Artocarpus heterophyllus (jackfruit)

Jackfruit are evergreen, latex-producing trees of up to 25 m that are native to India and Malaysia, that have spread to Sri Lanka, China, South-east Asia and to tropical Africa. They are cultivated for the large fruits that can vary in shape and size, and for timber. Propagation is normally by seeds, since vegetative propagation is difficult. Fruits can be cooked and eaten unripe as a vegetable (25-50% of full size), eaten ripe as a fruit, may be canned, used to make jams and jellies, or may be dried.

Principal sources: Janick and Paull (2008); Paull and Duarte (2012)

The following summary is from Witt and Luke (2017):

The genus Artocarpus (Moraceae) comprises about 50 species of evergreen and deciduous trees of importance for their edible fruits, timber and medicinal value (Jagtap and Bapat, 2010).

The generic name derives from the Greek words ‘artos’ (bread) and ‘karpos’ (fruit) (Orwa et al., 2009). The edible fruits are commonly called breadfruit. The specific name, ‘heterophyllus’, is Latin for various-leaved, describing its leaves of different sizes and shapes. This, in turn, is from the Greek word ‘heteros’ (different) (Orwa et al., 2009).

The jackfruit, A. heterophyllus Lam., and its very close relative the chempedak, Artocarpus integer (Thunb.) Merr., originated in India and Malaysia. There appears to be a higher diversity within the genus Artocarpus along the tropics of the Indo Malayan region compared to Australasia, and its taxonomic status has been recently assessed in Sri Lanka (Senavirathna et al., 2020).

There are two main groups of cultivars: one with soft rinds and the other hard (Uphof, J.C. Th., 1959) – see also GENETIC RESOURCES.

The common name ‘jackfruit’ derives from the Portuguese jaca, which in turn is believed to come from chakka in Malayalam, following the arrival of the Portuguese on the Malabar Coast of Kerala in 1499 (Pradeepkumar et al., 2008). The Malayalam term has a Proto-Dravidian root kā(y) meaning ‘fruit, vegetable’ (Southworth, 2004), Jackfruit is also known as jacquier (French), nangka (Java and Malay), langka (Filipino), khnaor (Cambodian), makmi, khanum, banum (Thai) and mit (Vietnamese) (Janick and Paull, 2008).

Medium-sized, evergreen, monoecious tree up to 20(-30) m tall and 80(-200) cm in diameter; all living parts exude viscid, white latex when injured. Bark rough to somewhat scaly, dark grey to greyish-brown. Crown dense, conical in young and shaded trees, becoming rounded or spreading in the older tree. New shoots, twigs and leaves usually glabrous but occasionally short-haired and scabrid. Stipules ovate-acute, 1.5-8 x 0.5-3 cm, deciduous and leaving annular scars on the twigs.

Leaves thin leathery, obovate-elliptic to elliptic, 5-25 x 3.5-12 cm, broadest at or above the middle, base cuneate, margin entire or in young plants often with 1-2 pairs of lobes, apex rounded or blunt with short, pointed tip; dark green and shiny above, dull pale green underneath; petiole 1.5-4 cm long, shallowly grooved on the adaxial side, sparsely hairy.

Inflorescences solitary, borne axillary on special lateral, short leafy shoots arising from older branches and main trunk; male flower heads barrel-shaped or ellipsoid, 3-8 cm long and 1-3 cm across, composed of sterile and fertile flowers closely embedded on a central core (receptacle), dark green, stalk 1.5-3.5 cm long and 0.5-1 cm thick, bearing annular ring near the distal end; sterile male flowers with solid perianth; fertile male flowers with tubular, bilobed, 1-1.5 mm long perianth, stamen 1-2 mm long; female heads borne singly or in pairs distal to the position of male heads, cylindrical or oblong, dark green, 5-15 cm long, 3-4.5 cm across, with a distinct annulus at the top end of the stout stalk, subtended by a spathaceous, deciduous bract, 5-8 cm long; female flowers with tubular perianths which are fused at both ends and projecting as 3-7-angled, blunt or pointed, minute pyramidal protuberances topped by spathulate or ligulate styles and stigmas.

