Effects of PGPR and AM Fungi on Growth and Zn Uptake by Corn Plant in a Zn- Contaminated Soil

Improving soil microbial activity and using synergistic relations including plant growth-promoting rhizobacteria (PGPR) as well as arbuscular mycorrhizal fungi (AMF) are profitable and have economical significance for plant growth in soils with heavy metals contamination. A greenhouse factorial experiment with corn plant was carried out using factorial design with four Zn levels (mg kg-1) Zn0، Zn100، Zn200 and Zn400 and three microbial inoculations including control (C)، PGPR inoculation (B)، AMF inoculation (F) and PGPR+AMF (BF). PGPRs inoculants were mixtures of fluorescent Pseudomonas spp and the AMF islolate belonged to Glomus versciforme. After 14 weeks plants were harvested and shoots and roots separately were weighed and dried. Growth parameters، Zn concentration and Zn content (accumulation) were determined in different parts of plants. Analysis of variances showed that Zn levels and microbial inoculations significantly affected the measured indices. High Zn levels decreased shoot dry weight (15%) and increased its Zn concentration as well as content compared to the sterile condition 2. 6 and 2 folds، respectively. Accumulated Zn in Zn0 treatment (907 μg/pot) was significantly increased in Zn300 treatment (2855 μg/pot). Microbial inoculation of corn has led to an increase in plant biomass compared to sterile plants at contaminated conditions. The highest plant biomass (21. 6 g/pot) was achieved in PGPR inoculation which was 2. 28 times higher than that of sterile plants (6. 6 g/pot). Microbial inoculation particularly with PGPR significantly increased (2. 95 fold) Zn uptake in comparison with sterile conditions. It is concluded that inoculation with PGPR decreased Zn concentration in the leaves but drastically raised its accumulation in the whole plant and thus PGPR seems to have the potential that can be used in soil phytoremediation process.