Contributive effect of growth regulator Trinexapac-Ethyl to oats yield in Brazil

Studies on efficient use of the plant growth regulator can make this technology possible for leveraging oat yield in Brazil. This study aims to define the optimal dose growth regulator in oat, which allows plant lodging at most 5%. Establishing equations describe the yield indicators behavior and by using the optimal growth regulator dose for lodging, simulate the expression of these indicators regardless of reduced, high and very high conditions of nitrogen fertilization and favorable and unfavorable cultivation year. The study was conducted in 2013, 2014 and 2015, in carrying out two experiments, one to quantify the biomass yield and another aiming at estimating grain yield and lodging. The experimental design was a randomized block with four replications, following factorial scheme 4 x 3 to growth regulator doses (0, 200, 400 and 600 mL ha-1) and N-fertilizer rates (30, 90 and 150 kg ha-1), respectively. The use of 495 mL ha-1 growth regulator trinexapac-ethyl active principle is shown efficient at the reduction of oat plant lodging, regardless of the agricultural year condition and N-fertilizer rate. In the expression of grain yield and harvest index, quadratic behavior is obtained, however with decreasing linearity on the biomass yield and straw by increasing the growth regulator dose. The optimal dose of growth regulator in reducing oat lodging does not affect grain yield, but it reduces biological yield via biomass straw with elevation on the harvest index. Key words: Avena sativa, biomass, straw, harvest index, multiple linear regression