Irrigation strategies with saline water and phosphate fertilization in cowpea culture

Abstract

The use of saline water negatively affects gas exchange and plant growth. However, fertilization with a mineral source has been used to mitigate salt stress on agricultural crops. The objective of this study was to evaluate the gas exchange and the initial growth of cowpea beans submitted to different irrigation strategies with saline water and phosphate fertilization. The experiment was conducted from October to December 2019, in full sun in the experimental area belonging to the Universidade da Integração Internacional da Lusofonia Afro-Brasileira (UNILAB), Redenção, CE, Brazil. The experimental design was entirely randomized in a 4 × 2 factorial scheme, referring to four irrigation strategies: E1 = irrigation with low-salinity water (0.3 dS m^-1) at germination, initial growth, and preflowering stages; E2 = saline water (3.2 dS m^-1) at preflowering only; E3 = saline water (3.2 dS m^-1) on germination and initial growth; E4 = saline water (3.2 dS m^-1) in the three phases, and two doses of phosphate fertilization (P1 = 50% of the recommended phosphorus dose and P2 = 100% of the recommended phosphorus dose), with four repetitions. Continuous salt stress in phenological phases negatively affects plant height, photosynthesis, transpiration, stomatal conductance, and leaf temperature of the cowpea crop. The dose of 100% phosphate fertilization mitigates the effects of continuous salt stress on chlorophyll pigment production.