Influência do manejo da palhada de azevém (Lolium multiflorum L.) e doses de nitrogênio no desenvolvimento e produção da cultura do milho (Zea mays L.)

Abstract

Corn (Zea mays L.) is one of the most important cereals in the world, with annual production of more than one billion tons. Productivity can be affected by several factors, including weed competition and nutritional deficiency, especially nitrogen. The objective of this work was to evaluate the soil cover approach associated with nitrogen doses in the competition between weed plants and maize crop. The experiment was conducted in Chapecó/SC. The experimental design was a randomized block design with four replications. The treatments were organized in a factorial scheme of 5 x 3, and the first factor was composed by the amount of ryegrass straw on the ground (mowing without straw, mowing, mowing and double thatch, soil upturned and soil upturned with weeding at CPFI), and the second factor nitrogen doses (N) in coverage (20, 50 e 80 Kg ha-1 de N). The variables analyzed were emergence of corn seedlings, plant height at flowering, number of spikes per m2, number of rows per spike, grains per row, grain per spike, mass of one thousand grains and grain yield. The weeds were collected during the flowering period and the dry mass was analyzed. For the variables plant height, grains per spike line, grain per spike and mass of one thousand grains, it was observed that the higher nitrogen doses brought the best results. However, only a thousand grain mass was influenced in the treatment of cover, where the best result was obtained in the treatment with soil rotation with weeding during the period of interference. Regarding the emergence variables of maize plants and dry matter of weeds, only considerable differences were obtained in the coverage management, and the mowing without straw promoted the best results. It was concluded that the management of coverage did not influence development and productivity components, and weeding was necessary to obtain better results. The management of the crop with soil cover is not enough to suppress weeds, and it is necessary the intervention with mechanical control to increase corn crop productivity. The increase of the nitrogen doses contributes to the growth of the plant and improves the productivity components of the maize crop. The increase in the nitrogen dose provided higher grain yield in all cover treatments. The management of the mulch without straw showed lower productivity