International Rice Research Newsletter Vol.1 No.2

Editorial

The second issue of the International Rice Research Newsletter (IRRN) offers an opportunity for the International Rice Research Institute (IRRI) to express appreciation for the favorable reception given this new newsletter. The enthusiastic response of scientists who contributed concise summaries of significant rice research findings is most welcome.

that the IRRN can serve as an effective and useful channel of communication among workers concerned with rice and rice-based cropping systems.

We expect the IRRN to stimulate further exchange of information among rice scientists. Readers who find the short, concise articles of others useful and interesting are encouraged to reciprocate by contributing summaries of their own research findings. Such contributions to the newsletter and constructive comments about it are invited and welcome.

We are encouraged by comments from readers of the first issue. It is obvious

Thank you for your encouraging support of this new forum for rice researchers throughout the world.

N. C. Brady Director-General

2 IRRN 1:2 (DECEMBER 1976)

Genetic evaluation and utilization OVERALL PROGRESS

Highlights of 1975 International Rice Testing Program (IRTP) Nurseries

The International Rice Yield Nursery (IRYN) was broadly divided into early and medium maturity groups. In the early group (nine countries, 27 trials),

IR2061-628-1-64, and IR2071-625-1-252 performed well at most locations. In the medium-duration group (eight countries, 21 locations), Biplab, BM2-87-1, BR51-91-6, and BG90-2 performed well.

Results from the International Rice Observational Nursery (IRON) are indicative of resistance of some entries to some of the major diseases at most locations (see table).

In the upland yield nursery (five countries, 19 locations), IR1 529-430-3, IR2035-242-1, and BPI 76 9 /Dawn (IR9575) produced the highest overall yields. Most test sites were in the Philippines (11 locations) and India (five bocations). The highest average yields for the Philippine locations were from IR1 529-430-3 and IR2035-242-1; the highest yields for the Indian locations were from IET 1444.

Twenty entries in the blast nursery showed resistance to blast at more than 15 of the 22 reporting locations (see table). Most of them derived their resistance from Tetep. Twelve were semidwarfs. Analysis of sheath blight

W6-1899-25-4, IR2061-465-1-5-5,

E. Heinrichs (IRRI), S. Pongprasert (Thailand), and P. Rao (India) check gall midge incidence in IRTP regional monitoring tour in Thailand.

nursery results for the past 3 years showed that seven entries displayed consistent, moderately resistant reactions: five semidwarfs (Bahagia, IR1544-340-6, IR32-76-67P, K8 mutant selection, and Pankaj) and two tall varieties (Laka and Ta-poo-choo-z). Eighteen varieties in the tungro nursery exhibited resistance to tungro at most of the eight test sites in five countries (see table). Significantly, 11 of these entries were accessions from the Assam Rice Collection.

Gangala, Ptb 19, Ptb 21, and ARC 6650 displayed resistance to brown planthopper under greenhouse conditions at nine of 11 test locations in five countries; however, such resistance does not fit into either the Bph 1 or bph 2 groups. Twenty-one other entries exhibited resistance of known gene sources: nine to the Bph 1 type (as in IR26, Mudgo, and RP9-6) and 12 to the bph 2 type (as in Chianung-sen-yu 11, CR94-13, and H 105).

In screening for salinity tolerance in the Philippines, Thailand, and India, three varieties were identified as promising: Pokkali, DA-29, and Nona Bokra.

Entries that were found resistant to three major diseases in the 1975 International Rice Testing Program (IRTP) nurseries, IRRI, 1975.

Varieties resistant to

Blast a Bacterial blight Tungro

IRON b

IR1544-181-1-1 IR1820-210-2 lR2588-60-1 lR2588-132-1-2 IR2793-80-1 IR2798-88-3 IR2798-88-3 IR2811-24-3 lR2851-41-3

IRBN c

ClCA 4//IR665-23-3-1/Tetep

IR665-23-3-1//IR665-33/Tetep I R29

IR665-23-3-1//IR841-65/C46-15

IR1520-52-2-4-1 IR2035-255-2-3-2 IR2058-435-3-2-2-2 IR2588-2-3-3 IR2793-10-2 lR2793-38-3 IR2793-80-1 Washabo (SML 56/7) Raminad Strain 3 lR1416-128-5-8 CA 435-b-5-1 CA 902-b-3-3 Carreon PI 184675-2 Ta-poo-choo-z Tetep

IRON BR51-49-6 BR51-67-1/C1 lR2053-362-14-4 IR2053-375-1-1-5 IR2055-481-2-6-2 IR2793-80-1 IR2863-22-3 IR2863-31-3 IR286348-2 IR2071-636-5-5 IR2070-423-2-5-6 R32

IRON IR2071-542-3-1 lR2863-31-3 IR2863-38-1

IRTN d

Ptb 8 ARC 13820 ARC 13901 ARC 13959 ARC 10342 Habiganj DW 8 ARC 7125 ARC 13677 Kataribhog (India) DWA8 ARC 7318 ARC 10531 Kataribhog (26683) SLO12 ARC 7140 ARC 13560 Ambemohar 159

a Varieties listed as resistant to blast under IRON showed resistance to both leaf and neck blast. b lRON: International Rice Observational Nursery. c IRBN: International Rice Blast Nursery (tested only for leaf blast). d lRTN: International Rice Tungro Nursery.

IRRN 1:2 (DECEMBER 1976) 3

Paleogeographic origin of the wild taxa in the genus Oryza and their genomic relationships

T. T. Chang, Plant Breeding Department, International Rice Research Institute

My recent postulate that the progenitors and wild relatives of the Asian and African cultivars O. sativa and O. glaberrima originated in the humid tropics of the Gondwanaland continents (Euphytica 25:425–441, 1976) not only can explain the pan-tropical distribution of the above taxa that have the AA genome in common but could also relate the geographic distribution of other wild species in the genus to their genomic composition.

Those taxa on the western component of the supercontinent (now South America) – O. alta, O. grandiglumis, and O. latifolia – have the CCDD genomes. The other taxa – O. eichingeri, O. punctata, O. minuta, and O. officinalis located on the eastern components of Gondwanaland (now the Indian subcontinent, Southeast Asia mainland, the east coast of Africa, and Malagasy) – have BB, CC, or BBCC genomes.

(genome EE ) and the African-based O. brachyantha (FF) do not readily fit into the pattern of continental drift.

The genomes of the remaining Asian species, O. granulata, O. longiglumis, O. meyeriana, O. ridleyi, and O. schlecteri, remain to be determined.

Cytogenetic evidence indicates that partial homology exists between the A and B genomes and between the A and C genomes.

The Australian-based O. australiensis

Prospects of rice breeding in Kerala state, India

K. I. James, rice breeder, All India Coordinated Rice Improvement Project, Rice Research Station, Pattambi, India

Thirty-four rice strains have been evolved by pure-line selection from the most popular local varieties in Kerala state, India. A few strains were intended for S. Kanara district of Karnataka state. Seventeen are suited to the first crop season and nine to the second. Ptb 10 is early maturing, suited for all

Cultures from promising crosses of intermediate height, Kerala state, India.

Pedigree Cultures (no.)

Triveni/lR2071-251-1-1-3 Jaya/lR2058/Mahsuri Jaya/lR2153/Bhavani Jaya/lR2071/Mahsuri Jaya/lR2153/Mahsuri Jaya/lR2153/23178

Blast-resistant cultures Triveni/lR1857-78-1-3 Jyothi/lR1857-78-1-3 Triveni/lR1702-74-3 Jyothi/lR2153-479-2-3 Jaya/lR2071-179-9-5 Bharathi/lR2071-25-1-1-3

42 120

115 82 16

80

26 30

8 58 52 8

Sheath blight-resistant cultures Jaya/S1 56 Triveni/S1 56 Jyothi/S1 56

BPH-tolerant cultures Bharathi/IR2071-625-3-1 Triveni/Mudgo Triveni/lR2061-464 Triveni/lR1539

22 8 4

103 75 95

126

three seasons. Ptb 18 and 21, resistant to stem borer and gall midge, are being utilized in breeding programs. Ptb 28, 29, and 30 are suitable for dry land ( modan ) conditions as a purely rainfed crop for the first crop season. Ptb 33 is resistant to brown planthoppers. Chennellu is a mass-selected variety suitable for shade (e.g. under coconut trees).

An intensive breeding program to combine desirable traits of local varieties with the high yield potential of the dwarf indicas began in 1964. Since then, seven high yielding rice varieties have been released for various agroclimatic regions of the state. The first Indian semidwarf variety Annapoora, from the cross Ptb 10/TN1, is red grained and early maturing. It has enjoyed unprecedented popularity in Kerala and has spread to parts of Tamil Nadu and Sri Lanka. It was followed by Aswathy, Rohini, Triveni, Sabari, Bharathi, and Jyothi.

Varieties already released and many of the promising cultures lack multiple resistance to diseases and pests. Future varieties should have moderate resistance to sheath blight, blast, and bacterial blight, and some ability to withstand the attack of brown planthoppers, stem borers, and leaf folders. Varieties that can be grown under minimum plant protection schedules have to be selected and, to provide straw, they should be

nonlodging varieties of intermediate height. From over 120 crosses, cultures promising in such qualities are under test. They are mainly from the crosses listed in the table.

