Water Stress Limits Growth and Physiological Performance of Jatropha curcas L. Seedlings

Jatropha (Jatropha curcas L.) is a potential biodiesel plant that gained much attention in non-oil production countries. We investigated the ability of the species to cope with water deficit occurring in semi-arid zones like Senegal climatic conditions. The layout of the experiment was a randomized complete blocks design with two factors (level and frequency of irrigation) and 6 repetitions. The trial was conducted from December 2012 to June 2013 in CERAAS/ISRA at Thiès, Senegal. Potted Jatropha seedlings were exposed, after three months under similar well-watered conditions, to three water regimes (100%, 50% and 25% of field capacity, respectively C100, C50 and C25) and two frequency of watering once and twice watering a week(F1 and F2, respectively). The different treatments didn’t affect significantly collar diameter and plant height during the time of the experimentation. Nevertheless, the trend line is up for collar diameter and plant height in well-watered plants. For the same frequency of irrigation, biomass accumulated was high in C100. No difference was found between plants biomass in C25-F1 and C25-F2. For physiological parameters, there are no differences between the treatments at the onset of stress. However, after 2 weeks of stress, photosynthesis, stomatal conductance and transpiration were affected permanently in treatments C100-F1, C50-F1 and C25-F1 and their values never reached those of plants of C100-F2, 50-F2 and C25-F2. The opposite was noted for leaf temperature. For the same frequency of irrigation, photosynthesis, stomatal conductance and transpiration were higher in C100 and the opposite occurred for the leaf temperature. These results demonstrate that growth and productivity of Jatropha are significantly affected by water stress conditions. Its need to be watered regularly to maintain physiological functions and biomass production definitely highlights that its growth in semi-arid zones is economically unlikely.