按单叶叶面积估测法评估蒿柳（Salix viminalis L．）第一生长季整株叶面积

本文在蒿柳（ＳａｌｉｘｖｉｍｉｎａｌｉｓＬ．）单叶叶面积（ＡＬ）估测的基础上预测枝条水平上的叶面积．ＡＬ与叶特征度量叶长（Ｌ）、宽（Ｗ）、Ｌ２、Ｗ２、乘积（ＬＷ），叶干重（ＷＬ）之间相关性分析表明，尽管大多数相关关系本质上为非线性，但线性（Ｙ＝ｂ×Ｘ）和非线性指数方程（Ｙ＝ｂ×Ｘｃ）均有较高的复相关系数ｒ２和较好的预测能力，且以ＬＷ最好。ＡＬ估测方程的建立必须考虑植物生长阶段、枝类型及叶片着生的相对高度的影响．椭圆和抛物面的组合能成功地拟合叶片形状，反映叶形变化和较准确的计算单叶面积．以主技基径Ｄ，枝长Ｈ，Ｄ２Ｈ以及主枝上的叶片数与基径的乘积（ＮＬ·Ｄ）为独立交量来估测主枝叶面积（Ａｐ）的非线性方程好于线性方程，但方程的估计精度因腋生枝的萌生而受影响．腋生枝数与主枝基径的乘积组合（ＮＳＳ·Ｄ）、腋生枝干重（ＷＳ）的非线性方程可用于估测胶生枝叶面积（Ａｓ），枝水平上叶面积的估测方程都因植物生长阶段的不同而有差异．

ASSESSMENT OF THE WHOLE SHOOT LEAF AREA ON BASIS OF SINGLE LEAF AREA ESTIMATES OF SALIX VIMINALIS DURING THE FIRST GROWING SEASON

Linear (Y=b×X) and nonlinear (y=b ×Xc) relations of leaf area (AL) With leaf length(L), leaf width(W), L2, W2 and LW were developed in Salix viminalis at the single leaf level, and used to assess leaf area at whole shoot level. Most relationships were significantly nonlinear, but both types exhibited good fits as indicated by r2 which was 0.941 (W)-0.998(LW) for the linear, and 0.982(W,W2)-0.998(LW) for the nonlinear equations.The nonlinear relationship between AL and LW was different for leaves from proleptic and sylleptic shoots, and varied with the growth stage. The nonlinear regression of AL on leaf dry weight (WL) varied with the leaf type and vertical position on shoot. Differences in leaf shape could be modelled successfully by geometric shapes, and leaf area could be obtained adequately with the hasal part of the leaf as a parabola and the distal part as an ellipse. The nonlinear equation performed better than the linear when used to predict the leaf area of the proleptic shoot (AP) with its diameter (D), length (H), D2H, D times the number of leaves (NL·D) on it alone, and the inaccuracy of the estimates of AP by both equation types could be increased after the emergence of the sylleptic shoots. With the nonlinear equation,leaf area of the sylleptic shoot (AS) could be predicted by its number within the proleptic shoot times D (NSS·D) or by its dry weight (WS) alone. All the nonlinear relationships of AP, As on shoot characters for both shoot types varied with the sampling occasion.