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The jackfruit A. heterophyllus Lam. (Moraceae) and its very close relative chempedak A. integer (Thunb.) Merr. originated in India and Malaysia.

Jackfruit is also known as jacquier (French), nangka (Javanese and Malay), langka (Philippines), khnaor (Cambodia), makmi, khanum, banum (Thailand) and mit (Vietnamese). The English name is most likely derived from the Portuguese jaca, taken from the Malaya tsjaka.

Jackfruit has been spread to Sri Lanka, southern China and south-east Asia, and further to tropical Africa. It was probably introduced into the Philippines in the 12th century and domesticated soon thereafter. The writings of Pliny the Elder as early as 100 AD mention jackfruit as being essential to the traditions in its place of origin (Campbell and Ledesma, 2003). The tree is still highly regarded by subsistence farmers from India and through south-east Asia for its fruit, timber and medicinal uses.

Chempedak, also known as bankong, baroh (Malaysian/Indonesia), sonekadat (Burmese), champada (Thai), cempedak, jack tree (English), kathal, kathar (Hindi), campedak, cempedak, comedak (Javanese), chakka, pilual (Tamil) and mit to nu (Vietnamese) is distributed in Burma, peninsular Thailand and Malaysia, the Indonesian islands and western New Guinea. Chempedak is separated from jackfruit by having a smaller size with a slender peduncle, a male infl orescence that is pale green to yellow and not dark green, smaller and roundish fruit with a thinner rind, and more juicy fl esh that is a darker yellow Table 2.2. Composition of 100 g edible portion of breadfruit, jackfruit, chempedak and marang (Dignan et al., 1994; Wenkam, 1990).

Constituent Breadfruit Jackfruit Chempedak Marang

Edible portion (%) 70 28 22 24–33

Proximate

Water (g) 62 83 67 65.7–84.2

Energy (kcal) 561 301 490 265–510 kJ

Protein (g) 1.3 1.6 2.5 0.8–1.5

Fat (g) 0.18 0.2 0.4 0.2–0.3

Carbohydrate (g) 37 25.4 25.8 32.4

Fiber (g) 1.45 5.6 3.4 0.6–0.77

when ripe. In addition, the embryo radicle is immersed while in jackfruit it is superfi cial (Jarrett, 1959). Chempedak is restricted to south-east Asia, with some trees in Australia and Hawaii, while jackfruit is spread throughout the tropics.

Ecology

Soil

A variety of well-drained soils with a pH 5–7.5 can be used for jackfruit. Deep alluvial sandy and clay loams are preferred. The soils used for chempedak are normally uneroded and well-drained, although the tree tolerates temporary water-logging.

Climate

Cold, drought and fl ood tolerance limits the distribution of jackfruit to areas with more than 1500 mm rainfall evenly distributed throughout the year, without a prominent dry season. A warm and humid frost-free climate with minimum temperatures of 16–22°C and mean temperatures of 25–30°C, an altitude below 1000 m, and regions 25° north and south are desirable for good jackfruit bearing. It is grown in protected subtropical regions 30° north and south. Temperatures below 5°C severely damage trees and frost will kill developing shoots and fruit, and sometimes main branches. The trees do not do well in exposed locations with drying winds. They have some salt tolerance, but poor drought and fl ood tolerance.

Chempedak is found at 0–1200 m in areas with a mean annual temperature of 13–47°C and mean annual rainfall of 1250–2500 mm. It is frequently an understory tree.

General characteristics

Tree

These monoecious, evergreen, latex-producing trees reach up to 25 m in height with a straight stem that branches near the base at an angle of 32–88°.

All parts of the plant produce a milky-white gummy latex. The diameter of the normally dome-shaped dense canopy is 3.5–7 m in 5-year-old trees. The trunk is rarely buttressed with a girth of 30–80 cm and a grayish-brown, rough, uneven, somewhat scaly bark. Minute white hairs up to 0.5 mm long are found on the surface. The tree produces a long taproot.

The glossy leaves are 4–25 u 2–12 cm (Fig. 2.2) and are usually hairy, with a dark-green top and pale-green underside. The leaves are arranged alternately on horizontal branches and spirally on ascending branches. Midrib and main veins are greenish-white to pale greenish-yellow. At the nodes, the stipules are

fused around the stem that leaves an encircling scar after the leaf abscises.

