Page 1
Evaluating Cashew Hybrids
in Northern Australia
Report for the Rural Industries Research and Development Corporation
by CSIRO Division of Horticulture
Principal Investigator: Dr Elias Chacko
(RIRDC Project CSH-43A)
January 1997 RIRDC Research Paper Series No 97/56
Page 2
© 1997 Rural Industries Research and Development Corporation.
All rights reserved.
ISBN 0 642 24677 8 ISSN 1321 2656
"Evaluating Cashew Hybrids in Northern Australia ”
The views expressed and the conclusions reached in this publication are those of the author/s and not necessarily those of persons consulted or the Rural Industries Research and Development Corporation. RIRDC shall not be responsible in any way whatsoever to any person who relies in whole, or in part, on the contents of this report unless authorised in writing by the Managing Director of RIRDC.
This publication is copyright. Apart from any fair dealing for the purposes of research, study, criticism or review as permitted under the Copyright Act 1968, no part may be reproduced in any form, stored in a retrieval system or transmitted without the prior written permission from the Rural Industries Research and Development Corporation. Requests and inquiries concerning reproduction should be directed to the Managing Director.
Researcher Contact Details
Principal Investigator: Dr Elias Chacko CSIRO Division of Horticulture PMB 44 WINNELLIE NT 0821
Phone: 08 8944 8484 Fax: 08 8947 0052
RIRDC Contact Details
Rural Industries Research and Development Corporation Level 1, AMA House 42 Macquarie Street BARTON ACT 2600
PO Box 4776 KINGSTON ACT 2604
Phone: 06 272 4539 Fax: 06 272 5877 email: [email protected] Internet: http://www.dpie.gov.au/rirdc
Published in June 1997 Printed by DPIE Copyshop
Page 3
Foreword Cashews rank third in world production of edible nuts and the Australian industry has grown significantly over the past ten years.
This report shows there is much scope for more development, especially in Australia’s northern regions, where cashews are well suited to the soils and climatic conditions.
The researchers identify 49 high-yielding hybrids and promise more in the next three to five years. The hybrids were tested at three sites in North Queensland and the Northern Territory. They were assessed for growth habit, yield and nut characteristics with high yield potential.
The project is a valuable contribution to the Rural Industries Research and Development Corporation’s Cashews Program which fosters a viable industry by encouraging:
• development of high yielding varieties through selection and breeding;
• environmentally acceptable and cost-efficient pest and disease control and plantation management strategies;
• development of processing and handling systems suited to Australian conditions; and
• exploring opportunities for economic processing and marketing of cashews for the world market.
Peter Core Managing Director Rural Industries Research and Development Corporation
Page 4
4
CONTENTS (ii) Non-technical summary 3
(iii) Background 4
(iv) Objectives 6
(v) Introductory technical information 6
(vi) Methodology 7
(vii) Results 15
(viii) Discussion 32
(ix) Implications and recommendations 37
(x) Project intellectual property 38
(xi) Dissemination strategy 38
(xii) Technical summary 39
References 42
Page 5
Final report CSH-43 A 5
(ii) Non-technical summary
Background
There is a large and expanding market for increased cashew production worldwide. Australia currently imports about $A26 m worth of nuts annually. Opportunities for establishing large cashew plantations exist in the tropical areas of north Australia provided such plantings can achieve yields of more than 4 t/ha compared with the current world average production of 0.5-1.0 t/ha nut-in-shell. Initial plantings in the Northern Territory and Queensland consisted of imported genetic material which produced only moderate yields in Australian conditions. To develop high yielding cultivars suited to local conditions, a hybridisation program involving some of the best imported and local selections was carried out during 1988-92. Collaborators in this program included RIRDC, CSIRO Horticulture, DPI&F NT, QDPI and several private companies. These hybrids were planted during 1989-93 at three test sites owned by the collaborating private companies (Wildman River Cashew Plantation Pty Ltd, NT; Melville Forest Products Pty Ltd, Melville Island; and Cashews Australia Pty Ltd, Dimbulah Qld).
Objectives
• Complete planting and maintain the cashew hybrids (produced during 1988-92) at three test sites (Wildman River Cashew Plantation NT; Melville Forest Products, Melville Island; Cashews Australia Qld).
• Assess growth habit, yield and nut characteristics of individual trees to identify hybrids with high yield potential.
• Initiate replicated trials with hybrids that produce high individual tree yields and medium-large nut and kernel weight during the early stages of assessment.
Research
During this project period the planting of hybrids was completed and initial evaluations, which commenced during the previous phase of the program (RIRDC CSH-36A), were continued and expanded. Information on growth habit, yield and nut characteristics (nut weight, kernel weight and kernel recovery) of individual trees that flowered and fruited well was collected from the hybrids produced during 1988-91 and planted during 1989-92 at the Wildman River Cashew Plantation NT and Cashews Australia Qld. A replicated trial with ten, high-yielding 1988-produced hybrids was commenced at Wildman River Cashew Plantation in 1994/5. These selections were multiplied for additional replicated trials at Cashews Australia Qld and Coastal Plantation, La Belle Downs Station NT during the next phase of the project.
Outcomes and implications
Evaluation of individual trees from the 1989-91 plantings (1988-90 hybrids) during 1992-5, resulted in the identification of a total of 49 high-yielding hybrids at the Wildman River Cashew Plantation and Cashews Australia. Based on such encouraging results during the early stages of assessment there are good prospects of
Page 6
6
identifying many more high yielding hybrids during the next 3-5 years of evaluation. Replicated trials with such high yielding selections are planned during the next phase of the program to confirm their ability to achieve high yields in commercial plantings.
Page 7
Final report CSH-43 A 7
(iii) Background
Cashew (Anacardium occidentale) ranks third in production among the major
edible nuts grown world wide. Current world production is about 500 000 tonnes but
demand is increasing due to greater consumption in Asia as per capita incomes in this
region grow. By the year 2000 it is expected that world production will be well short
of demand. This world situation presents a clear opportunity for new growers to enter
the market (Massari 1994).
Cashew is a crop with good potential for the Australian tropics. Large areas of
suitable land with adequate water supply are available in the Northern Territory and
far north Queensland. It is well suited to the seasonally wet/dry tropical climate and
does not suffer the perishability problems associated with other soft-fleshed tropical
fruits. It can be stored for long periods and can withstand long distance transport.
Since Australia currently imports about $A26 m of cashew annually, a local industry
would reduce this cost and may create export opportunities for value added products.
Although the Australian cashew industry is in its infancy, there has been
sustained interest during the late 1980’s and early 1990’s in developing new
plantations in northern Australia. During this period the CSIRO has worked
collaboratively with the state and territory departments (DPI&F, NT; QDPI, Qld;
Dept Agric, WA) and private companies (Britannia Pty Ltd (now Cashews NT),
Melville Forest Products, Melville Island, Cashews Australia, Dimbulah Qld (Peter
Shearer and Co)) to introduce a wider range of genetic material and to set up trial
plantations. Cashew material was imported with a view to assessing its performance
under the range of climatic conditions prevailing in the cashew growing areas from
north Queensland to the Northern Territory. In contrast to overseas management
practices, supplementary irrigation and fertilisers were applied in these trial
plantations to ensure maximal nut production. However, despite these inputs, results
from the initial plantings with the imported and some locally available selections
indicated that their yield potential (calculated from single tree yields) was no greater
than 3 t nut per hectare, with many trees yielding much less than this. It has been
stated that to be competitive on world markets the Australian industry needs to
Page 8
8
achieve yields of at least 4 t nut per hectare (Cann et al. 1987). To achieve this yield
would require a minimum yield of 20 kg nuts per tree when planted at a density of
200 trees per hectare.
On the basis of these early results the CSIRO in collaboration with RIRDC,
DPI&F (NT), QDPI (Qld) and the private companies listed above, instigated a cashew
breeding program during 1988-93 (RIRDC projects 008A and CSH-36A). The
approach was to use hand pollination techniques to produce a range of new hybrids
adapted to the local environment, by taking advantage of the wide range of genetic
material available in Australia. The next stage was to multiply these hybrids by
grafting and then to plant them out at a range of sites across northern Australia for
field assessment.
All the hybrid seedlings produced during 1988-92 or their corresponding
grafts were planted during the year following their production at the Wildman River
Cashew Plantation (NT), Cashews Australia (Qld) and Melville Island (NT). Some of
the 1990 hybrids (800) were also planted at a non-funded site at Katherine (NT) in
1992. These hybrids were grown under commercial management practices with
irrigation, fertiliser and pesticides provided in consultation with the project scientists.
Assessment of the 1988 hybrids, planted out in 1989, was commenced at the Wildman
River Cashew Plantation in 1992. RIRDC provided funding for a further term of three
years (1993-96) to continue the cashew genetic improvement program. The
subsequent RIRDC project reported here (CSH-43A), was based on (a) further
planting of the hybrids (produced in 1991/92) at the Wildman River Cashew
Plantation, Cashews Australia and Melville Island, (b) maintenance of the hybrids and
(c) field evaluation of the hybrids at all sites as they developed beyond the juvenile
phase. To facilitate this field work, one technical officer was appointed at each site -
Wildman River Cashew Plantation, Cashews Australia and Melville Island. These
staff were partially funded by RIRDC.
