Jatropha is a genus of about 175 succulent plants, shrubs and trees from the family Euphorbiaceae, subfamily Crotonoideae, and tribe Jatropheae. There are at least four important species, namely, J. curcas, J. gossrifolia, J. podarica, and J. multifada. It was botanist Carl Von Linne who first classified the plants in 1753 and gave the botanical name “Jatropha curcas” from the Greek word “Jatros” meaning doctor and “trophe” meaning nutrition. Originally a native of Central America and the Caribbean, it has become naturalized in many tropical and subtropical areas and now thrives throughout Africa and Asia brought by Portuguese traders. It is widely grown in Tamil Nadu, India, growing as weeds in Brazil, Fiji, Honduras, Jamaica, Panama, Puerto Rico, and El Salvador. Jatropha is easy to establish, grows relatively quickly and is hardy. Being drought tolerant, it can be used to reclaim eroded areas and grown as live hedge in arid or semiarid areas. In the Philippines, it is commonly used for fencing, hence the name tubang bakod (bakod = fence). Jatropha curcas is known to tolerate a wide range of rainfall (48 cm to 238 cm annually), grows in a wide range of temperature (18-28°C), but requires full sun. It thrives in any soil type, sandy, gravelly, saline, provided it is well drained. The trees are fast growing, easily propagated either by seeds or stem cuttings, and are adapted to marginal soils with low nutrient Content.
Known in the Philippines as tuba-tuba, tubang bakod (Tagalog), or galumpang (Pampanga), the oil plant Jatropha curcas (L) (Jatropha) or physic nut is a multipurpose and drought-resistant large shrub or small soft wooded tree with smooth gray bark that yields a whitish colored, watery latex when cut.
It normally grows between 3 to 5 meters high, but can attain a height of up to 8-10 meters under favorable conditions. It has spreading branches and stubby twigs, with milky and yellowish exudates. Its leaves are deciduous, green to palegreen, alternate but apically crowded, ovate, acute to acuminate, basally cordate, 3-5 lobed in outline, 6-40 cm long and 6-35 cm broad. The mature tree bears male and female flowers, with female flowers usually slightly larger and occurring during the hot season. The flowers are greenish cymes, yellowish and bell shaped. The petiole length ranges between 6-23 mm. The inflorescence is formed in the leaf axil. In conditions where continuous growth occurs, an imbalance of pistillate or staminate flower production results in a higher number of female flowers. The fruit capsule is approximately 2.5 cm to 4 cm in diameter.
Jatropha grows readily from cuttings or seeds. Use of fresh seeds improves germination and with good moisture conditions, germination takes 10 days. The seed shell splits, the radicula emerges and 4 small peripheral roots are formed. Soon after development of the first leaves, the cotyledons wither and fall off. Seedlings (3-4 month old) can be planted with the following distances: square planting: 2m x 2m (2,500 trees/ha) or 2m x 3m (1,666 trees/ha). The best time of planting is during the start of the rainy season. Caring for the plants is simple, involving only ring weeding during the first year and under brushing in later years to control vines and other competitive weeds. Seed production from plants propagated from seeds can be expected within 3-4 years. The use of branch cutting for propagation is also easy and results in rapid growth. The plant can be expected to bear fruit within one year of planting. The recommended spacing is 15-25 cm x 15-25 cm in one or two rows, respectively, for hedgerows or soil conservation, and 2m x 2m or 2m x 3m for plantations. With this spacing, there will be between 4,000 to 6,700 plants per km for a single hedgerow and double that when two rows are planted. The number of trees per hectare will range from 1,600 to 2,500. Wider spacing is reported to yield more fruits of up to about 794 kg/ha. When established, the trees need little attention or management and minimal fertilizer application. No insect pests are known to attack the crop and it is not palatable to ruminants (cattle or sheep, goat) making it a desirable plant for the fence lines.
Plants start bearing fruits within two years after planting and may produce several crops during the year if soil moisture is good and temperatures are sufficiently high. However, maximum productivity is attained only after 5 years.
The fruits are produced when the shrub is leafless. Each inflorescence yields a bunch of approximately 10 or more ovoid fruits. A three, bi-valved cocci is formed after the seeds mature and the fleshy exocarp dries. The fruits are harvested at yellow stage with each fruit containing 3-4 black color seeds 2 cm long and 1 cm thick. The yield per tree (fresh weight) ranges from 4-12 kg. The usual average yields by year are in the following order of magnitude: 0.4 tons/ha during the first 2-3 years, 2-3 tons/ha in 3-4 years, 5-6 tons/ha in 5 years to 50 years. The dry seed is about 15% of the fresh weight of the fruits and generally contains 32% meal, 30-38% crude oil, and 30-38% seed coat.
Pruning of jatropha during the first two years is important but this is a highly labor- intensive operation. The availability of relatively inexpensive labor is therefore a key factor in the profitability of a jatropha plantation. The top of the sapling must be cut in the nursery before sending it for planting. It is then pruned twice or thrice during the first two years. As a result of pruning, there will be less flowering and fruiting in the first two years but this will be compensated by bigger harvests in subsequent years. After every pruning, four branches emerge from the earlier node. In order to produce one kilogram of seeds after 2 to 3 years from a plant, it should have at least 24 to 30 secondary or tertiary branches.