Accumulation of NPK and sodium in castor bean under saline stress and nitrogen fertilization

The aim of this study was to evaluate the effects of irrigation with water of different salinities and doses of nitrogen fertilization on accumulation of NPK and sodium in the aerial parts of the castor bean, the experiment was conducted in lysimeters. A randomized block design in 5 x 5 factorial arrangement with three replications was used, and the effects of electrical conductivity of water (ECw) varying from 0.4 to 4.4 dS m(-1) associated with nitrogen dose (50 to 150% of recommended dose) were studied. The NPK and sodium contents in the aerial parts of to plant in the leaves in comparison to stems and evaluation times 120 days after sowing (DAS) > 46 DAS. In leaves the content at 46 DAS varied according to following sequence K > Na > N > P and at 120 DAS K > N > Na > P while in the stem in both study periods it accumulated in the order Na > K > P >= N under water salinity and K > Na > P = N depending on nitrogen fertilization. At 46 DAS, the increasing levels of ECw caused an increase in the N-leaf and K-leaf and nitrogen dose inhibited Na-leaf content. At 120 DAS the highest content of N-leaf was obtained in treatment ECw 4.4 dS m(-1) and in dose of 150% N while the contents of K-leaf and K-stem were obtained in the dose of 150% N. The P content was not affected by any of the studied factors.