The objective of this work was to evaluate the effects of the application of doses of the plant growth regulator trinexapac-ethyl on plant height, lodging index, and grain yield of the white oat cultivar Barbarasul at different cultivation environments and nitrogen doses. The experiments were conducted in the 2010 and 2011 crop seasons in the municipalities of Capão do Leão and Augusto Pestana, in the state of Rio Grande do Sul, and in the 2010 and 2012 crop seasons in the municipality of Lages, in the state of Santa Catarina, Brazil. A randomized complete block design was used, in a 4x2x6 factorial arrangement (dose of trinexapac-ethyl, development stage, and environment), with four replicates consisting of 3.0 m2 plots. In each environment, nitrogen fertilization was done with 30 and 90 kg ha-1 N. The evaluated traits were plant height, lodging index percentage, and grain yield. The application of the growth regulator trinexapac-ethyl, at the doses of 100 to 150 g a.i. ha-1 in 'Barbarasul' white oat plants, in the E31 and E32 development stages, reduces plant height and the percentage of lodging, without harming grain yield. The intensity of the reduction in lodging depends on the conditions of the cultivation environment.
Avena sativa; plant height; gibberellin biosynthesis; grain yield.
