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To examine the contrasting genetic potentials of different species, which would allow or prevent the evolution of tolerance to naturally saline environments, the growth of selected tolerant and normal lines of Agrostis stolonifera L., A. capillaris L., Holcus lanatus L., and Lolium perenne L., in NaCl, CaCl2, MgCl2 and seawater solutions was examined. NaCl tolerant line of all four species had significantly greater root growth in NaCl, CaCl2 solutions, and seawater than unselected lines, but in MgCl2 only the NaCl tolerant lines of H. lanatus had significantly longer roots than the unselected line. Screening of seedlings in solution culture in all four species, for tolerance to the same salt solutions, suggested that variability was available in each species for enhanced tolerance to each salt. When the selected material was tested as adults, the superior tolerance in response to increased seawater concentration remained for all lines in all species except those of A. capillaris and H. lanatus. The results suggest that all four species have genetic potential for the evolution of salt tolerance. The failure of some of these species to evolve salt tolerant populations in nature is likely to be due to other factors in naturally saline environments, for which the necessary adaptive genetic potential is lacking. [ABSTRACT FROM AUTHOR]

Scanning electron microscope examination of the morphology of adaxial and abaxial leaf surfaces of salt spray-tolerant and normal plants of Agrostis stolonifera L., Dactylis glomerata L. and Holcus lanatus L. was carried out. Differences were found in degree and types of waxiness of epidermal cells, number and size of macro-hairs and prickles, epidermal cell lengths and extent to which stomata were sunken. These differences were consistent with a reduction of the wettability, and hence salt spray damage, to adaxial leaf surfaces. Abaxial leaf surface differences were much less pronounced. [ABSTRACT FROM AUTHOR]

Tolerance to sodium chloride in solution culture and its genetic basis has been assessed for populations of Festuca rubra L., Holcus lanatus L., Agrostis stolonifera L., and Dactylis glomerata L. from salt marsh, spray zone, and inland habitats. Two populations of F. rubra from salt marshes and one population of A. stolonifera from a spray zone showed significant NaC1 tolerance. However, in the main, responses of populations to increasing NaCl in the rooting medium showed little relationship with electrical conductivity or Na content of the soil. Narrow-sense heritability estimates were high for all populations, except for one F. rubra population from a salt marsh and the population of A. stolonifera from a spray zone. Broad-sense heritabilities were high for all populations suggesting high genetic components for variation in NaCl tolerance. [ABSTRACT FROM AUTHOR]