Emergence, growth and production of the castor bean under saline stress and nitrogen fertilization

Abstract

The use of saline water in agriculture is becoming a reality in many regions of the world, given the increased demand for fresh water, both for irrigated agriculture, as well as for urban and industrial supply. In this context, the aim of this research was to evaluate the effect of different salinity levels in irrigation water, associated with amounts of nitrogen fertilizer, on the emergence, growth and yield of the castor bean, cv. BRS Energia, in an experiment where plants were maintained in lysimeters under field conditions, at the CCTA / UFCG. A randomised block design in a 5 x 5 factorial with three replications was used to study the effects of five levels of electrical conductivity of the irrigation water (0.4, 1.4, 2.4, 3.4 and 4.4 dS m-1) associated with five levels of nitrogen fertilizer (50, 75, 100, 125 and 150% of the dose recommended for testing in pots). The salinity of the irrigation water from 0.4 dS m-1 affects negatively and in a linear manner the percentage of emergence (PE), the emergence speed index (IVE), plant height (AP), the stem diameter (DC), the shoot dry-weight (FSPA) and root dry-weight (FSRaiz) and the seed mass of the primary raceme (MSemRP), whereas increasing levels of nitrogen caused an increase in DC, FSPA and FSRaiz. The application of increasing doses of N reduced the effect of salinity on the DC and FSRaiz of the castor bean cv. BRS Energia.