Estimation of vineyard leaf area by linear regression

Vineyard leaf area is a variable that must be determined when assessing the productive potential of a vineyard and for characterizing the light and thermal microenvironments of grapevine plants. The aim of the present work was to validate the Lopes and Pinto method for determining vineyard leaf area in the vineyards of central Spain and with the area's cultivars. The results obtained were compared to those provided by a traditional and accurate -but much more laborious- non-destructive direct method. Experiments were performed over three years in six vineyards growing either cvs. Syrah, Cabernet Sauvignon, Cabernet franc, Merlot or Tempranillo. Good agreement was found between the two methods both in the determination of primary and lateral shoot leaf areas for all cultivars and vineyards. The simplicity of the Lopes and Pinto method means much larger sample sizes can be examined in the same period of time, increasing the accuracy of final vineyard leaf area values. In fact, regression analysis of the data collected for the Lopes and Pinto method showed that only three field-measured variables need to be recorded for the inspected shoots of either type: the area of the largest leaf, the area of the smallest leaf, and the number of leaves.