采用正交旋转组合设计，首次系统研究了不同品种、不同播期、不同生长发育阶段、地上地下不同器官干重对比叶面积的影响，并建立了华双3号抽薹期SLA与密度、氮肥、磷肥、钾肥、硼肥的数学模型。单因子分析表明，密度、氮肥、磷肥、钾肥、硼肥与比叶面积均存在抛物线关系，各因子的绝对贡献为密度>钾肥>磷肥>氮肥>硼肥。冬油菜的比叶面积在发育进程中呈现降-升-降趋势，除越冬期外，其各生育期之间比叶面积变化差异显著，品种间的比叶面积差异不显著，与叶重、茎重和根重之间均呈负相关。通径分析表明，比叶面积不仅受叶重、茎重、根重的影响，而且受3者间交互作用的影响。比叶面积可以作为群体营养状况和临界施肥量的诊断指标。生育前期重点促进叶重和生育中后期重点促进茎重的增长有利于获得较小的比叶面积，实现优势群体。
Specific leaf area (SLA), the ratio of green leaf area to its dry weight, is one of most important parameters of leaf function evaluation, growth of crop and high yielding breeding. Second-order regression equation of relations between SLA and concerned agronomic factors (plant density, nitrogen, phosphorus, potassium and boron fertilizer) in rape cv. Huashuang 3 at elongation stage was firstly established according to second-order regression with orthogonal, rotatable and central composite design. In the meantime, the influences of different cultivars, development time and dry weight of shoot and root to SLA were also firstly studied systemically. Mono-factor analysis showed that absolute contribution ratio of each factor was plant density > potassium fertilizer > phosphorus fertilizer > nitrogen fertilizer > boron fertilizer. Moreover, Parabola relationship between SLA and nitrogen, potassium, phosphorus, boron fertilizers as well as plant density, respectively, showed that suitable plant density and proportional fertilizer application contributed to suitable population SLA pattern and optimum population morphogenesis. SLA of winter rape showed a trend of decline-increase-decline during its growth (Fig.1, 2). Multiple comparisons indicated that SLA remained steady during winter, but was significantly different at other developmental stages, and no significant difference between cultivars (Fig.1 and Table 3). SLA was negatively correlated with leaf weight, root weight and stem weight, respectively (Table 5, 6). Moreover, path analysis showed that SLA was influenced not only by root weight, stem weight and leaf weight but also by their interaction effects (Fig.3, Table 7). In conclusion, SLA could be another parameter evaluating colony nutrient level and critical fertilizer application. Leaf weight contribution in prophase and stem weight contribution in metaphase and anaphase could benefit to small SLA and optimum population morphogenesis.
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