Arbuscular Mycorrhizal Association in Plants Growing on Metal-Contaminated and Noncontaminated Soils Adjoining Kanpur Tanneries, Uttar Pradesh, India

Commonly occurring plant species on metal-contaminated soils and noncontaminated soils adjoining Kanpur Tanneries, Uttar Pradesh, India were surveyed for arbuscular mycorrhizal association. In the present study, pH, electric conductivity (E.C.), organic carbon, macronutrients (available phosphorus, available potassium), micronutrients (Cu and Zn), and toxic metals (Cr, Cd, Pb) were higher in metal-contaminated site compared to noncontaminated site. These factors were also significantly different between metal-contaminated and noncontaminated soils. High E.C. along with toxic concentrations of metals like Cr, Cd, and Pb may have acted as selection pressure for vegetation cover, making the metal-contaminated site hostile for cultivation purpose. The study recorded Arum type of arbuscular mycorrhiza. The highest mean total root colonization levels in metal-contaminated and noncontaminated soils were 100% (Parthenium sp.) and 34.16% (Parthenium sp.), respectively. Maximum mean spore density in metal-contaminated and noncontaminated soils was 19 spores rhizosphere soil⁻¹ (Parthenium sp.) and nine spores rhizosphere soil⁻¹ (Desmostachya bipinnata and Cynodon sp.), respectively. Studies revealed that for a particular plant species, the root colonization levels and spore density (except Cynodon sp.) were higher in contaminated soil compared to noncontaminated soils. A total of six species of arbuscular mycorrhizal fungi belonging to two genera viz., Glomus and Scutellospora were recovered during the study. Species richness of arbuscular mycorrhizal fungi was maximum in the noncontaminated site compared to the metal-contaminated site. This result suggests that continuous exposure of plants and associated arbuscular mycorrhizal fungi to heavy metals can result in tolerant species which can be used for phytoremediation.