Fruit (syncarp) barrel- or pear-shaped, 30-100 x 25-50 cm, with short pyramidal protuberances or warts; stalk 5-10 cm long, 1-1.5 cm thick; rind ca 1 cm thick, together with the central core (receptacle) inseparable from the waxy, firm or soft, golden yellow, fleshy perianths surrounding the seeds. Seeds numerous, oblong-ellipsoid, 2-4 x 1.5-2.5 cm, enclosed by horny endocarps and subgelatinous exocarps; testa thin and leathery; embryo with ventral radicle, cotyledons fleshy, unequal; endosperm very small or absent.

The jackfruit is most probably indigenous to (and in the past grew wild in) the rain forests of the Western Ghats, India. Since time immemorial it has been cultivated; it was introduced and became naturalized in many parts of the tropics, particularly in the South-East Asian region.

The following information is quoted from PROTA (2021):

A host of diseases and pests has been reported, but few are specific to jackfruit, and crop protection is not a major concern for growers. However, bacterial dieback caused by Erwinia carotovora [Pectobacterium carotovorum] is causing increasing losses in jackfruit as well as chempedak. Initially, the bacteria affect the growing shoots, but the disease spreads downwards and eventually kills the tree. To control the disease, chemicals, including trunk injection with antibiotics, are being tested in Malaysia although Garden Organic (2021) offers a good range of non-toxic organic alternatives, with tips offered on their International Resources webpage.

A serious disease in Assam (India) is blossom rot, also called fruit rot or stem rot, caused by Rhizopus stolonifer, leading to crop losses estimated at 15-30%. The inflorescences or the tips of the flowering shoots are infected. The inflorescences are blackened by the sporangia; they rot and drop. Copper fungicides are effective, and control of ants which carry the spores should be considered.

Leaf spots of various descriptions can often be found. Different fungi may be involved, including Colletotrichum lagenarium [Gloeosporium orbiculare], Phomopsis artocarpina and Septoria artocarpi. The well-known pink disease, Corticium salmonicolor [Phanerochaete salmonicolor], is a prominent disease of jackfruit. Thorough removal of affected parts is recommended so that the rainy season is entered with a low infection pressure.

Borers are the major pest. Caterpillars of Diaphania caesalis [Glyphodes caesalis], the shoot borer, tunnel into buds, young shoots and fruit. Removal of affected parts breaks the lifecycle since the caterpillar pupates in the tunnel; fruit may be bagged for protection. Bark borers, caterpillars of Indarbela tetraonis and Batocera rufomaculata, can be controlled by fumigating the holes. The brown bud weevil, Ochyromera artocarpi, is a specific jackfruit pest. The grubs bore into tender buds and fruits and the adults feed on the leaves. Infected parts should be destroyed and insecticides may be needed. Swarms of spittle bugs, Cosmoscarta relata, feed on young leaves. The nymphs live together in a mass of secreted froth, which may be collected and destroyed.

Maggots of fruit flies, Bactrocera dorsalis and B. umbrosus [B. umbrosa], may infest the fruit. To control the pest, the fruit is bagged, ripe and overripe fruit are not left around but buried deep in the ground, and bait sprays may be used. Other pests include numerous sucking insects such as mealybugs, aphids, white flies, thrips, etc. and also leaf-webber caterpillars.

Rodents and in particular rats eat germinating seeds, so nursery areas should be protected from them.

No major non-infectious disorders of jackfruit have been identified.

