 0.41-58.28 C101LAC 16 0.39 0.84 18.18-50.17 IR64 10 0.40 0.73 0.06-2.84

IRAT208 13 0.43 0.91 0.01-0.72 Sinam Pablo 19 0.48 0.91 0.47-61.70 Tedong 13 0.49 0.92 0.12-53.72 IRAT239 17 0.50 0.74 0-60.64 CNA4130 3 0.50 0.83 0-44.12 lR442-2-58 3 0.50 0.83 BL 1 10 0.50 0.92 0.04-0.04 K59 20 0.53 0.92 0.25-50.47 C22 11 0.58 0.86 0.01-29.38 Azucena 13 0.60 0.92 0.27-1.18 UPLRi-7 10 0.64 0.80 0-9.20 UPLRi-5 15 0.65 0.80 0-1.63 IAC165 6 0.67 0.95 Kusabue 8 0.68 0.86 0.04-1.47 IR66 17 0.70 0.93 0.24-0.66

Kinandang patong 17 0.70 0.87 0.01-45.26 17 0.72 0.92 0.01-2.12 15 0.72 0.90 0-2.18

Akashi 12 0.74 0.88 6.27 d

Moroberekan 2 1.00 1.00 0-0.26

a Relative area under the disease progress curve. Data were from IRRI-Blast Nursery (IRRI-BN) and Cavinti (WS) trials. b No infection was observed until flowering stage. c Cultivars were only planted at IRRI-BN (DS). d Seeds were damaged by rats at IRRI-BN (WS). It showed 10% diseased leaf area at IRRI-BN (DS) at 31 d after sowing.

c

CO 39 21 0.42 0.89 17.86-62.35

IRRN 20:3 (September 1995) 31

C104PKT

Fijisaka 5

2 12

37 2

2 47 1 1 80 4 69 4 72 4 1 55 6 54 6 30 3 2

2 18 1 2 18 1

29 7 2 43 6 2

49 14 2 38 14

4 56 10 5 3 18 3 1

37 12 5 18 5 3

2 21 9 2 1 3

1 3 13 4 2

1 31 21 1 35 2 11 7 1 1

1 16 7 2 1 2 14 4 5 1 38 12 1 26 1 1

1 2 4 6 9 5

13 15 13 1 24 12 29 7

3 15 4 1 10 1 26 14 1 9 3 5 25 7 1 8 5

1 1

–

–

Baños, Laguna, Philippines, during the 1992 wet (WS) and dry seasons (DS) and at the upland rice screening site in Cavinti, Laguna, during the 1992 WS. A mixture of IR50, IR64, IR66, IR72, UPLRi-5, Carreon, Kinarabao 3777, CO 39, and IRAT13 was used as spreader rows, sown 1 wk ahead in the DS at IRRI-BN and simultaneously with test materials in the WS at IRRI-BN and at Cavinti. The relative area under the disease progress curve (RAUDPC) was calculated from the visually estimated diseased leaf area (DLA%) at sampling (see table) at both the Cavinti site and IRRI-BN in the WS. A total of 1,516 isolates was recovered from the three collections and subjected to DNA fingerprinting using the repetitive probe MGR586.

DNA fingerprinting with MGR586 revealed 130 haplotypes (unique DNA hybridization profiles) of the blast fungus among the isolates. The relationships among these haplotypes were determined by cluster analysis of DNA banding data using UPGMA (unweighted pair group method, arithmetic mean). The robustness of the clusters formed was tested using bootstrap analysis in the program Winboot. Isolates grouped in the same cluster with greater than 85% DNA band similarity and high confidence from

bootstrap analysis were inferred to be related by descent, and the grouping was termed a lineage. Nine lineages were detected from Cavinti and four from the

The genetic diversity of the pathogen population was estimated based on Nei’s gene diversity index. The observed lineage diversity of the collection was 0.50 for IRRI-BN DS, 0.35 for IRRI-BN WS, and 0.74 for Cavinti WS, and the observed haplotypic diversity was 0.82, 0.89, and 0.83, respectively. Because the trap plants and the spreader rows were the same in the three collections, the differ- ences in blast severity of the same cultivar at the two sites and the differences in lineage composition in the three collec- tions reflected differences in the pathogen population structure and the environment in the two sites and two seasons for

IRRI-BN.

