Calculation of Leaf Area of Tripterygium wilfordii by Regression Equation

The leaf area, the length, width, the product of the length and width, the ratio between the length and width of the Tripterygium wilfordii leaves were measured and calculated. The results showed that T. wilfordii tree species possessed comparatively stable leaf form and the length and width ratio of the leaves. Five common equations were applied to model the features of the leaves. There were highly positive correlations among indices of the length, width, the product of the length and width and the leaf area of T. wilfordi tree species. It was testified that there were no significant differences between the practical values and the theoretical ones calculated by one-variable linear regression equation and by power regression equation for calculating the leaf areas and the product of the length and width of the leaves, and the error rate estimated was below 4%. These equations could be applied to calculate the leaf area of T. wilfordii tree species with comparatively high accuracy.