Cotton Yield and Nitrogen Content Under Different Row Spacings and Growth Regulator Application In the No-Tillage System In the Cerrado of Brazil.

Cotton cultivation is distributed in over seventy cotton-producing countries in various parts of the world. It has an important role in the Brazilian economy, occupying a prominent position in the country’s agribusiness chain. This study was conducted in the experimental station of the São Paulo State University, located at the country of Selviria, State of Mato Grosso do Sul – Cerrado region - Brazil, under the no-tillage system, using the cotton cultivar Deltaopal. The experimental design was the randomized completely blocks, with row spacings of: 0.45m, 0.70m and 0.90m; growth regulator management (mepiquat chloride) at a dose of 1.0 L ha^-1, with concentration of 50g L^-1: a- apportioned into four applications  (at 35, 45, 55, and 65 days after emergence (d.a.e.)), b- only at 70 days after emergency and c- without any regulator application. There were nine treatments with four replications, hence a total of 36 plots. The number of bolls per plant, the weight of 20 bolls and the yield of the cotton cultivar Deltaopal, in three growing seasons, were assessed. This study evaluates the yield and its components, according to different spacings and growth regulator application systems. The smaller number of plants, represented by the conventional spacings, produced higher numbers of bolls per plant. Depending of the growing season and the weather, the greatest mass of 20 bolls can be found using greater spacings, with apportioned applications of growth regulator. Similarly, the highest yields are also found for apportioned applications of the regulator, using reduced row spacings. The Chlorophyll content was increased by the use of growth regulator.