REGULADORES DE CRESCIMENTO APLICADOS EM DIFERENTES DOSES E ÉPOCAS EM CULTIVARES DE TRIGO.

Abstract

For the wheat crop is proven the importance of the use of growth regulators by reducing the lodging, mainly caused by high doses of nitrogen and the high susceptibility of some cultivars. As a result there is a need to use new technologies that will help to avoid productivity losses caused by lodging. In this sense, there were three experiments (E1, E2 and E3) to evaluate the effects of growth regulators applied at different doses and times in agronomic traits, yield components and yield of wheat cultivars. The experiments were performed at the Farm School, State University of Ponta Grossa (UEPG), Ponta Grossa, PR, in 2009. In E1 we used two regulators (trinexapac-ethyl and prohexadioncalcium) at doses of 0.0, 37.5, 75.0, 112.5 and 150.0 g ha-1 and 0.0, 41, 2, 82.5, 123.7 and 165.0 g ha-1 respectively,in the cultivar BRS-249. We used the experimental design of randomized blocks with ten treatments in a factorial 2 x 5 (x regulators doses) with four replications. In E2 we used two regulators (trinexapac-ethyl and prohexadion-calcium) at doses of 0.0, 37.5, 75.0, 112.5 and 150.0 g ha-1 and 0.0, 41, 2, 82.5, 123.7 and 165.0 g ha-1 respectively, in the cultivar Marfim. Experimental design used was randomized blocks with ten treatments in a factorial 2 x 5 (x regulators doses) with four replications. At E3 we used three growth regulators (trinexapac-ethyl, prohexadion-calcium and chloride 1,1 - dimethyl piperidine) at doses of 125.0 g ha-1, 137.5 and 125.0 g ha-1 g ha-1 respectively applied in two seasons (between the 1st and 2nd node and between 2 ° and 3 ° we have seen), the cultivar Marfim. Experimental design used was randomized blocks in 4 x 2 factorial arrangement and four replications. In the E1 prohexadion trinexapac-ethyl and calcium-promoted reduction of internode length and plant height, stem diameter increased, the number of leaves per plant, flag leaf width and productivity. In the E2 prohexadion-calcium and trinexapac-ethyl were effective in reducing internode length, plant height and mass of thousand grains, and prohexadion-calcium that showed potential for use in wheat crop. At the E3 prohexadion-calcium and trinexapac-ethyl promoted decrease in plant height without affecting the diameter of the stem and productivity. The 1,1- chloride dimethyl piperidine did not affect plant height, and promoted an increase in the number of leaves per plant, but without effect on components of production and productivity. The application period did not promote changes in most variables indicating a greater range of use of regulators in the cultivar Marfim.