Desempenho do algodoeiro de fibra verde em função de adubação nitrogenada e promotor de crescimento.

Abstract

Considering the great importance that the color cotton has been acquiring in the last times, this research had the objective of quantifying the isolated and combined effects of the nitrogen manuring and growth promoter factors on the color cotton variety BRS Verde. Two experiments were conducted in conditions of green house, belonging to the National Center of Cotton Research (EMBRAPA-CNPA), where in both the nitrogen manuring was applied in doses of 0, 80, 160 and 240 kg N ha"1. In the experiment I the growth promoter Stimulate® was applied in the seeds in doses of 10 and 17 mL per 0,5 kg of seeds and in the experiment I I in doses of 250 and 500 mL ha"1, with foliar application. For both experiments, the experimental design was in random blocks with nine treatments and three replications in a 4x2+1 factorial scheme, totaling 27 experimental units for each experiment, represented by plastic vases with approximately 25 liters of capacity. The variables related to the growth (plant height, stem diameter and foliar area), to the development (emergence of first flower button and of first flower, and opening of first cotton boll), to the production (production of cotton in pit, weight of a cotton boll, cotton boll number, fiber percentage, feather weight, phytomass of aerial part, phytomass of root and intrinsic characteristics of the fiber - length, uniformity, fiber index, resistance, elongation, thinness, reflectance, yellow degree and spinability) were evaluated. It was verified that the herbaceous cotton plant, variety BRS Verde, responded linearly to doses of nitrogen up to 240 kg of N ha"1, considering the variable production of cotton in pit per plant, independem of the use or not of a growth promoter applied in the seeds or in the leaves. The Stimulate® growth promoter didn't alter the growth and nor the production and components of the herbaceous cotton plant, as well as didn't interact with the applied nitrogen in the edafic médium. Independent of the dose factor and method of growth promoter application, the nitrogen promoted a signifícant linear decrease in the precocity of the herbaceous cotton plants, variety BRS Verde.