Comparative Studies On Characteristic Of Nitrogen Redistribution Of Different Oilseed Rape Cultivars

In order to inspect influence of physiological factor on N redistribution during later growing stages and its relationship with N use efficiency, the experiment is tested by 15N trace method under sand culture condition, and investigated differences of ahormones contents and activity of N redistribution enzymes under soil culture condition, to provide theoretical basis of N use efficient.Biomass, grain yield, harvesting index, N cumulant amount, N efficiency, N uptake efficiency, N use efficiency and N harvesting index of the two varieties have relatively higher different, and differences with different N application levels. Dry biomass, grain yield, harvesting index, N uptake efficiency, N use efficiency, N efficiency and N harvesting index of 742 are higher than 814 under normal N application level. Dry biomass, harvesting index and N use efficiency, N harvesting index of 742 are higher than 814 during elongation stage under low N application level, however, dry biomass, grain yield, N efficiency and N uptake efficiency of 742 are higher than 814 during harvesting stage.The results of 15N trace shows that the account of N redistribution is different under the two N application levels. T-test shows that N redistribution in grains and siliquing are significantly different, except redistribution in siliquing under the usual N level,742 redistributed less N to husk than 814 under the two N application levels, but opposite results are showed in grains. The trend is similar to N use efficiency.So it can be concluded that N redistribution has been benefit for N use efficiency. Under usual N level, N loss and proportion of 742 are higher than 814, but under low N level insteaded.The activity of related enzyme and amount of L-glutamine in phloem juice suggests activity of Proteolytic enzyme is not obviously different between cultivars at earlier siliquing stage,but 742 is higher than 814 at latter siliquing stage. Under usual N level,742 has similar activity of GS to 814 at earlier siliquing stage, but 742 is higher than 814 at latter siliquing stage. Under low N level,742 is higher than 814 at most time at the whole of siliquing stage. The activity of GOGAT and content of L-glutamine are only different at the later growing period between cultivars, and 742 is higher than 814. More activity of related enzyme is benefit for N redistribution and N use efficiency.The more activity of N redistribution, the more content of L-glutamine at later siliquing stage, the content of L-glutamine can be used for indirect index of N redistribution.The results of plant endogenous hormones content in leaves and siliquing during siliquing stage showed that ZR content in leaves of 742 is lower than 814 under normal N application level, but opposite results are showed in siliquing. Differences of ZR content in leaves and siliquing between cultivars under low N application level are the same with results under normal N application level, the opposite results are only showed at earlier siliquing stage. IAA content in siquiling of 742 is higher than 814 under the two N application levels. There are no significant different of ABA content between the two cultivars. It can be concluded that 742 have lower content of IAA and ABA in leaves and higher content of IAA and ABA in siliquing are benefit for N redistributed from leaves to siliquing, and improve N use efficiency.