When Jackfruit (Artocarpus heterophyllus) trees start flowering they often start with male inflorescences (upper left). Some people wonder why they do not get fruit set when they see those first inflorescences appear and it can very likely be that the tree has not produced a female inflorescence (lower right) that will get pollinated with the pollen from the male inflorescence and actually hold fruit.
By the way, the reason it is called an inflorescence and not a flower is because it is a compound flower. Each segment is an actual flower. So each individual one of the white small hairy structures you see on the female inflorescence (lower right) is an actual flower that will form an aril around it which is a fruit. Jackfruit is also a compound fruit.
Below you can find some additional information on Jackfruit that we are re-posting from the Useful Tropical Plants archive by Ken and Ajna Fern who we would like to thank for creating such an accessible and comprehensive database available to all.
Jackfruit is a fast-growing evergreen tree with a spreading and irregular crown, that can grow up to 25 metres tall, but is usually smaller[335 ]. The bole, which is usually up to 80cm in diameter but can reach 200cm, is usually unbuttressed, but can sometimes have small buttresses.
A very important multipurpose tree with a wide range of uses, it is particularly valued for its fruit. The tree is widely cultivated in tropical regions, especially southeast Asia and Brazil, for its edible fruit and seed[287 , 296 ]. There are many named varieties[301 ].
E. Asia – Indian subcontinent.
Rainforests[303 ]. Evergreen forests at elevations of 450 – 1,200 metres[525 ].
|Other Uses Rating|
|Cultivation Status||Cultivated, Wild|
A plant of the humid lowland tropics, growing best at an elevation below 1,000 metres, with a mean annual temperature in the range 24 – 28°c, a mean max temperature of 32 – 35°c, a mean minimum temperature of 16 – 20°c, and a mean annual rainfall in the range 900 – 4,000mm evenly distributed through the year[303 ]. Prefers a climate without a dry season, but can tolerate a short dry season[525 ]. Jackfruits can grow at higher elevations than the breadfruit and also in cooler and drier climates[200 , 303 ]. They can even succeed in warm temperate areas, but they remain small and any fruit is of poor quality[200 ]. Trees can bear fruit at latitudes up to 30° from the equator, with good crops up to 25° distant[303 ].
Succeeds in a variety of soils[296 ]. Prefers a deep, well-drained alluvial soil[200 ]. Prefers a pH in the range 5.5 – 7.5, tolerating 4.3 – 8[418 ]. Young plants need some shade, but need increasing light levels as they mature[200 ]. Mature plants are relatively drought resistant[296 ]. Plants have poor drought tolerance[418 ].
There are two main groups of cultivars, one group has soft rinds whilst the other has hard[46 ].
Jackfruits produce one of the largest fruits in the world[200 ].
The trees have a deep taproot[303 ].
Plants can produce their first crop within 3 years of the seed germinating, but 8 years is a more common time[296 , 418 ].
Flower and fruit loads are initially low and improve with increasing size and age; trees 2 years old produce about 25 flowers and 3 fruits; trees 5 years old bear as many as 840 flowers, and trees 6 years old 1,500 flowers[303 ]. However, only 15-18 fruits develop due to the low production of female spikes (about 0.6-5% of the total number of inflorescences[303 ]. Young trees bear more male than female flowers at a ratio of 4:1; production of female flower increases with age. A male-to-female ratio of 2:1 produces 250 fruits per tree, and as the trees ages, fruit productivity declines[303 ].
In suitable environments trees bear fruits and flowers throughout the year, but in areas with distinct dry and wet seasons, flowering occurs in the wet season[303 ]. In young trees, fruits are usually borne on branches and in older trees, on trunks and roots[303 ].
Jackfruit exhibits fairly rapid growth, attaining a height of 3 metres and a canopy diameter of 2 metres at 2 years of age. In 5 years, the tree height reaches 7 metres and the canopy diameter 4 metres; trees 20 years old are about 18 metres, as tree growth slows down with age[303 ].
