Pressure-Volume curves aad their relationship to stomatal conductance were obtained from single detached leaves of sweet cherry (Purunus avium L. cv. Biggarreau Morreau), plum (Prunes domestica L . cv. Queen Victoria), apricot (Prunes armeniaca L. cv. Keczkemeter), apple (Males domestica Borkh. cv. Golden Delicious) and pear (Pyres communis L. cv. Clapps Liebling), measured repeatedly and alternately with a pressure chamber and a steady-state porometer. And their stomatal responses to changing leaf water potential parameters could be precisely examined.
Stomata did not open wide at water potential near zero. However the maximum stomatal conductance occured when the water status was some lower than the saturation in all five species. Stomata began to close rapidly as leaf turgor pressure approached zero or was completely lost in sweet cherry, plum, apricot and apple leaves, but stotnata in pear leaves stayed wide open at the turgor loss point of - 3.17 ㎫ and reacted to close only at water potentials far below the turgor loss point.
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