IRRI-BN. Isolates collected from each cultivar

were pooled for genotypic diversity estimation (see table). Multiple haplo- types infected most hosts, and multiple lineages infected many of them. Two entries, C101A51 and Tetep, were attacked by a single lineage each. In no case were all the haplotypes or lineages recovered from a single cultivar. IR50, IR72, and IR442-2-58 have been used

alone for spreader rows at IRRI-BN in the Philippines. In this study, the lineage diversities of the pathogen recovered from them were very low, suggesting that a single cultivar is not sufficient for amplifi- cation of diverse pathogen genotypes. The diversity of the initial inocula multi- plied by spreader rows determines, to a great extent, the diversity of the pathogen population for the study. The observed genetic diversity in this study was far from what it would have been had all the detected types of the pathogen been equally represented (potential diversity based on lineage data ranged from 0.75 to 0.89, and from 0.97 to 0.99 based on haplotype).

We propose that criteria for choosing spreader row cultivars should include both the spectra of pathogen genotypes ampli- fied by the cultivars, as well as the cultivar’s field susceptibility. The results of this study provide the means to select spreader row components. We suggest that CO 39 or IR50, C101A51, Tetep, Akashi, IR64 or Carreon, and UPLRi-5 may be suitable candidates for a spreader row mixture at the IRRI-BN. Although some of these cultivars showed low RAUDPC, they could support the rare types in the population. This proposal remains to be tested.

News about research collaboration IRRI and UK intensify research collaboration Research collaboration between the Plant Sciences Programme (PSP) of the Overseas Development Administration (ODA) of the United Kingdom and IRRI intensified with the recent signing of a six-year agreement that fosters collaboration in agricultural research programs contributing to the improved management of renewable natural resources and sustainable agriculture in developing countries.

Witcombe, PSP manager, and Dr. George Rothschild, IRRI director general, is for joint planning and implementation of research projects between UK and IRRI

The agreement, signed by Dr. John R.

scientists. The overall aim of the col- laboration is to assist national agri- cultural research systems in efforts to increase rice production to improve the well-being of rice consumers and produc- ers in developing countries.

Projects being considered for possible collaboration between IRRI scientists and PSP are on assessing opportunities for nitrogen fixation in rice and production of low-nitrogen-input cereals by gene manipulation.

Scientists at the Natural Resources Institute (NRI) and IRRI are collaborat- ing to develop strategies for the effective management of tungro, which is the most destructive viral disease of rice in tropical Asia. Tungro outbreaks can quickly destroy rice plants in a large area.

In the past, ODA has funded projects undertaken jointly by UK-based institu- tions and IRRI. Based on the stripper rotor developed by the Silsoe Research Institute and patented by the British Technology Group Ltd., IRRI engineers have developed an inexpensive, light- weight, and simple stripper harvesting system that allows more timely harvest- ing of rice. In cooperation with national agricultural research systems, a working prototype of the machine was developed and pilot-tested in farmers’ fields. Cooperating small-scale manufacturers produced commercial units for trials. Blueprints of the stripper-gatherer are available to qualified manufacturers in developing countries where the stripper rotor patent may be used.

32 IRRN 20:3 (September 1995)

More projects on plant sciences, crop protection, natural resources, and postharvest technologies are being considered.

Genetic engineering of rice for sheath blight resistance Sheath blight, a disease caused by the fungus Rhizoctonia solani, is emerging as a major disease in irrigated rice systems where crop intensification and high nitrogen application are practiced.

with high tillering capacity favor the microclimatic conditions that enhance sheath blight development.

Recent studies conducted at IRRI showed that this disease significantly limited the yield of IR72 grown in an intensive system with high nitrogen input. To control the disease, IRRI researchers tested and evaluated numerous varieties and improved breeding lines. But no effective source of varietal resistance for the disease was found.

researchers at Kansas State University, are now genetically engineering rice plants to improve resistance to sheath blight.

Dr. Swapan K. Datta, IRRI tissue culture specialist, and his colleagues are experimenting with antifungal genes as a post-infection defense against the disease. Several of these genes have been isolated from infected rice plants and other sources. Dr. Datta and his team are introducing these genes into elite rice varieties. Preliminary studies with transgenic rice plants (those with one or more additional genes from diverse sources) indicate that they have enhanced resistance to R. solani. Related studies to determine the levels of resistance are being undertaken.

High-yielding, short-statured cultivars

IRRI scientists, in collaboration with

IRRI library reinvigorates rice literature collection in Cambodia

The latest literature on rice is now available at the Cambodia-IRRI-Australia Project (CIAP) headquarters in Phnom Penh.

The CIAP Office has the largest col- lection of printed materials on rice in the country, according to Mr. Ian Wallace, librarian at IRRI’s Library and Documentation Service. IRRI staff members as well as other scientists in Cambodia make use of this collection.

Personnel from the Library and Documentation Service are assisting the CIAP Office in computerizing its operations. Once done, the biblio- graphic data base on rice literature will be made available to the public in Cambodia.

