Nitrogen and Sulfur Induced Damages On the Photosynthesis of Physic Nut During the Early Development.

The use of physic nut oil as a source of biofuel has been well-explored. However there are few studies that address the nutritional assessment of nitrogen (N) and sulfur (S) in physic nut (Jatropha curcas L.) focusing on physiological responses, especially in terms of photosynthesis. The objective of this study was to evaluate the effects of N and S omission in Jatropha curcas (L.) grown in nutrient solution. The experiment was carried out in a randomized block design with four replications. The plants were exposed to the following treatments: complete solution – control (16 mmol L^-1 N and 2 mmol L^-1 S); lack of N and lack of S. Four times of plant assessment were also considered: 20, 30, 40 and 120 days after the beginning ot the treatments. The N and S deficiencies caused reductions of 68 % and 18 % in total dry matter yield, respectively. Leaf N and S concentrations increased with nutrient supply in the solution. Leaf N and S concentrations showed positive correction (p≤0.05) with leaf gas exchange parameters, such as CO₂ fixation, stomatal conductance and transpiration. Under N and S deficiency status, the nutritional stress caused reduction in leaf gas exchange parameters in all harvest time. However, the N deficiency was the most limmiting factor in all parameters evaluated. Maximum photosynthesis rates occurred in plants grown in complete solution, indicating that leaf gas exchange parameters might be a good indicator for the nutritional status to N and S, in physic nut. Physic nut in early development is sensitive to N and S nutritional imbalances.