Abstract:

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.

Key words: Rape, Specific leaf area, Second-order regression with orthogonal, rotatable and central composite design, Cultivation measures