Effects of Drought stress on seed dormancy in Hordeum spontaneum

Seed dormancy is a defensive system against unfavorable environmental conditions. This research was designed to evaluate the drought stress effects on seed germination and dormancy of Hordeum spontaneum genotypes. Therefore, 19 genotypes of the species and the Nosrat (cultivated barley) cultivar were evaluated under normal water condition and drought stress in a green house study. Complete randomized block design with three replications were used in this study and two stress levels including 95-100%FC and 25-30% FC, were imposed to the plants. Based on results, drought stress had significant effects on germination index, germination percentage, seed dormancy, germination value and germination energy. Drought stress increased the seed dormancy in most of Hordeum spontaneum genotypes. Principle components analysis of the traits in both water conditions showed that, stress tolerance index and length of coleoptiles are positively related, which indicates that genotypes with longer coleoptiles are more tolerant to drought stress conditions, and it seems that, this trait has evolved to increase the adaptation to drier climates.