About 8,000 rice references are added each year to the data base, Mr. Wallace says. These new citations are made available to scientists around the world in the form of the quarterly journal, Rice literature update. Annual requests for reprints are usually re- ceived from scientists in 60 countries. The monograph collection (books, pamphlets, reprints, and translations) at IRRI now totals more than 105,500 titles. It also contains 4,470 serial titles, of which about 1,500 are currently being received.

Rockefeller Foundation supports China-IRRI collaboration The Rockefeller Foundation has approved funding of US$54,900 to enhance research collaboration between IRRI and the People’s Republic of China. The amount supports two projects. A grant of US$34,400—for 3 years from 1 Jan 1995—finances a research project on genes controlling cytoplasmic male sterility in rice, in collaboration with the South China Institute of Botany of the Chinese Academy of Agricultural Sciences. A one-year grant of US$20,500 for research to produce transgenic rice containing genes carrying resistance to insects such as the yellow stem borer and leaf-feeders, will fund IRRI’s collaboration with the Biotechnology Research Center of the Chinese Acad- emy of Agricultural Sciences.

Training on rice germplasm collecting in Vietnam Vietnam lies within the primary center of origin and domestication of rice. Consid- erable diversity in cultivated and wild species occurs.

In recent years, many farmers have been opting to cultivate high-yielding modern rice varieties. This means that some of the traditional varieties are no longer grown or are grown by fewer and fewer farmers. Conversion of deepwater riceland to shrimp farming has resulted in the loss of traditional deepwater rice varieties.

Realizing that efforts needed to be made to accelerate rice germplasm collecting in Vietnam, the Ministry of Agriculture and Food Industry (MAFI) in Vietnam and IRRI jointly organized an in- country training course on collecting rice germplasm. Fifteen researchers from nine institutes and universities in Vietnam participated in the training, which was held in Hue City from 20 to 29 Jun.

The course content was specifically developed to meet the needs of Vietnam- ese scientists, with researchers from Viet- namese institutions and IRRI serving as trainers. Among the topics discussed during the 9-day training were rice re- search and development in Vietnam, diversity in rice germplasm from Viet- nam, planning collecting missions and preparations required for collecting, methods of sampling cultivated rice and wild relatives, collecting passport data, care and processing of collected material, and preparing reports to document germ- plasm-collecting trips.

To gain hands-on experience, the participants were divided into three teams to systematically collect rice germplasm for five days in three provinces. An experienced germplasm collector led each team. The participants then returned to Hue to share their experiences, prepare reports on germplasm collecting, and make presentations on their field-collect- ing activities.

The training course was funded by a grant from the Swiss Development Cooperation through the IRRI project “Safeguarding and preservation of biodiversity of the rice genepool.”

IRRN 20:3 (September 1995) 33

The International Rice Research Institute (IRRI) is seeking candidates for division head and either a plant physiologist or a systems resource agronomist for its Agronomy, Plant Physiology, and Agroecology (APPA) Division. It is anticipated that the division head will be either a plant physiologist or a systems resource agronomist.

The APPA Division has approximately 100 scientific staff members. It conducts research on nutrient and weed manage- ment; rice physiology; soil, water, and nutrient interactions; and plant demand for and crop ecology. The aim is to alleviate resources in rice-based cropping systems. The research, which is aimed to develop the conceptual and quantitative basis for successfully intensifying production systems in which rice is a component, is conducted in collaboration with other biological and social scientists and engineers and forms components of interdisciplinary research projects outlined in IRRI’s Medium-term Plan.

Division head The division head of APPA provides disciplinary leadership and assists IRRI management in identifying and prioritizing research activities and moti- vates the staff in implementing them through coordination of professional and research services. He/she promotes research collaboration with institutions in rice-growing nations worldwide and contributes to IRRI’s program of degree and nondegree training aimed to strengthen research capacity in national agricultural research systems.

We are looking for candidates with recognized capabilities to lead and manage a research team and demonstrated capacity to employ a systems perspective in the design and coordination of research. The candidate must have a Ph D in agronomy, agroecology, plant physiology, or related fields and at least 10 years’ research experience with a demonstrated record of scientific output. The division head will also conduct our research program in either plant (stress) physio- logy research or systems resource man-

Announcements IRRI positions announced agement. Thus, research experience in

stress physiology or systems resource

on rice is an advantage. below) is essential. Research experience agronomy (see position descriptions

drought and submergence in rainfed controlling tolerance of the rice plant for research on fundamental mechanisms The plant physiologist leads IRRI’s Plant physiologist

systems. He/she links such research on mechanisms to genetics and germplasm selection (including biotechnology approaches), crop and soil management,

constraints arising from drought and submergence. The plant physiologist contributes to IRRI’s program of degree and nondegree training in plant physiology.