Chempedak has long wiry brown hairs (<3 mm long) on the leaves, stipules and twigs.

Flowers

The fl owers in mature trees are found on short shoots from the trunk and older branches. In young trees, the fruit are borne on branches. The elongated hanging or drooping male infl orescence is 5–15 cm long and 2–4.5 cm wide, and produced singly. The whitish- or dark-green spikes have a smooth skin that becomes yellowish and rough when mature. The female spike is either solitary or paired and elliptical or round, with rough, light to dark-green skin, 5–15 cm on a 8–9 mm thick peduncle. When young, the male and female infl orescences are enclosed by a pair of stipules that abscise. Twice as many male than female infl orescences occur on one tree.

The chempedak male infl orescence is cylindrical, 3–5.5 cm long and 1 cm in diameter. The male and female infl orescences are similar to those of breadfruit.

Pollination and fruit set

Seedling trees start to bear in 4–14 years, with no photoperiodic response reported. In suitable hot, humid conditions with evenly distributed rainfall, jackfruit bear fl owers and fruit throughout the year. In areas with distinct wet and dry seasons, fl owering occurs in the fi rst 2 months of the dry season and the wet season. A load of fruit, however, may suppress further fl owering.

The male infl orescence matures 3–5 days before the female. The sticky yellow pollen has peaks of release between 2.00–4.00 am and 4.00–6.00 pm, with a sweet scent that attracts small insects; however, the fl owers may be also wind pollinated. Anthesis commences 2–3 weeks after emergence and lasts about 2 weeks. The fl ower normally rots before abscission, attracting numerous insects by the smell. The stigmatic surface is composed of papillae that becomes sticky 1–2 weeks after exertion and remains so for a further 2 weeks.

Jackfruit may be an outcrossing species with some self-incompatibility.

The juvenile period for chempedak from seed is 3–6 years, and 2–4 years for clonal trees. Chempedak is more seasonal than jackfruit, with blooms being more common in February to April and August to October in peninsular Malaysia. In western Java, the fruit fl owers in July and August with fruit ripening between September and December. Female fl ower heads are found only on caulifl orous shoots, while most male heads are on peripheral shoots of the canopy, possibly to facilitate pollination. Chempedak provides sticky pollen to attract diverse nocturnal insects and is pollinated by them. Female heads off er a protein-rich liquid. Stigmas remain receptive for 1–2 weeks.

The use of potassium nitrate and plant growth regulator sprays to induce fl owering has been trialed without success. Potassium nitrate sprays do induce vegetative growth.

Fruit

The multiple fruit are pear- or barrel-shaped syncarps, borne on a 5–10 cm stalk (Fig. 2.2), with jackfruit having a larger fruit (4.5–50 kg) than chempedak. Each achene that makes up the syncarp is indehiscent, one-seeded, and 4–10 cm long and 2–4 cm wide when mature. The fruit is pale or dark green when young, turning to greenish-yellow, yellow or brownish when mature. The thick rubbery rind (1 cm) in jackfruit has short blunt spines. The jackfruit receptacle is not separable from the waxy, fi rm-to-soft, golden yellow, fl eshy, edible perianth (25–40% of the total fruit) that surrounds the seed (5%

of the total weight). Unfertilized fl owers develop as strap-like tissue between fertilized developing fruitlets. The fruit can have up to 500 seeds, 2–4 cm long by approximately 2 cm, with each surrounded by a horny endocarp and subgelatinous exocarp. The seeds are fi rm and waxy, and weigh up to 15 g.

Initial fruit growth is rapid after stigma emergence and for the fi rst couple of weeks after anthesis. Fruit drop is then signifi cant (approximately 35%) with the peak occurring 60–80 days after anthesis. Fruit growth follows a sigmoid growth pattern (Fig. 2.4). The fruit matures in 3–4 months for diff erent varieties and may take up to 6 months or longer when grown at higher altitudes and in cooler areas.

