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

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 (g_s), and leaf conductance to CO₂ (g_CO2) in the emergent estuarine C₄ grasses Spartina alterniflora, S. anglica, and S. patens. Δ increased with increasing salinity in greenhouse and growth chamber experiments. g_s and g_CO2 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