Ecophysiology of cowpea (Vigna unguiculata L.) cultivated under different saline and biofertilizer levels

Abstract

The objective of this study was to evaluate the growth, physiology, and production of cowpea plants grown under different levels of salinity and doses of mixed biofertilizer. The experiment was set in a completely randomized 3 x 4 factorial design, corresponding to three levels of irrigation with saline water (ECw: 0.5, 2.5 and 4.5 dS m-1) and four doses of biofertilizer (0, 800, 1600 and 2400 milliliters - mL), with five repetitions. The biofertilizer was obtained by means of an aerobic process, using a mixture of water, goat manure, and wood ashes, and it was applied in the liquid form, once a week, and directly into the soil. After 70 days, gaseous exchanges were evaluated, and the length of the main stem, the diameter of the stem, and the leaf area were measured. Furthermore, the number of pods produced, mean pod size, total pod weight, total seed weight, hundred seed weight, and yield were estimated. It was observed that the application of mixed biofertilizer promoted increments of 28.98% in leaf area, 32.78% in length of the main stem, and 21.55% in total dry mass. Weekly doses of 1600 mL promoted significant increases in gas exchanges. The application of weekly doses of 1600 mL of mixed biofertilizer promoted growth increases in physiological and productive parameters when the plants were irrigated with saline water up to 2.5 dS m-1, suggesting that the biofertilizer reduces the deleterious effects of salinity.