Evaluating Cashew Hybrids in Northern Australia

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

© 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

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

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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

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

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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.


(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

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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.


(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

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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.


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


658 G

Cashews Australia, Dimbulah QLD

557 G

Melville Island, NT 602 S


840 G

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696 G



1300 G


1224 G



890 G


846 G


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


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.

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.


(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.

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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


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).

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(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


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.

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


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.

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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 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.


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 %.

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


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.


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

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


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


(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

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

Table 5 (a) Hybrids


(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

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

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.


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.

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

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

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

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).

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

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

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.

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

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,

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.

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).

Final report CSH-43 A xliii

References

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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.

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Northcote, K.H. (1979). A Factual Key for the Recognition of Australian Soils. 3rd Edition. Rellim Technical Publications, Glenside, South Australia.

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Evaluating Cashew Hybrids in Northern Australia

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