Abstract
To increase rice yield potential, field experiments were conducted in farmers’ paddies in 2011 and 2012 to evaluate the effects of different nitrogen applications on the yield and panicle components of three typical indica hybrid rice varieties in Sichuan Province. The number of grains per panicle resulting from late nitrogen application (LA) was 12 % greater than that obtained from traditional nitrogen application (TA); this increase was the main source of improvements in yield. The number of surviving and differentiated spikelets (NSS and NDiS) resulting from LA was significantly higher than that measured under TA, especially for the Fyou498 cultivar, where the NSS and NDiS increased by 15 % and 14 %, respectively. Compared with TA, the number of degenerated secondary branches and the percentage of degenerated secondary branches (NDeSB and PDeSB) were significantly reduced by 9 % and 11 %, respectively, by LA. This is the first study to demonstrate that an increase in NSS and a decrease in NDeSB lead to yield-improving effects attributable to LA. The grain yields of different varieties ranged from 9225.6 to 9408.7 kg ha−1, the PDeSB was as high as 31 %, and the number of surviving secondary branches (NSSB) was significantly and positively correlated with NSS. These data indicate that the yield of indica hybrid rice has considerable potential for being improved, and increasing NSSB is key to increasing NSS and improving the grain yield. These improvements should be pursued so as to increase the yield of hybrid rice to ensure both food security and sustainable agricultural development.
Highlights
The Green Revolution has greatly enhanced crop yield and has been successfully resolving the global food crisis since the 1960s (Wang and Li, 2011); the pressure on soil and other resources has intensified (Bueno and Ladha, 2009)
The grain yields of different varieties ranged from 9225.6 to 9408.7 kg ha−1, the PDeSB was as high as 31 %, and the number of surviving secondary branches (NSSB) was significantly and positively correlated with NSS
Nitrogen treatment had a significant effect on grain yield; late nitrogen application (LA) increased yield by approximately 6 % compared with traditional nitrogen application (TA)
Summary
The Green Revolution has greatly enhanced crop yield and has been successfully resolving the global food crisis since the 1960s (Wang and Li, 2011); the pressure on soil and other resources has intensified (Bueno and Ladha, 2009). Rapid population growth and economic development continue to exert growing pressure on the need to increase food production (Zhang, 2007). This being the situation, increasing the rice yield per hectare of land is the key to guaranteeing food security given the current amount of available agricultural land. Rice grain yield is determined by many factors, of which the NSS is the key factor. Our understanding of panicle growth and development is very clear, the mechanism underlying the influence of nitrogen applied at the panicle initiation stage is still unknown, especially for the heavy-panicle rice varieties
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