Abstract:

To study the effects of combined application of Rhodopseudomonas palustris, Bacillus velezensis, and seaweed-derived organic water-soluble fertilizer on tobacco leaf quality and phyllosphere microbial ecology, a field plot experiment was conducted with 6 treatments: 5×10⁹ cfu/mL Rhodopseudomonas palustris GJ-22 diluted 300× (treatment 1, Rho); 5×10⁹ cfu/mL R. palustris GJ-22 (300×)+150 g/L seaweed organic water-soluble fertilizer (1000×) (treatment 2, Rhor); 5×10⁹ cfu/mL B. velezensis (300×) (treatment 3, Bav); 5×10⁹ cfu/mL B. velezensis (300×)+150 g/L seaweed fertilizer (1000×) (treatment 4, Baor); 150 g/L seaweed fertilizer (1000×) (treatment 5, ORF); blank control (treatment 6, CK). Agronomic traits and main chemical components of tobacco were measured, and changes in the phyllosphere microbial community structure were analyzed. The results showed that treatment 2 significantly promoted the growth of flue-cured tobacco, increased the relative proportion of C3F and C4F grades, and markedly improved the leaf quality; treatment 1 significantly increased total sugar content in leaves; treatment 2 and 4 significantly increased the relative abundance of Gammaproteobacteria while reducing that of Bacteroidia in the phyllosphere; treatment 1 tended to increase the bacterial and fungal diversity in the phyllosphere, but its combination with organic water-soluble fertilizer did not significantly affect microbial diversity; treatment 3 had no significant effect on the bacterial diversity but significantly reduced fungal diversity; compared with treatment 5, it also significantly reduced the bacterial diversity in the phyllosphere. These findings provide a theoretical basis for the field application of microbial agents and organic water-soluble fertilizers.

Key words: Rhodopseudomonas palustris, Bacillus velezensis, seaweed organic fertilizer, tobacco quality, phyllosphere microorganisms