Two-year-old Actinidia vines, grown on their own roots, were subjected to artificial freezing tests in midwinter to determine their relative hardiness. Plant survival, growth recovery, and stem necrosis were used for estimating freezing injury. Actinidia deliciosa (A. Chev.) C.F. Liang & A.R. Ferguson var. deliciosa vines, which included `Abbott', `Bruno', `Greensill', `Hayward', and `Jones' kiwifruit, were all severely damaged by exposure to a temperature of –18C for 4 hours. Actinidia arguta (Sieb. et Zucc.) Planch. ex Miq., A. kolomikta (Maxim. et Rupr.) Maxim., and A. polygama (Sieb. et Zucc.) Maxim. appeared to be more tolerant to winter cold than A. deliciosa, indicating that potential germplasm exists for improvement of cold hardiness through interspecific hybridization.
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