Page 9
Final report CSH-43 A 9
(iv) Objectives
The aims of the project were to:
• Complete the planting of the hybrids produced in 1991-92 at the Wildman River
Cashew Plantation, Cashews Australia and Melville Island.
• Properly maintain the hybrids grown at each of these three sites by implementing
irrigation, fertiliser and pest management practices which were designed to be non-
limiting to tree performance. (At Melville Island the intention was to assess the
hybrids grown under rain-fed conditions.)
• Identify trees with high yield potential having upright growth habit with large
numbers of terminals capable of producing medium to large sized nuts (6 - 10 g)
and kernels (> 1.8 g).
• Commence replicated trials of the best hybrid selections together with their
parents/standard varieties (imported or local) for large scale, commercial
assessment with a view to identifying hybrids capable of producing >20 kg nuts
per tree at maturity (about 5 year old) and with compact tree structure to permit
planting density of at least 200 trees per hectare.
(v) Introductory technical information
World cashew production is predominantly from India, Brazil and Africa.
Average yield in these countries is low (0.5-1.0 t per hectare) because the planting
material is raised mostly from seedlings and inputs of irrigation, fertilisers and
pesticides are low or non-existent.
Cashew is a new industry for Australian horticulture and experience with local
cultivars is limited. Some of the imported cultivars have shown an increase in yield
potential (10-15 kg nuts per tree) when grown for five years under Australian
Page 10
10
conditions with regular inputs of irrigation, fertiliser and pest control (Ian Duncan,
personal communication). At a planting density of 200 trees per hectare these single
tree yields would be equivalent to 2-3 t per hectare. However, these yields are still
below the level considered necessary for commercial production (20 kg nuts per tree).
The approach to improving yield potential in Australian cashew plantations has been
to develop large-scale genetic variability by cross pollinating the best yielding
imported selections and existing Australian material. Strict selection criteria are
being used to identify trees which perform exceptionally well under Australian
conditions from this hybrid population. This approach was based on reports from
India that by using exotic parents or parents of diverse geographic origin, it is
possible to develop hybrids with marked improvement in yield compared with the
hybrids obtained from crosses among local selections (Nair et al. 1979). Also,
because of the precocious bearing behaviour of cashew seedlings/grafts grown under
best management practices in Australia, the identification of high yielding trees from
the large hybrid population can be commenced within 3-5 years of planting. This is a
short time-frame compared with cashew breeding programs in India where trees are
grown with low inputs and the identification of trees with high yield potential may
take as long as 10 years (Bavappa 1994).
(vi) Methodology
The breeding program was conducted over five years (1988-92) and generated 4539
hybrids. These hybrids (other than those from 1988) were multiplied by softwood
grafting and single trees of each hybrid were planted at Wildman River Cashew
Plantation and Cashews Australia. The original seedling of each hybrid was planted
on Melville Island.
The hybrids produced in each year were kept in the nursery at CSIRO Darwin for a
period of 6-8 months to encourage the rapid growth of the plants and to allow
multiplication by grafting. This period in the nursery meant that there was a time lag
of almost one year between producing the hybrids and planting them in the field.
Page 11
Final report CSH-43 A 11
To maximise uniformity, all rootstocks used for grafting the hybrids were raised from
seeds collected from the imported cultivar BLA39-4. Previous experience from a trial
planting in Darwin showed that seedlings raised from open pollinated seeds of
BLA39-4 are relatively uniform in growth and fruiting behaviour under field
conditions.
The number of hybrids produced each year and those surviving in the field at each site
are listed in Table 1.
The parents used in the hybridisation program, comprising a range of imported (58)
and local (7) selections originally planted at several sites near Darwin (including
CSIRO and DPI&F), were consolidated in a single planting block at one commercial
plantation during 1993/94. The parents were also multiplied for maintenance at the
CSIRO Darwin nursery and, in addition, may be planted at other commercial sites to
ensure the preservation of this valuable germplasm.
Table 1: Number of hybrids produced (1988-1992) and planted at three test sites in northern Australia
Year of No. of hybrids
Sites where hybrids No. of hybrids G - Grafted
crossing produced were planted at each site S - Seedling
1988 240 Wildman River Cashew Plantation, NT
210 S
1989 918 Wildman River Cashew Plantation, NT
658 G
Cashews Australia, Dimbulah QLD
557 G
Melville Island, NT 602 S
1990 935 Wildman River Cashew Plantation, NT
840 G
Page 12
12
Cashews Australia, Dimbulah QLD
696 G
Melville Island, NT 804 S
1991 1480 Wildman River Cashew Plantation, NT
1300 G
Cashews Australia, Dimbulah QLD
1224 G
Melville Island, NT 940 S
1992 966 Wildman River Cashew Plantation, NT
890 G
Cashews Australia, Dimbulah QLD
846 G
Melville Island, NT 603 S
TOTAL 4539
TOTAL Wildman River Cashew Plantation
3898 (counted May 1995)
Cashews Australia, Dimbulah 3323 (counted June 1996)
Melville Island 2949 (counted Jan 1995)
Description of sites
The test sites were selected to reflect the range in agroclimatic conditions that prevail
in the potential cashew growing areas of northern Australia. Details of each site are
provided below.
Climate and soil
(a) Wildman River Cashew Plantation, NT
This plantation is situated approximately 150 km S-E of Darwin in the Northern
Territory. The seasonal rainfall pattern at Wildman River Cashew Plantation reflects
Page 13
Final report CSH-43 A 13
the distinct differences between wet and dry season (Table 2). The annual rainfall
totals about 1600 mm but the period from May-September, which corresponds
approximately with flowering and fruiting of cashew in northern Australia, is virtually
rain-free. Class A pan evaporation varies between about 100 and 200 mm per month
and is clearly in excess of rainfall in all months except December to March. The daily
maximum temperature is relatively constant (30-35oC) throughout the year, but night
temperature varies with time of year, for example, ranging from 11oC in July to 24oC
in November.
The soil at Wildman River Cashew Plantation is a deep, sandy, red massive earth of
the Kiluppa family, Gn2.11 (Northcote 1979). Although this soil has a water holding
capacity of only 73 mm/m in the top 1.2 m of the profile (Calder and Day 1982), the
absence of any physical impediments to root growth to a depth of 4.0 m means that
the profile holds a potentially large supply of available water. The soil is highly
leached and regular applications of major and trace elements are required to maintain
fertility.
Trees grown in this area are known to be damaged by the white ant (Mastotermes
darwiniensis), a particularly aggressive pest that can kill a mature tree within a week.
Prior to clearing the site for cashew planting a white ant survey was carried out in the
natural vegetation and the colonies that were detected were eliminated using
commercial treatments (Mirant).
(b) Cashews Australia, Dimbulah Qld
The climate at Dimbulah is dominated by seasonally wet and dry conditions. Data in
Table 2 are for a typical year. The average annual rainfall is 757 mm and falls mainly
during the period December-March. Class A pan evaporation totals about 1800 mm
annually, with September to December being months of peak evaporative demand.
The maximum temperature ranges from about 26oC in July to 34oC in December,
while the minimum temperature ranges from 10oC in July to 20oC in December.
Page 14
14
The soil at the site is sandy, with more than 80 % coarse sand and about 10% fine
sand in the top 0.5 m of the profile. The bulk density is in the range 1.55 - 1.65 t/m3
and plant available water is low, at 78 mm in the top 1.0 m of the soil profile. The soil
is highly leached and requires regular inputs of major and trace elements to maintain
chemical fertility.
This site is free from Mastotermes spp.
(c) Melville Forest Products Pty Ltd, Melville Island, NT
This site was included to assess the potential for rain-fed cashew production. Melville
Island is approximately 60 km north of Darwin and is Aboriginal land vested in the
Tiwi Land Trust. Pirntubula Pty Ltd was established by the traditional owners in 1987
for the specific purpose of undertaking business activities, including management of
pine plantations. Melville Forest Products Pty Ltd was formed jointly by Pirntubula
Pty Ltd and Midmel Pty Ltd (Melbourne) to manage and expand the forestry
plantation and to conduct R&D for the identification of suitable tropical fruit and nut
crops that can be grown commercially on the island.
The climate of the island is distinctly monsoonal, with an annual rainfall totalling
1973mm (Table 2). Around 75-80% of this rainfall occurs in the four months
December-March but in comparison to the other sites the dry season is not as long
with significant rain falling until May and starting again in September. The maximum
temperature is constant throughout the year at about 32oC and the minimum ranges
from 18oC in July to 25oC in December/January.
The land selected for the cashew plantation is at Yapilika (17 Mile Plains). The soil at
the site is a deep, red, sandy loam of moderate fertility. As with the other sites regular
applications of major and trace elements are required to maintain soil fertility.
This site is free from Mastotermes spp.
Page 15
Final report CSH-43 A 15
(d) King Producers, Katherine NT
Although this is not a RIRDC funded site, the details are included here for
completeness. At this site only the hybrids produced during 1990 (and planted in
1992) were included.
Table 2: Typical long term climatic data for each test site in northern Australia.
