Increment on plant density: an alternative to improve maize grain yield in short growing season regions

摘要

The development of earlier hybrids, with shorter plant height, lower leaf number and upright leaves has increased maize potential adaptability to withstand high plant densities. This trend may be emphasized on the high lands of Southern Brazil due to their mild Spring and Summer temperatures and shorter maize growing season. Four trials were carried out, aiming to investigate the viability of using higher than recommended plant populations, as an alternative to improve grain yield. The maize hybrids Cargill 901 and XL 370 were evaluated at several plant populations, ranging from 37000 to 100000pl ha-1, under different management situations. In three out of four experiments, plant populations above 60000pl ha-1 maximized grain yield. The greater competition among individuals verified at high plant populations did not decrease substantially the number of ears per plant, which contributed to improve maize adaptation to high plant densities. Therefore, for regions with a short growing season, the use of early small stature maize hybrids may be accompanied by an increment in plant population up to a value varying between 65000 and 80000pl ha-1. This is conceivable as long as there is adequate soil fertility, water availability and stem lodging resistant genotypes.