Rices for late plantings in India

N. Shivanandappa, M. Mahadevappa, E. Yellappa, and M. Sangaiah, Regional Research Station, University of Agricultural Sciences, Shimoga, Karnataka, India

Tank-fed rice is grown on about 120,000 ha in Karnataka state, India, with paddy cultivation beginning in September and October. Because most of the vegetative and reproductive periods are exposed to low temperatures, yields are relatively low. Diseases are also more severe in such late plantings. We sought to identify comparatively disease-free and cold- tolerant varieties and cultures for areas where late planting is practiced.

Twenty-eight varieties and cultures were sown at Hebbal and at Mandya in the third week of August and again in the third week of September 1973. Three-week-old seedlings were planted in two replications in 3.6- x 3.0-m plots following a randomized block design. Observations for diseases were made at tillering and milky stages.

At Hebbal, some varieties showed susceptibility to blast, bacterial blight, bacterial leaf streak, and cold injury. Varieties S 317 and S 705 were susceptible to all three diseases. MR 249, 263, 271, 274, 275, 276, 277, 278, 280,

CR 126-53-1, Madhu, and Sona were moderately susceptible to bacterial blight or bacterial leaf streak, or both.

At Mandya, incidence of bacterial leaf blight and bacterial leaf streak was lower than at Hebbal. Blast incidence was as high as at Hebbal on S 317 and S 705.

Nine varieties and cultures were selected as having moderate resistance to blast, bacterial blight, bacterial leaf streak, and cold injury. They are MR 272,

CR 126-33-11, CR 126-42-1, IR20, and IEl 2295.

281, 288, Ch 2, Ch 45, CR 126-27-13,

MR 273, MR 279, MR 283, MR 65-1,


GENETIC EVALUATION AND UTILIZATION

Agronomic characteristics A possible donor for use in breeding monsoon rice D. V. Seshu, International Rice Testing Program, International Rice Research Institute Analysis of certain data from the All India Coordinated Rice Variety Trials indicates various degrees of photoperiod sensitivity in several semidwarfs derived from TKM 6. A variety’s photoperiod sensitivity can be determined from its flowering behavior with different sowing times at one site or with simultaneous sowings at different latitudes if temperature effects are minimized. Data were selected from the Uniform Variety Trials (UVT) of 1974–75 (see table). In UVT-1, five TKM 6 derivatives with comparable sowing times flowered 23 days earlier, on the average, at Garikapadu (18°N) than at Nagina (26°N). They also flowered more quickly in a September- planted trial than in a June-planted trial at Pattambi (11°N).

In UVT-2, two TKM 6 derivatives flowered 25 days earlier at Coimbatore (11°N) than at Gurdasphur (31°N), while photoperiod-insensitive Jaya flowered at nearly the same times. In a late-planted trial at Warangal, they flowered 23 and 31 days earlier than in the early-planted trial, while Jaya flowered at similar times in both trials.

TKM 6 and IR8 or TN1, the parents of the tested varieties, are photoperiod insensitive; there may be complementary gene action, or one of the parents may possess a hypostatic gene for photoperiod sensitivity. Since the results described here are not found in crosses of IR8 or TN1 with other insensitive varieties, it is presumed that TKM 6 contributed to the expression of photoperiod sensitivity that is being observed. Perhaps TKM 6 harbors a gene for photoperiod sensitivity along with an inhibitor gene. TKM 6 owes its origin to the photoperiod-sensitive variety GEB 24. Discrepant flowering behavior has also been noted in other TKM 6 derivative semidwarfs like IR20, Cauvery, and CR 44-1.

A photoperiod-sensitive gene in TKM 6 would have significant implications, because the variety can be an effective donor in breeding for monsoon rices. TKM 6 can contribute good grain quality and a general field tolerance to diseases and pests that is

important in monsoon rices. The varieties described here have only moderate photoperiod sensitivity since selection pressure was not applied for the photoperiod sensitivity attribute per se.

Semidwarf and intermediate-height progenies of TKM 6 with higher degrees of photoperiod sensitivity can be found. Genetic studies and breeding programs are underway in an attempt to develop improved photoperiod-sensitive monsoon rices.

Relation of flowering times of some semidwarf derivatives of TKM 6 to latitude and sowing time, AICRIP Uniform Variety Trials (UVT), 1974–75 a .

Location Latitude Sowing

Flowering time (days after sowing)

Nagina Garikapadu Pattambi Pattambi

Gurdaspur Coimbatore Warangal Warangal

26°N 18°N 11°N 11°N

31°N 11°N 18°N 18°N

June 29 July 2 June 13 Sept. 26

June 16 June 14 June 17 Aug. 14

IET 2813

123 95 85 75

UVT-1 IET IET

2830 2845

123 120 100 95 90 85 70 72

IET 3127

110 88 85 74

a All varieties, except Jaya, are TKM 6 derivatives.

IET 2656 125 100 113 90

UVT-2 IET 2815

119 93

115 84

Ratna

112 95 85 72

Jaya 104 102 100 103


Disease resistance Variation in response of some rice varieties to infection by bacterial blight

Anima Pal and C. R. Das, Rice Research Station, Chinsurah, West Bengal, India

During screening trials of rice for bacterial leaf blight Xanthomonas oryzae (Uyeda and Ishiyama) Dowson induced by clip inoculation, it was noted that some rices varied greatly in response to infection. To examine the consistency in infection response, some released and still-to-be-released rice varieties were subjected to field trials during kharif of 1973, 1974, and 1975 at the Rice Research Station, Chinsurah.

Disease responses in different years varied. The natural bacterial leaf blight pressure was higher in 1973 than in the

two succeeding years. The conditions for disease development might have been favorable in 1973, resulting in higher disease incidence in the inoculated plot in that year than in 1974 and 1975. Comparison of the data for 1973 with those for 1974 and 1975 reveals wide variations in disease response except in a few cases. The 1974 and the 1975 data show greater similarity in the responses of the individual varieties.

The varying response of a variety under different naturally occurring disease development conditions is greatly significant in the assessment of its resistance or susceptibility to bacterial leaf blight in similar environments.


date

Field screening of rice varieties against gall midge and rice tungro virus

U. K. Nanda, N. Shi, R. Naik, and K. C. Das, Regional Research Station of OUAT, Chiplima, Sambalpur, Orissa, India

In the national screening nursery of kharif 1975, 1,223 selections originating from various research stations were screened against gall midge ( Pachydiplosis oryzae ), and against rice tungro virus and its green leafhopper vector ( Nephotettix virescens and N. apicalis ) under high natural pressure. Screening was carried out at Chiplima, a hot spot for both rice tungro virus disease and gall midge. Entries were scored on the standard

0–9 scale. Gall midge incidence was heavy.

was accompanied by epidemic rice tungro virus disease. Only 57 of the entries survived at 50 days after planting. On the 80th day after planting, 18 varieties seemed to promise multiple resistance to the pest and the disease (see table), and survived until harvest. Only one variety, designated 52094 (IR8/MTU10), showed immunity to gall midge; three varieties, RP974-210-10-8, CRM14-29-R-75, and IR2071-621-2-3, were highly tolerant of the rice tungro virus disease.

A high buildup of the green leafhopper

Rice varieties showing multiple resistance to gall midge (GM) and rice tungro virus disease (RTV) in national screening nursery at Regional Research Station, Chiptima, kharif 1975.

Reaction a to Designation Cross

GM RTV

RP10-2 RP633-9-5-8-1 R2353 JR mutant 2-25-4 TNAU13610 RP974-112-1-6 RP974-210-10-8 32343 52094 CRM14-29-R-75 RP825-71-4-9 RP825-71-4-10 RP825-71-4-11 RP825-71-4-1 RP825-71-4-4 lR2071-875-2-3-4 lR2071-621-2-3 IR2071-747-6-3-2 (IR32)

Susceptible checks: for gall midge – Jaya for RTV – TN1

IR8/PTB10 (IR8/BJ1-43) × IR22 W1263/CR10-4011 Rexoro/R11 Co Mutant Sona/RP9-4

W1263/Tella Hamsa lR8/MTU10

Vijaya/PTB21 W1263/SM1-6

3 4 3 3 3 2 2 3 0 3 3 3 4 3 3 2 2 2

9 –

3 2 4 3 3 3 1 2 2 1 3 4 2 3 4 4 1 4

–

9

a Entries were scored for resistance on the standard 0–9 scale: 0–3 = good or high; 4–6 = fair or intermediate; 7–9 = poor or low.

A proposed key to the strains of rice tungro virus

A. N. Basu, M. D. Mishra, F. R. Niazi, and A. Ghosh, Division of Mycology and Plant Pathology, Indian Agricultural Research Institute, New Delhi, India

Since studies on the strains of rice tungro virus (RTV) began in 1967, eight strains have been reported from the Philippines and India. On the basis of the plant symptoms and the varietal reaction to


these strains, we propose a key to characterization of the strains.

In 1967, Rivera and Ou reported two strains of RTV which they designated as “S” and “M” strains. The two strains are differentiable on Acheh, FK 135, and Pacita, which respond to the “S” strain by developing symptoms of conspicuous interveinal chlorosis. The “M” strain produces mottling but not the yellowish stripes characteristic of the “S” strain. Further, the infection by the “S” strain causes much more stunting of FK 135 than does infection by the “M” strain.

