PACLOBUTRAZOL NO CRESCIMENTO E DESEMPENHO PRODUTIVO DA SOJA SOB DIFERENTES DENSIDADES DE SEMEADURA

Abstract

The growth regulators have been used in different cultures as cultural management technique that aims to reduce the size of the plant and also provide physiological changes that promote increases in grain yield. The objective of the study was to evaluate the effects of paclobutrazol on growth and yield performance of soybeans grown under different plant densities. The experimental design was a randomized block in factorial scheme (2 × 4 × 4), with four replications, two populations of plants (250 and 450.000 plants ha - 1 ), four doses of the plant growth regulator paclobutrazol (0, 12.5, 25.0 and 37.5 g ai ha - 1 ) and four stages of application (V 3 , V 6 , R 1 and V 3 + R 1 ). Averages for the effects of stadiums applications and plant populations underwent Scott Knott test at 5% probability of doses and the regulator to regression analysis. The population of 450.000 pl ha - 1 resulted in greater plant height, lodging and most lower productivity of soybeans. The use of paclobutrazol at V 3 soybean crop did not reduce plant height or grain yield, but reduced the percentage of lodging, and in the stadiums full development of culture (V 6 ) or early reproductive period (R 1 ) reduced height and lodging, as well as the grain yield of the crop. Increases in doses regulator paclobutrazol resulted in reducing plant height, lodg- ing and grain yield of soybean.