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VARIATIONS AMONG WOODY PLANTS IN STOMATAL CONDUCTANCE AND PHOTOSYNTHESIS DURING AND AFTER DROUGHT
W. J. DAVIES and T. T. KOZLOWSKI
Plant and Soil
Vol. 46, No. 2 (FEBRUARY 1977), pp. 435-444
Published by: Springer
Stable URL: http://www.jstor.org/stable/42935151
Page Count: 10
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Acer saccharum, Fraxinus americana, Juglans nigra, Acer rubrum, Cornus amomum, and Ulmus americana seedlings were subjected to a soil drying cycle and then rewatered. At frequent intervals during the drying cycle and following rewatering, determinations were made of equilibrium photosynthesis rates, leaf conductances and leaf water potentials. As the drying cycle progressed, leaf water potentials decreased, stornata closed, and rates of transpiration and photosynthesis were reduced. Stornata of the two Acer species initially were more sensitive to water stress than were those of the other species. At low leaf water potentials, stornata of Juglans and Cornus were more open than those of the other species. Photosynthesis oí Acer saccharum, Fraxinus and Juglans was significantly reduced by plant water stress, while photosynthetic water use efficiency of Cornus and Juglans was most unfavourable. Photosynthesis/leaf conductance ratios in water stressed leaves were higher in Fraxinus than in the other species. Immediately after rewatering, only limited stomatal opening occurred in Acer saccharum and Cornus with recovery of stomatal opening most protracted in Fraxinus and Ulmus. There was extended reduction of photosynthesis of all species as a result of the soil drying treatment. This effect was most significant in Acer saccharum and Juglans. Survival of plants on moist and dry sites is discussed in relation to stomatal control of transpiration and metabolic responses to water stress.
Plant and Soil © 1977 Springer