Effects of Transplanting Density and Nitrogen Fertilizer on Yield Formation and N Absorption in a Two-line Intersubspecific Hybrid Rice "Liangyoupeijiu"

A field experiment was conducted with different transplanting densities(22.5×10~4,27×10~4 and 31.5×10~4 hole/ha) and nitrogen fertilizer rates(0,112.5,225.0 and 337.5 kg/ha) using an intersubspecific hybrid rice,Liangyoupeijiu.The main results were as follows:(1) Influence of transplanting density on panicle per unit area and grain number per panicle was higher than that on seed-setting rate and 1000-grain weight.There was no significant difference in yield between treatments with transplanting densities ranging from 22.5×10~4 to 31.5×10~4hole /ha.(2) Effect of nitrogen fertilizer on grain number per panicle was lower than that on panicle number,seed-setting rate and 1000-grain weight.Seed-setting rate and 1000-grain weight were decreased significantly in the treatment with 337.5 kg/ha nitrogen fertilizer.(3) The amount of N-uptake was increased with the increment of nitrogen fertilizer rate.But excessive N-content and nitrogen accumulation were not of benefit to the transfer of nitrogen from vegetative organs(leaf,sheath and stem) to panicle,resulting in the reduction of N-accumulation amount in seeds,seed-setting percentage,1000-grain weight and yield.(4) The better N accumulation of stem,sheath and leaf before heading,the better N transfer from stem,sheath and leaf to panicle after heading,the better coordinate relationship among panicle number,seed setting rate and 1000-grain weight and higher yield would be obtained under medium-fertility field with nitrogen application of 225.0 kg/ha,transplanting density of 22.5×10~4 hole/ha and high peak seedlings of 500.0×10~4/ha.