Effects of Salinity on Germination and Growth of Solidago sempervirens var. mexicana (L.) Fern

Growth chamber experiments examined the effects of salinity on seed germination and seedling growth of Solidago sempervirens var. mexicana. Seeds were germinated at salinities ranging from 0-3% (weight/volume). Germination rate and percentage decreased with increased salinity. Seeds exposed to full strength (3%) sea water for 1-10 days and subsequently removed to fresh water gave 45-60% germination regardless of their length of exposure to sea water. Length of time in salt water affected the rate of germination; seeds exposed to sea water for 6-10 days germinated more rapidly than did seeds exposed for shorter periods. Seedlings subirrigated with 0-3% salt solutions showed optimum growth at 1% salinity, with decreasing growth and increasing succulence at salinities >1%. Despite addition of a dilute nutrient solution to all treatments, seedlings irrigated with freshwater only were slightly chlorotic. Responses of Solidago sempervirens to salinity indicate adaptation to oceanic dispersal and subsequent establishment in saline habitats, both of which may contribute to its wide geographic distribution.