Épocas de semeadura do milho e distribuição espacial de plantas

Abstract

The increase in plant density, as well as the decrease in row spacing and the suitability for sowing date, associated with hybrid choice, are among the practices employed to achieve a higher grain productivity in maize crops. The objective of this work was to study the behavior of maize cultivars under two sowing dates in no-tillage system, associated with three plant densities and two row spacings. The experiments were conducted in two seasons (11/30/2011 and 01/30/2012) in an experimental area at “Federal University of Lavras”, in Lavras/MG. In each season, the available area was divided into two plots. In the first plot, an experiment was settled with a spacing of 0.55 m; in the second, another experiment was settled with a 0.80 m spacing. For each experiment, the performance of hybrids DOW 2B 587, AG 4051, CD 384 HX and GNZ 2004 was evaluated, under three sowing densities (55,000, 70,000 and 85,000 plants. ha-1). Each experiment was conducted in a randomized block design, in a 4 x 3 factorial arrangement, with three repetitions, corresponding to four cultivars and three sowing densities. The data obtained were initially subjected to an individual variance analysis per experiment. A joint variance analysis was then performed, involving the two experiments at each sowing date and lastly, simultaneously considering all experiments conducted. The delay in sowing dates causes a significant reduction in the evaluated characteristics. For traits plant height and ear insertion height, the behavior of hybrids coincides, regardless of plant population ha-1. The choice of row spacing is independent on plant population ha-1. Prolificacy and grain productivity of hybrids are dependent on sowing date and spacing, and are independent on plant density.