Size and mineral composition of seeds of cowpea irrigated with saline water

Abstract

The objective of this work was to evaluate the effect of the irrigation with saline water, applied at different development stages of cowpea on qualitative and quantitative characteristic of the seeds. The experiment was set up in the field, in Fortaleza, Ceará, during the dry season. A completely randomized block design, with five treatments and five replications, was adopted. The treatments studied were: T1-Groundwater with electrical conductivity (ECw) of 0.8 dS m^-1 during the whole crop cycle; T2-saline water (ECw = 5.0 dS m^-1) during the whole crop cycle, starting after germination; T3-saline water until 22 days after sowing, DAS; T4-saline water from the 23rd to the 42nd DAS; T5-saline water from the 43rd to 62nd DAS. The plants of T3, T4 and T5 were irrigated with groundwater in the remaining stages. At the end of the crop cycle the following parameters were evaluated: dry mass of 1000 seeds, seeds size, and mineral reserve and crude protein concentration. The application of saline water during the whole crop cycle (T2) or at different growth stages (T3, T4 and T5) did not affect the quantitative parameters evaluated and the nutritional quality of the seeds, considering the concentration of crude protein and practically all minerals analyzed. The only changes observed in minerals concentrations in seeds and pericarps were the increases in Na, Cl, and Ca concentrations, especially in plants irrigated continuously with saline water (T2), and these changes were related to the high concentrations of these ions in the irrigation water.