LAUSR

Abstract Low and erratic rainfall can cause a significant reduction in crop yields in agriculture systems that rely exclusively on rain water. Some plant growth promoting rhizobacteria (PGPR) capable of producing 1-aminocyclopropane-1- carboxylic acid (ACC) deaminase can mitigate the negative impact of water stress on plant in rainfed agriculture through modulation of plant stress hormone ethylene. The present study was conducted in rainfed areas to demonstrate the potential of PGPR with ACC-deaminase activity to enhance the growth and yield of wheat (Triticum aestivum L.) under field conditions. Previously isolated bacterial strains (Serratia odorifera CC7, Aerococcus viridians CK3 and Serratia proteamaculans R20) having in-vitro ACC deaminase activity were used for inoculation. Peat, compost and biochar were used as carrier material for the formulation of biofertilizer. Our results show that application of the compost biofertilizer increased plant biomass up to 27% and grain yield up to 33.3% compared with uninoculated control. Maximum N and P content in grain was observed 24.7 % and 25.8% respectively. Maximum ACC-deaminase activity of 821 nmol g−1 biomass h−1 was observed with strain CC7, while root colonization activity was also highest in case of strain CC7 i.e 6.2 × 106 compared to other strains. All the strains showed positive response to phosphate solubilization activity as well. Furthermore, ACC deaminase gene isolated from CC7 strain showed 79.1% homology to the ACC deaminase gene of Achromobacter, 83.9% homology to the ACC deaminase gene of Pseudomonas. These findings indicate that PGPR isolated from rainfed area can be used for biofertilizer formulation which could be very effective to increase the production of wheat in rainfed agriculture system.