Weedy adaptation in Setaria spp.: IX. Effects of salinity, temperature, light and seed dormancy on Setaria faberi seed germination

INTRODUCTION The ability to grow and reproduce 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 in the soil during growth and reproduction until it becomes an established vegetative plant may require different mechanisms and plant traits than those needed to overcome dormancy, after-ripen and germinate in the same salty soils. Seeds that are able to establish themselves in soils with high salt content may respond differently depending on the light conditions (soil surface and shallow versus deep burial) and the dormancy states of the seed at the time of salty water imbibition. The relevance of these questions was most appparent with the discovery and collection of S. faberi seed, as well as those from S. viridis and S. pumila plants, thriving along the seacoasts of Southern Japan, often growing right at the high tide mark of the ocean water of the beach (Dekker, 2000; Dekker, 2014b). These plants had to 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 world's oceans consists of water and many dissolved solutes, notable various salts (e.g. NaCl). The salt content of seawater is consistent globally at about 3%. Our goal was not to duplicate either the seacoast tidal interface zone, or seawater as an inhibitor, but to conduct a preliminary study about the effects of one important seawater salt to guide future studies on the environmental factors that may interact in the complex processes involved below ground in the life history of weedy Setaria seeds in salty environments. In particular the effects of soil temperature, light and the dormancy-germinability states of the seeds during the times of after-ripening in salty soil and the subsequent process of germination.] Therefore the objectives of this paper are to determine the effect of salt (NaCl) in water imbibed by Setaria faberi (giant foxtail) seed during after-ripening and germination, as well as that of temperature and light, in environmentally controlled seed germination conditions. Hopefully these observations may also provide insights on the possible relationship between salt 2 and drought tolerance in the germination process relevant to other more dynamic conditions of climate and more complex sea salt inhibition. Previous studies in this series have documented the global genotypic population structure of the weedy foxtails (Wang, …