MEPS 313:305-310 (2006)  -  doi:10.3354/meps313305

Effects of environmental salinity on carbon isotope discrimination and stomatal conductance in Spartina grasses

Brian R. Maricle*, Raymond W. Lee

School of Biological Sciences, Washington State University, PO Box 644236, Pullman, Washington 99164-4236, USA

ABSTRACT: High salinity levels have long been recognized as an important environmental factor influencing plant growth and performance. Salt stress and concomitant water stress are likely to affect photosynthesis by reductions in stomatal conductance necessary to prevent loss of water vapor. Despite inundation with saline water, salt marsh communities exhibit high primary productivity. This study tested the effects of 0 to 40‰ salinity on leaf carbon isotope discrimination (Δ), leaf stomatal conductance (gs), and leaf conductance to CO2 (gCO2) in the emergent estuarine C4 grasses Spartina alterniflora, S. anglica, and S. patens. Δ increased with increasing salinity in greenhouse and growth chamber experiments. gs and gCO2 peaked at moderate salinity levels (10 to 20‰) but significantly decreased at higher salinities in all species.

KEY WORDS: Salt stress · Photosynthesis · Spartina · δ13C · Stable isotopes

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