Abstract:

A field experiment was conducted with different transplanting densities (22.5×10⁴，27×10⁴，31.5×10⁴ hole/ha) and nitrogen fertilizer rates (0，112.5，225.0，337.5 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 22.5×10⁴ to 31.5×104 holes per hectare. (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 of nitrogen 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 22.5×10⁴ hole/ha and high peak seedlings of 500.0×10⁴/ha.

Key words: Nitrogen fertilizer, Two-line intersubspecific hybrid rice, Yield, N-uptake and use efficiency