Effects of growth regulator and nitrogen on yield and lodging of irrigated wheat Regulador de crescimento e nitrogênio no desempenho produtivo e acamamento do trigo irrigado

High rates of nitrogen (N) increase plant growth, which can result in lodging. To avoid excessive growth of plants, plant growth regulators (PGRs), which cause internode length reduction, can be used. In this study, our objective was to evaluate the N nutritional status, growth, and yield of irrigated wheat as parameters using variable rates of nitrogen and growth regulator. Two experiments were conducted in Rio Paranaiba – MG in 2011 and 2012 using the BRS 264 cultivar. The treatments consisted of two concentrations of N (50 and 110 kg ha -1 as urea) and five concentrations of the growth regulator trinexapac-ethyl (0, 0.2, 0.4, 0.6, and 0.8 L ha -1 of Moddus ® containing 25% w/v of trinexapac-ethyl). Each plot consisted of 20 rows of wheat spaced 0.17 m, six meters in length. We evaluated plant height, shoot dry matter accumulation, thousand-grain weight, number of grains per spike, yield, leaf N content in the index leaf and grain, amount of N uptake and export, and lodging index. The PGR resulted in a linear decrease in plant height and shoot dry matter production. However, the rates of the growth regulator did not affect productivity. The rates of N influenced the yield only in 2011.