Growth Promotion and Increased Potassium Uptake of Tobacco by Potassium-Mobilizing BacteriumFrateuria aurantiaGrown at Different Potassium Levels in Vertisols

Potassium-mobilizing bacterial strain Frateuria aurantia was examined for plant-growth-promoting effects and nutrient uptake on tobacco (Nicotiana tabacum L.) grown in vertisols as a field experiment for two crop seasons, 2009–2010 and 2010–2011. Inoculation with bacterial strain Frateuria aurantia was found to increase biomass, nutrient content, and leaf quality of flue-cured Virginia (FCV) tobacco. Bacterial strain F. aurantia was able to enhance potassium uptake efficiently in tobacco plants when sulfate of potash was added to the soil. In tobacco, the ultimate product is the leaf that is consumed and has commercial value. In tobacco-growing soils treated with soluble potassium and inoculated with strain F. aurantia, the potassium content of the leaf was increased by 39%. Bacterial inoculation also resulted in greater nitrogen and phosphorus contents of aboveground plant components. The bacterial isolate was also able to colonize and develop in the rhizosphere soil of tobacco after root inoculation. Solubilization of potassium containing minerals by potassium-mobilizing bacteria in vertisols and their effect on tobacco plant growth, yield, and quality are reported in this study.