Components of production and soybean yield in relation to the time of burndown and of management in post-emergency

Abstract

Aiming to evaluate the yield and productivity of soybean crop in response to burndown time and herbicide application in post-emergence in conventional and transgenic genotypes, the area of Technological Center COMIGO, was used to conduct this study. The experimental design was a randomized complete block in factorial arrangement 2 x 7, adopting eight repetitions. The first factor corresponded to burndown times before seeding, performed 15 and 1 day before sowing (DBS). The second factor was constituted by seven managements postemergent, described as follow: 1 - BRS-GO Luziânia RR® without chemical control with manual weeding; 2 - BRS-GO Luziânia RR® uncontrolled post-emergence; 3 - BRS-GO Luziânia RR ® glyphosate application at 15 DAE; 4 - BRS-GO Luziânia RR® glyphosate application at 30 DAE; 5 - BRS-GO Luziânia RR® glyphosate application at 15 and 30 DAE; 6 - BRS-GO Luziânia with chemical control; and 7 - BRS-GO Luziânia without chemical control with manual weeding. All plots were manual weeding along the crop cycle, except those which were allocated to Treatment 02. Variables evaluated were: plant height at harvest, height of first pod, number of pods with 1, 2 and 3 seeds, total number of pods per plant, weight of one hundred grains and yield. The results allow the conclusion that: imazethapyr (30 g ha-1) + lactofen (84 g ha-1) + chlorimuron-ethyl (80 g ha-1) + haloxyfop-methyl (72 g ha-1) herbicides used on conventional soybeans caused smaller growth of soybean plants and smaller height of first pod; number of pods per plant was not affected by all treatments; the weight of one hundred grains and soybean productivity was reduced when it was realized early management (15 DBS) and none management in postemergence was adopted.