Another strain, designated as “T” strain, was reported from the Philippines by Rivera in 1970. This strain produces interveinal stripes on FK 135 but causes much less stunting than the “S” strain or even the “M” strain. The characteristic symptom of the “T” strain is the narrowing of leaves in rice cultivars TN1, IR5, IR8, and IR22.

Subsequent studies in India revealed the occurrence of five distinct strains of RTV, introducing complexity in strain differentiation and nomenclature. Shastry reported the occurrence of two strains in 1972 and designated them as RTV 1 and RTV 2 . Anjaneyulu and John provided evidence of the existence of four RTV strains in India in 1972. They retained RTV 1 as such, divided RTV 2 into the two distinct strains of RTV 2A and RTV 2B , and designated a new strain as RTV 3 . All four Indian strains behaved like the “S” strain on differentials used by Rivera and Ou in 1967, but were separable on the Indian set of differentials consisting of TN1, Pankhari 203, Ambemohar 102, Ambemohar 159, Kamod 253, and Latisail. Another Indian strain, designated as RTV 4 , was detected and characterized by Mishra, Niazi, Basu, Ghosh, and Raychandhuri in 1976.

A key to the strains of RTV (see figure) gives an idea of the latest position in this regard. The “T” strain and all the Indian strains have been grouped here under “S” strain on the basis of the reaction of FK 135.

of the RTV strains, we propose the following modifications: Leaving the “M” strain as such, the various constituents of the “S” strain complex should be designated as “S” in numerical sequence. Accordingly, the strains presently known

and RTV 4 should be designated as S 1

S 2 , S 3 , S 4 , S 5 , and S 6 , respectively. That would systematize the available information.

Because of anomalies in nomenclature

as “T”, RTV 1 , RTV 2A , RTV 2B , RTV 3 ,

A more comprehensive treatment of the subject is not yet possible because the RTV strains in various countries have not yet been identified. The situation calls for immediate study of strain differentiation on a global scale with due care to

"

" " " "

Key to the strains of rice tungro virus. Indian Agricultural Research Institute, New Delhi, India.

A 1 FK 135 shows mottling and no distinct interveinal stripes M strain

A 2 FK 135 shows distinct interveinal stripes

B 1 Produces distinct narrowing of leaves in TN1

B 2 No narrowing of leaves in TN1

C 1 Pacita susceptible. Latisail, if susceptible, shows foliar symptoms.

D 1 Does not infect Ambemohar 159 and Pankhari 203

D 2 Infects both Ambemohar 159 and Pankhari 203

E 1 Latisail resistant

E 2 Latisail susceptible

F 1 Ambemohar 102 and Kamod 253 susceptible. TN1 severely affected initially but later produces green leaves. If not, at least Pankhari 203 and Latisail show masking of symptoms.

F 2 Ambemohar 102 and Kamod 253 resistant. No such recovery or masking

C 2 Pacita resistant. Latisail symptomless carrier

maintain uniformity in experimental material and procedures. The standard set of differentials that we recommend for the purpose consists of Ambemohar 102, Ambemohar 159, FK 135, Kamod 253, Latisail, Pacita, Pankhari 203, and TN1. The differentials should be individually inoculated at the two- to three-leaf stage. To standardize the method of inoculation for determining strains, we suggest that three adults of the vector leafhopper Nephotettix virescens (Distant) that have earlier access to an infected plant for 24 hours be allowed to feed on each test seedling for 6 hours. Data on percentage of infection, extent of stunting, foliar coloration, and reduction of tillering should be recorded at 30 and at 60 days after inoculation.

S strain T strain

RTV 1

RTV 2A

RTV 2A

RTV 2B

RTV 2B

RTV 4

Screening of IRON against sheath blight at CRRI

A. Premalatha Dath, S. Devadath, C. Seshagiri Rao, V. Damodaram Naidu, and Arati Swain, Central Rice Research Institute, Cuttack, India

Three hundred twenty-two entries in the International Rice Observational Nursery were grown in the field and inoculated by inserting a sterile stem piece colonized by Corticium sasakii inside the leaf sheath when the crop was at maximum tillering stage. Very good infection developed in the entries, indicating that in centers such as Cuttack where humidity is very high, the stem-tape-inoculation method need not be used.

At 15 days after inoculation, the

Entries in the International Rice Observational Nursery (IRON) showing moderately resistant reaction to sheath blight and their cross reactions to bacterial blight and bacterial leaf streak at the Central Rice Research Institute, Cuttack, India.

Sheath Bac- Bac-

terial blight a

blight b leaf streak c

Designation

BR 20-28-2 BR 51-74-2 B 189b-29-4-3-1 B 462 b-Pn-1-3 IR578-95-1-3 IR1514 A-E 562-2 lR1704-13-3-2 lR2031-238-4-2-2-3 lR2058-74-2-1 IR2063-65-2-1 IR2068-65-3 IR2070-210-3-3-4 IR2070-439-3-4 lR2071-176-1-5-2 IR2172-64 lR2307-62-4-1 lR2328-27-3-6 IR2561-58-1 IR2562-17-4 IR2688-43-4-3 lR2755-E2-11-1-4 IR2760-E1-33-1-2 IR2793-15-2 lR2796-95-1 IR2844-5-2 lR2844-27-2 A 12-167-3 BW 196 Biplab

Bahagia

Ob 5.677 IR20

IR2070-423-2-5-6

IR480-5-9-3

IR2153-26-3-5-2 lR1917-3-10-3 lRl917-3-19-2

5.3 5.8 5.3 4.5 6.0 5.5 5.9 4.5 4.6 5.3 4.3 5.7 5.1 4.6 5.5 4.2 5.4 4.5 3.7 5.8 5.0 5.5 5.5 6.0 4.0 4.3 5.5 5.4 4.2 4.8 5.3 4.9 5.2 5.0 5.6 5.4 5.1

8 5 7 7 4 5 8 8 6 6 9 6 6 6 6 7 5 4 6 8 5 6 6 6 7 6 9 7 5 6 9 9 8 6 6 7 8

2 3 3 3 4 3 3 3 3 3 2 2 2 3 2 2 3 3 3 2 2 3 3 2 3 3 3 3 4 3 3 3 3 3 3 3 3

a Length of infection spread in cm. b Rated on a scale of 0–9; 0 = no infection. c Rated on a scale of 0–4; 0 = no infection.

extent of infection (total length of the diseased area in cm) was recorded. The entries were grouped tentatively by the following grade system: 1.0 to 3.0 cm, resistant; 3.1 to 6.0 cm, moderately resistant; 6.1 to 8.0 cm, moderately susceptible; and 8.1 cm and above, susceptible.

Only 37 of the entries showed moderate resistance to sheath blight at Cuttack (see table). No entry was graded resistant to sheath blight and no entry was uniformly resistant to sheath blight, bacterial blight, and bacterial leaf streak.


terial

GENETIC EVALUATION AND UTILIZATDN

Insect resistance

Varietal resistance to the brown planthopper Nilaparvata lugens (Stal) and its biotypes

P. K. Pathak and M. N. Lal, G. B. Pant University of Agriculture and Technology, Pantnagar (Nainital), Uttar Pradesh, India

IR26, bred for resistance to the brown planthopper (BPH) Nilaparvata lugens (Stal) at the International Rice Research Institute (IRRI), was introduced into Kerala after a 1973–74 BPH outbreak and was found to be susceptible there. Confirmation of that finding from various stations in India and Sri Lanka indicated the existence of a BPH biotype different from that at IRRI, and led to the study of Indian biotypes.

In 1975, varieties from the International Rice Brown Planthopper Nursery (IRBPHN) were screened for resistance to separate BPH cultures from Hyderabad and Pantnagar. First-

and second-instar nymphs were released on 10-day-old seedlings, whose reactions were scored on a 0–9 scale (0 = no damage; 9 = complete kill) when more than 95 percent of Taichung Native 1 (TN1) (susceptible control) plants were killed (see table).

resistant at Hyderabad (M. B. Kalode, 1976) and at Pattambi (B. Thomas, 1976). We also found ARC 6650 highly resistant to the Hyderabad culture. However, when it was screened for resistance to the Pantnagar culture, it scored 5.5; all the plants later succumbed to BPH damage. Gangala also reacted differently to the Hyderabad and Pantnagar cultures.

6650, Gangala, and Ptb 33 to BPH strongly suggest the existence of different biotypes in India. This possibility is being investigated.

Ptb 33 and ARC 6650 were reportedly

The differential reactions of ARC

Reaction of rice varieties to the brown planthopper in India.

Variety/germ plasm

Andaraghawewa Dalwa Sannam (Mtu 15) Thella Gerikasanavari (SLO 12) Ptb 21 RP 9-6 IR26 C 62-1-373 ASD 7 H 5 Murungakayan 3 Murungakayan 101b Murungakayan 303b Palisithari 601 Ptb 19 Chianung-Sen-yu 11 Co 9 ARC 6650 Muthumanikarn

Gangala Ptb 33 TN1

C 62-1-230

Resistant Reaction a

gene Pantnagar Hyderabad

Bph 1

bph 2

? ? ? ? ? ? ? ?

8.5 9.0 9.0 8.8 8.8 9.0 7.8 9.0 7.0 9.0 8.5 8.8 8.6 8.5 9.0 9.0 5.5 9.0 7.5 8.5 4.0 b

9.0 a Reaction score based on a 1-9 scale: 0 = no damage, 9 = complete kill. b Score based on 3 plants. c Reported from Hyderabad as resistant.


