Doses and Times of Trinexapac-ethyl Application in Soybean Development and Yield

The intense vegetative growth is one of the problems faced by soybean producers, causing the lodging, making difficult and damaging the harvest and, even, the efficiency of the application of agricultural defenses. The use of growth regulators is an important tool in the management of growth, in addition, it can favor the transport of photoassimilates for grain filling. Therefore, the objective was to evaluate the best dose and time of trinexapac-ethyl application in the development and yield of soybean varieties. The experiment was conducted in the Selviria County, Brazil (20°20′53″ S, 51°24′02″ W). The experimental design was used in randomized blocks with treatments arranged in a factorial scheme 5 x 3 (doses x times), with four replications. The varieties used were the BRS Valiosa RR and the BMX Potencia RR, the doses of the growth regulator were 0; 50; 100; 200 and 400 g ha-1 of trinexapac-ethyl (Moddus®) and the application times were at the phenological stages V7, V10 and R2. The varieties BRS Valiosa and BMX Potencia, respectively, were obtained at the phenological stage V10, with application of 200 g ha-1 of trinexapac-ethyl, greater dry matter accumulation of leaves and pods. Nevertheless, the same did not act on the foliar area of the BRS Valiosa RR variety in the same way that it did not induce changes in the production components of the BMX Potencia RR variety. Regardless of the application period (V7, V10 and R2) and the dose (up to 400 g ha-1), the application of trinexapac-ethyl was not a management capable of influencing the agronomic characteristics and the lodging of the plants in both varieties.