The Effect of Inoculation with Two Mycorrhizal Species on Fractionation and Uptake of Cadmium in Presian Clover

In addition to improving root growth and increasing the absorption of nutrients by plants, mycorrhizae affect the availability and different forms of heavy metals in the soil. This study investigated the effect of two mycorrhizal species on the partitioning of cadmium element and also the absorption of this element by persian clover.

This experiment was carried out in a completely randomized design by factorial method with three replications with three levels of mycorrhiza (without mycorrhizae, funnelliformis mosseae and rhizophagus intraradices) and two levels of cadmium (0 and 10 mg.kg-1) in the research greenhouse of the Faculty of Agriculture of Ferdowsi University of Mashhad in 2018. After harvesting the plant, the dry weight of the shoot and root as well as the concentration of cadmium in these two parts of the plant were measured. Two parameters of mycorrhizal colonization and contribution of mycorrhizal participation in cadmium uptake by shoots and roots were measured. Finally, the effect of experimental treatments on the chemical forms of cadmium in the soil was measured.

The results showed that cadmium caused an increase of 8.7% and a decrease of 31.5% in amount of colonization of funnelliformis mosseae and rhizophagus intraradices. Cadmium decreased the shoot dry weight by 28.7%. The behavior of two mycorrhizal species on the concentration of cadmium in the shoots and roots of persian clover was different. The presence of funnelliformis mosseae caused a significant (P<0.05) and 55.1% decrease in cadmium concentration of clover shoot and a 1.23-fold increase in concentration of this metal in plant roots. The measured decrease in the concentration of cadmium in the roots and shoots of clover in rhizo treatment was 14.5% and 14.3%, respectively, compared to the control. The carbonate form of cadmium had the highest amount of this metal in control soil (1.08 mg/kg) and contaminated soil (4.19 mg/kg). Mycorrhiza colonization of plant in control soil had no significant effect (P<0.05) on the concentration of different forms of cadmium.

Considering the increase of 70 (funnelliformis mosseae) and 63 (rhizophagus intraradices) percent of plant dry weight in contaminated soil in presence of mycorrhiza, as well as the low price of these fungi inoculum (80,000 Rials per kilogram at the time of purchase), the use of this microorganism can be a suitable solution in soils contaminated with heavy metals in greenhouse conditions.