Fenologia e desempenho agronômico de híbridos de milho em seis datas de semeadura em Cerro Largo - RS

Abstract

Variations in environmental conditions, such as thermal, water and solar availability, at different sowing times have a great influence on the phenology and development of the corn crop. The objective of this study was to evaluate the agronomic and phenological performance of 15 corn hybrids in six sowing dates according to the recommendation of the Climate Risk Zoning. The experimental design was randomized block in three blocks with 15 corn hybrids in six sowing dates in 2019, these being 08/08, 08/30, 09/29, 10/26, 11/30, and 12/31. Each of the six sowing dates consisted of 45 experimental units (15 hybrids X 3 blocks) at approximately 30 days intervals. Each experimental unit consisted of 6 sowing lines, 3 meters long, with spacing of 0,5 m between rows and 0,29 m between plants, for a population of 70.000 plants per hectare. The growth, development and productivity of corn hybrids were evaluated at each sowing date, analyzing plant height, aboveground dry mass, grain yield and the temperature sum in degree days required for each phenological phase. The experiment data were submitted to the Shapiro-Wilk normality test, Bartlett's variance homogeneity test, and the means were compared using the Scott-Knott test, adopting a 5% probability of error level for all analyses. From the results obtained, it was found that there was a reduction in the duration of the development subperiods of the hybrids evaluated with the delay of sowing. The hybrids sown in September and November reached greater height. The highest productions of aerial dry mass and grain yield were obtained in the August sowing dates. The results obtained allow us to conclude that the best sowing date for the 15 corn hybrids, based on yield, for the Cerro Largo - RS, in the crop year 19/20, was in August.