Jatropha curcas L. is one climate smart drought-resistant multipurpose plant with a variety of properties that have conjured interest all over the world due to its potential to produce biofuel. In this study, Jatropha curcas accessions were collected from three different climate zones of Botswana; Northern region (Maun), Central region (Mmadinare) and Southern region (Thamaga). These accessions were subjected to water stress to study their biochemical and physiological responses. Results showed that water stress increased malondialdehyde (MDA) content, electrolyte leakage as well as proline content in all the accessions. It is worth-noting that Maun accession exhibited highest proline content, when subjected to water stress. Maun accession also displayed less MAD and electrolyte leakage than the other two accessions, an indication of less perturbation to membranes under water stress. This could be attributed in part, to its higher catalase and superoxide dismutase contents, which presumably prevented lipid peroxidation by mopping up reactive oxygen species. The slightly higher dry weights exhibited by Mmadinare and Maun accessions could be ascribed to their ability to maintain membrane integrity under water stress conditions. It can therefore be concluded that Maun and Mmadinare accessions can be grown under drought conditions commonly experienced in Botswana.

The need to mitigate climate change cannot be more emphasized, which arises, as a result of increases in CO 2 emissions due to anthropogenic activities. Given the current world energy problems of high fossil fuel consumption which plays a pivotal role in the greenhouse effect, Jatropha curcas biodiesel has been considered a potential alternative source of clean energy (biodiesel is carbon neutral). However, the ability of Jatropha curcas, as a candidate source of alternative of clean energy, to grow in marginal and dry soils, has been poorly elucidated. This study, therefore aimed at investigating whether Jatropha curcas leaves could switch from carrying out C 3 photosynthetic pathway to Crassulacean Acid Metabolism (CAM) as a strategy to improve its water deficit tolerance. Thirty-five-day-old Jatropha curcas accessions, from three different climatic zones of Botswana, viz., Mmadinare (Central zone), Thamaga (Southern zone) and Maun (Northern zone), were subjected to water stress, by withholding irrigation with half-strength Hoagland culture solution. Net photosynthetic rate, transpiration and stomatal conductance were measured at weekly intervals. The leaf pH was measured to determine whether there was a decrease in pH (leaf acidification) of the leaves during the night, when the plants experienced water deficit stress. All the accessions exhibited marked reduction in all the measured photosynthetic characteristics when experience water deficit stress. However, a measurable CO 2 uptake was carried out by leaves of all the accessions, in the wake of marked decreases in stomatal conductance.There is evidence to suggest that when exposed to water stress J. curcas accessions switch from C 3 mode of photosynthesis to CAM photosynthetic pathway. This is attested to by the slightly low leaf pH at night. Thamaga accession exhibited an earlier stomatal closure than the other two accessions. This resulted in Thamaga accession displaying a slightly lower dry weight than both Mmadinare and Maun accessions. It could be concluded that Ja-How to cite this paper: Makholwa, K.,