J F M A M J J A S O N D Total
Wildman R Rain (mm) 398 313 294 263 20 0 9 0 20 44 171 100 1632
Evap. (mm) 149 123 149 156 161 156 171 192 207 223 189 167 2043
Tmax (oC) 33.3 33.8 31.8 32.8 32.8 30.8 31.8 33.8 35.9 35.9 34.9 32.8
Tmin (oC) 23.1 23.1 22.6 22.6 18.5 17.4 11.3 12.8 15.9 20.0 23.6 23.1
Cashews Aust.
Page 16
16
Rain (mm) 258 77 115 159 10 0 16 1 2 44 22 53 757
Evap. (mm) 150* 106 121 102 87 22 118 167 235 223 237 220 1788
Tmax (oC) 33.3 32.1 30.2 31.3 27.8 29.1 26.4 27.7 30.8 30.0 34.6 34.0
Tmin (oC) 20.2 20.2 18.6 17.7 15.0 12.4 10.3 12.8 12.9 17.7 18.6 20.7
* estimate
Melville Isl.
Rain (mm) 426 372 402 105 17 8 4 9 36 82 208 304 1973
No. rain days 21 20 21 10 3 1 1 1 2 9 14 18 121
Tmax (oC) 31.5 30.9 31.5 32.6 32.3 30.7 30.2 31.2 32.3 32.7 32.9 32.5
Tmin (oC) 24.7 24.4 24.2 23.2 21.4 19.1 18.2 19.6 21.1 22.8 24.2 24.7
Page 17
Final report CSH-43 A 17
The climate in Katherine is semi-arid with a distinct wet season between November
and March. During this period rainfall is heavy but irregular and totals about 900 mm
per year. During this time the maximum temperature is in the range 32-38oC and the
minimum is about 25oC. During the dry season, from April to October, rainfall is light
and sporadic, totalling less than 100 mm per year. The maximum temperature at this
time of year is in the range 30-42oC and the minimum is 17-25oC. The soil at Venn
block, where the cashews are planted, is a sandy red earth (Blain sand) with properties
that are similar to those of the soil at Wildman River Cashew Plantation.
Tree planting and management
At all sites the hybrids were planted 6m apart along the row, with 8m between rows.
The management regime adopted for the hybrid plantings was designed to maximise
growth and productivity. Details of irrigation, fertiliser and pesticide
recommendations are described below.
(a) Irrigation
At the Wildman River Cashew Plantation the trees were irrigated from May to
October with under tree sprinklers which delivered 400-800 L of water each week
depending on the age of the plants. The circular wetted area was of 2m radius.
Irrigation at the Cashews Australia plantation was by mini sprinkler for trees planted
in 1990 and 1991 and delivered 700 L of water at 1-2 weekly intervals. For trees
planted later, trickle irrigation delivered 350 L of water per tree at 1-2 weekly
intervals. Due to the short wet season irrigation is generally applied throughout the
period from April to November.
There was no irrigation for trees planted on Melville Island.
At the Katherine site 400-800 L of water was applied at 2 weekly intervals by
undertree sprinklers during the flowering/fruiting period (May-October).
Page 18
18
(b) Fertiliser
A general recommendation for fertiliser application was made for all sites. The
recommended application of major nutrients is detailed below in Table 3.
Table 3. Recommended annual application of N, P and K for hybrids at all sites
Tree age (years) Nutrient (g per tree)
N P K
1 87 25 40
2 174 50 80
3 260 75 120
4 347 100 160
5 434 125 200
6 521 150 240
Depending on farm management practices these fertilisers were either spread on the
soil surface or applied through fertigation. In addition, it was recommended to apply
extra fertilisers, including trace elements and calcium, if the results of leaf analysis at
each site relative to published standards (Marchal 1987) indicated that this was
necessary.
(c) Weed control
At all sites weed control was recommended during the wet season. Slashing and/or
application of the herbicide glyphosate were the main methods of weed control.
(d) Insect pests
Page 19
Final report CSH-43 A 19
The major pests affecting cashew in all the growing regions are mango tip borer
(Penicillaria jocosatrix), the cashew leaf rolling caterpillar (Anigrala ochrobasis) the
Helopeltis bug (Helopeltis spp), redbanded thrips (Selenothrips rubrocinctus) and the
fruit spotting bug (Amblypelta lutescens). Control of the above insects was carried out
by spraying with recommended insecticides on a needs basis.
Criteria for assessment of hybrids
Assessments of the hybrids in this project were based on the nut yield per tree,
individual nut and kernel weight and kernel recovery. In addition visual assessments
of tree form (canopy structure) were recorded and included such characters as height
- dwarf, intermediate or vigourous, shape - upright or spreading and canopy density -
foliage density.
Depending on the growth rate and precocity of the hybrids, these assessments
commenced 2-3 years after planting. Due to high costs and difficulties with recruiting
labour at remote localities it was only possible to quantify yield in the most
productive hybrids. Judgements about which hybrids to assess were based on a visual
assessment of potential nut yield at the time of flowering and fruiting or on past
performance.
Harvesting and sampling
Harvesting of individual trees has a high labour requirement. At Wildman River
Cashew Plantation manual harvest was aided by a machine that vacuums and collects
the nuts from the ground. At all other sites the harvest was entirely manual.
Page 20
20
The nuts from each tree were counted and the weight of a sub sample of 100 nuts with
apples removed was used for the determination of the total tree yield and average nut
weight after drying to constant weight at 70oC.
The kernel weight and kernel recovery were determined using smaller sub samples of
a minimum of 25 nuts each. A guillotine device was used to crack open the nuts and
retrieve the kernel. After redrying the kernels for 24 hours at 70oC the kernel weight
without testa was recorded. The kernel recovery was calculated by expressing the
kernel weight as a percentage of the average nut-in-shell weight.
(vii) Results
In the following sections only yield data relating to the best-performing hybrids are
presented. These data were collected from individual trees of each hybrid planted at
each site. The hybrid trees are identified by their CSIRO accession number, assigned
to hybrids produced during 1989-92. The hybrids produced in 1988 are identified by a
plant code number
Wildman River Cashew Plantation
(a) Field planting and maintenance of hybrids
During 1993 the field planting of the hybrids produced in 1992 was completed. A
total of 966 trees were planted and of these, 890 were growing satisfactorily at the last
count (Table 1). During 1993 a severe Helopeltis infestation that occurred at
flowering time could not be effectively controlled due to a breakdown of spraying
equipment. Due to extreme damage to the emerging panicles and developing nuts, the
yield of all hybrids was severely reduced. During September 1994 when the trees
were in full bloom a heavy infestation of aphids (Aphis gosspii) occurred throughout
the plantation which destroyed the panicles and nuts to a large extent. Such attack is
extremely rare and has not been reported elsewhere. Aerial and ground sprays of the
Page 21
Final report CSH-43 A 21
recommended insecticide Pirimor controlled the spread of the aphid damage but large
yield reductions occurred during the 1994 harvest.
(b) Hybrid assessment
During 1995 the technical officer (0.5 RIRDC funding: 0.5 Plantation funding)
resigned and a replacement could not be appointed. Subsequently, the operation of the
plantation ceased and vital tasks such as irrigation, fertiliser application and pest
management were not carried out. As a consequence it was not possible to record
production results in 1995 and only data from 1993 and 1994 harvests are available.
During 1993 a total of 1829 hybrids (planted in 1989-92) were assessed but during
1994 only 420 hybrids were assessed for tree structure and yield. The individual tree
yield data of the top yielding hybrids planted in each year and harvested in 1993 are
presented in Table 4 (a-d). The 1994 harvest data of the top yielding hybrids are
presented in Table 5 (a-d). (As a consequence of the severe insect damage outlined
above, data for all trees were not available in each harvest year, particularly the
hybrids planted in 1990 and harvested in 1994 (Table 5 (b)).
1993 Harvest
Of the 1988 hybrids planted in 1989 (Table 4 a) yield in excess of 10 kg nuts per tree
was recorded in 20 trees. Of these, the tree with plant code 82-24 produced a peak
yield of 16.35 kg nuts per tree and a kernel weight of 1.46 g. Two other hybrids, with
plant codes 95-40 and 88-28 produced in excess of 14 kg nuts per tree with kernel
weights exceeding 2 g. These trees were all in their fourth year after planting.
Data in Table 4 (b) show that the yield of 24 hybrids produced in 1989 and planted in
1990 (in their third year after planting) exceeded 3 kg nuts per tree. The maximum
yield of 6.1 kg nuts per tree was in the tree with CSIRO no. 177. The kernel weights
of nuts produced by most hybrids were in the range 1.5-2.0 g.
Page 22
22
The yield of trees planted in 1991 and 1992 (hybrids produced in 1990 and 1991) was
low at about 1.5-3 kg nuts per tree. Kernel weights were in the range 1.3 -2.7 g.
The yield data of these young trees are presented to highlight their precocious bearing
habit only one or two years after planting.
1994 Harvest
For the hybrids produced in 1988 and planted in 1989 there were 15 which yielded in
excess of 10 kg nuts per tree with kernel weight more than 1.5g. The highest yield of
18.4 kg nuts per tree was achieved by the tree 80-70 (plant code) with a kernel weight
of 1.8 g (Table 5 a).
Only data for ten hybrids produced in 1989 and planted in 1990 which yielded in
excess of 6 kg nuts per tree are presented (Table 5 b). The best yield of 12.9 kg nuts
per tree with a kernel weight of 1.95 g was recorded in the hybrid with CSIRO no.
