Enhanced soil Pb extraction by Acroptilon (Acroptilon repens) through inoculation with some arbuscular mycorrhizal fungi and plant growth promoting rhizobacteria

Arbuscular mycorrhizal fungi (AMF) and plant growth-promoting rhizobacteria (PGPR) are known to enhance plant growth and survival in heavy metal contaminated soils through different mechanisms. The objective of this study was to evaluate the enhancement of soil Pb extraction by Acroptilon repens through inoculation with some AMF (a mixture of Glomus species including G. intraradices, G. mosseaeand G. fasciculatum) and PGPR (a mixture of Pseudomonasspeciesincludeing P. putida, P. fluorescens, and P. aeruginosa). This study was carried out in greenhouse condition as a factorial experiment based on a randomized complete block design with two factors including Pb concentration (in four levels) and microbial treatment (in two levels) and in three replications. Consequently, a soil sample was selected and spiked uniformly with different concentrations of Pb (0, 250, 500 and 1000 mg Pb kg-1 soil). The contaminated soils were then sterilized and subsequently inoculated with AMF and PGPR. Results indicated that shoot biomass, Fe and Zn concentration in shoot decreased and bioavailable Pb, shoot Pb concentration and total Pb extracted by Acroptilon repens increased as soil Pb concentration increased. Inoculation with AMF and PGPR species increased shoot biomass of Acroptilon repens up to 2.7 and 1.4 times higher than control treatment, respectively. Pb extracted by shoots in AMF and PGPR treatments on the average was 3.2 and 2.2 times higher than control treatment, respectively. Therefore, it could be concluded that soil Pb extraction by Acroptilon repens enhances through inoculation with species of AMF and PGPR.