The relationship between stomatal resistance and abscisic-acid levels in leaves of water-stressed bean plants |
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Authors: | D. C. Walton Eva Galson M. A. Harrison |
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Affiliation: | (1) College of Environmental Science and Forestry, State University of New York, 13210 Syracuse, NY, USA |
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Abstract: | Leaf water potentials of Phaseolus vulgaris L. plants exposed to a -3.0 bar root medium were reduced to between -7 and -9 bars within 25 min and remained constant for the next several hours. This treatment led to considerable variation between leaves in both abscisic-acid (ABA) content and Rs, although the two were well correlated after a 5-h treatment. There was an apparent 7-fold increase in leaf ABA levels necessary to initiate stomatal closure when plants were exposed to a -3.0 bar treatment, but when plants were exposed to a -5.0 bar stress Rs values increased prior to any detectable rise in ABA levels. To explain these seemingly contradictory results, we suggest that the rate of ABA synthesis in the leaf, rather than the total ABA content, determines the status of the stomatal aperture.Abbreviations ABA abscisic acid - PEG polyethylene glycol - Rs stomatal diffusion resistance of lower leaf surface - leaf water potential |
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Keywords: | Abscisic acid (ABA) Leaf water potential Phaseic acid Phaseolus Stomates Water stress |
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