CHIKU is delicious fruit crop of tropical and sub-tropical countries and is cultivated on about 564 hectares with production at 2,018 metric tons.
In Pakistan, the mature fruits are also used for making jams as these provide a valuable source of raw material for the manufacture of industrial glucose, pectin and natural fruit jellies. They are also canned as slices.
The chiku fruit when fully ripe is delicious to eat. The pulp is sweet and melting. The usual practices are to eat only the pulp. The fruit skin can also be eaten since it is richer than the pulp in nutrient value.
Chiku is rich in protein, fibre and minerals like phasphorus, calcium and iron. The tree bear fruit within three years of planting. The main reasons for its popularity is that there is no danger of pilferage of the ripened in the basket and not on the tree where it remains hard, astringent and rich in latex.
The fruits not peeled show abnormal amounts of tannin contributed by the skin. The moisture range from 69-75.7 per cent; ascorbic acid from 8.9 to 41.4mg/100g; total acid 0.09-0.15 per cent, pH from 5-to 5.3; total soluble solids at the ratio of 17.4:23.7; carbohydrates and glucose range from 5.84 to 6.40 per cent.
The fruit has medicinal also as young fruit is boiled and its decoction is used in diarrhoea; an infusion of young fruits and flower relieves pulmonary complaints; decoction of old, yellowed leaves is good for cough, cold and diarrhoea; tea made from bark is also helpful in diarrhoea and dysentery.
Fluid extract of crushed seeds and leaves lowers blood pressure; paste of seeds is applied on stings and bites. The latex is used in filling tooth cavities. A major product of tree is the gummy latex called “chicle”, containing 15 per cent rubber and 38 per cent resin.
Chiku is a tropical fruit and can be grown from sea level up to 1,200 meters. The plant prefers warm and moist weather and can grow both in dry and humid areas. The coastal climate is best suited to this plant.
At higher altitudes, the fruit quality and tree health suffers. Areas with an annual rainfall of 125-250cm are highly suitable. Rain or cloud weather during any part of the year does not do any harm to fruit set. The optimum temperature is between 11°C and 34°C.
The fruits mature in four to six months after flowering. In the tropics, some cultivars bear almost continuously. The main season is from December to March. The trees bear from May to September with the peak of the crop in June and July. The most ideal soils are deep alluvium, sandy loams, red late rites and medium black soils. Sometimes it is planted in dry river beds with alluvial soil. Good drainage is essential. It is highly drought resistant and approaches the date palm in its tolerance of soil salinity.
Pits of the size of 60cm 3 or 100 cm 3 are prepared at a distance of 8-10m both ways depending upon the planting material and the soil. In low rainfall areas and soils with low fertility closer spacing is followed, while in heavy rainfall tracts and fertile soils a wider spacing is recommended. The top 30cm soil is kept separately on one side of the pit, while the remaining is kept on another side. The pits are left for a month or two.
The best time for planting is during early monsoon. Grafts, budded plants or layers are planted one in each pit in the centre and care is taken to ensure that the roots are gently and firmly pressed and stakes are provided to avoid wind damage. The plants are then watered.
Chiku plant can tolerate drought conditions to some extent, yet it responds well to irrigation. Young plants are watered regularly during dry season having long breaks in the monsoon and in winter and summer at an interval of six to 12 days. Young plants are given irrigation once in eight days from October onwards till monsoon starts. Protective irrigation is given during first two seasons.
Newly planted trees need small and frequent feedings to become established. Fertilizers that contain 6-8 per cent nitrogen, 2-4 per cent available phosphoric acid and 6-8 per cent potash give satisfactory results. First year applications should be made every two to three months beginning ¼ pound and gradually increasing to one pound. Thereafter, two to three applications per year are sufficient, in amounts proportionate to the increasing size of the tree.
Chiku is mostly propagated by seeds which remain viable for many years if kept dry. It takes five to eight years to bear. Since seed may not come true, vegetative propagation is desirable. Veneer grafting with seedlings as rootstock is the best method. Air layering and rooting of cuttings have not been successful.
In Sindh there are two varieties called oval and round.
Oval: Fruits of this variety are small to medium in size and oval in shape. Pulp is coarse grained and less sweet. It is shy bearing cultivar.
Round: The foliage of this variety is like green and fruits are large but the flesh is gritty and of moderate quality.
Pest and diseases: Generally, chiku tree remains quite healthy with little or no care. Insects and diseases usually don’t cause sufficient damage to necessitate control measures. The Woody White Fly can sometimes be a problem. The other leaf spot disease caused by a fungus phaeophleospora indica is characterized by numerous, small, pinkish to reddish brown spots with whitish centres. The sooty mould is also a fungal disease developing on the honeydew like excretion by scale insects and mealy bugs. This is a common disease and adversely affects the photosynthetic function of leaves and disfigures the fruit.
Chiku improves in quality after harvesting but immature fruits should not be harvested. The maturity can be judged by several external symptoms as mentioned below:
* Fruits at full maturity develop a dull orange or potato colour.
* A mature fruit when scratched lightly shows a yellow streak instead of a green streak which is a sign of immature condition.
* Brown scaly material disappears from the fruit surface as fruits approach full maturity.
* As fruit matures, milky latex content is reduced.
* The dried spine like stigma at the tip of fruit drops or falls off easily when touched.
Chiku tree yields 200 to 450lbs (90 to 180kg). At 30-35 years of age, the tree should produce 2,500 to 3,000 fruits annually. A great deal depends on the cultivar. A 10-year-old ‘oval’ tree gives 1,158 fruits weighing 184lbs (128.8kg), mature fruit will ripen in 9 to 10 days and rots in two weeks at normal summer temperature and relative humidity.
* Besides poor post-harvest life, soft fruit cannot be shipped in bulk over long distance.
* The crates have to be single layer packed for good results. With two crops a year, there is no reason for its availability year around.
* Packages similar to those for Kiwi, should easily promote its trade to Europe.
* With refrigerated transport from packing to marketing, it is possible to extend its life from 12 to 20 days.