Screening of Rice Cultivars for Nitrogen Use Efficiency and Yield Stability under Varying Nitrogen Levels

Excessive application of nitrogenous fertilizers has deteriorated the sustainable development of the earth's environment. Many researches focused on reducing the nitrogen (N) rate, but few studies concentrated on the stability of yield and nitrogen use efficiency (NUE) of different rice cultivars. We screened different rice genotypes (Super hybrid rice, Ordinary hybrid rice, and Commercial indica) under various N application rate (60, 120 kg N ha−1in 2012 and 0, 120 and 210 kg N ha−1 in 2013). Grain yield among different rice cultivars ranged from 7.6 to 9.2 t ha−1 under N120 across both years. Relative to the N60 and N0, rice yield was increased by 1.50 ~ 27.56% at 120 kg N ha−1. In 2013, the yield response of all rice cultivars was non-significant for 120 and 210 kg N ha−1. However, HHZ performed well compared to the rest of cultivar under higher N (210 kg ha−1) but the absolute values were not consistent in both years. Grain yield was significantly correlated with the dry matter at pre-heading and harvest index under different nitrogen applications and years. Based on principal component analysis, the yield and NUE of hybrid rice cultivars were more stable than the conventional rice cultivars. Therefore, hybrid rice cultivars are an efficient candidate for the green super rice and would contribute to rice breeding for saving N resources without sacrificing yield.