Role of phosphate-solubilizing bacteria in improving the soil fertility and crop productivity in organic farming

In the present study, two phosphate-solubilizing bacteria Pantoea cypripedii and Pseudomonas plecoglossicida isolated from an organic field were tested for their efficacy to solubilize rock phosphate (RP) and other plant growth-promoting activities such as nitrogen fixation and the production of indole acetic acid (IAA) and siderophores. Both of the bacteria effectively solubilized RP and released significant amount of phosphorous (up to 271 mu g P ml(-1)) in the culture medium. These isolates produced IAA and siderophores and failed to fix nitrogen as determined by acetylene reduction. Two-year field study was conducted to test the efficacy of these bacteria on the growth and yield of maize and wheat crops grown in organic farm with and without RP. Field trials for both crops were conducted in a completely randomized block design consisting of six treatments and each treatment with triplicates. Significant increase in growth parameters, grain yield, total P uptake, and soil fertility in context of organic carbon, available P, total P, and enzyme activities were observed in inoculation treatments along with RP fertilization compared with control. This study suggested that P. cypripedii and P. plecoglossicida along with RP play an important role in improving crop productivity in organic farming.