CHANGES IN CARBOHYDRATE CONTENT OF WHEAT PLANTS DURING THE PROCESS OF HARDENING FOR DROUGHT RESISTANCE

Abstract

Five varieties were hardened for drought resistance by growing them with insufficient water until permanent wilting and necrosis of leaf tips had set in. Then recovery was induced by irrigation. Analyses were made at 4 periods: At the beginning of wilting; at stage of permanent wilting; 24 hrs. after resumption of irrigation; and 8 days after recovery. At the beginning of wilting, monosaccharides and sucrose were increased, hemicelluloses decreased. At permanent wilting, sucrose was decreased, monosaccharides increased, and hemicelluloses decidedly increased, and above the controls for this fraction. With the beginning of irrigation, water content rose, but not as high as the controls. The soluble sugars decreased. After 8 days of recovery the drought treated plants were still lower in water content than the controls, monosaccharides were low, and sucrose and hemicelluloses were increased. The conditions seemed to have become "fixed" as a result of the treatment. The significance of hemicelluloses in drought resistance of wheat is discussed.