TRICHODERMA INOCULUM AND ELEVATED AMIBIENT CARBON DIOXIDE ENHANCED PHYTOEXTRACTION OF Zn-CONTAMINATED SOIL BY LOLIUM MUTIFLORUM

Effects of inoculation with Trichoderma asperelhun and elevated ambient carbon dioxide (CO2) were evaluated for their effects on plant growth promotion and zinc (Zn) uptake by Lolium mutiflorum grown in Zn-contaminated soils. The impacts of Trichoderma inoculum and elevated ambient CO2 on Zn availability, microbial biomass carbon and nitrogen in rhizosphere soils of L. mutiflorum were also investigated. Results showed that Trichodenna inoculation and elevated ambient CO2, in combination or alone, significantly promoted production of plant biomass dry weight by 14.8%-58.8% and total Zn uptake by 6.91%-111% compared with the control, with increased microbial biomass carbon and nitrogen, and decreased soil pH in the rhizosphere soils. Also, the bioavailable Zn concentrations in the rhizosphere under elevated ambient CO2 and Trichoderma inoculum treatments were increased by 13.1%-35.0%, indicating that there was more available Zn for plant uptake under elevated ambient CO2 and with Trichoderma inoculation. Results suggested that acidulated rhizosphere, enhanced microbial activity, and increased Zn availability may contributed to the efficiency of Zn accumulation in plants under elevated ambient CO2 and Trichoderma inocula. Thus, Trichodenna inocula and elevated ambient CO2 may be exploited for promoting plant biomass production and Zn phytoextraction in Zn-contaminated soil.