Cultivar development

High variability occurs in both jackfruit (2n = 56 [tetraploid]) and chempedak (2n = 56) characteristics: length of juvenile stage, seed germination, tree vigor, fruit shape and size, fl esh appearance, amount of latex, edible fl esh,

Length and Girth (cm)

Time After Fruit Set (Days)

Fig. 2.4. Change in jackfruit cv. NS1 girth and length after fruit set. (Redrawn from Muda et al., 1996.)

fl avor, aroma and fruit maturation time. No longstanding breeding programs have been undertaken. Jackfruit and chempedak occasionally hybridize 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 fl esh. This ability to hybridize between the two species attests to their close relationship.

Ripe jackfruit are divided into two types based on edible pulp. The fi rst type has thin, fi brous, soft, edible fl esh, acid to very sweet with a strong aroma.

The other type has thick, fi rm to crisp fl esh with less aroma. There are many varieties of both types. Some are more suited to canning than other fresh fruit varieties. A number of chempedak clones have been selected in Malaysia. Some of the preferred clones have an attractive orange fl esh and higher yields.

Australian selections are ‘Black Gold,’ ‘Cochin’ and ‘Golden Nugget.’ All three have deep-orange fl esh. ‘Cochin’ has little latex, while ‘Black Gold’ has a strong, sweet fl avor. ‘Dang Rasimi’ and ‘Mong Tong’ (Golden Pillow) are two Thai cultivars. These tend to have a mild sweet fl avor. ‘Dang Rasimi’ has larger fruit (8 kg) with 32% edible fl esh. ‘Tabouey’ is a popular Indonesian selection with an average weight of 12 kg and crunchy, pale-yellow fl esh. Twenty types of jackfruit have been identifi ed throughout India and are currently being perpetuated through vegetative propagation. ‘Torres,’ ‘Jo’ and ‘Jo2’ are major cultivars in the Philippines, while 13 cultivars have been characterized in Sri Lanka.

An extensive selection program in Malaysia has lead to the selections

‘J-30’ and ‘J-31.’ These produce fruit of 7 and 12 kg, respectively, with 36–38% edible fl esh. The deep-orange fi rm fl esh of ‘J-30’ has a sweet taste and only a slight aroma, while the deep-yellow fl esh of ‘J-31’ has a strong aroma. Another Malaysian program evaluated 400 samples, which led to the hybridization of ‘CJ1’ and ‘CJ6’ from which the ‘Mastura’ cultivar was developed. Commercial plantings of ‘Mastura’ began in 2000 in Malaysia.

It has a golden color with a sweet aroma, and is rapidly developing into a popular cultivar in the region.

Cultural practices

Propagation and nursery management

Seed from selected trees is the major means of propagation. The seed loses viability within 3 months of removal from the fruit, so is planted immediately.

Seedlings are best grown under shade. Germination can be improved by soaking in naphthalene acetic acid or gibberellic acid solutions.

Root cuttings are used to propagate a desirable tree, with stem cuttings and air layers also being successful with some varieties. Grafting and budding are now widely used in India and south-east Asia. Jackfruit can also be propagated in vitro. Budding, grafting and inarching are made onto 12-month-old root stocks 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.

Chempedak is generally grown from seeds taken from ripe fruit with desirable qualities. The seeds are recalcitrant and do not remain viable for long after removal from the fruit, and are sown immediately after cleaning with water.

Chempedak can be grafted to like rootstock, and some success with grafting chempedak to jackfruit and other Artocarpus species has been reported.

Field preparation

Orchards are prepared as for other tree crops.

Transplanting and spacing

Jackfruit transplanting needs to be carried out with care to avoid damage to the tap root and is best done before the trees are around 1 year old. The traditional spacing of 6–12 m on a square or triangular pattern has been recommended for these slow-growing trees. Narrower spacings of 3 m between trees in a row are now common in trees pruned to 3–5 m.

Chempedak seedlings are ready to transplant in 1 year and are placed 12–14 m apart, generally at the onset of the rainy season. Again, care is taken not to damage the long taproot.

Irrigation practices

Due to poor drought tolerance, irrigation is required especially during establishment. In the west Bengal dry season, watering with 30 l per 8-year-old plant at 30-day intervals has been found to signifi cantly increase fruit retention, fruit weight and date to fi rst harvest (Table 2.3). Drainage is essential if the land is subject to fl ooding.

