Seeds enriched with molybdenum improve cowpea yield in sub‐humid tropical regions of Brazil

Abstract

AbstractThe possible benefits of molybdenum (Mo)‐enriched seeds for grain legumes have yet to be addressed in sub‐humid tropical areas, where cowpea (Vigna unguiculata L.) is an important crop. In 2016, seeds with 0.014 (low), 0.674, or 1.987 (high) μg seed−1 of Mo were harvested from plants sprayed with 0, 250, or 850 g ha–1 of Mo, respectively. These seeds were combined with either Bradyrhizobium inoculation (with or without) in 2017 or nitrogen (0 or 60 kg ha−1) in 2018 and evaluated under small farmer management in Maranhão State, Brazil. Maximum nodules plant−1 in these trials was 5.2. In 2017, inoculation acted synergistically with Mo‐enriched seeds by increasing nodule weight. Averaged across inoculation levels, plants originated from high‐Mo seeds had 36% higher leaf N concentration than those raised from low‐Mo seeds. Inoculation did not affect yield, but plants grown from high‐Mo seeds yielded 42% more than those raised from low‐Mo seeds. In 2018, seed Mo content did not affect nodule and yield where urea was applied. However, without urea, plants raised from high‐Mo seeds had 3.5‐fold greater values for nodule number and weight and yielded 70% more than those grown from low‐Mo seeds. We conclude that using Mo‐enriched seeds associated with Bradyrhizobium inoculation would improve cowpea N nutrition and yield in a sustainable way.