Non-destructive estimation of leaf area in passion fruit (Passiflora edulis L.)

Abstract

The yellow passion fruit is the most commonly cultivated species of the genus Passiflora in commercial plantations in Brazil. Obtaining accurate and easy to perform measurements for determination of leaf area in passion fruit is crucial to understand the interaction between the plant and the environment. The objective of this study was to develop reliable mathematical equations to directly estimate leaf area in passion fruit using linear measurements. Passion fruit leaves may exhibit varying morphology across phenological stages, with lanceolate, bilobed or trilobed leaves. For each morphological pattern, 100 leaves without defects were collected. The real leaf area was measured with a LI-COR 3100 area meter and regression equations were estimated for real leaf area and measurements of length, width, and their corresponding products, using a millimeter ruler. The results showed that determination of leaf area can be easily and accurately performed for passion fruit leaves of varying morphology, using the product of the linear measurements of length and width. The linear equations chosen for determining leaf area through the product of width and length were 0.25 + 0.64x (lanceolate), -4.82 + 0.69x (bilobed) and -0.81 + 0.54x (trilobed).