摘要： 为探究氮、镁胁迫对油菜苗期养分累积及氮同化途径的影响，以油菜品种中双11为材料，通过营养液设置正常对照（CK）、低氮（-N）、低镁（-Mg）和低氮低镁（-N-Mg）4个处理，分析氮、镁胁迫对油菜苗期氮、镁吸收累积及氮同化关键酶活性的影响及差异。结果表明：氮、镁缺乏显著抑制油菜苗期地上部生长，与对照相比，-N、-Mg和-N-Mg 3种处理地上部生物量分别显著降低68.49%，35.49%，69.71%。-N处理刺激根系生长，根冠比显著增加；-Mg处理抑制根系生长，根冠比显著降低。并且氮、镁交互对油菜氮、镁吸收累积均有显著影响，-N处理油菜根部镁含量及累积量显著增加，而-Mg处理油菜地上部氮含量及累积量显著降低；缺镁会导致油菜NH₄⁺含量显著提升，并且-N-Mg对油菜氮、镁吸收累积影响的主要效应来自氮的缺乏。进一步比较不同处理下氮同化关键酶活发现，与对照相比，-N处理油菜新叶、老叶中NR、GS活性均显著降低，根部NR、GS和GOGAT活性均显著降低；-Mg处理GS活性也显著下降，但是降幅小于-N处理，而NR和GOGAT活性显著升高。综上所述，氮、镁缺乏对油菜苗期氮、镁积累存在交互作用，低氮胁迫会降低油菜苗期氮的吸收积累继而抑制植株氮同化；低镁胁迫可以通过提高铵态氮、NR和GOGAT活性来促进氮在无机氮间以及无机氮向有机氮的同化。

关键词: 油菜, 氮镁胁迫, 交互作用, 养分积累, 氮同化

Abstract: In order to explore nitrogen(N) or magnesium(Mg) deficiency on nutrient accumulation and N assimilation of rapeseed at the seedling stage, rapeseed cultivar ZS11 was applied in hydroponics and four treatments were set up, including control(CK), low N(-N), low Mg(-Mg), low N and low Mg simultaneously(-N-Mg). The effects of N or Mg deficiency on N and Mg uptake and accumulation, as well as key enzymes activity involved in N assimilation were analyzed. Results showed that, both N and Mg deficiencies significantly affected the growth of rapeseed shoots, compared with CK, shoots biomass were significantly decreased by 68.49%, 35.49%and 69.71% under -N, -Mg and -N-Mg treatments, respectively. While N starvation stimulated root growth and significantly increased root-shoot ratio, Mg deficiency interaction inhibited root growth and the root-shoot ratio of rapeseed seedling was significantly reduced. And N and Mg interaction also had significant effect on the absorption and accumulation of N and Mg of rapeseed, the Mg content and accumulation of rapeseed root were significantly increased under -N treatments, while the N content and accumulation of rapeseed shoots were dramaticlly reduced by -Mg treatment, whereas, Mg deficiency could lead to the significant enhancement of NH₄⁺ content, and the effects on the N and Mg uptake and accumulation which occurred in -N-Mg treatment were mainly originated from the lack of N. Further comparison in the key enzymes activity refer to N assimilation pathway under different treatments found that, compared with CK, both the NR and GS activities in young and old leaf, together with NR, GS and GOGAT activities in root of rapeseed were all significantly repressed under -N treatments. The activity of GS were also significantly reduced under -Mg treatments, but the decrement was obviously less than that of -N treatment, however, the activities of NR and GOGAT were significantly increased under -Mg conditions. In conclusion, N and Mg deficiencies took significant interactive effects on N and Mg accumulation of rapeseed at the seedling stage, additionally, N deficiency could reduce N uptake and accumulation and then inhibit the N assimilation pathway, but rapeseed could promote the assimilation process between inorganic N and also the process involved in inorganic N to organic N through increasing ammonium N content and the activity of NR and GOGAT under Mg deficiency stress.

Key words: Rapeseed, Low nitrogen and low magnesium stress, Interaction, Nutrient accumulation, Nitrogen assimilation

中图分类号: 

• S143.1