This study aims at inspecting the regulation mechanisms of NR activity and its relation to nitrate content in oilseed rape.A sand culture experiment with N treatment at normal (15 mmol L-1 NO3-) and deficiency (7.5 mmol L-1 NO3-) levels and NR activity obligate inhibitor treatment using oilseed rape genotypes with high nitrogen use efficiency (NUE) (H1: 742 and H2:Xiangyou 15) and low NUE (L1: 814 and L2: H8) was conducted to study differences of NR activity and nitrate contents between genotypes and N application levels. The results indicated that, compared with control treatment, inhibitor treatment under N normal and deficiency levels decreased NR activity by 54.1% and 55.9% respectively, but could not influence the nitrate content of leaves. NR activity and nitrate content of N normal level treatment were 46.9% and 16.4% higher than those of N deficiency level.Nitrate content of high NUE genotypes was significantly lower than that of low NUE genotypes. NR activity (NRAact) of H2 was significantly higher than that of low NUE genotype, resulting from that H2 possesses higher relative expression level of major NR gene (nia2). In conclusion, there are significant differences in NR activity and nitrate content between genotypes and N application levels. However, nitrate content can not be significantly influenced by somewhat changes of NR activity.
- Nitrate reductase (NR)
- Nitrate content
- Oilseed rape (Brassica napus L.)
- Nitrogen (N) application levels