Phytomass accumulation and mineral composition of cowpea (Vigna unguiculata) under salt stress and phosphate fertilization

This study aimed to evaluate the effect of irrigation with saline water and phosphate fertilization on phytomass accumulation and tissue mineral composition of cowpea shoots. The research was carried out in a greenhouse utilizing randomized block design in a 5 x 3 factorial scheme consisting of five levels salinity of irrigation water (0.5 as control, 1.5, 2.5 3.5 and 4.5 dS m-1) and three doses of P2O5- (60, 100 and 140% from a recommended dose of 60 kg P2O5- ha-1), with 5 replicates. The plants were grown in pots up to flowering and then phytomass accumulation and mineral composition of cowpea (indicate cultivar name) shoot were measured. Irrigation with saline water from 0.8 dS m-1 reduced phytomass accumulation and mineral composition of cowpea plants, making the plants to be considered moderately tolerant up to EC 2.5 dS m-1. The 40% increase in recommended phosphorus dose promotes high iron and copper accumulations and, less sodium accumulation into tissues of cowpea shoot as influenced by saline stress. 60% reduction of the recommended dose of phosphate fertilizer increased the manganese and zinc accumulation of tissues of cowpea shoot under salt stress.