Biochar as a carrier of antagonistic rhizobacteria suppressing Macrophomina phaseolina

Abstract

Biochar is currently being investigated for increasing soil fertility and mitigating climate change through its application in agricultural fields to reduce carbon dioxide emissions. Keeping in view it’ benefits, this study was intended to evaluate its role as a carrier of a beneficial bacteria, Paenibacillus illinoisensis RH-31 a rhizobacteria antagonistic to wide host pathogen M. phaseolina. We investigated sugarcane bagasse based biochar compared with peat and lignite under different temperature regimes (0, 10, 20, and 30 ºC) for carrying P. illinoisensis RH-31 over a period of six months. Bacterial population (CFU/g) was estimated every 30 days interval. It was noticed that biochar held much more bacterial cells as compared to peat and lignite and pH of the carrier material seemed to be the key factor in determining the ability of compound to serve as carrier. It was noticed that over a period of time, bacterial count rapidly declined in peat and lignite because of pH which was around 4 while pH of biochar was around neutral i.e. 7. In general, overall trend observed was biochar held more bacteria as compared to peat and lignite and highest increase was observed at 30 ºC after 30 days while at lower temperature the increase was slow. The impact of carrier materials on disease and plant growth was studied under greenhouse conditions and carrier materials were mixed with sterilized soil at 1% (w/w). Biochar and peat carrying RH-31 showed significant results as compared to lignite in decreasing the disease incidence and increasing plant growth.