Reducing the effects of drought stress on germination characteristics and initial growth of Astragalus fasciculifolius Bioss. through seed priming

Astragalus fasciculifolius Bioss. is one of the important medicinal plants in Sistan and Baluchistan regions, and the germination of this plant in this region faces a challenge due to the sensitivity of this plant to dry conditions in the germination stage. It was carried out in the laboratory in the form of a completely randomized design in three repetitions with a factorial arrangement in 2023. Experimental treatments included four levels of osmotic potential (0, -2, -4 and -6 bar) and eight seed priming treatments including hydro-priming, non-priming, priming with gibberellin, salicylic acid, potassium nitrate, zinc sulfate, humic acid and and silicon dioxide nano-particles. The results showed that decrease in osmotic potential caused a decrease in length and weight of seedling, seed vigor, percentage and rate of germination and alpha-amylase enzyme activity. But seed priming reduced the negative effects of stress on these traits and improved these traits. Among the seed priming treatments, gibberellin and zinc sulfate had the best effectiveness in improving germination characteristics and early growth of Astragalus fasciculifolius Bioss. under conditions of no stress (osmotic potential of zero bar) and severe stress (osmotic potential of -6 bar). In mild stress conditions (osmotic potential of -2 bar), seed pre-treatment with silicon dioxide nano-particles and hydro-priming had better effectiveness in improving the studied traits. Therefore, it seems that priming treatment of Astragalus fasciculifolius Bioss. seeds with these compounds can be recommended to improve the germination and early growth characteristics of this plant.