Densidade de plantas em híbridos de milho semeados no final do inverno em ambientes irrigados e de sequeiro

Abstract

The objective of this work was to determine plant density of maize hybrids sowed early (August and September), at the end of winter in the South of Brazil, in irrigated and rainfed environments. Two experiments were set in 2008/2009 (one irrigated throughout the whole cycle and another only from V15 to R2) and three in 2009/2010 (in addition to the previous levels, an experiment under natural rainfall was included). In each experiment, four densities (5, 7, 9, and 11 plants per square meter), four hybrids in 2008/2009, and three hybrids in 2009/2010 were evaluated. In 2008/2009, there were periods of water deficit that added 84 mm in the stages V3, V11 to V15, and R4. In 2009/2010, water deficiency occurred only in the R5 stage. In both years, maximum grain yield exceeded 13 Mg ha-1 and was obtained with densities higher than nine plants per square meter, regardless of water availability and hybrid. The use of high densities is an efficient strategy to optimize maize grain yield sowed during late winter in the warmer regions of the South of Brazil, as long as there is no water deficit between V15 and R2.