Plant Growth Promoting Rhizobacteria Impact on Typha latifolia and Phragmites australis Growth and Dissolved Oxygen

The current study is designed to investigate the impact of plant growth promoting rhizobacteria (PGPR) on the growth of Typha latifolia and Phragmites australis and the consequent impact on oxygen concentration in their rhizospheres. Initially, uninoculated plants are tested for the optimum temperature and light intensity combination by exposing them to sixteen combinations. An automated monitoring system for temperature and light intensity is deployed at the experimentation site. The PGPR strains T2, T5, and T7 collected from National Agriculture Research Council, Pakistan, are used to inoculate the plants and analyzed for number of leaves, fresh plant biomass, total chlorophyll, and oxygen concentration in their rhizosphere. The results indicate that the strain T7 increased chlorophyll content, number of leaves, and fresh plant biomass in T. latifolia and P. australis. The oxygen concentration is also enhanced significantly in the rhizosphere of both plants. However, strains T2 and T5 are not observed to be influencing the growth of T. latifolia and P. australis. Moreover, the enhanced oxygen concentration in the plants' rhizosphere is observed to significantly reduce the time consumption for achieving over 90% chemical oxygen demand and biochemical oxygen demand removal efficiency. Hence, it is determined that the efficiency of constructed wetlands can be improved by augmenting the rhizospheric oxygen using PGPR to accelerate the plant development. The technology has practical implications and potential to be scaled up in future.