Plant’s description. Jatropha curcas L. is found throughout the Philippines. In fact, different regions have their own common name for jatropha. In the Tagalog region, it is known as tubang bakod, tuba and sambo. Among the Bicolanos, it is called tuba and tuba-tuba; in Pangasinan and Nueva Ecija, it is called tagumbao; tawa-tawa in Ilocos and kalunay in Cagayan Valley. In the Visayas and Mindanao, it is also known as tuba-tuba; kasla among the Ilongos and tangan-tangan in Lanao Region.
Jatropha is a drought resistant perennial shrub or small tree that has an economic life of up to 35 years and can live for 50 years. It grows fast, with little or no need for maintenance and can reach a height of 3 to 8 meters. It has a smooth gray bark which exudes whitish color, watery latex when cut. The size of the leaves ranges from 6-15 cm in length and width. The leaves are green to pale, alternate to sub-opposite with 3 to 5 lobes. It sheds leaves in the dry season and rejuvenates during rainy season. Flowers are formed terminally, individually, with female flowers usually slightly larger. It is pollinated by insects especially honey bees. Two flowering peaks are often observed and occur during the wet season. Each inflorescence yields fruits. After the seeds mature, 3 bi-valved cocci are formed. The seeds become mature when the capsule changes from green to yellow about three months after flowering.
Site requirements. Jatropha curcas is a tropical and subtropical plant. It grows almost anywhere even on sandy, gravelly and saline soils and does well on high temperatures. Select a site with well-drained soils and good aeration.
Jatropha is well adapted to marginal soils with low nutrient content but the use of organic fertilizer would result to higher yield. Its water requirement is extremely low and can stand long periods of drought by shedding most of its leaves. It grows best when planted at the start of the rainy season.
Land preparation. For commercial plantation, prepare the planting site by weeding, cultivation and digging holes, with spacing of 2 x 2 m apart. For hedges, a distance of 1 x 1 m is recommended.
Seeds (Sexual propagation). For reproduction purposes, harvest the fruits when already yellow to dark brown in color. Two to four months after flowering, seeds should be collected when capsules split open. Experience shows that drying seeds in direct sunlight has negative effect on viability. The number of seeds per kilogram ranges from 600 to 1,600. De-hull the dried seeds using a hollow wooded plank then winnow to separate the hulls from the seeds. The seeds are orthodox and should be dried to 5-7% moisture content and stored in air-tight containers. The seeds can last for one year at room temperature. However, seeds that are oily cannot be stored for a long period.
For seedling production, select the seeds and treat them with water eight hours before sowing. This is done to soften the seed coat for easy germination. Then put the seeds in the mixture of soil, sand and manure prepared in plastic bags with water. It is best to avoid removing or breaking the seed coat before sowing due to risk of abnormal seedlings. To sow the seeds, pour water while pressing it lightly on the soaked soil. The first shoot is expected after 6 days. Water the plants twice a day for seven days and once for the succeeding days. After 2 months, the sapling is ready for plantation.
Stem cuttings (Asexual propagation). Cuttings should be obtained from at least 8 month-old mature plants, as much as possible 45-100 cm from the base of the stem. Use a saw or sharp bolo to cut it. The plant should be about 3-4 cm thick and has short internodes with many eyes. Cuttings serve as an immediate source of planting material that can produce seeds in less than 1-2 years.
Tissue culture. Tissue culture is a laboratory-based procedure which uses artificial and sterilized propagation media. Tissues from various parts of the plant can be used in this procedure. This method allows choosing desirable characteristics of the mother stock and improving the variety of jatropha.
Nursery operation. One of the most important components of plantation development is nursery operation since it increases the rate of survival of the planting material. The nursery should be accessible to the planting site, preferably on non-sloping area and near the source of water.
Planting jatropha. Transplant the two-month old seedling or cutting in holes 2 x 2 meters apart, or any preferred spacing. Cover the hole with topsoil in a hill-up manner to avoid erosion. Water the plants up to two weeks after transplanting. For cuttings, the same procedure can be adapted provided that the stalk is transplanted within 5 days after cutting.
Fertilizer application. To have higher yield and better quality seed, application of fertilizer is recommended. After applying, water the plants to avoid wilting. In highly rain-fed areas, fertilizers can be applied during the rainy days. Apply the fertilizer in a depth of 5-10 cm and 15-20 cm away from the plant. The use of organic fertilizer is highly recommended.
Harvesting. Seeds can usually be harvested one year after planting. Seeds for replanting can be gathered when the fruits are already yellow to dark brown. Seeds that are black and dry can already be used for oil extraction.
Yields. Potential yield ranges from 1.25 to 12.5 tons per hectare depending on the site, climate and tending operations. Based on the experience in India, 3 kilograms of jatropha seeds can produce one liter of crude jatropha oil.
Source: A Primer, How to Grow Jatropha for Biodiesel, Philippine Forest Corporation, 2007.