9 9 9 8.5 8.3 8.5 7.7 9.0 9.0 9.0 9.0 8.6 8.0 8.3 9.0 9.0 0.2 9.0 9.0 5.5 R c

9.0

Brown planthopper damage in Sri Lanka

A. M. Abeyratne, Secretary, Shramadana Committee, Palugolla, Hunupola, Nikadalupotha, Sri Lanka

Widespread infestations by the brown planthopper frequently destroy crops in Sri Lanka. In 1974 about 400 ha were damaged even though sprayed with agrochemicals by helicopter. The use of resistant H-501, BG 11/11 has been considered effective, but not entirely. In my own research I find that varieties with wide leaves and thick stems are more susceptible. Lines with a large number of silica cells have been found more resistant. The breeding of varieties containing much silica should receive more attention.

Brown planthopper outbreak in Bangladesh

S. Alam and A. N. M. Rezaul Karim, Bangladesh Rice Research Institute, Joydebpur, Dacca, Bangladesh

The brown planthopper (BPH) Nilaparvata lugens was first definitely recorded in Bangladesh in 1969, but its presence in undivided Bengal since 1917 is suggested by synonyms. A 1957 report also indicated the pest’s presence.

In Bangladesh, the first outbreak of BPH occurred in April–May, 1976, on boro (November–May) rice crops near Dacca city. IR8 and BR 3 fields of about 4 ha were burned in patches. The crops were in milky to hard-dough stage. Pajam II was free of infestation. The weather was dry, but the affected plots had standing sewage water. The hopperburned plots had 100 to 200 insects per hill. A second outbreak occurred in October, 1976, at the BRRI farm on the aman (July–December) crop of BR 3 which has luxuriant growth and heavy foliage. The affected plots had standing irrigation water, although the weather was mainly dry. Heavy BPH infestation (1,000 to 2,000 insects/hill) was accompanied by hopperburn. Adjacent plots with variety BR 4 also had heavy BPH populations.

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" " " " " "

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Pest incidence in Central Luzon, the rice granary of the Philippines

Isaias T. Domingo, Entomology Department, International Rice Research Institute

A team from the Entomology Department of IRRI investigated the incidence of rice pests in farmers’ fields at more than 100 sites in five provinces of Central Luzon: Bulacan, Pampanga, Nueva Ecija, Tarlac, and Pangasinan. About 95% of the area surveyed was planted to improved varieties. About 25% of the planting were the improved short varieties IR26, IR30, IR32, IR36, and IR38 which have insect and disease resistance and high yield potential. About 70% were the short or tall varieties and lines IR5, IR8, IR20, IR22, IR747, IR1529, IR1561, C4-63G, C4-137, and C22 which have high yield potential but are susceptible to insects or to diseases, or to both. The remaining 5% were local varieties Burma, BE3, Kennedy, Milagrosa, Tjeremas, glutinous rice, and others.

In several barrios of Candaba, Pampanga, both local and improved varieties (including IR26) and lines, except IR32, IR36, and IR38, were infested with the brown planthopper Nilaparvata lugens, the rice leaf folder Cnaphalocrosis medinalis, the white-backed planthopper Sogatella furcifera, and the green leafhopper Nephotettix virescens. From a distance, the slightly pale, yellow color of the rice plants could be mistaken for nitrogen deficiency. Close examination showed brown planthoppers at 1,000 nymphs/hill. In the adjacent rice fields the curled-up, whitish leaves of the rice plants were more visible. The farmers thought that planthoppers were causing the damage; the damage was in fact caused by the rice leaf folder.

In Bulacan and Nueva Ecija where larger tracts of rice land were surveyed, the plants were severely infected by tungro virus, and infested with more than 100 green leafhoppers/hill. Such pest populations, even without tungro, could cause severe stunting and yellowing. Fields planted to IR32, IR36, and IR38 showed strong resistance to

tungro and its vector. Stem borer damage was not significant.

In Tarlac and Pangasinan, insect infestation was very low; tungro was randomly distributed. The limited insect

damage was related to the low insect pest incidence rather than to the use of resistant varieties since most farmers in that area still plant traditional varieties.


Drought tolerance

Screening for seedling drought response

J. C. O’Toole, S. K. De Datta, and R. S. Aquino, Agronomy Department, The International Rice Research Institute

Because undependable or erratic onset of monsoon rains is common in many regions where rainfed rice is grown, seedling-stage drought is a major obstacle to crop establishment.

Breeders recognize the problem, but little organized screening of rices for reaction to seedling-stage drought has been done. Earlier, we developed a greenhouse technique to screen rices for drought tolerance at various growth stages using a natural-drying-of-soil concept. It gave reproducible results using the variety Moroberekan as a susceptible check variety, and IR1529-430-3 as a tolerant check. In the IRRI phytotron, we screened 206 rices from rainfed upland, lowland, and deep-water regions (deep-water rice is

A test in the IRRI phytotron demonstrates varietal differences found in the percent of survival (%S) of eight cultivars subjected to seedling drought. (The IR20 rows are guard rows.)

Seedling survival of rices from varying hydrological and cultural origins after exposure to severe growth chamber drought.

Survival rate (%) after exposure a for

7 days 10 days 12 days 15 days Variety/line Origin b

Rikuto Norin 21 Kinandang Patong 30-E 63-83 Monura Rangi Kharna Sigadis (check) Khao Dawk Mali 4-2-105 Goirol

Japan (U) Philippines (U) Liberia (U) Ivory Coast (U) Bangladesh (DW) Bangladesh (DW) Indonesia (RL) Thailand (RL) Bangladesh (DW)

0 3 3

65 85 95 98

100 100

0 3 0 5

37 90 83 75

100

– – – – – 5

26 30 60

– – – – – 0 0 0 5

a Rices with survival rate less than that of the check (Sigadis) at 10 days were not tested at 12 and

b U = upland; DW = deep water; RL = rainfed lowland. 15 days.


often sown in dry soil before flooding) for survival after severe soil and atmospheric drought.

Considerable variation was found in the rices representing a cross section of the hydrologic environments where rice is cultivated (see fig.). Surprisingly, upland rices were less well adapted to the test conditions than were rices from lowland and deep-water regions (see

table). The rices that had high survival rates were from areas prone to seedling- stage drought problems.

Detecting rices from the areas where natural selection has been acting gives confidence in the procedure. A similar procedure is currently used in a greenhouse to screen large numbers of varieties.


Deep water Deep-water rice workshop D. L, Esslinger, Office of Information Services, International Rice Research Institute The Deep-Water Rice Workshop, November 8-10, 1976, in Bangkok, Thailand, sponsored by The International Rice Research Institute (IRRI) in cooperation with the Thailand Ministry of Agriculture and Cooperatives, covered a variety of topics:

• Flowering responses of floating rices • Morphological, physiological, and

anatomical differences of varieties adapted to deep water

• Estimating heritability of elongation ability in crosses between floating

Participants in the 1976 Deepwater Rice Workshop toured the Thailand central plains and saw deep-water experiments in farmers’ fields and at the Huntra Rice Experiment Station. Left to right are Dr. P. B. Escuro, FAO rice improvement specialist, Burma; Dr. K. Zan, general manager, Agricultural Research Institute, Burma; and Dr. M. S. Ahmed, plant breeder, Bangladesh Rice Research Institute.


varieties and high yielding semidwarfs

elongation ability if one parent is a floating rice

development of photoperiod- sensitive deep-water hybrids

distinguishing between seedlings of floating and nonfloating varieties, rapid internode elongation, submergence tolerance, drought tolerance, and kneeing ability

• Nitrogen response of plants with elongation ability

• Yields of new semidwarf hybrids with elongation genes

• Pest management in deep-water rice • Results from the first International

• Seedling height as a predictor of

• A new procedure for rapid

• Screening for elongation,

Rice Deep Water Observational Nursery

• National research progress Recommendations were made for new

deep-water rice terminology and a new standard scoring system for measuring elongation ability of deep-water rice.

Determination of the adaptation of rice genotypes to water deeper than 30 cm — a new formula

D. K. Mukherji and S. K. Bardhan Roy, Rice Research Station, Chinsurah, West Bengal, India

A new formula for determining the floating ability or the adaptation to deeper-than-normal water in rice genotypes has been evolved. For better

Two indicators of water-depth adaptability of rice genotypes.

Rice genotype X F F D

Very high adaptability HTA 16-CNB-5 OC 1393 (M)-29 OC 1393 (M)-88 HTA 22-CNB-3

88.79 86.84 82.61

102.65

High adaptability HTA 826-CNB-23 87.83 HTA 108-CNB-24 75.35 HTA 448-CNB-16 88.64 OC 1393 85.38

Moderately high adaptability Pankaj HTA 171-CNB-12 HTA 607-CNB-8 Pankaj(M)-107 Pankaj(M)-86 Pankaj(M)-91

73.62 87.37 81.02 69.38 73.36 73.10

Low adaptability IR442-2-58 62.57

173.95 170.21 170.1 5 169.15

158.34 156.1 9 145.06 140.94

134.45 133.74 130.18 129.72 129.63 120.50

117.97

interpretation of field screening work, it may replace Morishima’s 1974 formula, at least in situations where water rises to 90 cm. Morphological data were taken from 15 rice genotypes grown at normal (up to 10 cm) and above-normal (up to 90 cm) water depths in fields at the Rice Research Station, Chinsurah (West Bengal) in 1975 kharif (wet season). Morishima’s X F values and the authors’ F D values showed wide differences. Field observations tallied closer with the latter. A scale for interpreting the values classifies the genotypes into four groups: very high ( F D 140–159), moderate ( F D 120–139), and low ( F D below 120) adaptation to increasing water depths (see table).

