Effects On Rice Plant Development and Soil Chemical Attributes From Nitrogen e Growth Regulator.

The “Vale do Ribeira”, southeast São Paulo State, Brazil was region highly grain producing, mainly rice cultivation, which makes it possible to adopt growing techniques to revival on production of this cereal. The aim of this study was to evaluate the effect of growth regulator and the use of nitrogen rates in the growth vegetative and soil chemical analysis when cultivated with upland rice crop IAC 202 cultivar in 2011/12 drop year. The experimental design was randomized blocks composed of nitrogen (0, 50, 100, 150 and 200 kg N ha^-1), urea font (45% N) in covering and application or non of growth regulator trinexapac ethyl (150 g active ingredient ha^-1) in three stages of plant development (active tillering, between tillering active and floral differentiation and floral differentiation). The study was carried out at São Paulo State University, Campus de Registro. Were evaluated height, stem diameter and number of rice plants tillers. Were also collected soil for chemical analysis on May 25, 2012 using a soil probe at depths 0.0-0.10 m. The samples were sent to the laboratory of soil fertility for the determinations of pH(CaCl₂), P, O.M., Al, K, Ca, Mg, S, (H+Al), sum of bases (SB), CEC, V% and Al-saturation (m%). The data were submitted to analysis of variance (test F), and the means were compared using the Tukey test and polynomial regression (p<0.01). The growth regulator application provides significant reduction in plant height mainly when applied at floral differentiation stage. Increasing N rates application increased height, diameter and number of tillers, reduction of phosphorus levels, pH, Ca, Mg, SB and V% and increased on CEC, Al, m%.