APLICAÇÕES FOLIARES DE ZINCO, COBRE E MANGANÊS EM DIFERENTES COMBINAÇÕES DE DOSES E ESTÁDIOS NA CULTURA DO MILHO

Abstract

Plant nutrition is one of the aspects that has a great influence on the performance of a corn (Zea mays) crop, and the adequate supply of some essential micronutrients proves to be an allied tool to achieve high levels of productivity. Therefore, the objective of this study was to evaluate responses of corn plants subjected to foliar applications of Zinc (Zn), Copper (Cu), and Manganese (Mn), at different doses and distributed in different combinations of crop phenological stages. The experiment was conducted in the experimental field of the Pontifical Catholic University of Paraná (PUCPR) Toledo campus, in a typical dystroferric Red Oxisol, with a randomized block design, containing 12 treatments based on doses of Cu, Zn and Mn applied in combinations of stages of crop development, with 5 replications, totaling 60 plots. Evaluations of the SPAD index, plant height, stem diameter, yield, mass of one thousand grains, number of rows per ear and number of grains per row were carried out, where the data were tabulated and subjected to an analysis of variance at the level of 5 % significance and, when differences were observed between treatments, they were subjected to the Tukey test. Significant differences were found in the evaluation of the SPAD index, with the control treatment, without any application of Cu, Zn and Mn, being significantly lower than treatment 6, which obtained the highest value, which was subjected to applications of 3.6 g ha-1 of Cu, 100 g ha-1 of Mn and 66.7 g ha-1 of Zn in stages V4, V8 and VT. Under the conditions of this experiment, no significant differences were observed for the values ​​of plant height (AP), stalk diameter (DC), yield (REN), thousand grain mass (MMG), number of rows per ear (NFE) and number of grains per row (NGF).