Optimized nitrogen managements and polyaspartic acid urea improved dry matter production and yield of indica hybrid rice

Abstract

Reasonable management of nitrogen (N) and the development of N fertilizers with higher use efficiency are the two main methods to increase rice yield. The effects of optimized nitrogen management (ONM) and polyaspartic acid urea treatment (PAU) on rice dry matter production and grain yield under different soil conditions in Sichuan, China, were studied in 2013. When the different N management regimes were applied there were differences in the rice tiller number, dry matter production, and yield observed. At Shehong, ONM3 (a 15% increase in the N rate over the farmer’s fertilizer practice) had the highest grain yield, and significantly (P<0.05) increased the percentage of effective tillers, biomass yield, the ratio of leaf lamina at anthesis and maturity stages, amount of post-anthesis transfer of accumulated dry matter into the grain (APA), and panicles per meter square. ONM2 (a 15% reduction in the N rate over the farmer’s fertilizer practice) significantly (P<0.05) increased the percentage of effective tillers, panicles per meter square, and grain yield at Wenjiang, as the rice plants had a reasonable amount of pre-anthesis stored dry matter from the vegetative organs to redistribute to the grain and APA. At both sites, PAU3 (polyaspartic acid urea (PASP-urea) spilt-applied in four stages) improved the grain yield due to an increase in APA, panicles per meter square, and spikelets per panicle. It was shown through correlation analysis that at both sites the grain yield was correlated positively with the panicles per meter square and APA (P<0.01). Therefore, it can be concluded that the increase in panicles per meter square and APA were the causes of the improved grain yields. PASP-urea promoted rice production, and PAU3 was suitable for use with different soils. Based on these results, the effect of spilt-applied N during the middle and later stages largely depended on the soil fertility, and the spilt-applied N being used at a suitable rate that was beneficial for improving the rice yield.