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Photosynthesis and the influence of CO 2 ‐enrichment on δ 13 C values in a C 3 halophyte
Author(s) -
GUY R. D.,
REID D. M.
Publication year - 1986
Publication title -
plant, cell and environment
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.646
H-Index - 200
eISSN - 1365-3040
pISSN - 0140-7791
DOI - 10.1111/1365-3040.ep11614337
Subject(s) - halophyte , photosynthesis , salinity , phosphoenolpyruvate carboxylase , stomatal conductance , chemistry , rubisco , transpiration , pyruvate carboxylase , botany , c4 photosynthesis , salt (chemistry) , environmental chemistry , biology , ecology , biochemistry , enzyme
Shifts in † 13 C of the graminaceous C 3 halophyte Puccinellia nuttalliana (Schultes) Hitch. can be induced by salinization. To investigate this phenomenon, three approaches were taken: assay of carboxylases, CO 2 ‐enrichment studies, and gas exchange analysis. Although ribulose‐1,5‐bisphosphate carboxylase activity decreased with salinity, phosphoenolpyruvate carboxylase activity did not increase and its levels were not atypical of C 3 plants. When plants were grown at four NaCl concentrations under atmospheres of 310 and 1300 cm 3 m −3 CO 2 , the CO 2 ‐enrichment enhanced the effects of salinity on † 13 C. This is consistent with a biophysical explanation for salt‐induced shifts in † 13 C, whereby there is a steepening of the CO 2 diffusion gradient into the leaf. Gas exchange analysis indicated that intercellular CO 2 concentrations were depressed in the leaves of salt‐affected plants. This resulted from a greatly decreased stomatal conductance coupled with only small effects on intrinsic photosynthetic capacity. Water‐use efficiency was enhanced.