Geraldo Antônio de Andrade Araújo

Corn crop characteristics under nitrogen, molybdenum and zinc fertilization

Fertilization is the factor that presents the highest contribution to corn yield, and may also affect grain quality. The objective of this work was to evaluate, in a an Ultisol, the fertilization with N, Mo and Zn on to determine yield and maize grain quality (protein and mineral nutrient contents) and to determine the best sampling time to analyse organic-N, NO3--N and total-N (NO3--N + organic-N). In addition, nutrient concentrations in maize grain were related to leaves. The experiment was a factorial 4x2x2 in a randomized complete block design with four replications in which the factors were: four N raes (0, 70, 140 and 210 kg ha-1), two of Mo (0 and 90 g ha-1) and two of Zn (0 and 3 kg ha-1). Leaves were sampled 25, 45 and 63 days after emergency (DAE). Tissue and grain were milled and analysed, and organic-N, NO3--N, total-N, protein, P, K, Ca, Mg, S, Zn, Fe, Cu and Mn contents were evaluated. Zinc and molybdenum applications and their interactions with N did not affect any yield characteristics. The weight of thousand grains, the number of ears per plant, the weight of ears with and without straw, and yield increased with increased rates. Maximum yield (8.58 t ha-1) was obtained with 201.2 kg ha-1 N. Protein content and analysed nutrients in grain increased with increasing N rate. Mo fertilization raised protein content, while Zn application increased protein content in grains. The critical levels of total-N were 2.73 and 2.00 dag kg-1 at 45 and 63 DAE. The best traits for diagnosis index and yield prediction was the organic-N content at 45 DAE. In general, grain mineral content was positively correlated with leaft mineral content at 63 DAE.

Adubação nitrogenada e molíbdica da cultura do feijão na Zona da Mata de Minas Gerais

Three series of experiments were carried out. In the first, the effects of N, Mo, and rhizobium were studied at two municipalities; in the second, conducted at another municipality, a factorial with four rates of N (0, 30, 60, and 90 kg ha-1) and four rates of Mo (0, 40, 80, and 120 g ha-1) was studied; and in the third, at six municipalities, the following combinations of N at planting time (kg ha-1), N as side dressing (kg ha-1) and Mo (g ha-1) were used, respectively: 0-0-0, 0-40-70, 20-0-70, and 20-40-70. In all experiments, Mo (as foliar spray) and N (as side dressing) were applied at about 25 days after plant emergence. Ordinary superphosphate (90 kg ha-1 of P2O5) plus potassium chloride (60 kg ha-1 of K2O) were applied as uniform fertilization for all experiments. The soils were contaminated by native strains of Rhizobium. Inoculation with selected strains of Rhizobium had no effect on grain yield. Molybdenum fertilization increased bean yield, and maximum yields were attained with 70 to 100 g ha-1 of Mo, depending on N fertilization: smaller rate of Mo was needed when greater dose of N was used and vice versa. Nitrogen applied at planting time was also essential and its absence could not generally be compensated by side dressing application. The N + Mo combination increased bean yield in approximately 90 to 200%.

Application of molybdenum and a desiccant herbicide to the common bean under direct seeding

Applying micronutrients together with the herbicides used in plant desiccation can ensure an adequate supply of these nutrients and a reduction in production costs under a direct seeding (DSS) system. The aim of this study was to evaluate the effect of dosages of molybdenum (Mo), applied both in a desiccation operation together with glyphosate on the straw of brachiaria (Brachiaria brizantha) and separately via the leaves, on the common bean (cultivar Ouro Vermelho) grown under DSS. A randomised block design was used with four replications in an arrangement of sublots. In the lots, dosages of Mo (0, 0.1, 0.2, 0.4 and 0.8 kg ha-1) were applied together with the desiccant herbicide (glyphosate), and in the sublots, two dosages of Mo (0 and 100 g ha -1) were applied via the leaves. Two experiments were carried out in the town of Coimbra, in the state of Minas Gerais, Brazil, one in 2009 and the other in 2010 (the same treatments having been applied in the experimental area in 2008). Foliar fertilization was carried out with sodium molybdate ((Na 2 MoO 4 ) ( 3 9 % Mo ) ) a t s t a g e V 4 i n t h e b e a n p l a n t s . T h e a p p l i c a t i o n o f Mo , w h e t h e r m i x e d w i t h t h e desiccant or applied via the leaves, had no significant effect on yield components or on productivity. Levels of Mo and N in the grain, and of N in the leaves, increased with the application of Mo, both when mixed with the desiccant and applied via the leaves.

Molybdenum mixed with glyphosate and alone via foliar spray in no-tillage common bean grown on corn stover

The effect of molybdenum (Mo) on common bean grown in desiccated corn stover in a no-tillage system was evaluated under two application modes: Mo mixed with the desiccant glyphosate and Mo direct spray to the bean leaves. The treatments (four replicates) were assigned to a completely randomized block design in a split-plot arrangement with the application of Mo (0, 100, 200, 400 and 800 g ha -1 ) mixed with glyphosate in the main plots and Mo foliar spray (0 and 100 g ha -1 ) in the sub-plots. The field experiments were carried out in 2009 and 2010 in the municipality of Coimbra, Minas Gerais State, with the common bean cultivar Ouro Vermelho. Mo mixed with glyphosate had neither an effect on common bean yield nor on the Mo and N contents in leaves, however it increased the Mo and N contents in seeds. Application of Mo via foliar spray increased Mo content in leaves and Mo and N contents in seeds. The reapplication of molybdenum with glyphosate for desiccation in subsequent crops caused a cumulative effect of Mo content in bean seeds.