Objective The study was carried out to investigate the effects of cultivation measures (transplanting density, nitrogen application rate) on the yield and quality of high-quality japonica rice variety Yunkejing 5.

Method Yunkejing 5 was used as tested material, and the split-plot design was adopted in the field. Four nitrogen levels (0, 150, 240 and 330 kg/hm²) and four transplanting densities (240 000, 300 000, 360 000 and 420 000 seedlings/hm²) were set. The yield characters, SPAD value, brown rice rate, amylose, polished rice rate, chalky grain rate, protein content and gel consistency were determined to explore the effects of nitrogen application rate and cultivation density on yield and quality of japonica rice Yunkejing 5.

Result In the range of 0-330 kg/hm², with the increase of nitrogen fertilizer application rate, tillers were increased significantly, and the number of individual tillers was the highest under high nitrogen rate, reaching 18.80 per cluster; with the increase of transplanting density, tillers were gradually decreased. The yield showed a downward trend with the increase of transplanting density. Under the treatments with various nitrogen application rates, the highest yield was 13 308 kg/hm² when the transplanting density was 240 000 seedlings/hm². Yunkejing 5 was apt to obtain high yield at the rate of 240 kg/hm², and the appropriate transplanting density could further improve the rice yield. With the gradual increase of the amount of nitrogen fertilizer, the chalky grain rate, chalkiness degree and gel consistency showed an increasing trend. A higher polished rice rate could be obtained with a transplanting density of 360 000 seedlings/hm² under various nitrogen application rates, with a highest rate of 75.10%. The head rice rate was higher under high nitrogen rate and high density, the brown rice rate and protein content were higher at high nitrogen application rates of 240 kg/hm² and 330 kg/hm², indicating that high nitrogen fertilizer could increase the brown rice rate and protein content of rice quality.

Conclusion Under the combination of nitrogen application rate of 240 kg/hm² and transplanting density of 240 000 seedlings/hm², the maximum yield of Yunkejing 5 is 13 308 kg/hm². The comprehensive judgment of rice quality is the second grade, which is the optimal combination and can be applied to actual production.