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Leaf area estimation from linear measurements in zucchini plants of different ages

Summary Simple, accurate and non-destructive methods to determine individual leaf areas of plants are a useful tool in physiological and agronomic research. Determining the individual leaf area (LA) of zucchini squash (Cucurbita pepo L.) involves measurements of leaf parameters such as length (L) and width (W), or some combinations of these parameters. Three greenhouse experiments were carried out during Spring-Summer 2001, Spring-Summer 2002 and Summer-Autumn 2003 to compare predictive models for zucchini leaf areas using simple linear measurements that could accommodate the effects of changes in leaf shape during different plant ages. The L:W ratio (leaf shape parameter) of zucchini squash decreased with increasing leaf area and became constant, with a similar pattern between growing seasons. Leaf area was predicted accurately from the product of L and W (R2 = 0.97 and Mean Square Error, MSE = 1,526 cm2), but this model was dependent on plant age. A linear model having W2 as the independent variable provided the most accurate estimate (R2 = 0.98, MSE = 972 cm2) of zucchini LA, independent of plant age. Validation of the model having the W2 of leaves measured in the 2002 and 2003 Experiments showed that the correlation between calculated and measured areas was very high.