Water requirement and use by Jatropha curcas in a semi-arid tropical location
Increasing emphasis on biofuel to meet the growing energy demand while reducing emissions of greenhouse gases, Jatropha curcas has attracted the attention of researchers, policy makers and industries as a good candidate for biodiesel. It is a non-edible oil crop, drought tolerant and could be grown on degraded lands in the tropics without competing for lands currently used for food production. J. curcas being a wild plant, much about its water requirement and production potential of promising clones in different agroclimatic conditions is not known. Water use assessment of J. curcas plantations in the semi-arid tropical location at ICRISAT, Patancheru indicated that crop evapotranspiration of J. curcas under no moisture stress varied from 1410 to 1538 mm per year during 2006e2009. Under field conditions the crop evapotranspiration varied from 614 to 930 mm depending on the atmospheric demand, rainfall and crop phenological stage. Patterns of soil-water depletion indicated that with growing plant age from two to five years, depth of soil-water extraction increased from 100 to 150 cm by fifth year. Monthly water use of Jatropha varied from 10e20 (leaf shedding period) to 140 mm depending on water availability and environmental demand. This study indicated that J. curcas has a good drought tolerance mechanism, however under favorable soil moisture conditions Jatropha could use large amounts of water for luxurious growth and high yield. These findings highlight the need to carefully identify suitable niche areas for Jatropha cultivation and assess the implications of large J. curcas plantations on water availability and use under different agroecosystems, particularly so in water scarce regions such as semi-arid and arid regions in the tropics.