We are looking for candidates with a demonstrated record of achievement in stress physiology at the molecular, biochemical, and cellular or whole plant levels and the ability to work with

with scientists in national agricultural research systems. The candidate must have a Ph D in plant physiology/ biochemistry with a minimum of 3 years of postdoctoral experience. Candidates with interest in the division head position will require additional experience as described above.

Systems resource agronomist The systems resource agronomist leads research on the effect of intensive lowland rice cultivation on soil quality and how changes in soil quality affect productivity as part of IRRI’s ongoing research on sustaining long-term productivity of irrigated rice systems. He/ she provides vision and leadership for research on agronomic management stra- tegies to achieve high and stable yields in irrigated rice systems. The systems re- source agronomist contributes to IRRI’s program of degree and nondegree train- ing in agronomy and farming systems.

We are looking for candidates with a record of scientific excellence in research on soil fertility/plant nutrition and

multidisciplinary teams and collaborate

nutrient cycling research and the ability to effectively work with and manage interdisciplinary teams and collaborate with scientists in national agricultural research systems. The candidate must have a Ph D in agronomy, soil science, or a related field with a minimum of 2 years of postdoctoral research experience. Experience with rice and/or other tropical cropping systems in the humid tropics is desirable. Candidates with interest in the division head position will require additional experience as described above.

The successful candidates for these positions will be assigned at the Insti- tute’s headquarters in Los Baños, Laguna, Philippines. Salary and perqui- sites are internationally competitive. IRRI offers children’s education allowances, medical insurance, annual fare-paid leaves, and other attractive benefits. IRRI provides a gender-sensitive work envi- ronment and particularly welcomes women applicants.

Send a comprehensive curriculum vitae and names, addresses, and fax num- bers of three referees by 31 Oct 1995 to

Dr. George Rothschild Director General IRRI E-mail: G.ROTHSCHILD@IRRI.

CGNET.COM

Please refer to Code IR-DH-002.

Biotechnologia Habana ’95 The Center for Genetic Engineering and Biotechnology, in collaboration with the United Nations Educational, Scientific, and Cultural Organization and the Food and Agriculture Organization of the United Nations, is sponsoring an international meeting on biotechnology. The event, with the theme “Biotechnologia Habana ’95: new opportunities in plant, animal, and industrial technology,” will be held in Havana, Cuba, on 12-17 Nov 1995.

For more information, contact the Organizing Committee, Biotechnologia Habana ’95, P. O. 6162, Havana, 10600, Cuba.

34 IRRN 20:3 (September 1995)

2nd International Symposium on Systems Approaches for Agricultural Development The second International Symposium on Systems Approaches for Agricultural Development will be held at IRRI on 6-8 Dec 1995. The objectives of the symposium are to review the status of applications of systems research and modeling in agricultural research, with specific focus on countries where agricultural development is facing major challenges, and to promote international collaborative activities and to increase awareness of opportunities for using systems approaches as a tool in research and planning.

It is organized by IRRI, the International Consortium for Agri- cultural Systems Applications (ICASA), and the Systems Analysis and Simula- tion for Rice Production (SARP) Network. For details, contact Dr. P. K. Aggarwal, IRRI.

IRRI group training courses for 1995 IRRI provides a limited number of scholarships for participation in its short- term group training courses. To be considered for an IRRI-funded scholar- ship, a scientist must be affiliated with a national institution that has an official collaborative agreement with IRRI in a rice-related research and training project. A scientist interested in an IRRI-funded scholarship should apply directly to his or her institution and not to IRRI.

IRRI also accepts scientists from other institutions and agencies for the courses if they are working in rice or rice-related areas. Their applications to participate in courses must be endorsed to IRRI by their employer and must specify funding sources to cover costs. IRRI’s group course training fee is approximately US$1,200/month: this does not include

Rice dateline 6-8 Oct France/IRRI Day, Montpellier, France ............ K. S. Fischer/R. D. Huggan, IRRI

9-13 Oct China-IRRI Collaborative Meeting, China ....... G. Rothschild/B. S. Vergara, IRRI

16-20 Oct 3rd International Rice Genetics Symposium, IRRI ........................................... G. S. Khush, IRRI

2 Nov INGER Project Support Team Meeting, IRRI ....................................... R. C. Chaudhary, IRRI

12-17 Nov Biotechnologia Habana '95, Havana, Cuba ....... Organizing Committee Biotechnologia Habana ’95, P. O. 6162, Havana, 10600, Cuba

