Macronutrients Foliar Contents and Cotton Yield As Function of the Glyphosate Low Doses and Growth Regulator Application System.

When characterizing the importance and the efficiency of the use of products for the control in height of plants, it becomes interesting from a productive point of view and of fiber quality to stimulate the same to the growth, by the appropriate handling of the regulator, to deviate the route of photoassimilates for reproductive structures. The present study was carried out in Jales city, Sao Paulo State, Brazil, agricultural year 2011/12 and had as objective to evaluate the macronutrients foliar contents and cotton seed yield cv. FMT 701 as function of the glyphosate low doses and growth regulator application system. The experimental design was a randomized block in 6x2 factorial with four replications, totaling 48 plots with: a- number of glyphosate low dose applications (20 g a.e. (acid equivalent) ha^-1): (zero, one, two, three, four and five), foliar applied respectively to 40; 40 and 50; 40, 50 and 60; 40, 50, 60, 70 and 40, 50, 60, 70 and 80 days after emergence of plants (d.a.e.); and b- managing of the growth regulator for foliar application (50 g a.i. (active ingredient - mepiquat chloride) ha^-1) being split application form (3 days after application of glyphosate low dose) or only way at 70 d.a.e. (in plots that didn’t receive a low dose); and without application. The cotton cultivar FMT 701 submitted to two applications glyphosate low dose has increased the leaf Mg concentration and cotton seed yield when combined with mepiquat chloride. The use of the growth regulator provides increased leaf Mg and N concentration. Five applications of glyphosate low dose associated with the use of mepiquat chloride provide reduction of cotton seed yield.