Nitrogen rate and plant density interaction enhances grain yield by regulating the grain distribution of secondary branches on the panicle axis and photosynthesis in japonica rice

Two japonica rice cultivars with different panicle trait index (PTI), HP917 (a high-PTI cultivar) and DP128 low-PTI were used to investigate the effects of nitrogen (N) rate plant density on grain distribution secondary branches axis, leaf photosynthetic characteristics, yield by a split plot design. The main plots assigned four N rates (0, 140, 200, 260 kg ha-1), subplots two densities: (D20, 15 plants m-2; D10, 30 m-2). Results showed that was increased increasing density, reaching peak at N200 D10. Compared N0 treatment, PTIs an increase in rate, respectively. 4% from D20 capacity significantly affected density. characteristics axis closely related yield. Correlation analysis PTI positively correlated net rate. These results suggested improvement 0.15 0.52 beneficial yield, which might contribute number middle bottom panicle.