Resposta de cultivares de feijao (Phaseolus vulgaris L.) às adubaçoes nitrogenada e molíbdica

Two experiments were carried out in Viçosa and one in Coimbra, Zona da Mata area, state of Minas Gerais, in order to study the effects on bean cultivars of the following treatments: 0, without N and Mo fertilizers; N + N, with 20 kg/ha of N at planting time plus 30 kg/ha of N as side dressing, 25 days after plant emergence; and N+Mo, with 20 kg/ha of N at planting time plus 20 g/ha of Mo as foliar spray, 25 days after plant emergence. Each experiment received a uniform application of phosphate at the rate of 80 kg/ha of P2O5, and included 17 bean cultivars. In two experiments (Viçosa 2 and Coimbra) the interaction fertilizer treatment x cultivar was not significant for yield. In Viçosa 2 N+Mo permitted a significant yield increase of 29 percent in relation to 0, while N+N brought about a yield increase of 20 percent, a difference also significant. In Coimbra, no significant difference was found between N+N and N+Mo, both significantly superior to 0 (32 percent and 41 percent, respectively). In the experiment Viçosa 1 the interaction fertilizer treatment x cultivar was significant for yield, but, in general, the cultivars followed the same tendency that was observed in the other two experiments. N+N and N+Mo brought about mean yield increases of 63 percent and 90 percent in relation to 0, respectively. As for the percentage of N in leaves, in two experiments (Viçosa 1 and Coimbra) N+N and N+Mo permitted average increases that varied from 25 percent to 36 percent. In Viçosa 2 only N+Mo had that effect, causing a 13 percent increase. In general, the increase of leaves' N percentage brought about a darker color to the leaves, a trend that was not followed by a few cultivars. It was concluded that molybdenum as foliar spray can be a "substitute" for nitrogen applied as side dressing