Effect of Slow Release Fertilizer on Nitrogen Use Efficiency for Grain Yield in Chinese High-Yielding Rice Cultivars

Abstract

Nitrogen (N) use efficiency for grain yield (the grain yield per absorbed N) in Chinese high-yielding rice cultivars grown with different types of slow release fertilizers (linear and sigmoid types) was analyzed. The amount of N absorbed and dry weight in Yangdao 4 (YD), Wuyugen 3 (WY) and Hinohikari (HH) were significantly increased by applying slow release fertilizers. With increasing amount of absorbed N, the N use efficiency for grain yield was lowered, but the N use efficiency for grain yield in YD and WY grown with sigmoid type slow release fertilizer tended to be higher than that with split application of ammonium chloride irrespective of the amount of N absorbed, due to higher percentage of grain filling. YD had a lower percentage of immature grains than HH, probably due to the high specific gravity of the heavy grains. In addition, the decrease in the amount of straw dry matter during the ripening stage was significantly larger in YD than in HH. These traits may result in the stably high percentage of grain filling.