STUDIES ON PHYTOREMEDIATION OF HEAVY METAL CONTAMINATED SOIL BY ARBUSCULAR MYCORRHIZAL FUNGUS

Abstract

Associative and symbiotic AM fungi are common beneficial microbes of cereals plants oat (Avena sativa). It is frequently suggested that AM may improve nutrition, enhance HM uptake, improve disease resistance in their host plants or adaptation to various environmental stresses. AM fungi and thereby benefit plant development and growth. The mycorrhizal symbiosis becomes even more important in sustainable agricultural systems such as in heavy metals polluted soil. The principal objective of this work was to attempt using dual inoculation of AM fungi to induce heavy metal tolerance of oat plants grown under heavy metals stress. From a number of physiological indices measured in this study, microsymbiont significantly increased dry weight, root : shoot ratios, leaf number and area, plant length, leaf pigments, total carbohydrates, N and P content of infected plants as compared with non infected controls at all levels of heavy metal concentrations. Tolerance index of oat (Avena sativa) plants was increased in the presence of microsymbionts than in their absence in polluted soil. Microsymbionts dependencies of oat (Avena sativa) plants tended to be increased at higher levels of Zn and Cd in polluted soil. Metals accumulated by microsymbionts-infected oat (Avena sativa) plant were mostly distributed in root tissues, suggesting that an exclusion strategy for metal tolerance widely exists in them. This study provides evidence for benefits of AM fungi in the protection of host plants against the detrimental effects of heavy metals. If so, AM-oat (Avena sativa) symbiosis could be a new approach to increase the heavy metal tolerance of cereals plants under heavy metal polluted soil.