NON-DESTRUCTIVE METHOD FOR LEAF AREA DETERMINATION OF GRAPEVINE, BRS-VIOLETA CULTIVAR

The objective of this work was to evaluate combinations between lengths of secondary and main veins of leaves to estimate leaf area from grapevine, 'BRS-Violeta' cultivar. Random sampling was made from 200 entire and completely developed leaves, within an area of experimental cultivation. Actual leaf area (AFR) and the lengths of secondary (left-right) and main veins were determined. Three regressions were obtained with the coefficients of determination in order to identify the most accurate relation, considering main vein length (CNP), sum of secondary vein lengths (SCNS) and sum of secondary and main vein lengths (SCNSP), as independent variables. AFR was considered dependent variable in the three regressions. Relation between AFR x SCNS resulted in a higher coefficient of determination (0.87). Leaf area estimated by the equation obtained from AFR x SCNS relation was 87% accurate, according to AFR x AFE (estimated leaf area) relation. Therefore, leaf area from grapevine 'BRS-Violeta' cultivar can be estimated by the equation: y = 0.2169 (SCNS)(2) + 5.3642 (SCNS) - 34.725, with adequate accuracy.