Anatomical Variations in the Wheat Leaf Following Internal Water Stress

Abstract

The second foliar leaves of Cheyenne, a drought-hardy, and Ponca, a drought-susceptible variety of winter wheat were compared anatomically before and after subjection to specific periods of moisture stress. Plants were grown in the greenhouse, and the severity of stress was estimated by measurements of the relative turgidity of the leaves. Stained and mounted serial sections were examined with regard to over-all histology, cell patterns, and cellular inclusions. Significant contrasts between untreated plants of the two varieties were: (a) relatively larger amounts of xylem tissue in Ponca, and (b) a greater proportion of sclerenchyma tissue in Cheyenne. The leaves of stressed plants showed pronounced wilting after more than 4 days of drought, and the water content level in the tissue was directly related to anatomical changes. Changes resulting from water stress were thickened cell walls, increased deposition of lignin in xylem elements and bundle sheath cells, and progressive plasmolysis in nuclei and pl...