Screening for crop response to Diazotrophic bacteria isolated from potato rhizosphere

Abstract

Microbe-plant interactions in the rhizosphere can be beneficial, neutral, or deleterious for plant growth. The present study aimed to characterize eight diazotrophic bacteria isolated from potato rhizosphere and to evaluate their effects on potato growth responses. Initially, soil bacterial isolates were screened for in vitro pH, nitrogenase activity, in vitro IAA production and seedling vigor. Then, they were further evaluated for their effects on growth responses of potato seed tubers using a pot experiment under greenhouse conditions. Out of the bacterial isolates, Bacillus sp., Acidomonas sp., Serratia sp. and Bradyrhizobium sp. responded positively to all screening and greenhouse experiments. The highest nitrogenase activity, IAA production, seedling vigor and the lowest medium pH were shown by Bradyrhizobium sp. (P < 0.05). Further, inoculation of potato with Bradyrhizobium sp. produced the highest tuber weight, tuber number and stolon number. Inoculum pH was inversely proportional to the production of IAA. Further, tuber weight and tuber number were increased with the reduction of soil pH. Positive relationships were observed between IAA production with seedling vigor, tuber weight, and tuber number, separately. Out of the bacterial isolates, Bradyrhizobium sp. was found to be the best since it showed the highest performance in all screening and pot experiments.

Keywords

• biofertilizers, plant growth promoting rhizobacteria, potato, rhizosphere microbes