Impact of plant growth-promoting rhizobacteria on yield and disease control of Nicotiana tabacum

An unexplored soil microbial community associated with the root system of Nicotiana tabacum was isolated to analyze its impact on growth and yield of the crop. A total of nine isolates out of 180 were biochemically screened and characterized as potential plant growth-promoting rhizobacteria due to the expression of growth-promoting traits. All isolates were positive for ammonia production, 8 were positive for phosphate solubilization but none for auxin production. The majority of the isolates were also found positive for hydrogen cyanide, siderophore and hydrolytic/degradative enzymes production, enabling them to restrict the growth of Fusarium oxysporum in an in vitro assay. Although all tested isolates enhanced tobacco growth significantly, Baj-ER-01 and CD-RS-03 were found to be the most promising in enhancing all aspects of growth. This study provides evidence for the enhancement of growth and yield of inoculated tobacco plants through an adequate supply of nutrients and/or controlling phytopathogens.