Non-destructive simple model to estimate the leaf area through midvein in cultivars of Vitis vinifera
Abstract Mathematical models are indirect and non-destructive methods for estimating the leaf area (LA), an important parameter associated with canopy vigor in Vitis viniferavineyards. This work aims to adjust and test mathematical models for estimating LA using the midvein length of the Vitis vinifera cultivars conducted in horizontal and vertical training systems in the Serra Gaúcha region, Brazil. Leaves were collected in ‘Chardonnay’, ‘Cabernet Sauvignon’ vineyards conducted in trellis and lyre training systems, and in ‘Merlot’ vineyards conducted in trellis and espalier systems. Models were tested for establishing the correlations among the parameters LA and midvein length, considering the cultivar/training system and the general data set. For validation, linear regression between the observed and estimated LA was defined. The relationship between the midvein length and LA was defined by non-linear potential equations (R2aj 0.95-0.98). The performances of the specific and general models were similar regardless of the cultivar/training system. The adjusted models showed excellent results in the validation step (correlation 0.95-0.98; Wilmott index >0.97 and confidence index>0.92). It is possible to estimate the LA of Vitis vinifera Chardonnay, Cabernet Sauvignon, and Merlot cultivars using a simple non-destructive model that employs one single measurement of the leaf blade, to optimize the vegetative canopy quantification in vineyards.