Study of fertilizer (NPK) effects on yield and triglycerids in Jatropha (Jatropha curcas)

Knowledge of the effect of fertilizer on yield, dry matter and oil content of Jatropha (Jatropha curcas) and determination of the best combination of fertilizers are important. The purpose of this study was to determine the effects of nitrogen, phosphorus and potassium on dry matter, grain yield and seed oil and fatty acids contents in Jatropha. An experiment was done as a 2×2×2 factorial arranged in a randomized complete block design three replications. The experimental factors were Nitrogen fertilizer (N) at two levels (N1=0, N2=70 kg/ha), Phosphorus (P) at two levels (P1=0, P2=120 kg/ha) and potassium (K) at two levels (K1=0, K2=150 kg/ha). At the end of the experiment, dry matter, grain yield and seed fatty acids were determined. The highest value of dry matter (617.3 g/m2) and oil (358 g/m2) were obtained from N2K2P2 treatment. Principle Component Analysis (PCA) showed that 43% of the variance was related to N, 38% to P and 19% to potassium. Multiple regression analysis was conducted to determine the regression coefficient between yield (Y) and fertilizers (N,P,K). The model developed was Y= 422.1+1.36X1+0.63X2+0.271X3 where X1=nitrogen, X2=phosphorus and X3=potassium. This shows that N, P and K fertilizers had the highest contribution in the variation of yield, respectively.