Differences of Nitrogen Absorption and Utilization in Rice Varieties with Different Productivity Levels

Abstract

The field experiment was carried out using 50 early-maturing late Japonica rice varieties, adopted in the region of Yangtze River, with seven nitrogen application levels (0, 150.0, 187.5, 225.0, 262.5, 300.0, 337.5 kg ha–1) to investigate the differences of the nitrogen absorption and utilization. We defined the highest rice yields under different nitrogen levels as the highest population productivity of N fertilization (HPPNF). The main results indicated that the top-and high-level yielding varieties had extremely significant larger amount of population spikelets than the middle- and low-level yielding varieties, and this superiority of total spikelets was mainly due to the extremely remarkable increase of spikelets per panicle. The nitrogen content and nitrogen absorption rate in plant at jointing, heading and maturity were all significantly increased with increasing productivity level. In transplanting to jointing and jointing to heading stages, there were no significant differences in ratio of nitrogen accumulation among four productivity levels, but a trend of decrease with the increase of productivity level. In heading to maturity stages, the ratio of nitrogen accumulation was significantly increased with increasing productivity level, which was 14.94% for top-level yielding cultivars. With the productivity level increasing, the apparent nitrogen recovery efficiency, agronomic nitrogen use efficiency and physiological nitrogen use efficiency were significantly increased. Taking into consideration of the production capacity and the apparent nitrogen recovery efficiency of all 50 rice varieties, 13 varieties with high yield and high nitrogen efficiency were selected and recommended.