Correlation between N application rate and the growth and development of hybrid rice

Experiments of N fertilizer applied to hybrid rice were carried out in Longhai.The results showed that dry matter accumulation and CGR had a linear relationship with N fertilizer applied at tilling stage of hybrid rice.Except those in leaves,dry matter accumulation of stems and sheaths,ears,whole plant and CGR correlated parabolically with N fertilizer applied to the hybrid rice at the middle-to-late stage of the crop.CGR significantly correlated with leaf area and somewhat negatively correlated with NAR.To improve CGR,N fertilizer application must be carried out at a reasonable rate so that the leaf area and NAR would reach an optimal balance.The rice yield was significantly correlated to the dry matter accumulation.It showed a parabolic correlation with N fertilizer application.In this experiment,the optimum dose of N fertilizer for hybrid rice was 200.0 kg·hm-2 for a target yield of 11000 kg. And,to produce 100.0 kg grain,it needed 1.8 kg N fertilizer on average,in which 30% to 40% went for the ear-grain fertilization.