Magnesium fertilization improves seed physiological quality in cowpea

Among the factors that affect seed quality within production systems, soil nutrient availability is one of the most relevant. Among these nutrients, magnesium (Mg) is directly involved in protein synthesis in plants, and despite its importance, studies addressing the effects of Mg fertilization on the yield and physiological quality of seeds of cowpea (Vigna unguiculata (L.) Walp.) genotypes remain scarce in the literature. Therefore, the present study aimed to evaluate the effect of magnesium fertilization on the seed yield and physiological quality of cowpea genotypes produced in the southwestern region of Piauí. The experiment was conducted at the Federal University of Piauí – Professora Cinobelina Elvas Campus, in Bom Jesus, PI, in a soil classified as a typical dystrophic Yellow Latosol. A randomized complete block design was adopted, with three replications, in a split-plot arrangement. The main plots consisted of two cowpea genotypes, BRS Guariba and BRS Tumucumaque, while the subplots comprised four magnesium doses: 0, 0.9, 1.3, and 1.7 cmolc dm⁻³ Mg applied to the soil. The following production components were evaluated: average plant height, number of pods per plant, number of seeds per pod, thousand-seed weight, and seed yield. Seed quality was assessed through the germination test, germination speed index, seedling dry mass, and electrical conductivity test. It was observed that increasing Mg doses did not promote improvements in seed yield or production components for either genotype. However, seed physiological quality increased progressively with Mg application up to the dose of 0.9 cmolc dm⁻³.