Water Relations of Cadmium‐Treated Plants

Turgor pressures, stomatal resistances, and transpiration rates were measured during a 50‐day period in leaves of chrysanthemum (Chrysanthemum morifolium Ramat. ‘Indianapolis White’) plants grown in nutrient solution with 0, 0.01, 0.1, and 1.0 µg/ml Cd added as CdSO4. At harvest, dry weight and Cd concentrations in roots, stems, and leaves were determined. Leaf abscission occurred on Cd‐treated plants. Turgor pressures were highest in plants grown with 0.01 µg/ml Cd and lower in plants treated with 0, 0.1, and 1.0 µg/ml Cd. Stomatal resistances were lowest in plants grown with 0.01 µg/ml Cd and progressively higher in plants treated with 0, 0.1, and 1.0 µg/ml Cd. Results indicated that quantities of Cd permitted in irrigation water in the United States (0.05 µg/ml) might be detrimental to growth because of reduced turgor pressure and increased stomatal resistance.