Dai QiGen

Effects of nitrogen application rate and growth-development type on milling quality in japonica rice.

Nitrogen is the most important and largest input required in rice production although over use of N causes so many environment problems. The milling quality is one of the important aspects of rice quality. The effect of nitrogen application rate on milling quality is varied in different rice varieties, especially in different types. In this research, the field experiment for milling quality was carried out with 57 japonica rice varieties including five growth-development types, planting in the region of Yangtze River, under four nitrogen levels (zero, low, medium, and high) to investigate the difference of rice types under four nitrogen levels. Genotypic difference of head rice rate in response to nitrogen levels was discussed and their types were also classified. The main results were as follows: (1) As the increase of nitrogen application, the brown rice rate, milled rice rate and head rice rate of all the rice varieties were improved although the range of improvement decreased gradually. And there was no significant difference in head rice rate between medium and high nitrogen level. (2) In general, the longer of rice growth duration, the better of rice milling quality. According to this research, the milling quality of late japonica rice was better than that of medium japonica rice and the milling quality of late mature rice variety was superior to that of early mature rice varieties. The head rice rate of late japonica rice was higher than that of medium japonica rice by 19.07% on an average. (3) The response of head rice rate to nitrogen varied significantly. According to the variation coefficient of head rice rate under different nitrogen levels, rice varieties could be classified into three types including insensitive type, intermediate type and sensitive type. The varieties with high and stable head rice rate under all nitrogen levels and with high head rice rate at only high nitrogen application rate were recommended to be used in production.