Oil content and yield of castor bean as affected by nitrogen fertilization and saline water irrigation

Abstract

The objective of this work was to evaluate the oil content and seed yield of castor bean 'BRS Energia' subjected to doses of N fertilization and irrigation water with different levels of salinity. The experiment was carried out in lysimeters, under field conditions, using a randomized complete block design, with three replicates. Treatments consisted of the irrigation‑water salinity levels of 0.4 (control), 1.4, 2.4, 3.4 and 4.4 dS m^‑1, associated to 50, 75, 100, 125 and 150% of the recommended N dose for trials. There was no significant interaction between irrigation water salinity and nitrogen levels for any of the studied variables. Water salinity of up to 1.4 dS m‑1 provided 47% of oil content in seeds. Nitrogen doses 64% above recommended promoted less than 48% of oil content. The highest shoot dry weight was obtained with 150% of the recommended N dose. Increasing water salinity from 0.4 dS m^‑1 increases the interval for emission of the primary raceme and reduces the yield components, of which shoot dry weight and number of fruits are the most affected. Electrical conductivity of irrigation water up to 1.9 dS m^‑1 and N levels up to 134% of the recommended dose provide a greater number of racemes.