F D is: A + 0.5 B + 0.2 C + D - 0.25 E Where: F D = floating ability or adaptation to

deeper-than-normal water.

3 cm;

normal water;

The suggested formula for calculating

A = number of internodes longer than

B = final height with deeper-than-

C = total increase in stem length; D = total increase in stem length from

sowing until 81 days later; C

stem elongation of normally grown plants

E = × 100

A standard scoring system for measuring the elongation ability of deep-water rice.

Score Description Biological check

0

1

3

5

7

9

- - - - - - - - - - - - - - - - - - - - - No information - - - - - - - - - - - - - - -

Best elongation response

Response better than that of T 442-57, not as good as that of the best local floating variety

Response equivalent to that of T 442-57

Response better than that of the nonelongating semidwarf, not as good as that of T 442-57

Poorest elongation, or none

Best local floating variety

T 442-57

Non-elongating semidwarf

Scoring the elongation ability of deep- water rice

M. S. Ahmed, Bangladesh Rice Research Institute; S. K. De Datta and D. HilleRisLambers, International Rice Research Institute; U. O. Kjaw, Agricultural Research Institute, Burma; Y. Ohta, University of Tsukuba, Japan; S. Subiyanto, Central Research Institute for Agriculture, Indonesia; and Nopporn Supapoj, Thailand Department of Agriculture

A standard scoring system (see table) for measuring elongation ability of deep- water rice was approved by the 1976 Deep-Water Rice Workshop. It is recommended as a replacement for that currently described in the Standard Evaluation System for Rice. It is used as follows:

1. Direct seed 5 g pregerminated seed for each 125-cm row in a wetbed nursery.

2. 0 to 30 days after seeding (DAS): Manage like lowland rice. Water depth

should not exceed 10 cm.

each row. 3. 30 DAS: Estimate percent stand in

4. 31 DAS: Increase water depth to 25 cm.

5. 33, 35, 37 etc. DAS: Increase water level by a maximum of 10 cm on alternate days until target depth is reached. Record scores at or near target depths of 50, 150, and 200 or more cm. As the biological check for the 50-cm target depth, use a nonelongating semidwarf. For 150 cm use T 442-57; for more than 200 cm use the best local floating variety. NOTE: If leaves of the check variety are visible above water on the second day at any target depth, add enough water to submerge them.

6. Score the plants at the target depths. Scores should indicate water depth and elongation behavior. For example, a score of 160-5 indicates that at a 160-cm depth the entry’s response was like that of T 442-57.

Deep water rice terminology

B. S. Vergara and H. D. Catling, International Rice Research Institute; S. M. H. Zaman, Bangladesh Rice Research Institute; and S. Saran, Agricultural Research Institute; and S. K. Datta, Chinsurah Rice Research Station, India

Scientists attending the 1976 Deep Water Rice Workshop in Thailand adopted a terminology which they recommended for use by all researchers:

1. Elongation – increase in plant length resulting from elongation of internode, leaf sheath, blade, or combinations. When necessary, specific plant parts should be designated, e.g. internode elongation.

2. Basal tillers, basal roots – tillers or

3. Nodal tillers, nodal roots – tillers or roots produced from the basal nodes.

roots which arise from the nodes above the plant base. The term “nodal” is used to differentiate them from the tillers produced on the upper nodes. The term “aerial tiller” and “branches” should be discarded.

4. Kneeing – change of direction of upper plant portions from horizontal towards the vertical.

mature plants, the first internode, the internode responsible for the exsertion of the panicle, is designated as n–0; lower internodes are designated successively as n–1, n–2, n–3, n–4.

5. Designation of internodes – In the


Temperature tolerance

Indonesian rice line named as variety for Philippine mountainous areas

Agapito Ronduen, Philippine Bureau of Plant Industry, and Rey Villareal, International Rice Research Institute

An early maturing line from Indonesia, Kn-1b-361-1-8-6-10, was approved as a new variety under the name RP Kn-2 by the Philippine Seed Board in April 1976. It is being multiplied by the Philippine Bureau of Plant Industry (BPI) for release to farmers in mountainous regions of the Philippines. RP Kn-2 is 90–120 cm high and resistant to lodging. It has from 10 to 13 productive tillers per plant.

600 rices from 10 countries and from IRRI that were screened by the BPI and IRRI under the unusually cold conditions of the ancient lfugao rice terraces of Banaue, Philippines, through the first International Rice Cold Tolerance Nursery (IRCTN). Its early maturation should make possible the growing of two rice crops per year in the mountain provinces where only one has traditionally been grown. RP Kn-2’s yields are higher than those of local varieties, especially if a moderate amount of complete fertilizer is used. In 1975 tests, they were 5.5 t/ha in the dry season and 2 t/ha during the wet season. RP Kn-2 is resistant to bacterial blight. Its eating quality is lower than that of local varieties, but as good as that of lowland varieties now imported into the Philippine mountains.

Jerak is a high-elevation rice from Indonesia. Lines from the Kn 361 cross have also performed well at high elevation in other countries in the IRCTN.

RP Kn-2 was selected from more than

Parents of RP Kn-2 are IR8 and Jerak.


GENETIC EVALUATION AND UTlLIZATlON

Protein content

High-protein mutants in rice

M. L. H. Kaul and N. K. Matta, BNC University, Kurukshetra, India

Rice is the main source of calories and protein for more than two thirds of the world's population. An increase in the protein content of rice would substantially improve the protein intake of rice consumers. Three of the most common locally grown rice varieties. Basmati 370, Jhona 349, and IR8, were subjected to (a) 20,30,40, or 50 kR gamma rays at 1,250 rad/min with a CO 60 source of IARI, Delhi, or (b) 0.5, 1, or 1.5% aqueous solutions of EMS or DES for 6 hours. From nearly 40,000 plants, 396 mutants were isolated in M2 and carried to M3 generation. Of these, 24 mutants exhibited enhanced seed protein content (see figures).

IR8 mutants IRm 1 to 12 have improved grain type and early maturity; IRm 13 is small grained; and IRm 14 to I7 are fine grained, early, and high yielding. The seed protein production of IRm 17 is the highest, followed by that of mutant numbers 16, 14, 15, 5, 12, and 2. IRm 16, 17, 14, and 15 are fine grained, early, and high yielding; however, they exhibit some degree of lodging under heavy fertilization. They represent the most promising mutants and donors for breeding an improved IR8 that has the ideal plant type visualized by earlier writers. The Jhona mutants Jm 12, 11, and 4 possess very high grain yield and seed protein production; Jm 4, a dwarf like Jm 11, also resists lodging. Bm 6 and Bm 7 represent the most promising mutants of Basmati. They are dwarf and high yielding, with tremendously enhanced grain and seed protein production, but have a slightly reduced grain fineness.

to 17 of IR8, Bm 6 and 7 of Basmati, and Jm 12 of Jhona are the most reliable genotypes (as judged by number of

Among the improved mutants, IRm 14


grains per panicle) for use in further breeding programs. However, while the grain fineness of most is improved, it is

reduced in the Basmati mutants. Also, the improved mutants Jm 4 and 11 have fewer grains per panicle than Jhona.

Grain yield and seed protein content of some high protein mutants ot rice, Kurukshetra, India.

Total seed protein production of some high protein mutants of rice, Kurukshetra, India.

Pest management and control DISEASES

A note on some direct and indirect effects of Udbatta disease on some rice yield components

N. Shivanandappa, junior pathologist, Regional Research Station, University of Agricultural Sciences, Mission Compound, Shimoga, Karnataka, India

A study at Mandya, India, in kharif 1974 showed a reduction in the number of healthy panicles, panicle length, number of primary rachis per panicle and grain weight per hill of rice culture MR 81 that had been affected by Ephelis oryzae Syd. – Udbatta disease (see table).

Shivanandappa et al. earlier reported yield loss in Udbatta-affected MR 118 paddy culture to be 2.44 panicles/hill with an intensity of 2.59. In another study, Shivanandappa and Govindu found that in MR 81 the direct and indirect losses due to Udbatta disease were 2.04 and 0.36 panicles/hill. The slight differences in direct and indirect losses in the present study may be due not only to varietal differences but also to the higher intensity of the disease. The data confirm that Udbatta disease affects the rice plant both directly and indirectly.

Effect of Udbatta disease on some yield components and yield of paddy culture MR 81. Rice Research Station, Mandya, 1974.

