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Effect of Water Stress on the Temperature Optima of Net CO 2 Exchange for Two Desert Species
Author(s) -
NOBEL PARK S.,
LONGSTRETH DAVID J.,
HARTSOCK TERRY L.
Publication year - 1978
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1111/j.1399-3054.1978.tb01621.x
Subject(s) - photosynthesis , photorespiration , respiration , transpiration , carbon dioxide , stomatal conductance , botany , biology , chemistry , ecology
The temperature dependence of net CO 2 exchange was determined at various soil water potentials for two sympatric desert species. Notholaena parryi D. C. Eat. (Pteridaceae) and Encelia farinosa Gray (Compositae). As water stress increased, the temperature optimum of apparent (net) photosynthesis shifted 7 to 10°C downward and the maximum rate decreased for both species. The downward shift in temperature optimum with water stress was the result of a greater fractional stomatal closure with increasing temperature and a lowering of the temperature where maximal CO 2 residual conductance of the mesophyll cells occurred. This lowering of the temperature for maximal CO 2 residual conductance appears to reflect (1) a greater effect of water stress on gross photosynthesis than on respiration plus photorespiration and (2) the higher temperature optimum for respiration plus photorespiration than for gross photosynthesis. The downward shift in the temperature optimum of apparent photosynthesis can have a significant effect on the predicted carbon balance of plants as the soil water potential decreases.