Table 2.3. Effect of watering and grass mulching during the dry season on jackfruit production. Eight-year-old trees received 30 l water per plant every 30 days (Ghosh and Bera, 2006).

Mulching, no irrigation 60 3.5 10 15 June

Irrigated from November to

Pruning

Shoots are sometimes thinned and branches cleared to allow harvesting access, although often it is only the dead wood that is removed. Newer pruning strategies aim for a tree that is 3–5 m high.

Fertilization

The Malaysian recommendation is for nitrogen, phosphorus, potassium and magnesium (ratio 8:4:2:1) at 30 g/tree for those 6 months old, doubled every 6 months to 2 years. Older trees receive 1 kg/tree at a ratio of 4:2:4:1, every 6 months. Higher rates of 2–3 kg are recommended in the Philippines.

Application is before and at the end of the wet season around the outer canopy drip line.

Pest management

Seed and blossom rots, leaf spots, pink disease and fruit rot occur on jackfruit.

The blossom and fruit rot are caused by Rhizopus artocarpi to both developing and mature fruit. Bacterial dieback (caused by Erwinia canetorora) can be a problem with most Artocarpus species. Corticium salmonicolor causes pink disease of jackfruit. Root rots caused by Fusarium and Phytophora are major problems, especially if the root system is fl ooded for a few days. Leafspot caused by Phomopsis artocarpina, Colletotrichum lagenarium and Septoria artocarpi is a problem in many areas.

Jackfruit is reported to be attacked by shoot borers, bark borers, bud weevils, spittle bugs, mealy bugs, scale insects and aphids. Larvae from oriental jackfruit fl y (Dacus umbrosus Fabricius and D. dorsalis) have been found in jackfruit and marang, but are controlled with modern baits and protective bags covering the fruit as it develops. In Asia, monkeys, bats and elephants are common pests.

Weed management

Once the tree is established, weeds are not a problem because of the dense shade under the canopy. Weeds should be controlled between trees by cultivation and the use of mulch.

Orchard protection

The tree can withstand moderate wind and is occasional planted as a windbreak with closer spacing. Depending on wind strength and duration, a windbreak may be required in commercial orchards.

Harvesting and postharvest handling

Fruit quality after harvest is very dependent on maturity at harvest (Fig.

2.5). Fruit maturity can be judged by a dull hollow sound when tapped, skin color changing from green to greenish-yellow or yellowish-brown, and a

characteristic odor and fl attening of the surface spines. The tapping method is regarded as being the most reliable. On peninsular Malaysia, the nearly mature fruit are often wrapped in palm leaves or bagged ostensibly to protect against bats, rats and fruit fl ies, and to attract ants that keep other insects away. Fruit are harvested by cutting the peduncle with a knife and handled carefully to avoid mechanical injury. The latex is allowed to drain in the fi eld, and fruit are then moved from the orchard. Latex fl ow is greater early in the morning and least in late morning and early afternoon. The fruit are sometimes allowed to fall and must be collected daily because they have a shelf life of only 2–3 days. Letting the fruit fall can cause damage, loss of shelf life and premature ripening.

Grading is not normally practiced and fruit are rapidly transported to the markets. Fruit from larger orchards and at packing sheds, and accumulation sites will be graded on size and appearance. A large fruit would be more than 15 kg and small fruit less than 7–8 kg.

This climacteric fruit shows the typical increase in respiration production of a strong sweet aroma, softening, increase in aril yellow carotenoids and conversion of starch to sugars over the 7–9 days of ripening (Fig. 2.5). During ripening, tannins also decline while acidity shows little change. Fruit harvested after 12 weeks in tropical areas should be organoleptically acceptable after ripening. Mature undamaged fruit can be stored at 10–12°C for 2–3 weeks.

Fruit ripen in 3–7 days at 22–27°C, depending on the stage of maturity at harvest.

Solids and Starch (%)

Time After Fruit Set (Days)

Acidity (% Citric)

Fig. 2.5. Changes in titratable acidity, total soluble solids and starch during jackfruit growth and development. (Redrawn from Muda et al., 1996.)