The Relationship Between Matric Water and Related Physiological Properties

Matric water was measured as the water retained by plant material on a pressure membrane or ultra filter after equilibration under 20 bars nitrogen gas pressure and the removal of free water. At increasing pressures lesser amounts of water are held by matric or colloidal surface forces. Twenty bars pressure, supplied by cylinder nitrogen for 48 hours, was used in this study. Matric water was expressed as a percent of either (a) the dry weight or (b) the original water content. Plant material was oven dried, ground, and then saturated with water prior to the determination. The matric water values of different aged leaves from a number of local species were studied. The highest values of matric water were found in the younger leaves. Both matric water and original moisture content were higher for spring than for fall or midwinter values. The linear relationship between matric water and original moisture content was established for all trees studied. Another linear relation was found between either the matric water or the water content of the tree leaves and the inverse of their age in months. Petioles had a higher matric water value as well as a water content than leaf blades in all the species studied. Roots and old stems had the lowest values of matric water. The matric water values increased during the cold hardening of Cabbage leaves. No appreciable differences in the matric water values for Sunflower leaves grown under different temperatures were found. The crude protein and cell wall materials were isolated and their matric water values studied. Crude proteins had a higher value of matric water than cell wall materials alone. The matric water values of several biocolloidal materials were determined also. Agar had the highest value of matric water, fibrous cellulose the lowest, and the proteins had intermediate values