Plant-water relations of NaCl and calcium-treated sunflower plants

Salinity has been shown to alter a number of physiological processes, including the plant-water relations of some crop species. We examined the initial effects of NaCl salinity on the plant-water relations of sunflower (Helianthus annuus L.) and the potential of calcium supplements to ameliorate those effects. Sunflower plants were grown in a controlled-environment and treated solely with 0, 50, 100, or 150 mM of NaCl or the same rates of NaCI plus 10 mM Ca+2. Increasing salinity levels significantly decreased stomatal conductance in the 100 and 150 mM treatments compared to the control and 50 mM treatments, produced significantly more negative water potentials in the 100 and 150 mM treatments compared to the control, and significantly decreased root hydraulic conductance in all treatments compared to the control. Calcium supplements did not ameliorate the adverse effects of NaCl. Our experiments indicated that short-term NaCl stress can alter the plant-water relations of sunflower and that calcium supplements of 10 mM do not ameliorate these effects. (C) 1999 Elsevier Science B.V. All rights reserved.