Effects of Seed Biopriming on Some Characteristics of the Germination and Growth of Astragalus Ovinus Boiss under Drought Stress

Abstract

This study was aimed to investigate the effects of seed biopriming with plant-growth-promoting bacteria (PGPB) on some characteristics of germination and growth of Astragalus ovinus Boissunder drought stress. This study was conducted as a factorial experiment in a completely randomized design, with three replications. Percentage, rate of germination, mean germination time, vigor, chlorophyll a, b, carotenoids, fresh and dry weight of radicle, shoot, embryonic leave, seedling and radicle length, shoot and seedling were determined. Plant-growth-promoting rizobacteria at five levels including Pseudomonas aeruginosa (Schroeter) Migula, Azospirillum lipoferm (Beijerinck) Tarrand, Bacillus cereus Frankland, Azotobacter chroococcum Beijerinck and the control treatment were considered as the first factor. The second factor was applying drought stress at four levels of 0.0, -0.2, -0.4 and -0.8 MPa. Among the four biopriming treatments tested, A. lipoferm and A. chroococcum were eliminated, because the seeds were failed to germinate and identified as agent pathogenic. Results indicate that the use of these two PGPB increase the characteristics of germination (percentage, rate of germination, mean germination time and vigor) and growth (fresh and dry weight, length and photosynthetic pigments) of A. ovinus. It can be concluded that these two bacteria increase effectively the growth of A. ovinus under different levels of drought stress. In general, these two bacteria play a role in reduction of the negative effects of drought stress on A. ovinus.

Keywords

• bacterial inoculation
• osmotic stress
• seed germination
• photosynthetic pigments