Canadian Journal of Pure & Applied Sciences

Abstract: The pot culture technique has been employed for development of mycorrhizal soil in the green house. Mycorrhizal soil is a symbiotic association of bacteria, fungi and Actinomycetes which provides the effective rhizosphere for the growth of plants. The enrichment of microbial enzymes and plants exudates in mycorrhizosphere influences phytoremediation. The heavy metals (cadmium, lead and zinc) toxicity at varying concentrations, viz. 5, 10, 20, 50, 75 and 100ppm has been assessed for seed germination and growth of Medicago sativa plants both in mycorrhizal soil and non mycorrhizal soil. Mycorrhizosphere has found to provide suitable conditions for seed germination and growth of plants at concentrations ranging from 5-50ppm. The germination rate was found comparatively lower in NMS at the metal concentrations 5-50ppm. The seed germination M. sativa in cadmium amended mycorrhizal soil was found 87, 80, 70 and 55% at concentration of 5, 10, 20 and 50ppm, respectively; while for lead amended mycorrhizal soil, the percentage of seed germination was observed 80, 75, 70, and 60% at 5, 10, 20 and 50ppm, respectively. The seed germination percentage was 95, 90, 91 and 89% when zinc was amended with the concentration of 5, 10, 20 and 50ppm, respectively in mycorrhizal soil. Similarly the root/ shoot growth of M. sativa for each of this metal was propound in mycorrhizal soil. The higher metal concentrations i.e. 75 and 100ppm were found inhibitory for the seed germination and root/shoot growth. The enzymes studied; in particular acid & alkaline phosphatase and dehydrogenase in mycorrhizal soil have propounded the growth of plants in the mycorrhizosphere. The present research study has proved the effect of mycorrhizal soil for phytoremediation of heavy metals at concentrations ranging from 5-50 ppm using M. sativa as a potential candidate.