Temperature and salinity regulation of growth and gas exchange of Salicornia fruticosa (L.) L.

Abstract

Salicornia fruticosa was collected from a salt marsh on the Mediterranean sea coast in Libya. Growth and gas exchange of this C species were monitered in plants pretreated at various NaCl concentrations (0, 171, 342, 513 and 855 mM). Maximum growth was at 171 mM NaCl under cool growth conditions (20/10° C) and at 342 mM NaCl under warm growth conditions (30/15° C) with minimum growth at 0 mM NaCl (control). Net photosynthesis (Pn) was greatest in plants grown in 171 mM NaCl with plants grown at 513 and 855 mM having lowest rates. Maximum Pn was at 20-25° C shoot temperatures with statistically significant reductions at 30° C in control plants while salt treated plants showed such reductions at 35° C. Salt treatments increased dark respiration over the control at 171 and 342 mM but reduced it at higher concentrations. Photorespiration was reduced by salt treatment and increased by increasing shoot temperature. Greatest transpiration was in 171 mM NaCl treated plants and increasing shoot temperature increased transpiration in all treatments. Stomatal resistance to CO influx was influenced only moderately by temperature while increasing salinity resulted in increased stomatal resistance. In general both temperature and salinity increased the mesophyll resistance to CO influx. The species seems adapted to the warm saline habitat along the Mediterranean sea coast, at least partially, by its ability to maintain relatively high Pn at moderate NaCl concentrations over a broad range of shoot temperatures.

The phytosociology of British sea-cliff vegetation with special reference to the ecophysiology of some maritime cliff plants

“…At least part of these reductions in gaseous exchange could be accounted for by the increases in the resistances. Mesophyll resistance is much higher than stomatal resistance at all salinities, as reported by Kaplan & Gale (1972), Downton (1977, Abdulrahman & Williams (1981) and other workers. These increases in resistances could be t~ L partly due to the effects of decreasing water potential within the plant as salinity increases (see Fig.…”

The effects of salinity, crassulacean acid metabolism and plant age on the carbon isotope composition of Mesembryanthemum crystallinum L., a halophytic C3-CAM species

“…Similarly, a shift in the isotopic signal in the halophyte Puccinellia nuttalliana was interpreted as a change in photosynthetic pathway (Guy et al 1980) but was subsequently re-interpreted as an effect of changing c i (Farquhar et al 1982a). Salinityassociated decreases in d 13 C values that are not linked to changes in the proportions of CO 2 gain during the light and the dark have been reported for halophytes that include Salicornia virginica (Card et al 1974), Salicornia fruticosa (Abdulrahman and Williams 1981), Avicennia marina and Aegiceras corniculatum (Farquhar et al 1982a).…”

Oxygen dynamics during submergence in the halophytic stem succulentHalosarcia pergranulata

“…The consequences of the unique characteristics of the succulent stems for intraplant O 2 dynamics will be the focus of this discussion. Succulent stems of another member of the Salicornioideae, the annual Salicornia fruticosa, have relatively high mesophyll resistance to CO 2 diffusion to chloroplasts (stems in the air, Abdulrahman & Williams 1981). This study of H. pergranulata evaluated underwater photosynthesis and gas transport in the succulent stems of submerged plants.…”