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

CLC Number: 

• S143.1