Weedy Adaptation in Setaria Spp.: IX. Effects of Salinity, Temperature, Light, and Seed Dormancy on Setaria faberi Seed Germination

Life in salty habitats is a function of tolerance to those chemicals at all critical phases of a plant’s life history. The ability to withstand salt as an established plant may require different mechanisms and plant traits than those needed to germinate in salty soils. Seeds establishing themselves in high salt content may respond differently depending on the light conditions and seed germinability at the time of salty water imbibition. S. faberi seed (and S. viridis and S. pumila) plants were discovered thriving along the seacoasts of Southern Japan.. These plants possess the ability to after-ripen, germinate, emerge and establish themselves, grow and reproduce in the salty soils and salt-laden atmospheres present in these windy habitats. The objectives of this paper are to determine the effect of salt (NaCl) in water imbibed by S. faberi seed during after-ripening and germination, as well temperature and light. Observations made also provide insights on the possible relationship between salt and drought tolerance. Seed germination of all phenotypes inhibited by 2% or more of NaCl. The effects of lesser amounts of NaCl on each of the three phenotypes was highly dependent on the specific temperature and light conditions. Regardless of non-isogenic germplasm used, the three test phenotypes encompassed complete range of seed germination in a wide range of temperatures (15-35ºC) and light conditions (+, -) in water: dormant, 4%; after-ripened, 26%; nondomrant, 90%. The provided a good range to detect responses to salinity over a wide range of germination phenotype expressions. The set of dormant, after-ripened and non-dormant S. faberi populations and phenotypes observed in these experiments provided an ideal group of seeds with which to compare the effects of salt, temperature and light over a wide range of germinability responses (0-98.3%). This full range of germinability states and responses represented the full range observable in seeds in natural soil seed pools, allowing the observation of both stimulatory and inhibitory responses.