Quantifica??o da área e do teor de clorofilas em folhas de plantas jovens de videira 'Cabernet Sauvignon' mediante métodos n?o destrutivos

摘要

This work was carried out to develop non destructive methods to estimate the area and chlorophylls content in the leaves of young grapevines 'Cabernet Sauvignon'. For leaf area estimation, the lengths of main and two secondary leaf veins were measured, in leaves ranging from small to large, followed by leaf area measurement with an electronic leaf area integrator. For the quantification of chlorophylls, leaves with tonalities varying from yellow green (chlorotic) to dark green were evaluated individually with a chlorophyll meter (Minolta SPAD-502) and with a colorimeter (Minolta CR-400, at the L, C and ho color space), at the abaxial (inferior) and adaxial (superior) faces, and, thereafter, destructively assessed for total chlorophyll and chlorophylls a and b. The main vein length measure provided a good estimate of leaf area. The value representing the sum of the two secondary veins length, as well this value plus the main vein length provided a very small increase in the power to estimate leaf area. The chlorophyll meter reading and the ho/ (LxC) ratio for the chroma meter, measured in both leaf faces, increased with the increment of chlorophylls content. The adjusted models between chlorophylls content versus chlorophyll meter readings and the ho/ (LxC) ratio for the chroma meter had similar R2. However, the ho/(LxC) ratio for the chroma meter, measured on the adaxial (superior) leaf face, provided the best estimate of chlorophylls content, expressed in terms of μg.cm-2 of leaf.