Our good friend Dr. William D. Dar; director general of the International Crops Research Institute for the Semi-Arid Tropic (ICRISAT) in India, recently sent us the guidelines for the production of Jatropha curcas(tawwa-tawwa in Ilocano) to help Filipino farmers, government agencies, and institutions interested in cultivating Jatropha.
He said that although the guidelines are not exhaustive and made for India, these would still be very helpful because there are only few studies on Jatropha and these could apply in the Philippines. We are therefore reproducing the ICRISAT guidelines with minor revision.
• Jatropha can be grown on degraded lands that are not suitable for growing agricultural crops. Good quality farmlands must be spared for growing food crops.
• The lands for Jatropha cultivation should be developed with suitable soil and water conservation measures to ensure that enough rainwater is stored in the soil and soil loss is minimized. Rainwater conservation measures such as continuous contour trenches (CCT), staggered contour trenches, gully control structures like loose boulder structures, and rainwater harvesting ponds must be applied.
• Avoid growing Jatropha in water-logging-prone and sodic soils with pH above 9. Under waterlogged conditions, these plants succumb to wilt disease. Well drained soils with slightly acidic to alkaline pH are suitable for cultivating Jatropha.
• Selection of right seeds is very critical as there are no improved cultivars and the plants have long life (30+) years. Seeds with over 35 percent oil content are well-developed and bold (>60 g seed weight for 100 seeds), and newly harvested should be used for plantation establishment. Estimation of oil content arid germination test is very essential. Storing seeds for longer period decreases seed viability, and well-tested seeds with germination rate of over 75 percent should be used for seedling production.
• Seedlings should be grown in a nursery and should be planted in the main field when they are 40 to 50 cm tall. Direct seeding can also be done under field conditions, but germinating seeds could be damaged by birds and rats resulting in poor crop establishment.
• Seedlings in the nursery can be grown in polyethylene bags filled with well-mixed soil, sand, and farm manure in equal proportion. Diammonium phosphate (DAP) may be added at 1 g for every 2 kg of nursery medium. To minimize seed wastage, soak the seeds in water overnight. The soaked seeds can be sprouted on moist filter paper or in old clothes at room temperature. Keep the seeds moist during the sprouting process to ensure enough humidity. Sow the sprouted seeds in polyethylene bags. Seeds soaked in cow dung slurry for 12 hours show early and enhanced germination.
• Inoculate seedlings with suitable arbuscular mycorrhizal culture to obtain healthy seedlings.
• Seedlings can also be grown from cuttings, but these seedlings do not develop taproot and are prone to damage by strong wind. Seedlings grown from seeds have well-developed taproot and stand against strong winds.
• When planting Jatropha, dig pits at 2 x 2 or 3 x 2 m depending on the soil and rainfall situation. Row to row spacing of 3 m enables machinery operations for inter row cultivation. Pits of 30 x 30 x 45 cm can be excavated; fill each pit with 1 to 2 kg of farm manure and 50 g of DAP for better plant stand. Then apply 5 to 10 g of methyl parathion (2%) dust or 5g of phorate, lOG while filling the pit to keep away termite damage to seedlings.
• Nursery grown seedlings can be transplanted in the pits at the onset of the rainy season when the soil is wet.
• Once established, Jatropha plants generally survive well unless affected by disease such as wilt or infested with stemborer. The plants drop all their leaves during dry season, leaving the main stem naked:
• The onset of rains or availability of soil moisture through irrigation initiates sprouting of new flushes of leaves and flowering buds.
• During the first year when the plants shed their leaves, prune plants at 0.5 to 0.6 m height from the ground to promote profuse branching and in turn more flowering buds. Annual pruning of the branches after leaf shedding needs to be done for better flowering and fruiting.
• Every year once the rainy season sets in, fertilize each plant with 100g urea and 38g single supe-rphosphate.
• The leaf miner Scutellera nobilis is a serious pest in Jatropha plantations during flowering and fruit development stages. The leaf miner seems to be severe during the onset of the rainy season and during the active growth stage of the plants.
• During first year of plant growth, supplemental irrigation during dry summer increases the survival rate and improves plant growth.
• In between Jatropha rows, grasses or short duration hardy legumes can be grown to improve soil fertility and to be a source of fodder for livestock.
• Jatropha generally starts yielding during the third year in the semi-arid tropics, but with better moisture, fruiting could start early. Likewise, increased yields can be obtained through supplemental irrigation.
However, exact yield potential as well as water and nutrient requirements of Jatropha are yet to be established.
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