assessment of winter cold tolerance traits on clones of some seeded grape varieties of iran

nowadays, a lot of frost damage is inflicted upon vineyards because of changing weather conditions as well as introducing new of cultivars and genotypes from different geographical regions. on the other hand, the prevalence of a wide variety of grapes in iran, the provides possibility of selection of superior and cold tolerant varieties (or single plants) which is proposed a strong hypothetical solution. throughout this study, cold tolerance as well as damages inflicted upon some clones of some iran seeded grape varieties were determined. four branches (one year old) per each experimental plant were selected. upon the incidence of cold (natural and artificial), the number of healthy and damaged buds were counted. then, statistical and cluster analyses were performed. the results divided varieties and clones into four groups (from sensitive to quite tolerant). the highest tolerance against winter cold was observed in ‘fakhri’ and ‘siyah angoor’ while semi-tolerance in ‘molaei’ and ‘chafte’. cold tolerance thereshold (in the best clones) was observed at –20±1°c. high damage occured during the first 24 hours and its continuation for longer time did not increased the degree of damage to buds. there was significant phenotypic correlation among the traits. a significant regression was fitted to estimate the level of cold tolerance of cultivars using morphological traits.