CASTOR BEAN PRODUCTION AND CHEMICAL ATTRIBUTES OF SOIL IRRIGATED WITH WATER WITH VARIOUS CATIONIC COMPOSITIONS

This study aimed to evaluate the production of castor beans, cv. 'BRS Energia', in terms of soil chemical composition as a function of the cationic nature, and salinity levels, of the irrigation water. The experiment was carried out using lysimeters in a controlled environment at the Center of Technology and Natural Resources of the Federal University of Campina Grande, from November 2013 to February 2014. The treatments consisted of six types of salinity (S1 - Control; S2 - Na+; S3 - Ca2+; S4 - Na+ + Ca2+; S5 - K+, and S6 - Na+ + Ca2+ + Mg2+), distributed in randomized blocks with four replicates; each plot consisted of five plants for evaluation, totaling 120 experimental plots. Plants in the control treatment (S1) were irrigated with water with an electrical conductivity (ECw) of 0.6 dS m-1, and the other treatments (S2; S3; S4; S5 and S6) with ECw of 4.5 dS m-1, but with (a) different cation(s). Water salinity of 4.5 dS m-1 hampers castor bean production, regardless of the cationic nature of the water; castor bean 'BRS Energia' was more sensitive to salinity caused by the presence of potassium salts in the irrigation water; the mass of seeds in the primary raceme is the most sensitive variable to salinity and the cationic nature of the irrigation water; the adopted leaching fraction (0.10) was not sufficient to avoid salt accumulation in the soil; irrigation with low ECw promoted the lowest value of exchangeable sodium percentage. RESUMO: Objetivou-se, com o presente trabalho, avaliar a produção da mamoneira cv. BRS Energia e os atributos químicos do solo em função da natureza catiônica e nível salino das águas de irrigação. O experimento foi desenvolvido em lisímetros em ambiente telado no Centro de Tecnologia e Recursos Naturais da Universidade Federal de Campina Grande, entre novembro de 2013 e fevereiro de 2014. Estudaram-se seis tipos de salinidade da água (S1 -Testemunha; S2 - Na+; S3 - Ca2+; S4 - Na++ Ca2+; S5 - K+ e S6 - Na++Ca2++Mg2+), distribuídos em delineamento de blocos ao acaso com quatro repetições, sendo a parcela constituída de cinco plantas úteis, totalizando 120 parcelas experimentais. Salienta-se que as plantas do tratamento testemunha (S1) foram irrigadas com água de condutividade elétrica (CEa) de 0,6 dS m-1, e os demais tratamentos (S2; S3;S4; S5 e S6) com CEa de 4,5 dS m-1, porém com diferente (s) cátion (s). A salinidade da água ao nível de 4,5 dS m-1 prejudica a produção da mamoneira, independente da natureza catiônica das águ