The pulp of young fruit is cooked as a vegetable, pickled or canned in brine or curry; pulp of ripe fruit is eaten fresh or made into various local delicacies (e.g. 'dodol' and 'kolak' in Java), chutney, jam, jelly and paste, or preserved as candies by drying or mixing with sugar, honey or syrup. The pulp is also used to flavour ice-cream and beverages, or made into jackfruit honey, or reduced to a concentrate or powder and used for preparing drinks. Addition of synthetic flavours such as esters of 4-hydroxybutyric acid greatly improves the flavour of canned fruit and nectar. The seeds are eaten after boiling or roasting, or dried and salted as table nuts, or ground to make flour which is blended with wheat flour for baking. Young leaves are readily eaten by cattle and other livestock. The bark contains ca 3.3% tannin, and is occasionally used in making cordage or cloth. A yellow dye extracted from wood particles is used to dye silk and the cotton robes of Buddhist priests. The latex serves as birdlime and is employed as a household cement for mending china and for caulking boats.

The timber is classified as medium hardwood; it is resistant to termite attack, fungal and bacterial decay, easy to season and takes polish beautifully. Thus, though not as strong as teak, jackfruit wood is considered superior to teak for furniture, construction, turnery, masts, oars, implements and musical instruments. The wood is widely used in Sri Lanka and India, and is exported to Europe. Roots of older trees are highly prized for carving and picture-framing.

The jackfruit tree is also renowned for its medicinal properties. In China, jackfruit pulp and seeds are considered as a cooling and nutritious tonic, useful in overcoming the effects of alcohol. In South-East Asia, the seed starch is used to relieve biliousness and the roasted seeds are regarded as an aphrodisiac. Heated leaves are placed on wounds, and the ash of the leaves burned with maize and coconut shells is used to heal ulcers. Mixed with vinegar, the latex promotes healing of abscesses, snakebite and glandular swellings. The bark is made into a poultice. The wood has sedative properties and its pith is said to induce abortion. The root is used as a remedy against skin diseases and asthma, and its extract is taken in cases of fever and diarrhoea.

Propagation and Planting

Propagation is normally by seeds, since vegetative propagation is difficult; only in Thailand does vegetative propagation predominate. Successful in vitro propagation has recently been reported from India. Seed should be obtained from outstanding mother trees; large seeds only are used. Extraction includes thorough washing to remove the slimy coating around the seeds, and removal of the horny part of the pericarp; this improves germination. The seed is sown fresh; if short-term storage is necessary, the seed should not be allowed to dry out. Seeds with about 40% of their original moisture content and stored in air-tight polythene containers at 20°C remain viable for about 3 months. Under suitable conditions germination begins within 10 days, and 80-100% germination is achieved within 35-40 days after sowing. The seeds are laid flat or with the hilum facing down to hasten emergence. Young seedlings are potted at the latest when they have four leaves, since older seedlings are hard to transplant. This problem can be avoided by sowing 1-2 seeds directly into containers. The seedlings are best raised under shade (50-70% of full light intensity). They should be planted out when still young - usually less than one year old - and before the roots grow outside the pot, since disturbance of the roots may be fatal. It is possible to propagate through cuttings (from forced, etiolated shoots treated with 5 g IBA per litre), air layers (treated with 25 ppm NAA or 100 p.p.m. IBA solution), budding (modified Forkert method or patch budding) and grafting (cleft grafting and wedge grafting), but the results are variable and the methods need to be refined.

Budded material of the main clones is usually available in Malaysia. In Australia very good results are obtained by wedge grafting onto young vigorous rootstocks in an enclosed high humidity chamber (polythene covers). In South-East Asia, the only method which is routinely applied on a large scale, i.e. in Thailand, is 'suckle-grafting', a form of inarching: young potted seedling rootstocks are decapitated and inserted in twigs of a selected mother tree. The percentage take is high and the method can be applied at any time of the year. Various studies have shown that A. integer (chempedak), A. hirsutus, A. rigidus and A. altilis (breadfruit) can also serve as rootstocks. In Indonesia the best results were obtained by budding 8-11-month-old chempedak rootstocks. Orchard trees are spaced 8-12 m apart in square or hexagonal patterns; the usual density is 100-120 trees/ha. The best planting time is at the onset of the rainy season. Shade is provided and the leaves are halved to reduce transpiration. Additional watering may be needed during the first 2 years. Jackfruit is occasionally planted as an intercrop, for example in coconut groves in the Philippines. In Peninsular Malaysia, jackfruit trees have been used as intercrop and shade trees in durian orchards. In India the trees are intercropped with mango and citrus, and are also used as shade trees for coffee and black pepper. Young jackfruit orchards may be intercropped with annual cash crops such as banana, sweet corn and groundnut. Closely planted rows may serve as windbreaks (Australia).