Fruit – raw or cooked in a variety of ways[301 ]. The pulp of young fruit is rich in carbohydrates and is usually cooked as a vegetable[K ]. The fruit becomes sweeter as it ripens, as some of the carbohydrates are converted into sugars. It is often eaten raw at this stage, but is also still cooked as a vegetable[K ]. The rind of the fruit yields a fair jelly[301 ]. The fruit case is enormous, it can be 30 – 50cm long, weigh up to 20kg and contain up to 500 individual golden-coloured fruits[46 , 296 ]. They have rather a strong smell which some people do not like, though they can be dried when the smell is less[296 ]. A sticky white latex can impede separating the edible part of the fruit – inexperienced eaters can get it stuck all over their hands, but it can be removed by using cooking oil.
Seed – cooked. Lovely when boiled or roasted, with a flavour and texture similar to chestnuts[63 , 296 , 301 ]. They can be ground into a powder and used in making biscuits[301 ]. The seeds have a high starch content and about 5% protein[63 ]. When boiling the seeds, the water is sometimes changed 2 or three times in order to remove an objectionable odour[63 ].
Very young fruits and leaf shoots – cooked in soups and stews[301 ].
Young male flowers are eaten mixed with chillies, sugar, salt etc[301 ].
The ashes of leaves, with or without oil, are used to treat ulcers, diarrhoea, boils, stomach-ache and wounds[303 ].
The pulp and seeds of the fruit are regarded as a cooling tonic[303 ]. The seeds are said to be an aphrodisiac[303 ].
The sap is an anti-syphilitic and a vermifuge[303 ].
The wood is claimed to have sedative properties, and its pith is said to be able to induce abortion[303 ].
A root decoction is used to alleviate fever, treat diarrhoea, skin diseases and asthma[303 ].
The bacteriolytic activity of the latex is equal to that of papaya latex[303 ]. Dried latex yields artotenone, a compound with marked androgenic action; it can also be mixed with vinegar to promote healing of abscesses, snakebite and glandular swellings[303 ].
The tree has a wide-ranging root system and can be planted to control floods and soil erosion in farms[303 ]. It is suitable for use in reforestation projects[418 ].
The tree is often used in mixed plantings. It can be used as a shade tree for coffee, planted with coconut groves, has been used as an intercrop in durian orchards, and with mango and citrus[303 , 418 ]. Young jackfruit orchards may be intercropped with annual cash crops such as banana, sweet corn and groundnut[303 ].
The inner part of the bark or bast is occasionally made into cordage or cloth[303 ].
The latex obtained from the trunk and branches yields 71.8% resin, consisting of 63.3% fluavilles (yellow) and 8.5% albanes (white). These resins may be valuable in varnishes[303 ].
The latex is commonly used as adhesive for mending broken chinaware or earthenware, caulking boats, mending holes of buckets and trapping birds. In India and Brazil, the latex serves as a substitute for rubber[303 ].
The bark yields a dark, water-soluble resinous gum that contains 3.3% tannin[303 ].
When boiled with alum, the sawdust or chips of the heartwood produce a rich yellow dye used for silk and the cotton robes of Buddhist priests[303 , 525 ].
Wood is yellow at first, becoming red. It is classified as medium hardwood. It is resistant to termite attack and fungal and bacterial decay and is easy to season[303 ]. It takes polish beautifully. Though not as strong as teak, it is considered superior to that wood for furniture, construction, turnery and inlay work, masts, oars, implements and musical instruments. The wood is widely used in India and Sri Lanka and is even exported to Europe[303 ]. The roots of old trees are highly prized for carvings and picture framing[303 , 899 ].
The wood is used for fuel[418 ].
Seed – under suitable conditions, germination begins within 10 days, and 80-100% germination is achieved within 35-40 days after sowing[303 ]. The seed quickly loses viability and so should be sown as soon as possible[296 ]. Seedlings produce a long taproot and can be difficult to transplant, so it is best to pot them up into deep pots as soon as they are large enough to handle and to plant them out into their permanent positions as soon as possible. The seed germinates best at a temperature of 24 – 27c[200 ].
Source: Tropical Plants Database, Ken Fern. tropical.theferns.info. 2021-11-15.