Thidiazuron increases upland rice yield

Abstract

The use of plant growth regulators in rice can provide reductions in plant height and decrease plant lodging. This study aimed at verifying the influence of the thidiazuron plant regulator on upland rice in the Brazilian Savannah region. The BRS Esmeralda and IAC 202 cultivars were used, as well as a randomized blocks design, in a 4 x 3 factorial arrangement for each cultivar, consisting of thidiazuron doses (0 g ha^-1, 0.3 g ha^-1, 0.6 g ha^-1 and 0.9 g ha^-1) and three application times (tillering, floral differentiation and booting), with four replications. The number of spikelets per panicle and spikelet fertility of the BRS Esmeralda cultivar were higher when using the thidiazuron dose of 0.9 g ha^-1 in the tillering stage. The weight of 100 grains of the BRS Esmeralda cultivar fitted a quadratic equation, while the IAC 202 fitted a linear equation, with the best time of application taking place during the tillering stage. For hectoliter weight, the results for the BRS Esmeralda also fitted a quadratic equation, while for the IAC 202 a significant difference was observed only among times, being the booting stage the best application time. Grain yield fitted a positive linear equation for both the BRS Esmeralda and IAC 202 cultivars, with gains of 23.5 % and 6.5 %, respectively, when compared to the control. Thidiazuron positively influences grain yield for upland rice.