Husbandry

Mulching helps to conserve moisture during the dry season. It is recommended to fertilize twice per year, at the onset and before the end of the rainy season. The recommended rates vary from 1 kg compound fertilizer per tree per application (Peninsular Malaysia) to 2-3 kg (the Philippines). Pruning is limited to thinning the shoots when the trees are planted and some clearing of the bearing branches to facilitate access to the fruit for wrapping up and harvesting. Fruit is often protected by bagging or weaving a 'coat' around it, using for instance palm leaflets. This deters rodents and fruit bats, and also attracts ants which keep other insects away.

Harvesting

Fruit maturity is determined by the following criteria: (1) dull, hollow sound when tapped; (2) change in skin colour from pale green to greenish- or brownish-yellow; (3) emission of characteristic odour; (4) flattening of the spines and widening of the spaces in between. The stalk is cut with a sharp knife and the fruit carefully lowered to the ground.

Yield

Based on trees grown on experimental stations, the potential yield has been variously estimated as (20-)100-200(-500) fruit/tree per year, each fruit weighing (10-)20-30(-50) kg. However, the actual yield is a tiny fraction of these unrealistic figures which would add up to 2000-4000 kg/tree per year: the average yield is about 70-100 kg/tree per year in Malaysia and the Philippines.

Handling after Harvest

The fruit is collected by wholesalers or taken directly to the market and sold to retailers or cut open and sliced into pieces for direct sale to consumers. Often the fleshy perianths are extracted, cleaned, and sold fresh. During gluts in the supply much fruit is preserved; the flesh is separated from the seeds, washed, pressed and sun-dried with or without addition of sugar or syrup. The products are sold as dried candies. Canneries operate in Peninsular Malaysia.

Orchard trees may be spaced 8-12 m apart in hexagonal or square patterns, usually at a density of 100-120 trees/ha (Seibert and Jansen, 1991). They sometimes serve as windbreaks in closely planted rows in Australia (Seibert and Jansen, 1991). Planting is best done at the onset of the rainy season (Seibert and Jansen, 1991). Shade can be provided and leaves halved to reduce transpiration (Seibert and Jansen, 1991).

Artocarpus heterophyllus is usually planted on smallholder cane farms in India, in home-gardens in Fiji and also in rural gardens and home-gardens in other areas of the Pacific (PROTA, 2021) and eastern Africa.

The species is sometimes planted as an intercrop, e.g. in the Philippines in coconut groves, in Peninsular Malaysia to provide shade for durian and in India with mango and citrus, and also as shade for coffee and black pepper (Seibert and Jansen, 1991). Young A. heterophyllus orchards can also be intercropped with annual cash crops such as groundnut, corn and banana (Seibert and Jansen, 1991).

Warm and humid, frost-free climates with minimum temperatures of 16-22°C and mean temperatures of 25-30°C, below 1500 m and 25°N and S are desirable for good jackfruit bearing. Cold, drought and flood tolerance limits the distribution of jackfruit to areas having greater than 1500 mm rainfall evenly distributed throughout the year, without a prominent dry season. Temperatures below 5°C severely damage trees and frost will kill developing shoots, fruit and sometimes main branches. The tree does not do well in exposed locations with drying winds. The trees have some salt tolerance and poor drought and flood tolerance.

