Selection of culturable PGPR from diverse pool of bacteria inhabiting pigeonpea rhizosphere

A total of 113 rhizobacteria were isolated from different rhizotic zones of pigeonpea using nine selective and three non-selective media. Maximum isolates were obtained on King's A medium closely followed by King's 6 and nutrient agar. Seed treatment using four isolates viz. RS29, RS39, RS41 and RF3 resulted in 90% seed germination in contrast to 50% obtained in untreated control after 72h of incubation. Radicle length was also influenced significantly by some of the isolates. None of the isolates obtained from different rhizotic zones on EM6 agar could promote seed germination or seedling growth. In contrast all the isolates obtained from rhizosphere on SEM or Nfb media could stimulate seed germination or radicle length. The study indicate that media like soil extract agar (SEA), N-free malate (Nfb) and Pseudomonas fluorescens agar (PFA) could yield higher percentage of plant growth promoting rhizobacteria. Out of the 42 isolates RS34, ER17, RF7 and RS41 increased shoot height and 25 isolates produced higher shoot dry biomass as compared to uninoculated control whereas isolates RS45, RS36, RS57, ER23, RF24 influenced root dry biomass significantly.