Sesame (Sesamum indicum L.) was grown to full maturity in three sand culture experiments with variable rates of N, P, and K. Tissue samples of the most recently matured leaves were taken at three stages of growth for chemical analysis and correlation with optimum yield and quality of the seed. Nutrient response curves were obtained along with approximate critical concentrations of N. P, and K.
Samples taken at early flowering stage appeared to be best suited for use in establishing diagnostic criteria for the fertility requirements of sesame. The approximate critical concentrations of leaf NO3-N, total P, and K were 0.51%, 0.52% and 2.4%, respectively.
Increasing substrate levels of N, P, and K resulted in increases in all components of yield, while effects on seed quality were mixed. Increased levels of substrate N resulted in increased protein and decreased oil content. Potassium demonstrated a similar, although smaller, increase in protein and corresponding decrease in oil content. Phosphorus alone had no effect on protein or oil content.