Artocarpus germplasm collections of mainly cultivated species are held in Fiji (Koronivia Research Station, Namsoni) and Papua New Guinea (Lowlands Agricultural Experiment Station, Keravat) (PROTA, 2021), Germplasm collections are also available in Indonesia (Centre for Research and Development in Biology, Bogor), the Philippines (Institute of Plant Breeding, Los Baños), Thailand (Plew Horticultural Research Centre, Chantaburi), and the United States (US Department of Agriculture, Subtropical Horticultural Research Unit, Miami and the College of Tropical Agriculture and Human Resources, Hawaii) (PROTA, 2021). A list of 32 accessions, including 13 active and 13 available, is provided by USDA-ARS (2021).

No hybridization has been undertaken and rootstock studies have yielded only preliminary results. The cultivars now in use are the result of selection and clonal propagation. Most jackfruits are extremely heterozygous, but the cultivars 'Rudrakshki' and 'Singapore Jack' (= 'Ceylon Jack') in India are said to breed more-or-less true to type from seed. Morton (1987) gives a detailed description of varieties.

Nearly all the species of the genus are being tested in public and/or private collections in Queensland, Australia (PROTA, 2021).

There is high variability in jackfruit (2n = 56; tetraploid) and chempedak (2n = 56) characters including: length of juvenile stage, seed germination, tree vigour, fruit shape and size, flesh appearance, amount of latex, edible flesh, flavour, aroma and fruit maturation time. No long-standing breeding programmes have been undertaken, but many local selections exist.

Jackfruit and chempedak occasionally hybridise and a clone has been selected in Malaysia called Nangka-chempedak CH/NA. This selection, ‘Cheena’, has smaller fruit (2.5 kg) and 33% edible flesh. This ability to hybridise attests to their close relationship. Ripe jackfruit are divided into two types based upon edible pulp. The first type has thin, fibrous, soft edible flesh, which is acid to very sweet with a strong aroma. The other type has thick, firm to crisp flesh with less aroma. There are many varieties of both types. Some are more suited to canning than other fresh fruit varieties.

Australian selections are ‘Black Gold’, ‘Cochin’ and ‘Golden Nugget’. All three have deep orange flesh. ‘Cochin’ has little latex while ‘Black Gold’ has a strong, sweet flavour. ‘Dang Rasimi’ and ‘Mong Tong’ (golden pillow) are two Thai cultivars. These tend to have a mild sweet flavour. ‘Dang Rasimi’ has larger fruit (8 kg) with 32% edible flesh. ‘Tabouey’ is a popular Indonesian selection with an average weight of 12 kg with crunchy, pale yellow flesh.

Twenty types of jackfruit have been identified throughout India and are currently being perpetuated through vegetative propagation. ‘Torres’, ‘Jo’ and ‘Jo2’ are major cultivars in the Philippines while 13 cultivars were characterized in Sri Lanka. An extensive selection programme in Malaysia has led to the selections ‘J-30’ and ‘J-31’; the fruit are 7-12 kg, respectively, and have 36-38% edible flesh. The deep orange firm flesh of ‘J-30’ has a sweet taste and only a slight aroma, while the deep yellow flesh of ‘J-31’ has a strong aroma. Another Malaysian programme evaluated 400 samples which led to the hybridization of CJ1 and CJ6 from which the ‘Mastura’ cultivar was developed. Commercial plantings of the ‘Mastura’ (CJ-USM 2000) began in 2000 in Malaysia. It has a golden colour with a sweet aroma and is rapidly developing into a popular cultivar in the region.

