Seed molybdenum concentration and yield of cowpea as influenced by foliar application of sodium molybdate and soil application of simple superphosphate.

Cowpea is a legume rich in amino acids and proteins, cultivated worldwide. However, the crop has low grain yield, which is attributed to inadequate management of fertilizers. Therefore research was conducted to evaluate the effect of phosphorus applied via soil and molybdenum via leaves on productivity and seed molybdenum concentration of cowpea. The experiment was carried out in a greenhouse, in a 4 x 4 factorial scheme: Molybdenum doses (Mo) (0, 100, 250 or 500 g ha⁻¹ of sodium molybdate) and doses of phosphorus (0, 50, 100 or 150 kg P₂O₅ ha⁻¹), in a randomized block design, with four replications. Mo applications were split in the flowering and maturation phase to ensure the best absorption of micronutrients. At the end of maturation, pod length, pod mass, number of grains per pod, 100 grain mass, grain yield, seed molybdenum and concentration were measured. There was a significant interaction between the doses of phosphorus and molybdenum for pod length and number of grains per pod with increments in production and optimal dose estimated at 374.15 g ha⁻¹ of molybdenum and 123.43 kg ha⁻¹ of phosphorus. Phosphate fertilization increases grain yield, pod dry weight and 100-grain weight by 41%, 51% and 20%, respectively, compared to the control treatment. The splitting of molybic fertilization is an effective way to increase the nutrient concentration in the seed, which leads to a reduction in the cost of producing Mo-rich seeds, without causing toxic effects on plants. [ABSTRACT FROM AUTHOR]