12-23 Nov INGER Advisory Committee Meeting- cum-Monitoring Tour, IRRI ...................... R. C. Chaudhary, IRRI

16-17 Nov ARBN Steering Committee Meeting .......... J. Bennett, IRRI

4-5 Dec Systems Analysis and Simulation for Rice Production (SARP) Symposium, IRRI ........... J. Sheehy/M. J. Kropff, IRRI

6-8 Dec 2nd International Symposium on Systems Approaches for Agricultural Development ( in conjunction with SARP Symposium ), IRRI ... J. Sheehy/P. S. Teng, IRRI

participants’ round-trip international headquarters unless otherwise indicated. airfare, en route expenses, or shipping For additional information, contact the allowance upon return home. The Head, Training Center, IRRI. courses are conducted at IRRI

Date Course

2-27 Oct Geographic Information Systems

9 Oct-1 Dec Rice Production Research a

(Pathum Thani Rice Research Center, Thailand)

6 Nov- 15 Dec Engineering for Rice Agriculture b

(India Institute of Technology, Kharagpur, India)

13-24 Nov Gender Perspective and Analysis in Rural Development c

(International Institute of Rural Reconstruction, Silang, Cavite, Philippines)

20 Nov-1 Dec Frontiers of Social Science Research Methods for Agricultural Systems Analysis

Reconstruction and IRRI. a Thailand Rice Research Institute and IRRI. b lndia Institute of Technology and IRRI. c lnternational Institute of Rural

IRRN 20:3 (September 1995) 35

New IRRI publications Modeling the impact of climate change New publication on rice production in Asia. 1995. 289

Host plant resistance to insects. 1995. Wallingford, Oxon OX10 8DE, U.K.; LDC, Satapathy, and V.D. Shukla 431 pages. Highly developed countries pages. HDC, please send order to CABI, Rice tungro. A. Anjaneyulu, M.K.

Wallingford, Oxon OX10 8DE, U.K.; less $18.00 Plus $8.00 airmail or $2.00 surface Order from Science Publishers, Inc., 52 (HDC), please send orders to CABI,

postage, developed countries (LDC), $14.00 plus

LaBombard Road North, Lebanon, NH

US$13.00 airmail or $2.00 surface Although recent rapid industrialization 03766, USA. Fax: (603) 448-2576.

postage.

The overuse and misuse of insecticides some four decades ago created major environmental problems and was fol- lowed by the development of an “inte- grated pest management” approach to control crop pests. This approach utilizes a combination of host plant resistance and cultural, biological, and chemical control methods. Crop improvement programs emphasize the breeding of crop varieties with multiple resistances to pests. Resistant varieties developed in recent years represent some of the greatest achievements of modern agricul- ture.

This book presents a broad overview of host plant resistance to insect pests. It shows how plants can defend themselves naturally and how insects have adapted to overcome these mechanisms through coevolution. It also describes screening and breeding for insect resistance.

in cooperation with IRRI. CAB International published this book

has contributed greatly to improved living standards, it has also resulted in an increase in concentration of “greenhouse gases” leading to global warming. The relationship between climate change and agriculture is particularly important, as world food production is under pressure from a growing population. Rice is the second most important crop in the world after wheat, with more than 90% cur- rently grown in Asia where it is a staple food. It has been estimated that rice production needs to increase by 70% over the coming decades to meet the demands of population growth. Hence it is vital to understand the effect of climate change on rice growth, development, and production.

rative study between the United States Environmental Protection Agency’s Environmental Research Laboratory and IRRI. It quantifies the impact of climate change on rice production using crop simulation models and integrates existing knowledge of the effects of increased levels of carbon dioxide and temperature.

CAB International published this book

The book is the outcome of a collabo-

in cooperation with IRRI.

Rice literature update reprint service Photocopies of items listed in the Rice literature update are available from the IRRI Library and Documentation Service. Reprints of original documents (not to exceed 40 pages) are supplied free to scientists of developing countries. Rice scientists elsewhere are charged US$0.20 for each page or part of a page copied, plus postage. Make checks or money orders payable to Library and Documentation Service, IRRI.

mentation Service, IRRI. E-mail: [email protected].

Address requests to Library and Docu-

Call for news Individuals, institutions, and organizations are invited to tell readers about upcoming events in rice research or related field in the Rice dateline. Send announcements to the Editor, International rice research notes, IRRI.

IRRI address International Rice Research Institute P. O. Box 933 1099 Manila, Philippines Tel: (63-2) 818-1926 Fax: (63-2) 891-1292 Telex: (ITT) 40890 RICE PM E-mail: [email protected]

36 IRRN 20:3 (September 1995)