Primary Panicles (no.) Panicle rachis Grain

length per weight (cm) panicle (g/hill)

(no.) Healthy Diseased Total

Healthy hills Diseased hills Loss

10.82 9.24 1.58

1.30 1.30

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Simultaneous occurrence of node blast and stem rot on Basmati 370

B. K. Rattan and C. D. Mayee, Regional Rice Research Station, Punjab Agricultural University, Kapurthala, India

At the Regional Rice Research Station, Kapurthala, Punjab, rice variety Basmati 370 was simultaneously infected by two diseases, node blast caused by Pyricularia oryzae Cav., and stem rot caused by Magnaporthe salvinii (Catt.) Krause and Webster. To examine the possible relationship between the two diseases, we studied five blocks of Basmati 370 which were uniformly affected by node blast and stem rot.

between node blast and stem rot. Although blast incidence was low and stem rot was high, they decreased panicle weight both individually and in combination.

Results indicated a definite association

10.82 10.54 0.28

16.15 15.65 0.50

7.18

0.35 6.83

15.30 12.45

2.85

Averaged over different categories, node blast and stem rot registered 17.09 and 35.87 percent infection, respectively. A high positive correlation (r = 0.926) between occurrences of the two diseases indicated that the increase in one was accompanied by corresponding increase in the other, and the reduction in panicle weight on account of either disease was stimulated by the other.

Although the incidence of stem rot was higher than that of node blast, the reduction in panicle weight due to node blast was appreciably greater than that due to stem rot.

Both diseases usually appear late in rice growth. The stem rot pathogen is an established wound parasite. Wounds may be caused by such factors as insect attack or lodging. Node blast causes lodging; thus it is logical to expect more severe stem rot in plants that are infected by node blast. Earlier, researchers had

reported varieties of the Basmati group to be resistant to stem rot in Punjab. The decline of relative resistance may be due partly to the predisposition to stem rot development of Basmati 370 infected by node blast.

Seminar on planthoppers and leafhoppers of the rice crop, Yogyakarta, Indonesia, June 1–3, 1976

O. Mochida, IRRI-Central Research Institute for Agriculture (CRIA), and S. Tatang, CRIA, Sukamandi, Indonesia

A seminar on rice planthoppers and leafhoppers was held at the first meeting of the Entomological Society of Indonesia (President, Ir. Soenardi). It was sponsored by the Faculty of Agriculture of Gadjah Mada University and the Entomological Society. About 200 participants, including plant protection specialists, entomologists, agronomists, breeders, and agricultural spray pilots attended. Thirty-six papers were presented. The participation of many persons in various fields indicated the importance of the brown planthopper in Indonesia. About 290,324 tons of rice were lost to the brown planthopper and to grassy stunt virus in the fiscal year 1974–75.

Influence of nitrogen fertilization on the development of bacterial blight

S. Kannaiyan, A. Venkata Rao, T. L. Subramanian, K. Chandramani, and K. Tera, Regional Agricultural Research Station, Aduthurai, Tamil Nadu, India

EDITOR’S NOTE: In the article carrying the above title, which appeared in IRRN 1:1 (October 1976), the name of the senior author, S. Kannaiyan, was inadvertently omitted.


Preliminary observations on the incidence of some rice diseases in relation to planting dates and growth stages

Anima Pal and C. R. Das, Rice Research Station, Chinsurah, West Bengal, India

Knowledge of changes in the disease situation due to shifts in environmental conditions, and of the occurrence of diseases at particular stages of crop growth permits the selection of the proper screening season and the testing of breeding populations against particular diseases. We undertook a field experiment with different planting dates and observed the attendant disease situations at the Rice Research Station, Chinsurah. TN1 and Padma were used as test materials. Transplanting began in the first week of December 1973 and

continued at monthly intervals until October 1974.

Rice tungro, bacterial blight, and sheath rot were observed at three stages of growth: 1) early tillering, 2) maximum tillering, 3) 15 days after flowering. The preliminary results indicated that the incidence of the diseases differed in relation to planting dates as well as to stages of crop growth (see figure). The period of susceptibility to tungro was from September to October; to bacterial blight, from February to August; and to sheath rot, from December to May. While the crop is susceptible to tungro at the early and maximum tillering stages, and to bacterial blight and sheath rot at the flowering stage, the period of susceptibility to any disease may vary, depending on the factors that favor its development.

Incidence of three diseases of rice in relation to planting dates and stage of plant growth, Chinsurah, India, 1973-74.


Pest management and control INSECTS

The rice brown planthopper Nilaparvata lugens Stal in Karnataka, India

G. P. ChannaBasavanna, G. Gubbaiah, P. Shivaram Rai, and M. Mahadevappa, University of Agricultural Sciences, Bangalore, India

In recent years the brown planthopper Nilaparvata lugens Stal (BPH) has been reported in epidemic form in several countries of Southeast Asia. India reports its appearance as a serious pest in fairly large tracts of rice in various places. However, the literature has had no report of its occurrence as a pest in Karnataka state.

In May 1975, BPH was noticed in a form so severe as to cause hopperburn patches in one rice field near Mandya. Later during kharif (July–October) 1975, the pest was reported from Mandya, Mysore, Shimoga, Chitradurga, Chickmagalur, Bangalore, Bellary, Tumkur, Raichur, and North Kanara districts in Karnataka. Thus, the pest appeared to be widespread in Karnataka, though in small patches in each place. Some rice varieties that have been attacked are Jaya, IR20, MR 301, IET 2295, and S 701. BPH infestation seems likely to become severe in all rice-growing areas of Karnataka.

Occurrence of rice mealy bug in Kerala

K. V. Mammen, senior entomologist, Rice Research Substation, Moncompu, Kerala, India

The rice mealy bug Ripersia oryzae Green, considered a minor pest of paddy, has recently become important in parts of Quilon and Alleppey Districts in Kerala. Infestation was severe in the first crop paddy sown in April-May in unirrigated and upland fields. Lack of monsoon rains aggravated the infestation.

Farmers considered the damage to be a result of the unexpected drought and took no protective measures.

Infestation started in patches and spread to entire fields. The infested plants became stunted; leaves started to turn yellow and to dry. In severely infested fields, tillers were covered with thousands of nymphs and adults, giving them a whitish, waxy coating. The insect outbreak may be attributed to the inordinate delay of the monsoon rains during the growth phase. The infestation was reduced after the rains. Farmers were advised to spray phosphamidon (0.05%) or dimethoate (0.03%), or to apply carbofuran (0.5 kg a.i./ha) or phorate (1.2 kg a.i./ha) granules.

IRRI 1976 insecticide evaluation results available

The results of laboratory and field evaluation of insecticides conducted at IRRI in 1976 are available. The report includes not only results of coded and named insecticides but also results of various methods of application. The report can be obtained free of charge by writing the Head, Department of Entomology, IRRI, P.O. Box 933, Manila, Philippines.

Rice insect pests in Laos

G. J. W. Dean, Entomology Department, Rothamsted Experimental Station, Harpenden, Hertfordshire, England

The insect problems of rice in landlocked Laos, where a single crop of predominantly local, glutinous varieties is grown, were investigated in 1973–75. Insect populations were generally low. Insecticide control was usually not required and probably not economically feasible.

The most common pests on upland rice were the Bombay locust Patanga succincta L. and the bugs Nezara viridula L. and Leptocorisa spp. In contrast, those insects were uncommon on lowland paddy rice, which had more of the smaller grasshoppers Oxya and Euscyrtus spp. in the seedbeds, and stem borers Sesamia inferens (Walk.) and Chilo spp. in the transplanted rice. Few rice gall midges Pachydiplosis oryzae

(Wood-Mason) or whorl maggots Hydrellia philippina Ferino were found.

Few cicadellids and delphacids were found on the local rice varieties; small, experimental plots of IR varieties were often more heavily infested with Nephotettix spp. and Nilaparvata lugens Stål.

Stem flies in Haringhata, Nadia, West Bengal, India

P. Sen and S. Chakravorty, Faculty of Agriculture, University of Kalyani, West Bengal, India

Four stem flies, Atherigona indica Mall, Oscinella sp., Steleocerus ensifer Thom, and Gaurax sp., belonging to the families Anthomyiidae and Oscinidae ( Diptera ), were found responsible for extensive damage to rice seedlings in upland rice nurseries of four rice varieties.

Damage, starting after the seedlings were about 3 weeks old, was visible even 3 weeks after transplanting. The usual symptoms were the withering of central leaves, yellowing of leaf sheaths, and root rot.

Mortality among young seedlings in field nurseries may even reach 50% in a transplanted experimental plot it was 33%.

Infestation rates in the different varieties of the aus and aman rices tested were significantly different. A maximum of 9.5% infestation was found in the variety Kalma 222 of aman rice. In the Dular variety of aus rice, the rate was only 0.7%. Different stem fly species were never found on the same plant.

Occurrence of a mite in Tainan District, Taiwan

Yung-Tung Ou, Tainan District Agricultural Improvement Station, Taiwan, Republic of China

Sterility of rice is epidemic in Tainan District during the second crop and causes extensive damage. It has occurred for some time now but its cause is still unknown. Recently, while examining rice ears and sheaths under a microscope, we unexpectedly found many mites. The density of adults and eggs was high.

The mite Steneotarsonemus madecassus is new to Taiwan. It could be the major cause of the sterility. Farmers, however, have not been aware of its importance.

S. madecassus in Tainan District. About 20 percent of the crop was seriously damaged. All varieties except indicas were attacked. The outbreak may be attributed to high levels of synthetic organic phosphorus insecticides applied to rice, and to prohibition of the use of synthetic organic hydrochlorinated insecticides. As one of the phoretic mites, S. madecassus may be spread by insects or other arthropods. Note: Anyone who has observed a similar problem is invited to write to the editor or to Mr. Ou. Replies to IRRN may be published.

