Winter cold tolerance screening of 22 grapevine cultivars of Kurdistan province

In this research, the bud and cane winter cold tolerance of 22 field-grown grapevine cultivars of Kourdestan province Agricultural and Natural Resources Research and Education Center was evaluated at Jan. and Mar. stages in 2012. In these cultivars soluble carbohydrates and water content changes of buds and canes during dormant period also were measured. After exposure to different freezing temperatures (-10 to -30ºC), the bud and cane LT50 values were estimated using electrolyte leakage measurement (EL LT50) and bud browning (BB LT50) to determine cold tolerance of vines.Significant differences (P≤0.01) were found among cold tolerance of cultivars in both stages. The two assays correlated positively, and marked cultivar differences in FT were found.Based on the bud EL LT50 values, the highest FT (LT50 = -26.5 ºC) in this stage was related to ‘Bolmaskah’ and ‘Gwen Kalahbab’ showed the lowest FT (LT50 = -20.8 ºC). Based on the bud EL LT50 values in Jan., cultivars were classified as hardy (LT50 = -25º to 27ºC; ‘Bulmaskah’, ‘Sarqulah’, ‘Khalili’, ‘Bidane-Qermez’ and Farkhi-Zoodras’), moderately hardy (LT50 = -23º to 25ºC; ‘Sharshareh’, ‘Shahini’, ‘Shirazi’, ‘Gaznei’, ‘Rasheh’, ‘Tabarzeh’, ‘Bidaneh-Sefid’, ‘Nafti’, ‘Molaei’and ‘Farkhi-Dirras’) and least hardy (LT50 = -21º to 23ºC; ‘Sahebi’, ‘Laal’, ‘Sahnaei’, ‘Askari’, ‘Marahei’, ‘Rish-Baba’ and ‘Kalehbab’). Unlike to soluble carbohydrates concentration, the bud water content was lower in cold hardy cultivars such as ‘Bulmaskah’, ‘Sarquleh’, ‘Khalili’, ‘Bidane-Qermez’ and ‘Farkhi-Sefid’compared to the other cultivars which confirms the involvement of bud tissue dehydration and carbohydrates soluteaccumulation in freezing protection, demonstrating that these materials can be use as surrogates to evaluate FT in a range of grape germplasm resources.