Beneficial effect of plant growth promoting bacteria isolated from the roots of potato plant

This study was conducted with a view to isolate bacteria associated with the roots of sweet potato plants (Ipomoea batatas (L.) Lam.) and to assess their functional potentialities in relation to plant growth promoting activities. Seven bacterial isolates namely P18, P19, P31, P32, P35, P39, and P42 were obtained from surface sterilized healthy roots of sweet potato. The isolates were tested for morphological and biochemical characteristics. The results of in vitro assays showed that all isolates can produce IAA, while four isolates i.e. P18, P31, P35, and P42) solubilize rock phosphate. These isolates having abilities for IAA production and phosphate solubilization were tested as bioinoculant to potato tubers. The results of inoculated plants showed significant differences in vegetative growth parameters as well as photosynthetic pigments and N, P, and K concentrations compared with control. Consequently, the more efficient isolates namely P31 and P35 were identified by 16S ribosomal DNA sequencing analysis as Bacillus cereus and Achromobacter xylosoxidans, respectively. These can be recommended as biofertilizers for reducing the dependence on chemical fertilizers and providing a step forward toward sustainable agriculture.