To clarify relationships among factors associated with winter stress in orchardgrass (Dactylis glomerata L.), water-soluble carbohydrate (WSC) concentration, resistance to snow mold, and tolerance to prolonged snow cover were evaluated under both conditions of natural infection and chemical control of snow mold. A total of 18 cultivars from Japan, Europe, and the United States were transplanted into the field at Hokkaido in October 2003 and 2004. Crown samples were collected before the start of snow cover in fall and after melting of the snow in spring and were analyzed for WSC concentration. The total WSC concentration of cultivars originating in cold regions was higher in spring than that of cultivars originating in warm regions. The WSC concentration in fall was not correlated with tolerance to prolonged snow cover and resistance to snow mold. Otherwise, WSC concentration in spring was significantly correlated with spring regrowth and resistance to snow mold. Although dry wt. in the fall was negatively correlated with spring regrowth and snow mold resistance, it was not correlated with tolerance to prolonged snow cover. WSC concentration of crown tissues in spring should be an important selection criterion for a superior winter- hardy cultivar with rapid regrowth in spring. Cultivars that show both more fall growth and better tolerance to prolonged snow cover could be used in crosses with winter-hardy cultivars to increase forage yield in the fall.
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