The objective of this work was to evaluate the effects of molybdenum (Mo) leaf application in beans on leaf and grain concentration of Mo, total N, organic N and nitrate as well as the grain nutrient accumulation. Beans cv. "Ouro Negro" was cultivated at the Universidade Federal de Viçosa. Treatments consisted of increasing levels of Mo (0, 40, 80 and 120 g ha-1), using ammonium molybdate applied to the leaves 25 days after emergence. The experimental design was a randomized complete block with four replications. There was a quadratic response due to increasing doses of Mo applied, on the leaf and grain concentrations of Mo, total N and organic N. Leaf Mo increased from 0.49 mg kg-1 (control) up to 0.95 mg kg-1, what improved N utilization resulting in higher leaf and grain concentrations of total N and organic N, better plant growth and darker green leaves. Plants without Mo showed lower N concentration 26.6 g kg-1 of N, on the average, and severe N deficiency symptoms. There were no effects of Mo application on leaf or grain NO3- concentration 0.39 g kg-1 NO3- and 0.03 g kg-1 NO3-, respectively. Considering an application of 80,3 g ha-1 of Mo for an estimate productivity of 1,893 kg ha-1 of grains, the amount of nutrients removed by the bean crop per ha would be: 72 kg of N; 15.7 kg of Ca; 15.3 kg of K; 9.4 kg of P; 4 kg of Mg; 102 g of Fe, 63 g of Zn; 25 g of Cu; 23 g of Mn and 3.2 g of Mo.
common beans; plant nutrition; micronutrients; nitrogen