Evaluation of diverse range microbes for their plant growth promoting abilities and their pesticide compatibility

Abstract

Plant growth-promoting rhizobacteria (PGPR) contribute to an increase in crop yield through an environmentally friendly method, therefore eight rhizospheric bacteria, two of each genera Bacillus, Pseudomonas, Azotobacter and Azospirillum were examined for their efficacy to solubilize mineral nutrients using atomic absorption spectrophotometry and a flame photometer. Their potency to produce phytohormones, synthesis biocontrol components and their compatibility with pesticides using in vitro assays was studied. All of the chosen bacterial isolates proved positive for the above-mentioned Plant Growth Promoting traits. Among the eight bacterial isolates Pseudomonas isolate P69 showed the highest phosphorous solubilization efficiency of 190.91 % and another isolate P48 produced a maximum of 27.63µg mL-1 of gibberellic acid, Bacillus isolate B120 could solubilize maximum amount of ZnO and ZnCO3 accounting for 21.3ppm and 25.9ppm, respectively, not merely in terms of solubilization when compared to the other isolates, B120 produced the highest levels of HCN (77.33 ppm TCC) and siderophores (48.87psu). On day 9 after inoculation, Azotobacter isolate AZB17 performed effectively in potassium solubilization of 6.25g mL-1 with a pH drop to 3.83. The Azospirillum isolate ASP25 outperformed all other isolates in terms of IAA production (22.64g mL-1) and Bacillus isolate B365 was found to be more compatible with eight different pesticides used in the field at varying concentrations. All of these factors point to the possibility of using these bacterial isolates B120, P48, P69, AZB17, and ASP25 as biofertilizers in sustainable agriculture.