Production in the castor bean cultivated with saline water and dosages of nitrogen

Abstract

The aim of this research was to evaluate production of the castor bean cv. BRS Energia, when subjected to irrigation with water at different levels of salinity and to fertilization with different levels of nitrogen, in an experiment carried out using lysimeters under field conditions at the experimental area of the Federal University of Campina Grande (UFCG), in Pombal, in the state of Paraíba, Brazil. A design of randomised blocks was used in a 5 × 4 factorial, with three replications, to test the combination of five levels of electrical conductivity of the irrigation water - CEa (0.3, 1.2, 2.1, 3.0 and 3.9 dS m-1) and four levels of nitrogen (70, 100, 130 and 160 mg N kg-1soil). An increase in the salinity of the irrigation water caused a reduction in the number of fruits and seeds, and in the weight of seeds on the primary and secondary raceme. Irrigation with water of up to 3.9 dS m-1 prolonged the issue of primary and secondary racemes in the castor bean, and when subjected to irrigation with a CEa of 3.3 dS m-1, the oil content of the seeds on the primary raceme was over 48%. The application of increasing levels of nitrogen increased the number of fruits on the primary raceme and the time needed for emission of the secondary raceme. The interaction between the level of salinity of the irrigation water and the level of nitrogen significantly affected the effective length of the primary and secondary raceme, and the oil content in the seeds of subsequent yields.