Effect of irrigation levels and foliar application of fertilizers on some agronomic and oil characteristics of castor bean (Ricinus communis L.)

Abstract

To study the effect of irrigation levels and foliar application of fertilizers on some agronomic and oil characteristics of castor bean, an experiment was conducted at the East Azarbaijan Agricultural Research and Education Center, Tabriz, Iran in 2017-2019 cropping seasons. The experiment was laid out as a split-plot design based on a completely randomized block design with three replications. In the present study, main cluster length, number of branches, number of capsules per plant, number of seeds per capsule, 100-grain weight biological yield, grain yield, oil percent and oil yield were measured. Irrigation intervals (normal irrigation (irrigation after 60 mm), irrigation after 80 mm and 140 mm of evaporation) was established as main plots and the foliar applications of fertilizers (N, K, S, N + K, and N + S, K + S, N + K + S and control) input as sub-plots. The results showed that, except for the oil percentage, all the examined traits were decreased by water limitation. The highest values of the traits, other than the 100-grain weight, were obtained for foliar application of N + K + S. This treatment improved the grain yield per unit area under normal irrigation and moderate irrigation and severe stresses by 62.76%, 41.46% and 28.98% respectively. Thus, the foliar application of S (2000 ppm) + N (3000 ppm) + K (3000 ppm) fertilizer is the best treatment for mitigating some harmful effects of water deficit on castor bean.