Evaluation of NaCl Tolerance in the Physical Reduction of Jatropha Curcus L. Seedlings

Abstract

Jatropha curcas L. is an important bio-fuel crop however, it’s tolerance to salinity especially with reference to changes in physical characteristics has been hardly studied. This work aimed to evaluate Jatropha. curcas L. tolerance to salinity stress using physical growth patterns, leaf shedding and mineral nutrient deposition. Jatropha curcas L. seedlings were grown under four different levels of NaCl concentration: 0 (control), 25, 50 and 100 mM under greenhouse conditions. Harvesting was done when average transpiration of each treatment was less than 50% and 75% as compared to the control. Results showed a significant variation in transpiration rate among the salinity treatments and control. A gradual reduction in the biomass yield of seedlings with increasing concentration of NaCl was observed. Reference to the result of IC50, the seedlings were tolerant to NaCl irrigation up to 54 mM. Additionally, seedling stems and roots accumulated large amounts of Na and K; a large amount of K particularly accumulated in the stem part, and was likely responsible for the low Na/K ratio observed in the stem. Defoliation however occurred with even irrigation of as low NaCl concentration as 25 mM. Thus, we report that Jatropha curcas L. is highly sensitive to Na accumulation, especially in the root-zone.