Nitrogen Modulates Grain Yield, Nitrogen Metabolism, and Antioxidant Response in Different Rice Genotypes

To provide a theoretical basis for further research on improving nitrogen absorption and utilization efficiency, in this study we investigated the effects of nitrogen fertilization on the yield, nitrogen metabolism, and antioxidant response of different rice genotypes. A pot experiment was conducted with three different rice genotypes (NIL-7, NIL-8, and 02428) grown under two different nitrogen application levels (HN, 1.88 g N/10 kg soil, and LN, 0.94 g N/10 kg soil). The grain yield, growth, antioxidant attributes, and N metabolism of different rice genotypes were assessed. We found that HN treatment significantly improved effective panicles per pot, total dry weight, and yield, but reduced harvest index of NIL-7, NIL-8, and 02428 compared with LN treatment. Compared with LN, HN treatment increased grain yield in NIL-7, NIL-8, and 02428 by 9.05%, 16.75%, and 48.35%, respectively. The activities of the enzymes involved in the nitrogen metabolism were changed and the regulation of antioxidant attributes was observed in HN treatment as compared to LN. The content of malondialdehyde (MDA) was decreased for HN relative to LN. Moreover, the efficiency of the N application was different among genotypes. In conclusion, nitrogen application regulated the grain yield, nitrogen metabolism, and antioxidant response of different rice genotypes.