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Effect of crop load per leaf area ratio on the quality of 'Merlot' and 'Syrah' grown in high altitude in Santa Catarina, Brazil

Malinovski, L. I., Brighenti, A. F., Cipriani, R., Cesconeto, J. F., Vanderlinde, G., Simon, S., Silva, A. L., Allebrandt, R., Bem, B. P. de
Acta horticulturae 2017 no.1157 pp. 393-398
acidity, altitude, anthocyanins, cultivars, grapes, harvest date, leaf area, pH, photosynthesis, polyphenols, surface area, total soluble solids, vines, vineyards, viticulture, winemaking, Brazil
The leaf area/yield is a key aspect in all vine management. This ratio, which provides a good measurement of the vine capacity to adequately ripe a crop, is largely a function of the active photosynthetic surface area per plant (m2 plant-1) and the fruit mass (kg plant-1). In high altitude areas of Southern Brazil, where viticulture is showing a great potential for wine production, more information about this kind of parameters is needed. The objective of this study was therefore to evaluate different leaf area/yield ratios on the quality of 'Merlot' and 'Syrah' cultivars. The experiment was done in vineyards of São Joaquim-SC Experimental Station (EPAGRI) (28°16'30”S, 49°56'09”E, altitude 1,400 m, at Santa Catarina State, Brazil. The evaluations took place in 2010/2011 season. 'Syrah' was submitted to four different leaf area/yield ratios: 0.5, 1.0, 1.5 and 2.0 kg of crop m-2 leaf area. 'Merlot' was submitted to three different leaf area/yield ratios: 0.5, 1.0 and 1.5 kg of crop m-2 leaf area. At harvesting time the physical-chemical (total soluble solids, pH and total acidity) and the phenolic components (total polyphenols and anthocyanins) were determined. Plants with the lowest yields, 0.5 kg of crop m-2 leaf area, produced heavier clusters, which suggests a compensatory effect. The results showed that different leaf area/yield ratios did not affect the technological maturity of both cultivars. The lowest yield obtained with 0.5 kg of crop m-2 leaf area ratio resulted in the highest anthocyanin content for 'Syrah'. In 'Merlot', the plants not subjected to a reduction in crop load, with a leaf area ration of 1.5 kg of crop m-2, produce grapes with higher contents of total polyphenols and anthocyanins.