Role of PGPR in the reclamation and revegetation of saline land

A field experiment was conducted to investigate the effect of PGPR inoculation on growth and yield of maize as well as on reclamation of saline sodic soil of Soil Salinity Research Institute Pindi Bhattian Pakistan, during 2015-16. Seed of maize genotype "Islamabad Gold" were soaked (2-3 h) prior to sowing in the broth culture of 4 bacterial strains i.e. Pseudomonas putida (accession no. KX580766), Pseudomonas fluorescens (accession no. KX644132), Exiguobacterium aurantiacum (accession no. KX580769), Bacillus pumilus (accession no. KX580768) and Lysinibacillus sphaericus (accession no. KX580767). In vitro analysis of bacteria confirmed that they metabolize ACC deaminase, solubilize insoluble phosphate and produce significant quantity of auxin in the presence of L-tryptophan. Inoculation of maize with bacteria along with application of 1L inocula / treatment in the field gave a significant (P = 0.05) increase in germination (76%), leaf chlorophyll (24%), proline (65%), anthocyanin (38%) and soluble sugar content (56%). P. putida inoculation resulted in maximum increase in plant height, leaf area, no of grains cob-1 (459.8), 1000 grain weight (330.9 g) and grain yield (3.25 tha-1). P. fluorescens was least effective. The rhizosphere soil analysed after harvesting exhibited significant decrease in electrical conductivity (49%), sodium absorption ratio (98%), and cation exchange capacity (94%) concomitant with a significant increase in organic matter (52%), NO3-N (37%), available P (48%) and K (31%). The highest efficiency of P. putida may be attributed to the maximum ACC deaminase activity, higher production of indole acetic acid and greater potential for Phosphate solubilization. The favorable effects of PGPR were more pronounced in the successive year 2016. (author)