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The water relations and growth responses of an extreme halophyte, Salicornia virginica, and a common glycophyte, Raphanus sativus, were comparatively examined in a hydroponic growth experiment employing a broad range of salinities. Root conductivity (in growth solutions and distilled water), expressed sap osmolality, water use efficiency, relative growth rate, and salt uptake were the primary responses monitored. Salicornia responded to increasing salinity by decreasing root conductivity (in the growth solutions) and increasing salt uptake, while water use efficiency and growth rates were minimally affected. The inhibitory effects of salinity upon root conductivity were reversible in distilled water, and, importantly, the highest recovery rates were from plants grown in the moderate and high salinities. Salicornia displayed an enhanced ability to absorb water in distilled water following growth in solutions with elevated salinities. In contrast, Raphanus responded to comparatively small increases in growth solution salinity by drastically decreasing growth rates as well as root conductivity (in the growth solutions), while salt uptake and water use efficiency increased under the moderate salinity level. In Raphanus the inhibitory effects of increased salinity upon root conductivity were only partially reversible in distilled water, and the highest recovery rates were from plants grown in the low salinity. Thus, once salinity stress was withdrawn, Raphanus exhibited a suppressed ability to move water through the roots. The results are discussed in the light of selected, commonly proposed mechanisms of salinity-induced growth inhibition. [ABSTRACT FROM AUTHOR]

The in vitro effect of NaCl on NAD‐malate dehydrogenase (E.C. 1.1.1.37; MDH) from desalted extracts of roots and leaves of six salt marsh halophytes was investigated. The plants, all native and important constituents of the salt marshes of the east coast of the U.S., included Spartina alterniflora Loisel., Spartina patens (Aiton) Muhl., Distichlis spicata (L.) Greene, Juncus roemerianus Schleele, Salicornia virginica L., and Borrichia frutescens (L.) DC. In the leaf extracts of all species except Borrichia frutescens, the MDH activity was slightly stimulated by NaCl at concentrations around 0.05 M at optimal pH (8.0–8.5) and was reduced by NaCl in higher concentrations. MDH activity in the leaf extract of Borrichia frutescens was more salt‐tolerant and maximal activity occurred around 0.25 M NaCl at optimal pH (7.0). Even though similar pH optimums for activity were exhibited in the root and leaf extracts of each species, the MDH activity in the root extract was more salt‐tolerant than that in the leaf extract. NaCl at concentrations up to 0.1 M stimulated the MDH activity in the root extracts of all species except that of Borrichia frutescens, which had an optimal activity in 0.5 M NaCl. In the root and leaf extracts of Borrichia frutescens, the activity of cytosol MDH was much more salt‐tolerant than that of the mitochondrial MDH. A shift of the optimal pH to more acidic values with increasing concentrations of NaCl was noted in the extracts of all the species except Borrichia frutescens. The action of NaCl on MDH activity appeared to be a general ionic effect as judged by the response of the enzyme activity in the presence of iso‐ionic concentrations of other salts and isoosmotic mannitol. Thus, the response of the MDH from five of the salt marsh plants to NaCl is similar to that of glycophytes. However, Borrichia frutescens possesses a salt‐tolerant MDH that has optimal activity in a salt concentration as high as that of the environment. [ABSTRACT FROM AUTHOR]

The photosynthesis and biomass production of two contrasting species, Salicornia rubra and Distichlis stricta from the same habitat, were studied under different light intensities and osmotic conditions. Application of NaCl increased the biomass and succulence of Salicornia and decreased that of Distichlis. Ethylene glycol, EG mol. wt. 62.07, and 1:1 NaCl-EG killed Salicornia and affected Distichlis adversely. The CO2 uptake of both the species increased with increasing light intensity and was strongly influenced by the application of NaCl. All concentrations of NaCl stimulated the CO2 uptake of Salicornia, but decreased that of Distichlis. NaCl significantly decreased the light compensation point of Salicornia but had no effect on that of Distichlis. The CO2 efflux of the two species at 4.52 klx was not significantly different. The rate of CO2 uptake of both the species declined with time at all levels of treatment. Salicornia had a more rapid decline in CO2 uptake in absence of NaCl, whereas that of Distichlis was relatively unaffected by it. Although the tissue Na concentration of the two species increased with increasing NaCl concentration in the medium, the increase in Salicornia was 3.0 to 5.5 times greater than that of Distichlis. Increasing NaCl concentration decreased the chlorophyll concentration of Salicornia and increased that of Distichlis. This resulted in higher ratios of photosynthesis/chlorophyll concentration in Salicornia as against lower ratios in Distichlis. The tissue OP (osmotic potential) of both the species decreased with decreasing OP of the medium. In Salicornia the tissue OP decrease was concurrent with an increase in the CO2 uptake, whereas the CO2 uptake of Distichlis declined with decreasing OP of the medium despite a decrease in its tissue OP. It is concluded that Salicornia requires NaCl for its normal development, whereas Distichlis is adversely affected by it. Both species however, are better adapted to osmotic stress due to natural osmotic agents like NaCl, than to the osmotic stress due to artificial osmotic agents like ethylene glycol. [ABSTRACT FROM AUTHOR]

