Title : Evaluate the appropriate fertilizer usage to narrow the rice yield gap in the major super-hybrid-rice-growing areas
Abstract:
The yield of super hybrid rice had achieved world recognized marks and accumulated a lot of valuable experiment, but the yield potential maximum only at the special ecologic regions and the grain yield varied sharply among normal ecologic regions. In this study fifteen field experiments with five super hybrid rice varieties and four N levels were conducted at eight locations from 2015-2017 to illuminate the effect of yield components’ variation on the yield gap and the yield-improving effects response to N levels. In this study, the yields of super hybrid rice varied from 8.98 to 10.59 t ha-1, 7.82 to 9.24 t ha-1 and 8.59 to 10.63 t ha-1 in 2015, 2016 and 2017 respectively, their amplitude of variation significantly negative correlate with the that of panicles ha-1(r=-0.6614) and grain weight (r=-0.6599). The grain yield gap was highest under no fertilizer treatment (N1) and had been decreased 12.97% at most when fertilizer applied moderately. The yields which were increased by fertilizer had been affected by N levels significantly and by regions extremely significantly, and it positive correlate with spikelets ha-1 that increased by fertilizer (r=0.5247). Compared with N1, the treatment of N3(20kg ha-1) had increased yield about 3.03 t ha-1,in which the yield gap was smaller 5.49% and 16.32% than that of N2 and N4 respectively. So we concluded that the super hybrid rice varieties which have the characteristic of multi-panicle and heavy-grain was basic for narrowing the grain yield gaps among different regions. In addition, reasonable fertilizer at the level of 20 kg ha-1 nitrogen was beneficial to the sink size improving and was essential for the realization of high and stable yield simultaneously. Therefore, this study provided a theoretical support and technical guidance for minimizing yield gaps in the major super-hybrid-rice-growing areas.