Some 2,000 ha have been infested with

A note on the chemical control of Dichdispa armigera Olivier in a rice nursery

G. V. Subbaratnam and A. Perraju, Entomology Department, Agricultural College, Bapatla, Guntun District, Andhra Pradesh, India

Because Dicladispa armigera Olivier has been a serious pest of rice since 1970 in all the coastal districts of Andhra Pradesh, India, the effect of various chemicals (granular and spray) against hispa in the nursery was studied. Tested in granular form were chlorpyrifos, basudin, carbaryl-lindane, disulfoton, phorate, monocrotophos, endosulfan, BHC, fenthion, chlorfenvinphos, and quinalphos. Tested in sprays were fenitrothion, dichlorvos, phosphamidon, Ambithion, carbofuran, and monocrotophos. The granular formulation was applied with the seed. The germination rates of seed, the phytotoxic effects of the chemicals, and the mortality of the beetles released on the germinated seedlings were recorded. Length of root and shoot, number of leaves, and wet and dry weights were measured. The foliar chemicals were sprayed 15 days after sowing. Beetles were released on the seedlings 15 days after sowing; their mortality was recorded daily up to 35 days after sowing.


None of the insecticides retarded seedling growth at the tested doses. Chlorpyrifos, disulfoton, monocrotophos, endosulfan, and basudin favored seedling growth. Of the granular formulations, phorate at 12.5, 10.0, and 7.5 kg a.i./kg seed per hectare was effective against the pest both in initial and residual toxicities; it was closely followed by chlorfenvinphos and disulfoton at 12.5

kg a.i. Next in order of effectiveness were chlorfenvinphos and disulfoton at 10.0 kg a.i., fenthion at 12.5 and 10.0 kg a.i., and quinalphos and chlorpyrifos at 12.5 kg a.i. Among the foliar sprays, carbofuran at concentrations of 0.1% and 0.075% was superior. Monocrotophos was next in effectiveness.

application of phorate at 7.5 kg a.i./350 It was concluded that a single

kg seed per hectare, applied along with rice seed, can keep it free of the adult D. armigera throughout the nursery period. Carbofuran at 0.1% is the choice among foliar sprays. The granules were tried at high levels to check for adverse effect on the seedlings. Very low levels of 1 to 1.5 kg ai. were also found effective.

Residues of phorate-gamma BHC and mephosfolan in Jaya grain and straw

P. B. Chatterjee, entomologist, Operational Research Project on Integrated Control of Rice Pests, Pandua, Hooghly, West Bengal, India

Granular insecticides, introduced on a large scale in India during 1967 and 1968 have become popular with lndian farmers. Following application, translocation may result in retention of small quantities of poisons or their metabolites in the plant tissue. In view of the possible health hazard, it is imperative to analyze quantitatively the residue to find out if it is below or above the tolerance limit.

Two recently introduced granular insecticides, phorate-gamma BHC — Paddigard 7.5 G, containing 5% phorate (thimet) plus 2.5% BHC — and

mephosfolan (Cytrolane 5 G), were tested during boro (summer season) to determine the residues in the grain and straw of Jaya. Table 2. Cytrolane residue a in Jaya rice grain and straw.

Cytrolane (ppm)

Grain Straw Treatment

Cytrolane 5 G 0.5 kg/ha at 25 and 55 DT




Control

0.03

0.06

0.06

0.04

0.04 a Mean of 3 replicates. DT = days after transplanting.

0.13

0.36

0.1 3

0.28

0.01

Table 1. Phorate and gamma BHC residues a in Jaya rice grain and straw, Burdwan, India.

Treatment

Paddigard 7.5 G 1.5 kg/ha at 25 and 55 DT b

Paddigard 7.5 G 1.5 kg/ha at 25 and 70 DT

Control (grain)



Control (straw)

Phorate Phorate

analogue analogue Phorate oxygen oxygen sulphone

Phorate Gamma BHC (ppm) sulphone (ppm)

(ppm)

(ppm) (ppm)

0.02

0.02

0.02

0.02

0.02

0.02

0.04

0.04

0.04

0.05

0.05

0.05 a Mean of 3 replicates. b DT = days after transplanting.

Grain

0.06

0.06

0.06

Straw

0.06

0.06

0.06

0.04

0.04

0.04

0.05

0.08

0.04

0.02

0.02

0.02

0.06

0.06

0.06

Each of the seven treatments was replicated three times in the experimental plots in Burdwan, India. Impounded water was maintained at a depth of about 4 cm during the vegetative and reproductive phases. The soil was fine loamy (clay loam). After harvest, random samples of rice and straw were airshipped to the ACCO Product Development Laboratory, Europe-African Region, Gosport, England, for gas-liquid chromatographic assay. The results are summarized in Tables 1 and 2.

Operational Research Project on Integrated Control of Rice Pests

P. B. Chatterjee, entomologist, Department of Agriculture, Pandua, Hooghly, West Bengal, India

The intensification of farming practices, deforestation, indiscriminate use of pesticides (especially broad-spectrum and persistent ones) and a consequent decline in population of natural enemies of insects, and other disrupting forces in the ecosystem have accentuated the problem of insect pests on rice, particularly in the warm and humid tropics. Generally the nontolerant high-yielding rice varieties (HYV) suffer most from insect damage, especially during kharif (wet season) when the main rice crop is grown. Low yield associated with the kharif crop may be one reason for limited use of HW during that season.

An “Operational Research Project on Integrated Control of Rce Pests,” drawn up by the Indian Council of Agricultural Research, started to function during kharif 1975 in the pest-prone area of Pandua, Bengal. Its principal objectives are 1) to determine why only about 15


percent of farmers’ fields carried HW during kharif, 2) to determine the constraints on the transfer of technology and the constraints the farmers face in efficient pest management, and 3) to study how the gap between the farmers’ yield and that achieved at rice experimental stations can be minimized. The farmers are being trained and encouraged to adopt improved packages of practices; to integrate different methods of pest management such as nursery treatment, use of more or less specific pesticides (preferably granular formulations when the insect population is at the economic threshold), weed control, land tillering after harvest, close cutting of the crop, planting of resistant varieties, use of light traps for monitoring; and surveillance, crop rotation, and other relevant practices.

The Operational Research Project on Integrated Control of Rice Pests aims at an interdisciplinary attack on other farmers’ problems as well as pest management.

Some insecticide schedules tested against the paddy ear-cutting caterpillar in rice

D. Konar, research fellow, and Lallan Rai, professor and head, Department of Entomology and Agricultural Zoology, Banaras Hindu University, Varanasi, India

Some insecticide schedules were tested in 4- x 3-m plots of Saket-4, a rice that matures in about 110 days, during the July–October 1975 season at the Regional Agricultural Testing and Demonstration Centre, Varanasi, India. Combinations of paddy-water application of carbofuran, mephospolan, phorate, and disulfoton granules, and foliar sprays of fenitrothion and Ambithion were tested. Larval counts were taken at 76 days after transplanting (DT) by checking 20 hills diagonally across each plot.

The poorest control (1.8 larvae/hill) was attained with one application of 1.2 kg a.i. disulfoton/ha at 25 DT. None of the granules or sprays provided adequate control when applied alone. Results indicated that granules should be applied in combination with foliar sprays up to 65 DT to control ear-cutting caterpillar on early maturing varieties.

Incidence of rice gall midge and its parasites in Karnataka, India

P. S. Rai, Gavi Gowda, and B. S. Naidu, University of Agricultural Sciences, Regional Research Station, Mandya, Karnataka, India

The rice gall midge is endemic in coastal Karnataka State. During the last 3 years, its presence has also been noted in the interior. Incidence has been severe in the summer crop. In summer 1975, 49 slender-grain cultivars were planted in three replications. The growing season varied from 92 to 120 days. The percentage of hills showing galls varied from 16.6 to 70.3. The number of galls per square meter varied from 9.5 in IET 3368 to 65.5 in IET 3201. All cultivars were susceptible to attack.

collected in the field, the following parasites emerged in the laboratory:

Platygasteridae – Platygaster sp. Eupelmidae – Neanastatus grallarious

Eulophidae – Tetrastichus sp. Braconidae – ? Gyrocampa sp. Ichneumonidae – Gelis areator

(Panzer) Ceratopogonidae – Unidentified

Of the six, Platygaster sp. and Neanastatus sp. parasitized more than 50% of the larvae.

From the gall midge affected plants

(Masi)

Occurrence of the American rice water weevil in Japan

T. Iwata, chief, Division of Entomology, National Institute of Agricultural Sciences, Nishigahara, Kita-Ku, Tokyo, Japan

In May 1976, the rice water weevil Lissorptrus oryzophilus Kuschel was found in two regions of Aichi prefecture. The reports were the first of the pest in Japan. Specimens were sent to Australia and identified by Dr. G. Kuschel.

In the region of Tokoname, the weevils occurred in paddy fields of 600 ha. Over 10 grubs per hill were found on rice roots in June; rice plants were severely injured. In the region of Koda cho, about 30 m away from Tokoname, about 130 ha were damaged by the weevil. It is supposed that the

insect immigrated with hay imported from America 1 or 2 years earlier. Since the male adults have never been found, the insects are considered a parthenogenetic strain.

