Características agronômicas e degradação de grãos e da planta de milho em diferentes épocas de semeadura e de maturidade

Abstract

The objective of this study was to evaluate the degradation of grain and plant corn hybrids of high and low density grains at different times of sowing and maturity of plants and verify the correlation between dry matter content of whole plant, the productivity dry matter and grain with the degradability of grain and forage. The study was conducted in the experimental area, Department of Agriculture from Federal University of Lavras, located in Lavras, MG. Two experiments were conducted with sowing on 11/11/2010 and 12/12/2010 under tillage system. Eight corn hybrids were used of different agronomic characteristics, gathered in groups of high and low density of grains. The corn hybrids were harvested at three grain maturity stages: half milk line, three quarters of the milk line and black layer. The randomized block design in factorial scheme 8 (hybrid) x 3 (cutting times) with three replications was used. The degradability of dry matter (DEG) of whole plant, DEG of grain, DEG of milled grain, dry matter content of whole plant, dry matter yield of whole plant, grain yield and grain density were evaluated. It was carried out individual analysis of variance for each experiment and subsequently a joint analysis of variance. It was obtained estimates of the correlation between mean variables. The hybrids group that have a low density of grains is the most suitable for the production of corn forage, because they present higher dry matter yield of grain and forage degradability of the whole plant. The sowing realized in November is the best suited for the corn forage production. The plants harvesting at the ½ LL provides better forage quality. The grains degradation is more dependent on the phenological stage of plant and grain yield than the grains density. The dry matter degradability of whole plant has a higher correlation with the degradability of grain and with the dry matter content.