174.
The best yield of the hybrids produced in 1990/91 and planted in 1991/92 (Table 5 c,
d) was in the range from 4 to 7.2 kg nuts per tree with kernel size ranging from 1.3 to
3.2 g. These trees had been planted for 3 and 2 years, respectively.
The effect of insect damage in 1993 and 1994 is reflected in the year to year yield
data of 21 high-yielding 1988 hybrids (planted in 1989) which had shown high yield
potential in 1991 and 1992 (Table 6). Despite the good early yields these hybrids did
not continue to improve in later years which was a direct effect of the severe insect
damage at flowering and fruiting time in 1993 and 1994.
Cashews Australia
(a) Field planting and maintenance of hybrids
Page 23
Final report CSH-43 A 23
A total of 3323 hybrids produced between 1989-92 have been planted at Cashews
Australia. Some of the hybrids produced in 1991 and all of those from 1992 were
planted in 1993.
The east coast of Australia experienced unusually dry conditions during the period
1992-95. With the irrigation system at Cashews Australia it was not possible to ensure
optimal conditions of soil moisture for achieving maximum growth of the hybrids
during this period. In addition, the inherently low natural fertility of the soil at
Cashews Australia meant that although fertilisers were applied, general nutrient
deficiencies (particularly of micronutrients) depressed the growth of hybrids in all
years.
In general the plantation was kept free from insect damage but occasional outbreaks
of Amblypelta lutescens occurred and were controlled with insecticide sprays.
(b) Hybrid assessment
The hybrids that were produced in 1989 and 1990 (planted in 1990 and 1991) were
assessed during the cropping years 1992-1995. Based on a visual appraisal, only those
trees that flowered and fruited well were assessed for yield. Those planted during
1992 and 1993 are still too young for yield assessment. At the end of the project a
total of 1530 hybrids had been assessed.
Table 7 shows the best yielding hybrids over the four years of measurement. The
hybrids produced in 1989 and planted in 1990 were affected by frost damage during
the winter of 1990. Despite this early setback, yields in excess of 6kg nuts per tree
were recorded in three hybrids with CSIRO nos 585, 601 and 546 during the 1995
harvest (five years after planting). The kernel weights in these hybrids were all above
2 g with kernel recovery ranging from 32 to 35 %.
Page 24
24
In 1995, among the hybrids produced in 1990 and planted in 1991, 11 hybrids yielded
in excess of 6 kg nuts per tree with kernel weights ranging from 1.8 - 2.5 g.
Furthermore, several hybrids (CSIRO nos 1815, 1889, 1873, 1487 and 1369) achieved
yields of 8 -10 kg nuts per tree. These trees were in their fourth year of growth.
Although the data in Table 7 reflect a general increase in yield over time, analysis of
year-to-year correlation was considered inappropriate because of the limits to tree
performance imposed by low management inputs.
Melville Forest Products
(a) Field planting and maintenance of hybrids
The planting of hybrids, including those produced in 1992, was completed in
November-December 1993. At the time of planting the trees received 80 g of
Nitrophoska Blue fertiliser. Training and pruning of the earlier planted hybrids were
carried out and fertiliser at the rate of 200-300 g per plant was applied during the
following wet season.
The technical officer appointed during the first year of the project resigned due to the
remoteness of the plantation site. The Melville Island site suffered from the additional
problems of low fertility, particularly zinc, and occasional insect damage from tea
mosquito (Helopeltis spp), redbanded thrips (Selenothrips rubrocinctus) and the fruit
spotting bug (Amblypelta lutescens). Timely application of fertilisers during the wet
season did not occur due to a lack of labour and difficulties associated with
application of fertilisers in wet weather. Frequent breakdown of the spray equipment
meant that insects could not always be controlled adequately.
Despite these difficulties in management, flowering and fruiting was observed in all
hybrids in the second and third years after planting. However, the nut production was
insufficient to warrant full yield assessment.
Page 25
Final report CSH-43 A 25
Due to factors beyond the control of the Principal Investigator, the cashew plantation
was neglected during the second and third years of the project. The level of inputs to
the cashew trees was unacceptably low during the second year of the project. As there
was no improvement in the maintenance of the plantation at the end of the second
year, the Principal Investigator, in consultation with RIRDC, withdrew funding for
this site during the third year.
Table 4 (a)
Hybrids
1993
Series Year of Total Nut Kernel Kernel number Plant code Production Planted Yield Weight Weight Recovery
(kg) (g) (g) %
1 82 24 88 03-89 16.35 4.97 1.46 29.32 2 95 40 88 04-89 14.50 7.68 2.16 28.07 3 88 28 88 07-89 14.11 8.75 2.08 23.75 4 92 46 88 04-89 13.72 5.03 1.58 31.35 5 88 20 88 07-89 13.55 6.55 1.99 30.38 6 82 62 88 07-89 13.43 7.09 2.15 30.27 7 85 31 88 07-89 12.92 5.20 1.66 32.00 8 88 34 88 07-89 12.69 5.56 1.72 30.88 9 92 43 88 04-89 11.99 6.02 1.90 31.52 10 89 48 88 04-89 11.69 5.59 1.70 30.41 11 82 64 88 07-89 11.66 5.18 1.63 31.49 12 89 44 88 04-89 11.43 6.99 2.15 30.74 13 95 43 88 04-89 11.10 5.42 1.56 28.81 14 92 44 88 04-89 10.93 6.17 1.80 29.13 15 85 66 88 07-89 10.82 5.09 1.49 29.31 16 82 37 88 03-89 10.45 6.13 1.80 29.32 17 88 32 88 07-89 10.44 5.43 1.69 31.11 18 92 41 88 04-89 10.24 6.33 1.89 29.83 19 89 45 88 04-89 10.23 5.65 1.70 30.04 20 79 39 88 07-89 10.21 6.21 2.03 32.68 21 79 42 88 07-89 9.74 6.99 1.98 28.39 22 85 72 88 07-89 9.66 6.10 1.70 27.92 23 80 63 88 04-89 9.66 7.07 1.71 24.22 24 85 61 88 07-89 9.62 4.77 1.41 29.64 25 82 26 88 03-89 9.51 6.41 1.97 30.72 26 82 21 88 03-89 9.46 4.73 1.52 32.14 27 88 33 88 07-89 9.36 6.76 1.93 28.52 28 79 53 88 07-89 9.36 6.78 1.90 28.06 29 79 45 88 07-89 9.33 6.54 2.03 31.05 30 85 39 88 07-89 9.19 5.44 1.65 30.38 31 88 24 88 07-89 9.17 6.04 1.94 32.06 32 92 40 88 04-89 8.87 7.80 2.18 27.97 33 89 52 88 04-89 8.78 5.69 1.73 30.37 34 88 21 88 07-89 8.67 6.80 1.96 28.85 35 80 43 88 04-89 8.66 6.08 1.81 29.76 36 80 52 88 04-89 8.53 6.60 1.98 30.09 37 92 48 88 04-89 8.50 6.14 1.79 29.20 38 89 50 88 04-89 8.45 6.59 1.98 30.00 39 85 38 88 07-89 8.34 4.54 1.43 31.56 40 88 66 88 07-89 8.33 6.61 2.12 32.03 41 88 36 88 07-89 8.31 5.55 1.79 32.23 42 80 42 88 04-89 8.28 6.86 1.98 28.93 43 85 60 88 07-89 8.24 4.78 1.43 29.96 44 95 42 88 04-89 8.22 4.92 1.35 27.37
45 92 49 88 04-89 8.13 5.25 1.53 29.06
Page 26
26
Table 4 (a)
Hybrids
1993
Series Year of Total Nut Kernel Kernel number Plant code Production Planted Yield Weight Weight Recovery
(kg) (g) (g) %
