GENOTYPE X ENVIRONMENT INTERACTION IN GRAPES RIPENING METABOLIC TRAITS

Objectives of the first part of research program were the effect of some environmental and physiological aspects on the intensity of flavonoid synthesis. The trial was carried out during the 2011 growing season in the commercial vineyard of the Plantaze, Podgorica (Montenegro). Two grapevine cultivars were compared: Vranac and Cabernet Sauvignon. The following experimental treatments were compared: early leaf removal (flowering time), cluster thinning (veraison time) and combination of both treatments. The early defoliation reduced yield per vine in Cabernet Sauvignon and Vranac. In Cabernet Sauvignon defoliation initially delayed berry growth. In cultivar Vranac defoliation did not modify the berry growth and berry weight. In the treatments “defoliated-thinned” is observed reduction of the cluster weight, berry weight and berry number per cluster. Early defoliation and cluster thinning in both varieties raised the concentration of anthocyanins and proanthocyanidins. The enhanced contents of these compounds per berry in variety Vranac is the result of increased synthesis. The objective of second study was to improve the knowledge of the eco-physiological basis of the genotype x environmental interaction. The experimental plan included the study of the Sangiovese grapes, a variety by a particular responsiveness to changing environmental conditions, and Cabernet Sauvignon grapes, a so called international cultivar characterized by more stable features. It was operated within the framework of Appellations of Origin Bolgheri (Tuscany coast), Montalcino (Tuscany Apennines) and Misano (Romagna coast). The experiment was conducted during two growing seasons (2011-2012) through grape development and ripening from fruit set to ripe stage. Since carotenoids are the precursors to C13-norisoprenoid aroma compounds in wine, relationship between carotenoid and norisoprenoid levels in grapes was investigated. In the first phase of berry ripening, before veraison, sites with greater global solar radiation (Montalcino and Bolgheri) showed positive correlation with the intensity of total carotenoids accumulation. Location Montalcino was also characterized by a greater water stress. Correlation between carotenoids accumulation prior to veraison and accumulation of norisoprenoids were not observed. Sangiovese showed a greater reactivity to the environment compared to Cabernet Sauvignon. The norisoprenoids levels in variety Sangiovese largely varied between different years and sites. The synthesis of norisoprenoids appears to be more related to the specific ecophysiological conditions that occur during maturation, rather than to the carotenoids content at veraison.