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This study aimed to evaluate the water relations, cell damage percentage and growth of the castor bean cv. ’BRS Energia’ as a function of salinity and cationic nature of the water used in irrigation. The experiment was conducted in drainage lysimeters under greenhouse conditions in eutrophic Grey Argisol of sandy loam texture. Six combinations of water salinity and cations were studied (S-1 - Control; S-2 - Na+, S-3 - Ca2+, S-4 - Na+ + Ca2+; S-5 - K+ and S-6 - Na+ + Ca2+ + Mg2+), in a randomized block design with four replicates. In the control (S-1), plants were irrigated with 0.6 dS m(-1) water, whereas the other treatments received 4.5 dS m(-1) water, obtained by adding different salts, all in the chloride form. Higher relative water content in the leaf blade of plants irrigated with K+-salinized water associated with leaf succulence are indicative of tolerance of the castor bean cv. ’BRS Energia’ to salinity. Saline stress negatively affected castor bean growth, regardless of cationic nature of water. Among the ions studied, ’BRS Energia’ castor bean was more sensitive to the presence of sodium in the irrigation water, in terms of both water relations and leaf succulence.