Physiological Mechanisms Involved with Salt and Drought Tolerance in Jatropha curcas Plants

Abstract

Although the importance ofJ. curcasplants as a bioenergy source is well recognized, the key physiological processes involved in drought and salt tolerance are poorly known. The geographical distribution ofJ. curcasstrongly suggests that this species is drought tolerant. However, the features of the physiological parameters of drought tolerance were based, until now, on a narrow genetic basis that was not well characterized. In the tropical, semi-arid regions where the cultivation ofJ. curcasis increasing, problems of primary salinity and secondary salinization caused by irrigation can be critical. In this review, we present recent results regarding the most important physiological processes related to drought and salt tolerance inJ. curcas,including osmotic adjustment, photosynthesis and oxidative protection. Overall, the data reported suggest thatJ. curcashas both biochemical and physiological characteristics that confer drought tolerance and relative salt sensitivity during its initial growth phase. The possibility of sustainable production ofJ. curcaswithout irrigation in semiarid regions is controversial, partly because the physiology of this species is not yet sufficiently known and the plant breeding has presented little progress. In addition, the development of “evergreen crops” with irrigation also requires physiological studies and genotypes that respond adequately to water investment under adverse conditions of high temperature and salinity.