Abstract

The present study was conducted to isolate and characterize plant growth promoting rhizobacteria (PGPR) from the rhizosphere of rice grown in cold climate at Swat and to assess their impact on plant growth when used as inoculants. A total of 18 bacterial strains were isolated from roots and rhizosphere of rice. With the exception of 3 strains, all isolates showed IAA production in pure culture. Three bacterial strains (Azospirillum brasilense R1, Azospirillum lipoferum RSWT1 and Pseudomonas Ky1) were used to inoculate rice at two experimental sites in Swat (Agriculture Research Institute (N) Mingora and Udigram). Plant growth promotion was observed in all inoculated treatments over non-inoculated control which was evident from increase in number of tillers, straw and grain yields and total weight of the plants. A. brasilense R1 was more effective in plant growth promotion than other strains. At ARIN Mingora, Swat, inoculation of rice variety Fakre Malakand with A. brasilense R1 increased the straw weight by 16.6%, grain weight by 22.7% over control. Inoculation with A. lipoferum RSWT1 and Pseudomonas Ky1 increased grain weight by 4.8 to 13.5% and 17.3 to 18.5%, respectively. At Udigram, Swat, inoculation with A. brasilense R1 increased the straw weight by 14.2% and grain weight by 22% than the control.

Key words: Azospirillum, Pseudomonas, inoculation of rice, effects of inoculation.