Influences of the defoliation, the root-cutting and soil conditions on the water relations of trees

Abstract

The physiological investigations on the water relations of trees have been desired to be done especially in the cases which a considerable portion of leaves as well as roots are removed from a tree, that are very common treatments in the landscape planting. In the papers a discussion was done on the influences of the defoliation as well as the rootcutting with various soil conditions on the several characteristics of the water relations, such as the sap flow velocity, the xylem water potential, the leaf diffusive resistance and the transpiration rate. The experiments elucidated that the root-cutting more severely affected the water relations, particularly on the transpiration rate, than the defoliation though each treatment influenced it unfavorably. It was also clarified that the irrigation might not be so sufficient to the water relations of a tree as the physical property of the soil. It was showed that the transpiration rate or sap flow velocity would be the most suitable measurement to check the water relations of a tree because of its stability as well as sensitivity.