1 82 24 88 03-89 16.35 4.97 1.46 29.32 2 95 40 88 04-89 14.50 7.68 2.16 28.07 3 88 28 88 07-89 14.11 8.75 2.08 23.75 4 92 46 88 04-89 13.72 5.03 1.58 31.35 5 88 20 88 07-89 13.55 6.55 1.99 30.38 6 82 62 88 07-89 13.43 7.09 2.15 30.27 7 85 31 88 07-89 12.92 5.20 1.66 32.00 8 88 34 88 07-89 12.69 5.56 1.72 30.88 9 92 43 88 04-89 11.99 6.02 1.90 31.52 10 89 48 88 04-89 11.69 5.59 1.70 30.41 11 82 64 88 07-89 11.66 5.18 1.63 31.49 12 89 44 88 04-89 11.43 6.99 2.15 30.74 13 95 43 88 04-89 11.10 5.42 1.56 28.81 14 92 44 88 04-89 10.93 6.17 1.80 29.13 15 85 66 88 07-89 10.82 5.09 1.49 29.31 16 82 37 88 03-89 10.45 6.13 1.80 29.32 17 88 32 88 07-89 10.44 5.43 1.69 31.11 18 92 41 88 04-89 10.24 6.33 1.89 29.83 19 89 45 88 04-89 10.23 5.65 1.70 30.04 20 79 39 88 07-89 10.21 6.21 2.03 32.68 21 79 42 88 07-89 9.74 6.99 1.98 28.39 22 85 72 88 07-89 9.66 6.10 1.70 27.92 23 80 63 88 04-89 9.66 7.07 1.71 24.22 24 85 61 88 07-89 9.62 4.77 1.41 29.64 25 82 26 88 03-89 9.51 6.41 1.97 30.72 26 82 21 88 03-89 9.46 4.73 1.52 32.14 27 88 33 88 07-89 9.36 6.76 1.93 28.52 28 79 53 88 07-89 9.36 6.78 1.90 28.06 29 79 45 88 07-89 9.33 6.54 2.03 31.05 30 85 39 88 07-89 9.19 5.44 1.65 30.38 31 88 24 88 07-89 9.17 6.04 1.94 32.06 32 92 40 88 04-89 8.87 7.80 2.18 27.97 33 89 52 88 04-89 8.78 5.69 1.73 30.37 34 88 21 88 07-89 8.67 6.80 1.96 28.85 35 80 43 88 04-89 8.66 6.08 1.81 29.76 36 80 52 88 04-89 8.53 6.60 1.98 30.09 37 92 48 88 04-89 8.50 6.14 1.79 29.20 38 89 50 88 04-89 8.45 6.59 1.98 30.00 39 85 38 88 07-89 8.34 4.54 1.43 31.56 40 88 66 88 07-89 8.33 6.61 2.12 32.03 41 88 36 88 07-89 8.31 5.55 1.79 32.23 42 80 42 88 04-89 8.28 6.86 1.98 28.93 43 85 60 88 07-89 8.24 4.78 1.43 29.96 44 95 42 88 04-89 8.22 4.92 1.35 27.37
45 92 49 88 04-89 8.13 5.25 1.53 29.06
Table 5 (a) Hybrids
1993 1994 Series Year of Planted Total Total Nut Kernel Kernel number Plant code Production Yield Yield Weight Weight Recovery
(Kg) (Kg) (g) (g) %
1 80 70 88 04-89 2.56 18.40 5.54 1.79 32.36 2 92 57 88 04-89 5.39 18.03 4.58 1.49 32.51 3 82 76 88 07-89 0.04 16.16 6.17 1.88 30.54 4 82 74 88 07-89 4.71 16.10 6.06 2.02 33.39 5 80 61 88 04-89 * 15.00 8.40 2.44 29.10 6 92 40 88 04-89 8.87 15.00 6.83 1.88 27.52 7 95 40 88 04-89 14.50 14.30 6.92 2.15 31.05 8 80 71 88 04-89 2.22 13.67 5.79 1.92 33.14
Page 27
Final report CSH-43 A 27
9 82 78 88 07-89 0.87 12.93 6.50 1.96 30.11 10 95 58 88 04-89 2.70 12.80 8.28 2.34 28.25 11 80 66 88 04-89 7.03 12.71 5.48 1.93 35.13 12 82 75 88 07-89 2.56 12.42 6.57 1.87 28.52 13 85 73 88 07-89 2.78 11.15 5.75 1.64 28.47 14 92 58 88 04-89 4.98 11.00 6.84 2.17 31.70 15 95 57 88 04-89 5.61 10.90 6.73 1.79 26.56 16 80 57 88 04-89 7.46 10.20 6.06 1.73 28.50 17 95 45 88 04-89 4.95 10.00 6.75 2.05 30.34 18 82 77 88 07-89 0.33 9.75 5.88 1.74 29.62 19 95 49 88 04-89 5.56 9.60 8.27 2.34 28.24 20 79 62 88 07-89 6.69 9.42 7.41 1.98 26.76 21 88 77 88 07-89 0.45 9.31 5.94 1.63 27.42 22 95 56 88 04-89 3.17 9.20 8.01 2.15 26.77 23 95 47 88 04-89 4.58 9.15 7.20 1.91 26.54 24 82 62 88 07-89 13.43 9.12 7.19 2.25 31.26 25 80 59 88 04-89 8.02 8.98 4.92 1.54 31.23 26 80 52 88 04-89 8.53 8.97 8.19 2.54 31.01 27 80 65 88 04-89 7.67 8.87 4.84 1.50 30.97 28 95 52 88 04-89 4.39 8.60 8.99 2.30 25.56 29 80 45 88 04-89 6.71 8.51 6.36 1.83 28.82 30 92 47 88 04-89 6.24 8.14 5.43 1.65 30.34 31 89 40 88 04-89 8.12 7.90 7.51 2.26 30.11 32 88 73 88 07-89 0.65 7.87 5.79 1.72 29.69 33 79 70 88 07-89 3.04 7.77 7.59 2.45 32.28
Table 5 (a) Hybrids
1993 1994 Series Year of Planted Total Total Nut Kernel Kernel number Plant code Production Yield Yield Weight Weight Recovery
(Kg) (Kg) (g) (g) %
1 80 70 88 04-89 2.56 18.40 5.54 1.79 32.36 2 92 57 88 04-89 5.39 18.03 4.58 1.49 32.51 3 82 76 88 07-89 0.04 16.16 6.17 1.88 30.54 4 82 74 88 07-89 4.71 16.10 6.06 2.02 33.39 5 80 61 88 04-89 * 15.00 8.40 2.44 29.10 6 92 40 88 04-89 8.87 15.00 6.83 1.88 27.52 7 95 40 88 04-89 14.50 14.30 6.92 2.15 31.05 8 80 71 88 04-89 2.22 13.67 5.79 1.92 33.14 9 82 78 88 07-89 0.87 12.93 6.50 1.96 30.11
10 95 58 88 04-89 2.70 12.80 8.28 2.34 28.25 11 80 66 88 04-89 7.03 12.71 5.48 1.93 35.13 12 82 75 88 07-89 2.56 12.42 6.57 1.87 28.52 13 85 73 88 07-89 2.78 11.15 5.75 1.64 28.47 14 92 58 88 04-89 4.98 11.00 6.84 2.17 31.70 15 95 57 88 04-89 5.61 10.90 6.73 1.79 26.56 16 80 57 88 04-89 7.46 10.20 6.06 1.73 28.50 17 95 45 88 04-89 4.95 10.00 6.75 2.05 30.34 18 82 77 88 07-89 0.33 9.75 5.88 1.74 29.62 19 95 49 88 04-89 5.56 9.60 8.27 2.34 28.24 20 79 62 88 07-89 6.69 9.42 7.41 1.98 26.76 21 88 77 88 07-89 0.45 9.31 5.94 1.63 27.42 22 95 56 88 04-89 3.17 9.20 8.01 2.15 26.77 23 95 47 88 04-89 4.58 9.15 7.20 1.91 26.54 24 82 62 88 07-89 13.43 9.12 7.19 2.25 31.26 25 80 59 88 04-89 8.02 8.98 4.92 1.54 31.23 26 80 52 88 04-89 8.53 8.97 8.19 2.54 31.01 27 80 65 88 04-89 7.67 8.87 4.84 1.50 30.97 28 95 52 88 04-89 4.39 8.60 8.99 2.30 25.56 29 80 45 88 04-89 6.71 8.51 6.36 1.83 28.82 30 92 47 88 04-89 6.24 8.14 5.43 1.65 30.34 31 89 40 88 04-89 8.12 7.90 7.51 2.26 30.11
Page 28
28
32 88 73 88 07-89 0.65 7.87 5.79 1.72 29.69 33 79 70 88 07-89 3.04 7.77 7.59 2.45 32.28
Page 29
Table 5 (a) Hybrids
1993 1994 Series Year of Planted Total Total Nut Kernel Kernel number Plant code Production Yield Yield Weight Weight Recovery
(Kg) (Kg) (g) (g) %
1 80 70 88 04-89 2.56 18.40 5.54 1.79 32.36 2 92 57 88 04-89 5.39 18.03 4.58 1.49 32.51 3 82 76 88 07-89 0.04 16.16 6.17 1.88 30.54 4 82 74 88 07-89 4.71 16.10 6.06 2.02 33.39 5 80 61 88 04-89 * 15.00 8.40 2.44 29.10 6 92 40 88 04-89 8.87 15.00 6.83 1.88 27.52 7 95 40 88 04-89 14.50 14.30 6.92 2.15 31.05 8 80 71 88 04-89 2.22 13.67 5.79 1.92 33.14 9 82 78 88 07-89 0.87 12.93 6.50 1.96 30.11
10 95 58 88 04-89 2.70 12.80 8.28 2.34 28.25 11 80 66 88 04-89 7.03 12.71 5.48 1.93 35.13 12 82 75 88 07-89 2.56 12.42 6.57 1.87 28.52 13 85 73 88 07-89 2.78 11.15 5.75 1.64 28.47 14 92 58 88 04-89 4.98 11.00 6.84 2.17 31.70 15 95 57 88 04-89 5.61 10.90 6.73 1.79 26.56 16 80 57 88 04-89 7.46 10.20 6.06 1.73 28.50 17 95 45 88 04-89 4.95 10.00 6.75 2.05 30.34 18 82 77 88 07-89 0.33 9.75 5.88 1.74 29.62 19 95 49 88 04-89 5.56 9.60 8.27 2.34 28.24 20 79 62 88 07-89 6.69 9.42 7.41 1.98 26.76 21 88 77 88 07-89 0.45 9.31 5.94 1.63 27.42 22 95 56 88 04-89 3.17 9.20 8.01 2.15 26.77 23 95 47 88 04-89 4.58 9.15 7.20 1.91 26.54 24 82 62 88 07-89 13.43 9.12 7.19 2.25 31.26 25 80 59 88 04-89 8.02 8.98 4.92 1.54 31.23 26 80 52 88 04-89 8.53 8.97 8.19 2.54 31.01 27 80 65 88 04-89 7.67 8.87 4.84 1.50 30.97 28 95 52 88 04-89 4.39 8.60 8.99 2.30 25.56 29 80 45 88 04-89 6.71 8.51 6.36 1.83 28.82 30 92 47 88 04-89 6.24 8.14 5.43 1.65 30.34 31 89 40 88 04-89 8.12 7.90 7.51 2.26 30.11 32 88 73 88 07-89 0.65 7.87 5.79 1.72 29.69 33 79 70 88 07-89 3.04 7.77 7.59 2.45 32.28
Table 6: Progressive yield data at harvest for the most promising 1988 hybrids (planted in 1988) at Wildman River Cashew Plantation
Plant 1991 Nut
