| In this study,66conventional rapeseed cultivars (Brassica napus.L) were cultured from year2008to2010. The tested rapeseed cultivars were classified into low, medium and high amount of nitrogen absorption types based on their amount of nitrogen absorption and low, medium and high nitrogen utilization efficiency types based on their nitrogen utilization efficiency (expressed in nitrogen utilization efficiency for grain production) by the MinSSw method. The characteristics of biomass yield, yiled components, nitrogen content, nitrogen amount and nitrogen allocation ratio of different amount of nitrogen absorption and nitrogen utilization efficiency of rapeseed cultivars were studied. The results of this study had some theoretical and practical value for screening and breeding of high nitrogen efficient varieties and drawing up reasonable cultivation measures. The results were as follows:1. Significant differences were existed in the amount of nitrogen absorption and nitrogen utilization efficiency of different rapeseed cultivars. The numbers of rapeseed cultivars of three amounts of nitrogen absorption types were20and10,34and29,12and27respectively in2009and2010. The numbers of rapeseed cultivars of three nitrogen utilization efficiency types were22and9,31and34,13and23respectively in2009and2010.2. The amount of nitrogen absorption of rapeseed cultivars with different amount of nitrogen absorption types had extremely significant differences. The amount of nitrogen absorption of rapeseed cultivars of high-amount of nitrogen absorption types were respectively7.56%～8.63%and16.20%～17.32%higher than medium and low amount of nitrogen absorption types. However, differences of nitrogen utilization efficiency among grain production of different amount of nitrogen absorption types were slight, and the difference between maximum and minimum value was less than1%. Nitrogen utilization efficiency for grain production of different nitrogen utilization efficiency types had significant differences. Nitrogen utilization efficiency for grain production of rapeseed cultivars of high nitrogen utilization efficiency types were respectively14.51%～16.54%and7.33%～7.43%higher than medium and low nitrogen utilization efficiency types. But the difference of the amount of nitrogen absorption was slight in different nitrogen utilization efficiency types and the difference between maximum and minimum value was less than3%.The correlation analysis of the amount of nitrogen absorption and nitrogen utilization efficiency for grain production of different rapeseed cultivars showed that there was no correlation between the amount of nitrogen absorption and nitrogen utilization efficiency for grain production. It inferred that rapeseed cultivars of high amount of nitrogen absorption did not necessarily have low nitrogen utilization efficiency for grain production. As the same, rapeseed cultivars of high nitrogen utilization efficiency for grain production did not necessarily have low amount of nitrogen absorption. So, choosing rapeseed cultivars of high amount of nitrogen absorption and high nitrogen efficiency for grain production are not contradictory.3. The dry matter of stem, shell, seed and the whole plant of various cultivars of different amount of nitrogen absorption types was gradually increased with the increasing of the amount of nitrogen absorption, and the differences were highly significant. The dry matter of stem, shell and the whole plant of various cultivars of different nitrogen utilization efficiency types had no significantly correlation with nitrogen utilization efficiency, but, the correlation between seed dry matter and nitrogen utilization efficiency was extremely significantly positive.4. Pod number per unit area increased as the increasing of nitrogen absorption, and the differences among different amount of nitrogen absorption types were all highly significant. However, seed number per pod and1000-seed weight had no significant correlation with the amount of nitrogen absorption. Pod number per unit area increased as the increasing of nitrogen utilization efficiency, and the differences among different nitrogen utilization efficiency types were all highly significant. Seed number per pod and nitrogen utilization efficiency was extremely significantly positive correlated in2009, but there was no significant difference in2010.1000-seed weight and nitrogen utilization efficiency also had no significant difference.5. The nitrogen content of stem, shell, seed and the whole plant of different cultivars showed a downward trend with the increase of the amount of nitrogen absorption. However, stem and seed nitrogen content was not significantly correlated with the amount of nitrogen absorption. Shell and the whole plant nitrogen content were not significantly correlated with the amount of nitrogen absorption in2009, but it was significantly correlated in2010. The nitrogen content of different organs and whole plant of different nitrogen utilization efficiency types were highly significantly or significantly negatively correlated with nitrogen utilization efficiency.The amount of nitrogen in stem, shell and seed of differentcultivars were increased with the increase of the amount of nitrogen absorption of whole plant, and the correlation was highly significant. The amount of nitrogen in stem and shell of different cultivars showed a downward trend with the increase of nitrogen utilization efficiency, and the correlation were all highly significant. However, the total amount of nitrogen in seed increased with the increase of nitrogen utilization efficiency, and the correlation were also highly significant.The percentages of the amount of nitrogen of stem, shell and seed to the whole plant amount of nitrogen of different amount of nitrogen absorption types were changed less with the increase of the amount of nitrogen absorption. The percentages of the amount of nitrogen of stem and shell to the whole plant amount of nitrogen of different nitrogen utilization efficiency types showed a decreasing trend with the increase of nitrogen utilization efficiency, and the correlation was highly significant. However, the percentage of the amount nitrogen of seed to the whole plant amount of nitrogen had an increasing trend with the increase of nitrogen utilization efficiency, and it was extremely significantly correlation in year2009and2010.6. Correlation analysis and path analysis showed that the amount of nitrogen absorption and nitrogen utilization efficiency had no significant correlation. The amount of nitrogen absorption and nitrogen utilization efficiency had extremely significantly positive correlation with seed yield and their direct path coefficients to seed yield were large and the vales were similar, so it illustrated that the effects of the amount of nitrogen absorption and nitrogen utilization efficiency on seed yield were both larger. Form the results could be seen that not all the high-yielding rapeseed varieties had both high amount of nitrogen absorption and high nitrogen utilization efficiency, as the same, not all the low-yielding rapeseed varieties had both low amount of nitrogen absorption and low utilization efficiency. But if wanted to get high yield, the amount of nitrogen absorption of rapeseed must generally achieve high or medium, or in general, the nitrogen utilization efficiency of rapeseed also must achieve high or medium. When one of the amounts of nitrogen absorption or nitrogen utilization efficiency was high and the other one was middle, the rapeseed varieties were easier to obtain high yield. |
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