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<br />II") <br />00 <br /> <br />r- <br /> <br />("') <br />C) <br />.--- <br />-- <br /> <br />could not find an overall correlation with salinity, Solar <br />radiation flux was the over-riding factor. Longstreth and <br />Strain (1977) found that Spartina alterniflo~a grown at low <br />illumination and high salinity (30 g/liter) exhibited a 50% <br />reduction in g~owth, Yet, when light was increased in <br />intensity and duration, growth returned to rates equivalent to <br />those in fresh wate~, This suggested that increasing salt <br />concentrations draw increasing amounts of photosynthetic energy <br />away from growth, <br /> <br />Giurgevich and Dunn (1978), examining the influence of salt on <br />photosynthesis, growth, transpi~ation, and wate~-use efficiency <br />of the salt marsh halophyte Juncus roemerianus, found that, over <br />a ~ange of temperatures (15 35uC) at all seasons, <br />photosynthetic rate increased with increasing light in!2nsit~luP <br />to the equivalent of full sunlight (200 nEins, em see ). <br />Distinct light saturation was observed only at the highest light <br />intensities and then only at low temperatures. Water salinity <br />was 2.5%, Significantly, no effect of temgerature was found on <br />the transpiration rate over the range 8 - 40 C, <br /> <br />These studies tend to confirm the wo~k of Thomson, Luttge and <br />Smith, and others with respect to the energy drain imposed by <br />salts, the diffe~ences between species in their capacity to <br />function in saline environments, and the strong influences light <br />intensity and duration have on the production of salt marsh <br />halophytes. <br /> <br />b, Engineering for Saline Water Irrigation <br /> <br />Jenson (1980) and Shainberg (1975) show clearly the adverse <br />effect of salinity on soils and soil structure, Binding of ions <br />to the cha~ged surfaces of clays and other soil components. <br />including organic materials that impart richness to agricultural <br />lands, can breakdown soil structure and destroy soil <br />permeability, This results in the retention of salts within the <br />~oot zone, a reduction in yield, and eventual death of all <br />vascular plants, <br /> <br />Falco and Cali (1977) reviewed this challenge with respect to <br />the establishment of artificial salt marshes on dredged <br />material, and recommended that methods of rapid drainage be <br />developed to allow successful colonization and establishment of <br />salt marsh species, Seneca (1980). working on salt marsh <br />creation along the east coast, Mason (1980) along the California <br />coast and Ternyik (1980) along the coast of the Pacific <br />Northwest each dete~mined that silty sands p~ovided good <br />flushing and tidal exchanges conducive to plant establishment <br />and growth. Lee. et al. (1981) characte~ized the soil of one of <br />the most productive salt marsh areas of Georgia as 61% sand, 12% <br />silt, and 26% clay, While sandy marshes tended to provide the <br />best yields and the lowest amount of soil salinization, they <br />also showed inefficient use of nutrients (Gallagher, 1975). As <br />a result, Gallagher (1980) recommended the use of shallow rooted <br /> <br />20, <br />