Principal sources: Janick and Paull (2008)

Propagation is normally by seeds, since vegetative propagation is difficult; only in Thailand does vegetative propagation predominate. Successful in vitro propagation has recently been reported from India. Seed should be obtained from outstanding mother trees; only large seeds are used. Extraction includes thorough washing to remove the slimy coating around the seeds, and removal of the horny part of the pericarp; this improves germination. The seed is sown fresh; if short-term storage is necessary, the seed should not be allowed to dry out. Seeds with about 40% of their original moisture content and stored in air-tight polythene containers at 20°C remain viable for about 3 months. Under suitable conditions, germination begins within 10 days, and 80-100% germination is achieved within 35-40 days after sowing. The seeds are laid flat or with the hilum facing down to hasten emergence. Germination can be improved by soaking in naphthalene acetic acid (NAA) or gibberellic acid (GA) solutions.

Young seedlings are potted at the latest when they have four leaves, since older seedlings are hard to transplant. This problem can be avoided by sowing 1-2 seeds directly into containers. The seedlings are best raised under shade (50-70% of full light intensity). They should be planted out when still young - usually less than one year old - and before the roots grow outside the pot, since disturbance of the roots may be fatal. It is possible to propagate through cuttings (from forced, etiolated shoots treated with 5 g IBA per litre), air layers (treated with 25 ppm NAA or 100 ppm IBA solution), budding (modified Forkert method or patch budding) and grafting (cleft grafting and wedge grafting), but the results are variable and the methods need to be refined. To propagate a desirable tree, root cuttings can also be used. Grafting and budding are now widely used in India and South-east Asia. Jackfruit can also be propagated in vitro.

Budded material of the main clones is usually available in Malaysia. In Australia, very good results are obtained by wedge grafting onto young vigorous rootstocks in an enclosed high humidity chamber (polythene covers). In South-East Asia, the only method which is routinely applied on a large scale, i.e. in Thailand, is 'suckle-grafting', a form of inarching: young potted seedling rootstocks are decapitated and inserted in twigs of a selected mother tree. The percentage take is high and the method can be applied at any time of the year. Various studies have shown that A. integer (chempedak), A. hirsutus Lamk, A. rigidus Blume and A. altilis (breadfruit) can also serve as rootstocks. In Indonesia, the best results were obtained by budding 8-11-month-old chempedak rootstocks. Orchard trees are spaced 8-12 m apart in square or hexagonal patterns; the usual density is 100-120 trees/ha. The best planting time is at the onset of the rainy season. Shade is provided and the leaves are halved to reduce transpiration. Additional watering may be needed during the first 2 years. Jackfruit is occasionally planted as an intercrop, for example in coconut groves in the Philippines. In Peninsular Malaysia, jackfruit trees have been used as intercrop and shade trees in durian orchards. In India, the trees are intercropped with mango and citrus, and are also used as shade trees for coffee and black pepper. Young jackfruit orchards may be intercropped with annual cash crops such as banana, sweet corn and groundnut. Closely planted rows may serve as windbreaks (Australia).

Principal sources: Janick and Paull (2008)

Budding, grafting and inarching are made onto 12-month-old rootstocks of A. integer, A. heterophyllus, other Artocarpus species and the same species. However, the suitability of these rootstocks has not been evaluated in a range of environments.

Principal sources: Janick and Paull (2008)

Jackfruit is a good source of carbohydrates and vitamin A, and is a fair protein source. 100 g of raw jackfruit contains: 73.46 g of water; 95 kcal; 1.72 g protein; 0.64 g total lipid; 23.25 g carbohydrate; 19.08 g total sugars; 1.5 g fibre; 24 mg Ca; 0.23 mg Fe; 29 mg Mg; 21 mg P; 448 mg K; 2 mg Na; 0.13 mg Zn; 13.7 mg vitamin C; 0.105 mg thiamin; 0.055 mg riboflavin; 0.920 mg niacin; 0.329 mg vitamin B6; 24 µg folate; 5 µg vitamin A, RAE; 110 IU vitamin A; and 0.34 mg vitamin E (USDA).

Principal sources: Janick and Paull (2008)

 

A disadvantage of the species is that it cannot tolerate poor drainage or drought. Other negative attributes include an unpredictable yield, both in terms of timing and quantity, strong odour, crop losses due to pests and diseases and the large fruit size which limits potential in export markets, all of which cause financial returns to be low (PROTA, 2021).