1992 Nut
1993 Nut
1994 Nut
Average Nut
Average Average Kernel
code Yield (Kg)
Yield (Kg)
Yield (Kg)
Yield (Kg)
Wt. (g) Kernel Wt.(g)
Recovery (%)
95-40 8.80 15.20 14.50 14.30 6.77 2.11 30.17
82-62 6.80 15.20 13.43 9.12 6.79 2.12 31.24
89-40 6.40 14.40 8.12 7.90 7.14 2.18 30.60
79-39 8.00 14.40 10.21 5.21 6.21 1.96 31.65
95-49 4.80 14.40 5.56 9.60 7.74 2.27 29.32
95-52 7.60 13.60 4.39 8.60 7.98 2.24 28.23
79-70 6.80 13.60 3.04 7.77 6.82 2.11 30.79
Page 30
xxx
88-66 2.20 10.00 8.33 11.88 6.61 2.40 36.13
92-40 4.40 12.80 8.87 15.00 6.64 1.90 28.89
79-62 5.20 13.40 6.69 9.42 6.36 1.77 27.88
85-33 4.80 14.40 0.52 7.14 6.30 1.81 28.85
95-58 5.20 12.00 2.70 12.80 7.55 2.25 29.81
89-48 7.20 13.60 11.69 6.61 5.35 1.53 28.79
79-53 5.60 11.20 9.36 3.77 6.24 1.89 29.53
82-72 3.30 12.80 0.14 13.55 6.06 1.64 26.78
82-76 7.20 13.60 0.39 16.16 6.44 1.84 28.63
80-39 3.40 12.00 7.75 5.50 6.00 1.61 26.82
79-38 4.00 11.20 7.35 5.42 5.87 1.89 32.26
82-69 1.60 12.80 5.48 9.14 5.33 1.56 29.31
92-45 6.80 12.00 8.00 7.30 7.64 1.94 26.11
95-56 4.80 11.20 3.17 9.20 7.58 2.20 29.08
Table 7: 1992-1995
C S I R O Year of Date Total yield (kg) Me
Accesion no. Production Planted 1992 1993 1994 1995 wei
585 1989 Jul-90 0.283 4.289 3.110 6.862 5601 1989 Jul-90 0.080 3.675 2.465 6.370 6
546 1989 Jul-90 0.060 3.442 2.546 6.292 6
108 1989 Jul-90 0.564 3.896 1.489 5.954 5
688 1989 Jul-90 0.122 3.327 2.994 5.153 7
653 1989 Jul-90 0.236 3.361 3.307 4.551 9
52 1989 Jul-90 0.649 3.413 2.560 4.668 6
164 1989 Jul-90 0.404 4.467 2.117 3.853 6
681 1989 Jul-90 0.324 2.348 4.013 3.995 6
597 1989 Jul-90 0.104 2.858 3.061 4.373 8
Page 31
Final report CSH-43 A xxxi
578 1989 Jul-90 0.126 3.881 2.478 3.782 9
656 1989 Jul-90 3.386 1.760 4.864 6
507 1989 Jul-90 2.808 1.098 5.968 8
2 1989 Jul-90 0.205 2.284 2.663 4.406 7
191 1989 Jul-90 0.159 2.167 2.026 4.975 6
1916 1990 Oct-91 0.521 4.808 7.553 6
1815 1990 Oct-91 0.504 1.161 10.106 7
1889 1990 Oct-91 0.435 2.726 8.421 6
1873 1990 Oct-91 0.836 2.364 8.285 5
1645 1990 Oct-91 0.104 3.060 7.587 6
1862 1990 Oct-91 1.017 3.742 5.759 7
1699 1990 Oct-91 0.643 2.131 7.466 5
1487 1990 Oct-91 0.255 1.536 8.295 5
1886 1990 Oct-91 0.078 2.300 7.566 7
1874 1990 Oct-91 0.203 3.026 6.671 5
1369 1990 Oct-91 0.086 1.179 8.601 6
1491 1990 Oct-91 0.228 3.028 6.608 6
1088 1990 Jul-91 1.150 4.265 4.364 6
ing Producers
(a) Field planting and management of the hybrids
At this site 800 grafted trees from the 1990 hybrid population were planted in late 1992.
The trees were fertilised with 1kg of NPK + trace elements split over two applications at
the beginning and end of the wet season. Irrigation using under tree sprinklers at the rate of
400-800 L every 7-14 days was applied throughout the dry season. Insects were monitored
and controlled as required. In general the trees grew well but damage due to Mastotermes
darwiniensis killed more than 50 % of the hybrids planted at this site. This infestation has
been controlled since January 1996 using Mirant, a commercially available product
containing the active ingredient mirex.
(b) Hybrid assessment
Although the trees started flowering in the second year after planting yield was recorded
only during the 1995 season. Officers of the DPI&F NT, Katherine visually rated
approximately 300 trees and manually harvested the nuts from 16 of the highest yielding
trees. The yield data for the ten best of these hybrids is presented in Table 8.
Table 8: Yield in 1995 of top ten yielding hybrids planted at King Producers, Katherine.
Page 32
xxxii
Plant CSIRO Year of Planted Total Yield
Nut Weight
code No. Production
(kg) (g)
6-1 1161 1990 1992 8.8 5.86
6-8 1199 1990 1992 7.96 5.91
7-6 1320 1990 1992 7.89 4.19
8-16 1873 1990 1992 7.38 5.60
8-12 1542 1990 1992 6.93 8.13
7-2 1576 1990 1992 6.62 3.77
9-4 1483 1990 1992 6.38 6.21
5-7 1540 1990 1992 6.12 5.85
8-28 1604 1990 1992 5.70 5.40
4-37 1500 1990 1992 5.38 5.18
1 kernel recovery not determined
The three year old trees produced yields ranging from 5.4 kg nuts per tree (CSIRO no
1500) to 8.8 kg nuts per tree (CSIRO no 1161). With the exception of hybrids 1320 and
1576, nut size in all trees was in excess of 5 g and in hybrid no 1542 was highest at 8.13 g.
Assessment of tree structure and foliage density
Although assessments of tree structure and canopy density were carried out for several
high yielding hybrids at the Wildman River Cashew Plantation and Cashews Australia
during this period a meaningful interpretation of these characteristics will only be possible
after the trees reach maturity. These results are therefore not considered in this report.
Comparison of genotypes between sites
As outlined above, several shortcomings in the management of the hybrids were
experienced at all sites regarding pest control, irrigation or nutrition. The damage due to
insect attack was particularly severe at the Wildman River Cashew Plantation during 1993
Page 33
Final report CSH-43 A xxxiii
and 1994. Also, the death in 1995 of the owner of the Wildman River Cashew Plantation
resulted in the cessation of operations at this site. On Melville Island the growth and nut
production of the rainfed seedling hybrids were adversely affected by inadequate fertiliser
and pesticide management. These problems meant that a comparison of the productivity of
individual hybrids between sites was not possible during this project period. At Cashews
Australia the irrigation and nutrition of the hybrids are currently being upgraded. The
Wildman River Cashew Plantation has new owners from April 1997 (Cashews NT).
Upgraded management practices at these two plantations, which are now being
implemented, may allow a comparison of some genotypes between the sites during the
next project period.
(viii) Discussion
Cashew is a highly cross-pollinated crop, with insects as the major pollinators (Heard et al.
1990) . Therefore, plantations raised from open pollinated seedlings are highly
heterozygous and exhibit a wide range of genetic variability in both growth and yield.
Crop improvement programs in Brazil and India have been initially based on selection of
high yielding trees and then multiplication of such trees by asexual propagation (Nair et al.
1979; Ascenso 1986).
Brazil, the centre of origin of cashew, has the widest range of genetic material. From this
genetic base a number of high yielding selections exhibiting dwarf, semi-dwarf and
vigourous growth habits have been made (Ascenso 1986).
Genetic improvement of cashew through hybridisation was started in India during the
1950’s (Nair et al. 1979; Bavappa 1994). Despite the narrow range of genetic variability of
Page 34
xxxiv
the parents used in the hybridisation program, over 50 high yielding selections (hybrids)
have been produced during the past forty years. These hybrids are now replacing the
original seedling-based plantations in India.
