Abstract
To clarify the role of nonstructural carbohydrate in the snow endurance of winter annual forage crops, two varieties each of barley and rye were grown at four nitrogen application rates (4, 8, 16 and 24kg/10 a). Contents of nonstructural carbohydrate, yield in autumn and the snow damage just after the thawing of snow were measured. Increased nitrogen (N) application rates markedly decreased the concentration of NSC. The rate of decrease of the NSC concentration was higher in barley than in rye, and in the low snow endurance varieties than in the high ones in the both species. The snow damage became greater as the nitrogen application rates increased in every species and variety. Significant interaction was also found between varieties and nitrogen application rates. This indicates that varietal traits in the snow endurance are not absolute but could be altered by environmental factors. The amount of the snow damage tends to relate inversely to the NSC concentration. The regression lines between the snow damage and NSC concentration, however, lie apart distinctly between the varieties in each species. We consider that the snow endurance is not only affected by the carbohydrate status but also some unknown factors.
