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Ecophysiological Significance of CO2-Recycling via Crassulacean Acid Metabolism in Talinum Calycinum Englem. (Portulacaceae)
Martin, Craig E. Higley, Michael Wang, Wei-Zhong
Martin, Craig E.
Higley, Michael
Wang, Wei-Zhong
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Abstract
High levels of variability in gas exchange characteristics and degree of
CAM-cycling were found in the same and different individuals of Talinum
calycinum Engelm. collected from rock outcrops in Missouri. Differences
in CO, assimilation were mostly correlated with differences in shoot conductance
to C02 not shoot internal C02 concentration. As found previously,
CAM acid fluctuations were evident in well-watered plants exhibiting
C3 gas exchange patterns (CAM-cycling) and also in drought-stressed
plants with stomata closed, or nearly so, day and night (CAM-idling).
Drought stress also resulted in rapid stomatal closure, conserving water
during droughts. Maximal CO, uptake rates occurred below 35°C; higher
temperatures induced decreases in CO. assimilation and conductance while
shoot internal C02 concentrations remained similar. Plant water-use-efficiency
was severely curtailed at temperatures above 30°C. Tissue acid
fluctuations were the result of changes in malic acid concentrations. Calculations
of the amount of water potentially conserved by CAM-cycling
yielded values of approximately 5 to 4 4% of daytime water loss. Thus,
CAM-cycling may be an important adaptation minimizing water loss by
perennial succulents growing in shallow soil on rock outcrops.
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This is the publisher's official version, also available electronically from: http://www.plantphysiol.org/content/86/2/562.full.pdf
Date
1988
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American Society of Plant Biologists
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Martin, C.E., M. Higley, and W.-Z. Wang. 1988. The ecophysiological significance of CO2-recycling via Crassulacean acid metabolism in Talinum calycinum Engelm. (Portulacaceae). Plant Physiol. 86: 562-568.