The Indian experience was that whenever one exotic parent (Brazilian) was involved the
progeny showed marked improvement in yield compared with hybrids obtained from
crosses among local selections. Such a result is to be expected given the established
concept of hybrid vigour, wherein vigour is manifested in crosses involving parents with
greater genetic diversity (Nair et al. 1979). The Australian breeding program aimed to use
a similar strategy to create hybrids with high yield potential by using parents of wide
genetic diversity.
During the first phase of the current breeding program a range of high yielding genotypes
was imported for assessment under Australian conditions. Based on the growth and yield
potential of this exotic germplasm, the parents for the Australian cashew breeding program
were selected. In addition some local material selected from early introductions by DPI&F
NT and QDPI were included as parents.
Although several factors such as tree structure and canopy density contribute to yield
determination in cashew this breeding program concentrated on measuring yield (kg nuts
per tree) and its components (nut and kernel weight; kernel recovery) in individual trees.
This decision was based on the need to assess a large number of hybrids with limited
resources. Also, it had been reported that individual tree yield (nut weight) offers the best
scope for selection for yield improvement in cashew (Ramadas and Thatham 1982; Faluyi
1987; Dela Cruz 1996). Faluyi (1987) also reported from a study involving eight nut traits
within three genetically broad-based populations that only nut weight per tree and its
components showed genetic gain values above 20%, demonstrating that these traits can, to
a certain extent, be improved by selection.
As cashew is a perennial tree crop true assessment of yield potential is achieved only after
seven to ten years growth (Bavappa 1994). Cashew is a new crop to Australia and the aim
Page 35
Final report CSH-43 A xxxv
of the current phase of the breeding program was mainly to establish the hybrids at the
various sites and assist the growers to develop management practices that are non-limiting
to tree growth. During this period yield assessment of some 2-5 year old hybrids that were
fruiting were also undertaken. These early assessments demonstrated the precocious nature
and the potential for very high yield in several hybrids at each irrigated site (Tables 4-8).
As well as high yield per tree the nuts from these hybrids produced kernels that were
generally larger than 1.5 g. Cashew kernels are graded to an international standard (Nair et
al. 1979) with eight major grades ranging from W500 (450-500 kernels per lb) to W180
(170-180 kernels per lb). The kernels from the hybrids assessed in this project period fall
in the range between W 320 (1.4-1.5 g) and W180 (2.5-2.7g)). Although there is no
difference in the price of kernels between grades W320 and W180 on the world market,
large kernels (above grade W320) are desirable to establish a premium brand on the
international market for Australian grown cashews (Ian Duncan personal communication).
The kernel recovery from these nuts was generally in the range 26-32 % which compares
very favourably with the nuts from commercial hybrids grown in India (Anon. 1994).
At the Wildman River Cashew Plantation several of the 1988 hybrids, planted in 1989,
yielded about 7 kg nuts per tree in only their second year of growth (Table 6).
Furthermore, in their third year (1992 harvest) some of these hybrids increased their yield
almost 2-fold to about 10-15 kg nuts per tree. Given the continued growth of these young
trees during 1993 and 1994 the expectation was that yield would continue to increase
rapidly over time. However, problems with management of the plantation outlined earlier
in this report caused the yield of these hybrids to remain static or decrease in 1993 and
1994. Nonetheless, the yields of the above hybrids in their early years were far in excess
of those recorded for high yielding selections grown with best management in India where
yields of 4 kg nuts per tree after five years were considered satisfactory (Nambiar 1976)
and yields of up to 16 kg nuts per tree were achieved only after 8-10 years (Bavappa
1994).
Page 36
xxxvi
The later planted hybrids (Tables 4b-d, 5b-d) also showed precocity but their yield,
although high for their age by world standards, was depressed as a consequence of the pest
damage outlined earlier.
A replicated trial with ten trees each of the ten high yielding selections from the 1988
hybrid population was planted at Wildman River Cashew Plantation at the end of 1994 to
assess their performance when planted on a larger scale. However, management issues at
the plantation affected maintenance of the trial. During the next phase of the program such
replicated trials will be planted at Cashews Australia and Coastal Plantation, La Belle
Downs Station NT . (During 1996, the replicated trial with 20 trees of each hybrid was
planted at Coastal Plantation NT. A duplicate trial will be planted during 1997 at Cashews
Australia after the previous problems with irrigation and fertiliser management at this site
have been addressed.)
During 1995/96 operations at Wildman River Cashew Plantation were wound down due to
the death of the overseas owner. From this time until April 1997 the plantation was
completely neglected. New owners (Cashews NT Pty Ltd) took possession of the
plantation in April 1997 and plan to resurrect and expand the cashew operation. Although
no irrigation or fertiliser have been applied during the last two years, most of the hybrids
are still present and it is expected that they will respond well to careful management under
the new owners. Depending on their rate of recovery, these hybrids may be assessed again
during the next phase of the program. Replicated trials using the 1988 hybrids will again
be included during this phase.
The site at Katherine has a climate that is very favourable for cashew production. The
yields of 5-9 kg nuts per tree recorded from the best hybrids in 1995 (1990 hybrids,
planted in 1992) reflected a similar precocity and high yield potential as those planted at
Wildman River Cashew Plantation (Table 8).
At Cashews Australia the cool winter climate and the extremely low natural fertility of the
soil slow the development of cashew trees and hence delays the attainment of full yield
Page 37
Final report CSH-43 A xxxvii
potential compared with the sites in the Northern Territory (Table 2). In addition,
deficiencies in the irrigation and fertiliser management of the hybrids were identified
which contributed to the slow development of the trees. Despite this, yields from several of
the 1989 and 1990 hybrids (planted in 1990 and 1991) were in the range 5-10 kg nuts per
tree during their fourth and fifth years after planting.
Improvements in irrigation and fertiliser management based on experience and the results
of associated RIRDC and CSIRO research at this site (Grundon et al. 1996; O’Farrell et al.
1996) have been recommended for the next phase of this program. Such improvements in
management are expected to support much higher yields from the hybrids growing at this
site.
The plantation on Melville Island was established to assess the growth and yield potential
of the hybrids under rainfed conditions. Under such conditions it was not expected that the
hybrids would produce assessable yields until 4-5 years after planting. Although the trees
grew well during their first two years and exhibited precocious flowering, issues arising in
the joint venture company affected the management of the plantings. During 1995/96
funding for the site was stopped and yields were never assessed.
A comparison of the best-performing hybrids at each irrigated site (Tables 4-8) revealed
only one hybrid (CSIRO no 1873, produced in 1990 and planted at Cashews Australia and
King Producers Katherine, harvested in 1995) was amongst the best at more than one site.
Although a harvest was not carried out in 1995 (due to reasons explained above), this was
not one of the best performing hybrids at the Wildman River Cashew Plantation in earlier
years. These differences in relative performance between sites may have been due to
differences in genotype x environment interaction between sites or variability in
management (pest, irrigation and fertiliser management). A meaningful comparison of the
hybrids common to Wildman River Cashew Plantation and Cashews Australia will only be
possible when the management practices are uniformly upgraded at each site.
With regard to the recommendations of the RIRDC review team the next phase of the
program will include statistical analysis of the data on quantitative traits (tree yield, nut
Page 38
xxxviii
weight and kernel weight) including the calculation of age-age correlations, heritabilities
or clonal repeatabilities for each trait. Due to the high cost of manual harvest only data
from Cashews Australia will be analysed in this way. Such analyses were not possible with
the data from the current phase of the program because not all hybrids in each parental
combination were assessed due to a lack of labour and limited financial resources.
Furthermore, the problems with management of the trees at each site resulted in tree yields
which were probably not a true reflection of their genetic potential. It is expected that these
problems will be fully rectified in the next phase of the program.
(ix) Implications and recommendations
Australia currently imports about $26 m of cashew annually. Although there are large
areas of land suitable for cashew in Australia, labour costs are high and an Australian
industry will only be able to compete on the world market if high-yielding cashew
cultivars and intensive systems of management are developed.
The genetic material available from overseas has been tested and found to produce only
moderate-low yields under Australian conditions. A subsequent crop improvement
program (phase 1- RIRDC CSH-34A) has produced a range of hybrids for which field
evaluations have commenced. During the second phase of this program reported here,
planting of all the hybrids was completed at the three test sites. Furthermore, evaluation of
the early-planted hybrids demonstrated the potential of some of these to produce
commercially acceptable yields for their age. Whether this potential, derived from
individual tree data, is achievable on a commercial scale will only be known after the
completion of replicated trials during phase three of the program (1996-2001). The next
phase of the program will also allow for further evaluation of the later planted hybrids.
Page 39
Final report CSH-43 A xxxix
Difficulties encountered with hybrid maintenance on farmers properties during the current
phase of the evaluation program have highlighted the shortcomings of Australian soils in
terms of nutrient (major and trace elements) and irrigation management. Also the
importance of pest management in the Australian environment has been underlined. The
true genetic potential of the hybrids planted at the test sites will only be reflected when
such management problems are rectified. The current agronomic research on irrigation and
fertiliser management being conducted by CSIRO (MDP) and QDPI (RIRDC funded) is
expected to develop best practices for the management of cashew including the hybrids
planted at the test sites.