Brown planthopper attack in East Godavari, A.P., India

P. S. Prakasa Rao, P. Israel, and A. G. Krishna, Central Rice Research Institute, Cuttack 753006 (Orissa)

Of about 1 million ha of rabi 1976 paddy that was grown in nine blocks in East Godavari District, India, about 3,250 ha was severely infested by brown planthoppers (BHP) and an estimated 200 ha suffered hopperburn. Many other fields harbored 100 to 1,000 BHP per clump by early April. Yield loss appeared widespread. RP 4-14 and Jaya were extensively grown among high yielding varieties.

only one application of granular carbofuran, 40 to 50 days after planting, were practically free of BHP, while much of the nearby area received repeated insecticidal sprays at intervals of 7 to 10 days from 10 to 15 days after planting and suffered severe infestations. A survey in early April revealed hectic dusting or spraying in affected fields at 3- to 4-day intervals. Spiders, beetles, and hymenopterous parasites were absent from such fields. Indiscriminate, repeated spraying beginning with the early crop stage may have been responsible for the unprecedented outbreak. Dense plantings (70 to 90 clumps/sq m), while affording a favorable microclimate for BHP buildup, rendered sprays ineffective. An integrated strategy for combating the menace was tested in kharif 1976. BHP-resistant, high yielding cultures like CR57-MR.1523 were grown without plant protection, or susceptible varieties were grown and the following treatments were applied: dipping seedling roots for 12 hours in 0.02% chlorpyriphos before transplanting, transplanting not more than 40 to 50 hills/sq rn, and applying granular insecticides when necessary on the basis of economic thresholds.

Some 8- to 16-ha farms that received


Soil and crop management Deep placement of fertilizer phosphorus in rice

G. Dev, Department of Soils, Punjab Agricultural University, Ludhiana, Punjab, India

Phosphate application significantly increased the rice yield of IR8, and 60 kg P 2 O 5 /ha (superphosphate) produced significantly more paddy than 30 kg P 2 O 5 /ha (see table 1) in a microplot field experiment in the Punjab Agricultural University rice research area. The soil of the experiment field was sandy loam with pH 8.4, E.C. 0.01 pmho/cm, organic carbon 0.384%, and Olsen’s extractable P 10 kg/ha. Rice plants were spaced 20 x 15 cm. Super- phosphate tagged with 32 P was applied in mudballs at transplanting, broadcast at transplanting, or topdressed 2 weeks after transplanting. The mudballs, (approx. 2.5 cm in diameter) were prepared by mixing superphosphate with soil and some water; they were pushed 7–9 cm deep into the soil at transplanting. A basal dose of 60 kg N/ha (as urea) and 60 kg K 2 O/ha (as muriate of potash) was added at puddling, and an additional 60 kg N/ha was applied in equal parts 21 and 42 days after transplanting. The rice crop was raised under flooded conditions.

Fertilizer P uptake was also investigated at 6 weeks (maximum tillering), 8 weeks (between maximum tillering and panicle emergence), and 11 weeks (ear emergence) after transplanting.

The yield that was attributable to the P ranged from 360 to 720 kg/ha with 30 kg P 2 O 5 /ha, and from 550 to 1,470 kg/ha with 60 kg P 2 O 5 /ha.

Deep placement of 60 kg P 2 O 5 /ha at transplanting produced the highest yield; 30 kg P 2 O 5 /ha deep placed as mudballs yielded as well as 60 kg P 2 O 5 broadcast at transplanting. The efficiency of fertilizer P was highest with deep placement as mudballs. At 60 kg P 2 O 5 /ha,


24.5 kg rice/kg P 2 O 5 was produced with deep placement, 9.1 kg with broadcast at transplanting, and 9.6 kg with topdressing 2 weeks after transplanting.

P removal by grain was also highest with P buried in mudballs (table 2); it was significantly higher at the recommended dose of 60 kg P 2 O 5 /ha.

The relative efficiency of P application by different methods for yield and total P removal (table 2) was calculated using the relationship: ( Y t = Y o ) / ( Y s - Y o ) Where Y t = yield or P removal in treatment under

test

Y o = yield or P removal in the control Y s = yield or P removal in standard

For both grain yield and total P removal, deep placement at transplanting was the most efficient methoa of P application.

At 30 kg P 2 O 5 /ha, deep placement of P at transplanting resulted in the highest percentage of P in plant derived from the fertilizer in all three stages of plant growth (table 3).

The results indicate that IR8 taps applied P most efficiently when the P is placed in the immediate vicinity of the roots. IR8’s shallow and compact rooting system makes that understandable. Deep placement may also result in minimum fixation of the applied P in the soil.

treatment.

Table 1. Yield and total P removal by paddy grain as affected by different methods of P application. Punjab, India.

Yield (kg/hal P removal by paddy grain (kg/ha)

Treatment 30 kg 60 kg Mean 30 kg 60 kg Mean

P 2 O 5 /ha P 2 O 5 /ha P 2 O 5 /ha P 2 O 5 /ha

Broadcast at transplanting Deep placement at transplanting Topdressing 2 weeks after

transplanting

Mean

Control

C.D. (5%) for control vs. treatment for level for method

51 87 5326

5542

5352

5373 6294

5402

5689

4823

5.00 3.32 3.70

5280 5810

5472

12.75 12.69

13.20

12.88

14.47 16.75

14.63

15.28

11.48

3.85 0.98 n.s.

13.61 14.72

13.91

Table 2. Relative efficiency values of different methods of P application for paddy yield and total P removal by grain, Punjab, India.

Treatment

Broadcast at transplanting Deep placement at transplanting Topdressing 2 weeks after transplanting

Relative efficiency value

Grain yield P removal by grain

100 216 142

100 1 52 114

Table 3. Phosphorus in plant derived from fertilizer. Punjab, India.

Treatment

Broadcast at transplanting

Deep placement at transplanting

Topdressing 2 weeks after transplanting

a WT = weeks after transplanting.

Phosphorus (%) in plant P 2 O 5

(kg/ha) 6WT a 8WT a 11WT a

30 60

30 60

30 60

40 40

49 27

29 38

36 35

42 20

22 24

22 35 44 19

22 25

The kribit method of raising seedlings

Abdur Rashid Gomosta, senior scientific officer, Bangladesh Rice Research Institute, Joydebpur, Dacca, Bangladesh

In the kribit (Bengali: artificial seedbed) method of raising seedlings, light competition is encouraged in a primary seedbed and discouraged in a secondary bed. The kribit method is of two types: 1) the kribit stripping method (KSM), and 2) the kribit transplanting method (KTM).

substratum (3–4 cm thick) on banana leaves or polyethylene sheets. Decomposed organic matter (25% by volume) and NPK (20-20-20 kg/ha) are

The primary bed is a clay soil

mixed with the soil. Seeds having 80% viability are soaked for 24 hours and incubated for 48 hours, then sown on the substratum at the rate of 1 kg/sq m and covered with well-dried straw measuring 20–50 cm long. Water is sprayed on the straw immediately, then once a day during humid weather or twice a day during dry weather. On the fourth day after sowing, the straw is removed; the seedlings turn green within 12 hours.

In KSM, the primary bed is divided into strips 6–10 cm wide and 1 meter long on the fifth day after sowing. The strips are placed 6–10 cm apart in the secondary bed, which is made of

puddled soil, and fertilized with urea at 6–100 g/sq m. In KTM, seedlings are transplanted in bunches of 30 to 40 on the seventh day. They are then well irrigated for 1 to 3 weeks. The secondary bed is twice the size of the primary.

Two-week-old kribit seedlings produce double the dry matter of 2-week-old modified dapog seedlings; they are also greener and stiffer. Three- or four-week-old kribit seedlings are similar to or sometimes better than wetbed seedlings. They are transplanted from the secondary bed, two or three seedlings to the hill.

Machinery development & testing

Modification of dusters by Thai farmers

Vichai Khusakul and Raywat Pattarasudhi, Division of Entomology and Zoology, Department of Agriculture, Bangkhen, Bangkok 9, Thailand

The use of granular insecticides against brown planthoppers is not practical where the water is more than 12 cm deep because the water dilutes the insecticide.

Nakornpathom province, Thailand, in 1974 found that they could not control the planthoppers even with the most effective dusts. Since brown planthoppers produce their progeny near the water level, and most rice varieties used by the farmers are the high-tillering, dwarf types, good penetration by dust insecticides at maximum tillering is not possible. The farmers have found an easy, rapid, and inexpensive solution.

One end of a small aluminum beer can or tin can is removed; near the other end, two smooth holes about 2 cm in diameter are bored opposite each other on the sides of the can. The can is then fitted firmly to the duster hose (Fig. 1a).

Farmers in Narapiron district,

The duster fan forces insecticide through the horizontal holes, covering several rows of rice (Fig. 1b) in two directions. Farmers save dusting time

and are better able to control insecticide placement. The amount of insecticide is also reduced and there is less danger of oral and inhalation toxicity.


The International Rice Research Newsletter (IRRN) invites all scientists to contribute concise summaries of significant rice research for publication. Contributions should be limited to one or two paragraphs and a table, figure, or photograph. They are subject to editing and abridgement to meet space limitations. Authors will be identified by name, title, and research organization.

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International Rice Research Newsletter Vol.1 No.2

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