Effects of Seed-Coating Preparations of Living Streptomyces Globisporus on Plant Growth Promotion and Disease Control Against Verticillium Wilt in Cotton

This study explored the role of viable cells and active metabolites in the seed-coating preparations of living Streptomyces globisporus in plant growth promotion and disease control against Verticillium wilt of cotton. Pot experiments were carried out to evaluate the effects of seed coating with living (LA), inactivated (IA), and 10-fold diluted living (DLA) preparations of S. globisporus Act7 and Act28 on plant growth performance and disease index of cotton seedlings under attack by Verticillium dahliae. Compared with the control, leaf greenness was increased by 50.0–70.1% across all the three treatments of Act7 (LA7, IA7, and DLA7), and the leaf area of LA7- and DLA7-treated seedlings was increased by more than twice (p < 0.05). DLA7 also increased shoot weight by 62.2%, while IA7 and DLA7 improved plant biomass by 30.4% and 72.1%, respectively (p < 0.05). The root vitality of IA7- and DLA7-treated seedlings was enhanced by 69.1% and 75.8%, respectively. The disease index of Verticillium wilt was reduced by 31.9% (LA7), 25.0% (IA7), and 66.7% (DLA7) after treatments. The effects of Act28 preparations were similar to those of Act7 preparations. Through the combined action of viable spores and active metabolites, seed coating with an appropriate dose of living S. globisporusan can considerably promote plant growth and improve root vitality, while reducing the incidence of Verticillium wilt in cotton seedlings under attack by V. dahliae.