Effects of Trinexapac-ethyl in Combination with Nitrogen Fertilizer on Growth and Yield of Three Rice Varieties

Abstract

Application of excess nitrogen fertilizer is one factor contributing to rice lodging. Trinexapac-ethyl is a plant growth regulator that reduces stem elongation and helps strengthen cell walls. The objective was to find the optimum rate of nitrogen fertilizer to use together with trinexapac-ethyl foliar spray for increasing yield and reducing lodging. A split plot in RCB with 3 rice varieties: PT 1, PT 80 and PT 200 as main plot and 4 rates of nitrogen application: 0, 62.5, 125, and 187.5 kg/ha as subplot was performed. Trinexapac-ethyl foliar spray was applied at a concentration of 100 ppm two times, at seedling and tillering stage, at the same time as nitrogen application. The results showed that plant height, chlorophyll content, leaf area, internode length, panicle and seed numbers were not significantly different among 3 rice varieties under trinexapac-ethyl treatment combined with various nitrogen rates, but statistical significance were noted in yield, 1,000-grain weight, filled grain percentage, harvest index, cellulose, and lignin content. Application of nitrogen at different rates resulted in significant differences in plant height, chlorophyll content, internode length, yield, panicle numbers, harvest index, and cellulose content but did not show significant differences in leaf area, seed number per panicle, 1,000-grain weight, filled grain percentage and lignin content. From these results we can conclude that spraying trinexapac-ethyl 100 ppm two times at seedling and tillering stage together with nitrogen at the rate of 125 kg/ha results in the highest yield for PT200 variety, and the rice plants tend to be stronger and resist lodging.