It is not clear why so few statistics are available; jackfruit is, after all, a major fruit and even assumes the role of a staple in periods of food scarcity. The crop is grown in Thailand, the Philippines and Malaysia. In South-East Asia, jackfruit is planted mainly in home gardens and mixed orchards; in the 1980s, several larger commercial orchards were planted with jackfruit as an intercrop for durian. The large perishable fruit does not lend itself to the export trade, but canned products are exported to Australia, Europe, etc. by canneries in Peninsular Malaysia.

Jackfruit is spread throughout the tropics and can produce 20-250 fruit/tree/year, sometimes up to 500, each fruit weighing from 10 to 30 kg. Jackfruit has a tendency to be somewhat biennial in bearing. Commercial yields average 70-100 kg/tree/year. Orchards in Malaysia report a yearly average of 17,000 kg/ha. For the year 2000, the Philippines reported 11,735 ha of jackfruit in production with yields of 4.08 t/ha. India is probably the largest producer (Thomas, 1980) (Love and Paull, 2007).

The prospects for expansion of jackfruit in South-East Asia are rather bleak. The tree and the fruit have several negative attributes: unpredictable yield, both in quantity and timing, crop losses due to diseases and pests, the strong odour, and the large fruit size which limit its potential in export markets. Consequently, the financial returns are low in comparison with, for instance, carambola, durian and guava. However, there is a wide gap between potential and actual yield. Planting of high-yielding cultivars is the crucial step towards closing the gap. There are also cultivars with fruit whose smell and taste appeal to the uninitiated consumer; these might be used to penetrate other markets. Actual yield also lags behind because it is not clear how jackfruit trees function in the course of the year, so that the grower cannot time his operations to raise yield rather than just stimulating growth. Where cultivars replace seedling populations, it becomes easier to study tree phenology as all trees of a cultivar have the same genotype. This means that differences between trees in growth rhythm, flowering time, pollination intensity, fruit set and yield must be due to environmental factors. Thus the study of the phenology of a cultivar in different environments offers insight into how trees function and gives clues for the elimination of yield-limiting factors. The future role of jackfruit hinges on general use of clonal planting material and a better understanding of tree phenology and fruitfulness.

Ibrahim AG et al., 1980. Plant protection in orchards. In: Yaacob O, ed. Fruit production in Malaysia. Faculty of Agriculture, Universiti Pertanian Malaysia, Serdang, Selangor, Malaysia,163-190.Bhutani DK, 1978. Pests and diseases of jackfruit in India and their control. Fruits,33: 352-357.Burgess PF, 1966. Timbers of Sabah. Forest Department, Sabah, 399-406.Ch'ng GC, Ahmad IH 1980. Nutritive value and utilization of Malaysian fruits. In: Yaacob O, ed. Fruit Production in Malaysia. Faculty of Agriculture, Universiti Pertanian Malaysia, Serdang, Selangor, Malaysia, 242-259.Corner EJH, 1939. Notes on the systematy and distribution of Malayan Phanerogams, II. The jack and the chempedak. Garden's Bulletin Straits Settlements, Singapore, 10: 56-81.Coronel RE, 1986. Promising fruits of the Philippines. 2nd edition. College of Agriculture, University of the Philippines at Los Banos, 251-272.Hashim MY, Hussein MA, 1981. A report on the techno-economic survey of the Malaysian Fruit Industry, 1980. MARDI-UPM, Serdang, Selangor, Malaysia. Molesworth-Allen B, 1967. Malayan fruits: an introduction to the cultivated species. Singapore:Donald Moore Press, 202-205.Roy SK et al., 1990. In vitro propagation of jackfruit [Artocarpus heterophyllus Lam.]. Journal of Horticultural Science, 65(3): 335-358.Wong TM, 1982. A dictionary of Malaysian timbers. Malayan Forest Record No 30, 95-97.