The potential to achieve the target yield of the hybrids (20 kg nuts per tree, 6-10 g nut
weight and >1.8 g kernel weight) will only be realised after the trees mature under
conditions of best management. Replicated trials of high yielding hybrid selections during
the next project period will provide an estimate of per hectare yields.
Associated with these cashew research programs there are strong signs that the industry is
currently in a phase of rapid expansion. Several companies are reported to be planning to
significantly expand their cashew plantings. If the high yield potential demonstrated at
Katherine is sustained and effective control of Mastotermes spp. is achieved then large
scale plantings are likely to occur in this region.
To ensure the viability of the ongoing commercial development of the cashew industry in
Australia it is imperative that the crop improvement program and related agronomic
research continue at least until 2000.
(x) Project Intellectual Property
Participating growers are a party to testing agreements governing the trialing of the
hybrids. Also, parties agreed in principle during the 1994 cashew R&D meeting in Cairns
to certain arrangements for eventual commercialisation of selected hybrids. These
arrangements included ready access to the high yielding selections for current participating
Page 40
xl
growers and a proposed levy on cashew crops along with a royalty payable for planting
material supplied to new growers who are not a party to the current project. (With the
change in ownership of the Wildman River Cashew Plantation to Cashews NT Pty Ltd, a
new testing agreement will need to be formalised.) Legal agreements with respect to
ownership of the intellectual property and commercialisation of the hybrids need to be
drawn up and signed by all parties as soon as possible.
(xi) Dissemination Strategy
Information arising from this project will be disseminated as follows:
(a) Progress in the crop improvement program will be available to the existing and
potential growers and other interested scientists through direct contact with the research
personnel involved in NT (CSIRO and DPI&F) and Qld (QDPI) and by participating in the
RIRDC cashew R&D conferences as they arise. This final report has been prepared as a
public document.
(b) RIRDC is currently sponsoring the production of a data base and a best practice
manual for cashew in Australia. Information from the crop improvement program will
form part of the data base and the manual. This manual will be readily available to all
current and prospective growers. After the next phase of the crop improvement program
initial recommendations of suitable hybrids for commercial planting will be made and
included in updated versions of the manual.
(c) After the next phase of the program it will be possible to prepare scientific papers
and popular articles to further disseminate the knowledge within Australia and overseas.
(xii) Technical Summary
An Australian Cashew Crop Improvement Program was undertaken during 1988-92 with
financial support from RIRDC. The partners in the program included CSIRO Horticulture,
Page 41
Final report CSH-43 A xli
DPI&F NT, QDPI, and three companies involved in cashew production in Australia
(Wildman River Cashew Plantation, Cashews Australia, Melville Forest Products Pty Ltd).
Using an efficient protocol developed for controlled pollination, 4539 hybrids were
produced using various combinations of parents involving a range of imported and local
selections. These hybrids were multiplied by grafting and planted at three test sites in
northern Australia where commercial plantings are under trial. After accounting for field
losses there are 3898 established trees at Wildman River Cashew Plantation, near Darwin
NT; 2949 established trees at Melville Forest Products Pty Ltd, Melville Island; and 3323
established trees at Cashews Australia, Dimbulah QLD. An additional test site (not funded
by RIRDC) involving some of the 1990 produced hybrids was also established at
Katherine NT (King Producers) where there are currently about 400 trees.
In the second phase of the crop improvement program reported here (1993-96),
identification of high yielding trees from the large hybrid population was undertaken by
visual observation of trees (more than 2-3 years old) at flowering and fruiting time. Tree
growth habit (tree structure and canopy density) and flowering time were ranked. Yield
components (individual tree yield, nut weight, kernel weight, kernel recovery) were
determined by manually harvesting the nuts from individual trees which exhibited high
yield potential.
The majority of the hybrids produced during 1990-92 and planted during 1991-93 are too
young for full assessment of their productive potential. However, evaluation of the early
planted hybrids, produced during 1988-90 and planted in 1989-91, demonstrated that 49
hybrids from the Wildman River Cashew Plantation and Cashews Australia have high
yield potential based on their individual tree yields. Twenty-one hybrids produced in 1988
yielded 10 to 15 kg nuts per tree at Wildman River Cashew Plantation after three years
growth. At Cashews Australia, of the 29 best yielding hybrids (planted in 1990 and 1991),
18 yielded 5 to 10 kg nuts per tree after 4-5 years growth. In all cases nut and kernel
characters were acceptable. Despite limitations to growth caused by sub-optimal irrigation,
fertiliser and pest management practices these yields are high by world standards and
indicate the potential of the hybrids to produce even higher yields as the trees approach
maturity.
Page 42
xlii
A replicated trial with the ten hybrids (10 trees of each) selected from the 1988 hybrid
population that exhibited precocious bearing and high yields as individual trees in their
second and third year after planting was established at the Wildman River Cashew
Plantation during 1994. This trial was set up to assess the level of productivity of these
hybrids when planted on a larger scale. Additional grafts of these hybrids are maintained at
the CSIRO nursery for planting (20 trees of each) at Cashews Australia Qld and Coastal
Plantation NT.
The cashew germplasm consisting of imported and local selections used as parents in the
hybridisation program were grafted and planted at one site. Duplicates of this valuable
germplasm are also maintained at the CSIRO Darwin nursery and will be planted at
selected commercial sites to further ensure its conservation.
It is expected that the promising hybrids identified in the early phases of the crop
improvement program will form the basis of new plantings by the current growers.
However, only after the next phase of the program will it be possible to start making firm
recommendations about high yielding hybrids for commercial planting in Australia.
Such recommendations will be disseminated through a variety of ways including personal
contact with growers, written papers and reports and as part of a best practice manual (to
be produced over the coming year).
Page 43
Final report CSH-43 A xliii
References
Anonymous (1994). A Farmer’s Primer on Growing Cashew. KJP Research Foundation, Trivandrum, Kerala, India.
Ascenso, J.C. (1986). Potential of the cashew crop I and II. Agriculture International 38:11, 324-327; 38:12, 368-370.
Bavappa, K.V.A. (1994). Cashew in 21st Century. In ‘Proceedings of the seminar Cashew in the 21st Century-Problems and Prospects for India’. (Ed. P.S. Kelath) pp 9-24. KJP Research Foundation, Trivandrum, Kerala, India.
Calder, G.J., and Day, K.J. (1982). Fertility studies on four soils of the northern lateritic uplands, Northern Territory. Northern Territory Department of Primary Industries and Fisheries Technical Bulletin No 48, Darwin.
Cann, B., Baker, I., and Kuppelwieser, W. (1987). An economic assessment of cashew production in the Northern Territory Top End. Northern Territory Department of Primary Industries and Fisheries Technical Bulletin No 10, Darwin.
Dela Cruz, F.S. (1996). Identification of superior cashew trees for northern Australian conditions. PhD thesis. University of Queensland Gatton College.
Faluyi, M.A. (1987). Genetic variability among nut yield traits and selection in cashew (Anacardium occidentale L.). Plant Breeding 98: 257-261.
Grundon, N., Blaikie, S., and Chacko, E. (1996). The CSIRO cashew multi-divisional project. pp 25-29. In ‘Eighth Cashew Research and Development Workshop Working Papers’, Kuranda, Queensland.
Heard, T.A., Vithanage, V., and Chacko, E.K. (1990). Pollination biology of cashew in the Northern Territory of Australia. Australian Journal of Agricultural Research 41: 1101-1114.
Marchal, J. (1987). Miscellaneous tropical. In ‘Plant Analysis as a Guide to the Nutrient Requirements of Temperate and Tropical Crops’. (Ed. P. Martin- Prevel, J. Gagnard and P.Gautier) pp 440-453. Lavoisier Publishing Inc. New York, USA.
Massari, F. (1994). Introduction. In ‘The World Cashew Economy’. pp 3-4. L’inchiostroblu: Nomisma Economic Research Centre.
Page 44
xliv
Nair, M.K., Bhaskara Rao, E.V.V., Nambiar, K.K.N., and Nambiar, M.C. (1979). Cashew (Anacardium occidentale L.). Monograph on Plantation Crops 1. Central Plantation Crops Research Institute, Kerala, India.
Nambiar, M.C. (1976). Technology for increasing cashew production and productivity. In ‘Increasing Production and Productivity of Cashew In India.’ pp 21-24. Central Plantation Crops Research Institute, Kerala, India.
Northcote, K.H. (1979). A Factual Key for the Recognition of Australian Soils. 3rd Edition. Rellim Technical Publications, Glenside, South Australia.
O’Farrell, P.J. (1996). Evaluation of growth habit, yield, and nut weight and shelling percentage of cashew hybrids planted at three test sites (Wildman River, NT; Melville Island, NT; and Dimbulah, NQ). A Report of the Hybrid Evaluations at Dimbulah, NQ. pp. 18-24. In ‘Eighth Cashew Research and Development Workshop Working Papers’, Kuranda, Queensland.
Ramadas, S., and Thatham, D.V. (1982). Variability and correlation of certain characters in cashewnut. pp. 229-236. Proceedings of the 4th Annual Symposium on Plantation Crops, Mysore, India.
RIRDC Final Report (1991). Improving productivity of cashew in northern Australia. Project No. 008A.
RIRDC Final Report (1993). Genetic improvement of cashew through hybridisation and evaluation of hybrid progenies. Project No. CSH-36A.