Studies on the Snow-Blight Diseases of Winter Cereals. III.

Abstract

The present paper deals with the results of the writers' experiments on the changes of the amounts of sugar and various nitrogen compounds concentrations of wheat varieties in each stages under snow-cover during three years since 1947.The amounts of sugar concentrations decrease gradually in all varieties tested and those decreases occur suddenly after 2 months since snow-cover. The snow-resistant varieties contain more sugar concentrations than the less resistant in each stages before and after snow-cover. The ways of decreases in the amounts of reducing and non-reducing sugar concentrations have the same tendencies.The amounts of both protein and non-protein nitrogen compounds concentrations hardly change in the initial stage of snow-cover, but the decrease of the former occurs following by the sudden decrease of sugar concentrations, and the increase of the latter begins slowly by the decomposition of protein after 2 months since snow-cover. The snow-resistant varieties have more higher ratio of protein and non-protein nitrogen compounds to the green weight than the less resistant in all stages before and after snow-cover. The changes of ammonia and amide nitrogen compounds con-centrations are irregular, but it seems to have the tendencies of increasing the amounts of ammonia nitrogen compounds in the less resistant varieties, and those of increasing the amide nitrogen compounds in the resistant under the final stage of snow-cover.The amounts of sugar and non-protein nitrogen compounds of the snow-resistant varieties are more higher than the less resistant even before snowfall, so the amounts of the synthesized proteins are also higher in the former varieties, and they maintain these conditions in all stages under snowcover According to those facts, the mechanism of snow-damages was discussed in connection with the facts of pathological chanoes of the physical states of protoplasm in wheat cells.