Mechanical damages in grains of commercial corn hybrids as a function of the crop moisture content

摘要

The objective of this work was to evaluate the mechanical damages in grains of five commercial corn hybrids due to harvest humidity. The work was conducted in Astorga - PR, during the autumn/winter harvest of 2007 and the summer harvest of 2007/2008. The harvests occurred in five distinguished periods (7.20, 7.27, 8.03, 8.10 and 8.17.2007 in the autumn/fall harvest and 3.15, 3.22, 3.31, 4.07 and 4.22.2008 in the summer harvest) and also in five replications, being the grain samples underwent to moisture content determination at an oven heated to 103 ± 1 ºC for 72 h in the laboratory. After that, the mechanical damage (cracked grain, torn grain and broken grain) was evaluated with a diaphanoscope and a magnifying glass of increase of 10x, and the corn grain samples were willing in a completely randomized design. The data were submitted to analyses of variance and regression. It was observed that the occurrence of endosperm scratched and the fragmented corn grains increased, while, the occurrence of compressed grains was decreased, in function of the reduction of the moisture content in the grain, for occasion of the harvest. The results suggest that the mechanical damages in the corn grains, in the harvest stage, are smaller in the superior moisture content between 22 % and 26 %.