Effect of the genotype: Environmental interaction on phenotype variation of the bunch weight in white wine varieties

The aim of this paper is to establish the interaction of phenotypical variations, components of yield for the widest spread wine varieties and external factors of the Danube region in the central Serbia. The number of fruitful buds per vine for twenty-one varieties was the same, whereas the yield and the components of the yield were different. The growing season, from bud burst to full ripening of the grapevine and the sum of active temperatures for the same period, were of crucial importance. In the factor analysis, three factors have been singled out: the first factor couples the mean air temperature; the second factor delineates the values according to genotype characteristics, sugar content and acids in the must, and the third factor indicates that bunch weight had the major effect on the yield of grapes. By the application of bunch analysis, a hierarchy tree was formed to include the four groups of varieties. The most numerous group, consisting of 18 varieties, is characterized by top quality grapes (21.5% sugar content), medium yield (1.52 kg/m2) and a proportional relation of total acids (7.5 g/l) and this is achieved during the middle of the ripening period.