Functional strains of Arthrobacter and Bacillus enhance tobacco (Nicotiana tabacum cv. XJ-14) leaf productivity and quality

Plant growth-promoting microorganisms (PGPMs) have shown great promise in enhancing plant development, improving stress tolerance, and modulating key physiological traits. However, their specific effects on cigar tobacco (Nicotiana tabacum) growth and leaf quality under controlled conditions remain poorly understood. In this study, we evaluated several PGPM inoculants, including Sinomonas atrocyanea, Bacillus velezensis, Bacillus cereus, Paenibacillus sp., Arthrobacter atrocyaneus, and other three Arthrobacter sp., for their effects on cigar tobacco growth and key quality traits under controlled conditions. Results showed that several treatments, particularly those containing Arthrobacter sp. and Bacillus velezensis, significantly increased total leaf number, leaf area, stem diameter, and plant height. These treatments also enhanced chlorophyll a and b accumulation, indicating improved photosynthetic capacity. Moreover, soluble sugar content and glandular trichome density, important indicators of flavor and aroma quality, were substantially elevated, Arthrobacter sp. showing the most pronounced sugar accumulation. These improvements are likely associated with microbial traits such as phytohormone production and nutrient solubilization. Our findings suggest that selected PGPMs can serve as effective biofertilizers for enhancing both biomass and quality-related characteristics of cigar tobacco, offering a viable pathway toward greener and higher-value tobacco production.