Non-destructive estimation of leaf area for different plant ages and accessions of Capsicum annuum L.

Accurate measurements of leaf area are important for agronomic and physiological studies. To be able to perform repeated measurements of leaf area on single (genetically unique) plants, a method was developed to estimate leaf area from non-destructive measurements in Capsicum annuum L. independent of plant age and accession. Leaf length (L), width (W), position (leafno) and area of individual leaves were measured on 160 plants of four Capsicum accessions with different leaf shapes at different plant ages. Leaf area could be predicted from the product of length and width (alpha-LW), but this model could not account for changes in leaf shape during development of individual leaves and was dependent on both plant age and accession. The model became independent of plant age and accession when leaf width terms (W-2, W) were added. Validation on leaves measured in a second experiment containing three accessions and 200 genetically unique F-3 plants showed that the relation between calculated and measured area was very high. The model could still be refined by addition of the leaf position terms (R-2 = 0.996). Even when the length and width of only 25% of the leaves were measured, total plant leaf area was predicted well using the model with both leaf width and leaf position terms. Therefore, the models including the leaf width terms (W-2, W) in addition to the LW term are useful tools in physiological research and breeding in Capsicum.