Germination ecology of coastal plants in relation to salt environment

Abstract

Responses of seed germination to salinity were examined using 37 species collected from salt marshes, cliffs, and fore (unstable) and hind (stable) sand dunes along Japanese coasts. For comparison, seed germination of nine inland species was also examined. The soil salinities in salt marshes ranged from 150 to 300 mmol/L NaC1, whereas those in fore and hind dunes ranged from 0 to 50 mmol/L NaC1, with a few exceptions. Cliff soils showed relatively high salinities up to 300 mmol/L NaCI. Cliff and foredune soils that encountered a typhoon and storm showed high salinities > 300 mmol/L NaC1. Salt tolerance in seed germination of coastal plants was ordered by comparing the responses of percentage and rate of germination to salinity conditions up to 200 mmol/L NaC1, being in the order of salt marsh > cliff > foredune "" hind dune ~" iniand. These results indicate that salt tolerance in seed germination of coastal plants is dosely related to the salinity conditions of their habitats. Germination experiments under favorable conditions showed that a high percentage of the seeds of salt marsh species germinate rapidly, those of cliff species germinate slowly and those of foredune species exhibit a low percentage and low rate of germination. It seems that these germination characteristics contribute to the success of germination at the 'safe site' and the subsequent survivorship of emerged plants in their natural habitats.

Melilotus indicus (L.) All., a salt-tolerant wild leguminous herb with high potential for use as a forage crop in salt-affected soils

“…Because the early stages of plant growth are sensitive to habitat salinity (Baldwin et al, 1996;Mariko et al, Table 4. Effect of salinity (NaCl) concentration in the nutrient solution, on leaf area (LA), specific leaf area (SLA), density of the leaf tissue (D), relative water content (RWC), succulence (S), water content at saturation (WCS) and water saturation deficit (WSD) of Melilotus indicus (n ¼ 5).…”

Effects of various pretreatments on seed germination ofCalystegia soldanella (Convolvulaceae), a coastal sand dune plant

“…One previous study of C. soldanella showed that, although pretreatment with sulfuric acid increased germination to 90% (Mariko et al, 1992), the treatment period was too long and the length of the evaluation was not definite. In contrast, our current research demonstrated that a 3-h pretreatment of stirring with H2SO4 resulted in 100% success, a rate that was significantly higher than any of our other pretreatments.…”

Germination and reproductive biology in salty conditions of Asplenium marinum (Aspleniaceae), a European coastal fern

“…Cliffs have an irregular salt regime depending on winds, waves and rain. Mariko et al (1992) suggested that plants colonizing sea cliffs need a larger tolerance to salinity in the growing season than in the germination period. Fern spores could germinate at relatively high salt conditions, but if substrate salt concentration of their growing place would not be sufficiently diluted gametophyte development would be hampered or at least reduced and retarded so that gametangia production might fail.…”

“…Such a pattern would exclude A. marinum from places where salinity is constant. But salinity is more variable in cliffs than in other saline environments (Mariko et al, 1992). Salt marshes, influenced by the tide regime, have a uniform salt contribution, although periodical.…”