Effects of nitrogen regulation on dry matter accumulation and grain yield of rice under different cultivation models and two kinds of ecological conditions

The effects of nitrogen regulation on dry matter accumulation,grain yield and its components under different cultivations were studied in Wenjiang(WJ)and Hanyuan(HY)by using hybrid rice,Ⅱ-you 498.The cultivation models were wide-narrow row spacing cultivation,triangle cultivation,sparse planting by expanding spacing and reducing plant space,and scattered planting cultivation.The result indicates that the 180 kg/ha of nitrogen application is the optimum amount for all cultivation models.When the total nitrogen application amount is 180 kg/ha,the rational ratio of nitrogen application at the transplanting stage,tillering stage and booting stage is 6∶3∶1 under the wide-narrow row spacing cultivation and triangle cultivation,and is 5∶2∶3 under sparse planting by expanding spacing and reducing plant space.The ratios are 4∶1∶5 and 5∶2∶3 under scattered planting cultivation in WJ and HY,respectively.Each cultivation model is cable of obtaining high yield by increasing population spikelets and biomass yield under suitable nitrogen regulation in WJ.In HY,the biomass yield is significantly increased in the triangle cultivation under suitable nitrogen regulation,and the harvest index(HI) is high as well,so its potential yield is higher than those of other cultivation models.Compared to the sparse planting by expanding spacing and reducing plant space,the wide-narrow row spacing cultivation has a certain degree marginal effect,the effects of ecological condition and nitrogen regulation on dry matter accumulation and grain yield depend on crop population sizes at the late stage and conditions of temperature and light.The scattered planting cultivation has a great advantage in dry matter production before the heading stage,so increasing dry matter accumulation after the heading is key to get high grain yield by suitable postponing nitrogen measures under different ecological conditions.