The response of glycolate oxidase from shoots of Salicornia europaea L. and from leaves of Pisum sativum L. to salt treatment during assay was studied by DCPIP reduction and O2 uptake. In Pisum there was found up to five times more glycolate oxidase activity per gram fresh weight than in Salicornia. However, the calculation of the specific activity pointed out that this result was caused only by the high level of enzyme protein in Pisum, and that specific activity from both species was of equal size. By the DCPIP method it was shown that in test media containing up to 1.0 M NaCl or KCl glycolate oxidase of Salicornia was of equal size compared with the control (medium without additional salts). With 2.0 M NaCl or KCl the activity decreased by about 80 and 30% respectively. Glycolate oxidase of Pisum was somewhat more salt sensitive. 1.0 M NaCl or KCl reduced the activity by about 35%. In the presence of 2.0 M NaCl or KCl the enzyme activity from Pisum was inhibited to about 80 and 60% respectively. By substituting sulfates for chlorides the activity of glycolate oxidase from both Salicornia and Pisum was stimulated strongly. 1.5 M Na2SO4 and 0.5 M K2SO4 (both are saturated solutions) caused an increase of glycolate activity from Salicornia of about 225 and 185% respectively, and from Pisum of about 50 and 30% respectively. Studying the response of glycolate oxidase to salt treatment by O2 uptake one must establish that with this method the degree of inhibition of enzyme activity at higher salt concentrations was always more severe than with dye reduction. Addition of 1.0 M NaCl or KCl to the assay medium caused an inhibition of glycolate oxidase activity from Salicornia of about 50% and from Pisum of about 60%. 2.0 M NaCl or KCl reduced the enzyme activity of both Salicornia and Pisum to nearly 10% of control activity. Furthermore, in contrast to DCPIP reduction no stimulating effect of sulfates on glycolate oxidase activity was detectable. Indeed, the inhibitory effect of sulfates was very slight. 1.0 M Na2SO4 caused a mean inhibition of glycolate oxidase activity of only 15% with both species, and in the presence of 1.5 M Na2SO4 50% of control activity was measured. At maximal K2SO4 concentrations (0.5 M) glycolate oxidase from both Salicornia and Pisum was also unaffected. It is supposed that the described salt tolerance of glycolate oxidase in vitro, possibly is due to an adaptation of the enzyme to high salt levels within peroxisomes in vivo. [ABSTRACT FROM AUTHOR]

Seeds of Salicornia europaea L. were analyzed for their nutrient reserves. The content of potassium and sodium was 216 and 39 mmol (kg dry seeds)‐1, respectively. Calcium and magnesium accounted for 30 and 138 mmol (kg dry seeds)‐1, respectively. Whereas most of the alkali metals were water soluble, the alkaline earth metals were mostly acid soluble. The acid‐soluble calcium plus magnesium corresponded well with the acid‐soluble phosphate. Chloride was accumulated to a level equivalent to that of sodium. Carbonate was present at a concentration of 9 mmol (kg dry seeds)‐1. Carbohydrates accounted for 93 g (kg dry seeds)‐1, nearly half of which was derived from sucrose. Fructose and glucose were present only in traces. Total nitrogen was determined to be 55 g (kg dry seeds)‐1, 16% of which was diethylether soluble. The remaining nitrogen was separated into 39 g (kg dry seeds)‐1 ethanol‐insoluble and 8 g (kg dry seeds)‐1 ethanol‐soluble nitrogen. About 10% of the ethanol‐soluble nitrogen were derived from amino acids. Total lipid content was about 280 g (kg dry seeds)‐1. The alcoholic component of the storage lipids was glycerol and the glycerides were calculated from gas chromatography to be 66% of the total lipids. About 90% of the fatty acids consisted of unsaturated acids, linoleic and oleic acid, the majority (77%) of which was linoleic acid. [ABSTRACT FROM AUTHOR]

Seeds of Salicornia bigelovii were germinated at 4.4°C, 15.5°C, and 26.6°C in saline solution containing from 0% to 8.08% sea salt. At 4.4°C, germination was delayed until the 26th day, but the final germination per cent was high in all salinities. At 15.5°C, germination was delayed until the 19th day, and the germination per cent was higher in the higher salinities. At 26.6°C, the germination began within one day and the germination per cent was higher at the lower salinities. With the exception of 26.6°C data, the maximum germination occurred at a sea salt concentration at 4.04 % which is very close to the salinity of the sea. [ABSTRACT FROM AUTHOR]