Influência de lâminas de irrigação e densidades de plantas sobre o cultivo do milho “safrinha”

Abstract

The maize (Zea mays L.) stands out among the great cultures of global economic importance. In Brazil presents itself as the third most cultivated cereal, because its use ranging from animal feed to high-tech industries. However, productivity is still low or suffers fluctuations due to poor distribution of rainfall. As the drought caused by lack of water, the main production factor affecting the productivity of this crop in the main producing regions of the country. What, for RS West Frontier region is no different. Thus, the use of supplemental irrigation presents itself as a fundamental alternative to minimize the effect of water stress and increase productivity. Another limiting factor is the adequacy of plant density in scenarios with the use of supplemental irrigation. The purpose of the present study was to asses the effect of different irrigation strategies and plant densities on the yield components of maize crop cultivated in second season. This work took place at Instituto Federal Farroupilha - Alegrete Campus/RS, from January to June 2014. The treatments were arranged in a randomized disign in a factorial scheme 4x5 with 3 replications. The moment of irrigation was defined in turn fixed irrigation of five days and the amount of water applied, based on evapotranspiration of culture (Etc). The treatments were 0% (rainfall without irrigation), 50%, 75%, 100% and 125% of the Etc was set four densities of plants (40, 70, 100 and 130 thousand plants.ha-1). It was assessed: Plant height, ear insertion height, stem diameter, leaf area index, dry matter of the aerial part, ear length, ear diameter, number of corn ear per plant, number of grains per ear, aboveground dry matter, mass of 100 grains, harvest index and grain productivity and efficient use of water. There was a population of plants that maximized the yield of corn for each irrigation strategies adopted. The different irrigation strategies influenced mainly the stem diameter, leaf area index, dry matter of the shoot, the length of ear number of grains per ear, the mass of one hundred grains and grain productivity and efficient use of water. The use of supplementary irrigation is recommended to maximize the productivity of maize second crop to the border region west of the RS. The choice of the plant density is a crucial variable in the cultivation of maize crops, since the different populations significantly influenced the components of yeld. Furthermore, there is a plant density which maximizes the yield of corn grain for each blade irrigation adopted. The combination which obtained greater grain productivity was 130 thousand plants.ha-1 with the strategies 100% of irrigation Etc (15.25 t. ha-1).