Bacterial inoculation: A tool for red clover growth promotion in polluted soil

Red clover (Trifolium pratense L.) seeds were inoculated with several plant growth-promoting bacteria (PGPB) and sown in the substrate contaminated with polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and organometallic derivatives of tin (OT). The aim was to determine if selected PGPB strains can promote the growth of red clover in the substrate contaminated with several organic pollutants. The influence of bacteria on red clover growth (height, root length and biomass) was monitored during the three-month experimental period. The most significant improvements of seedling height were noted in the treatment with Bacillus amyloliquefaciens D5 ARV and Pseudomonas putida P1 ARV. Root growth was positively affected by Serratia liquefaciens Z-I ARV. The same isolates significantly affected biomass production. Those isolates caused total biomass increases of 70%, 48% and 33% compared to control. Bacterial strains used in this study were already confirmed as PGPB by biochemical testing, as well as by an in vivo test of mixed inoculums on several woody plants grown in the coal-mine overburden site. This work is the first-time record on their individual effects on one plant species. Obtained results confirmed that inoculation with several PGPB strains can enhance red clover growth in polluted soil.