Abstract:

This study aims to screen rhizobia strains that demonstrate antagonistic effects against pathogens causing root rot in Chinese herbal medicines materials and exhibit significant growth-promoting properties. The target strains isolated from soil were purified using the plate streaking method. Following purification, the antagonistic activity of the strains, their fermentation broths, and sterile supernatants was evaluated against 4 pathogenic bacteria. The species identification of the tested strains was conducted using morphological and molecular biological techniques. The control effect and growth-promoting effect of the tested strains on root rot disease of Chinese medicinal materials were evaluated by seed soaking and root irrigation experiments. The results showed that the isolated strain LQR-15 was identified as Sinorhizobium meliloti. The antagonistic effect of this strain on four pathogenic bacteria ranged from 10.61% to 24.17%. The indoor control effect on Astragalus root rot was 78.58%, and the field control effect was 68.42%. In addition, after treatment with LQR-15 strain, the plant height of Astragalus membranaceus, Scutellaria baicalensis, and Hedysarum polybotrys increased by 30.39%, 32.79%, and 67.99% respectively compared to the control group (CK), and the biomass increased by 0.14 g, 0.26 g, and 0.26 g respectively. The root length, aboveground and underground dry weight was significantly higher than those of the control group. In summary, the selected Sinorhizobium meliloti strain demonstrates strong antagonistic effects and certain control effects on the root rot pathogens of Chinese medicinal materials, while also significantly promoting the growth of Chinese medicinal materials.

Key words: Chinese herbal medicines, Sinorhizobium meliloti, antagonism, growth-promoting effect, efficacy