Antioxidant Enzyme Activities in Arbuscular Mycorrhizal (Glomus intraradices) Fungus Inoculated and Non-inoculated Maize Plants Under Zinc Deficiency

A greenhouse experiment was conducted to examine the changes in antioxidant enzyme activities of arbuscular mycorrhizal (AM) fungus Glomus intraradices Schenck and Smith inoculated (M+) and non-inoculated (M−) maize (Zea mays L.) plants (variety COHM5) under varying levels of zinc (0, 1.25, 2.5, 3.75 and 5.0 mg kg−1). Roots and shoots sampled at 45 days after sowing (DAS) were estimated for its antioxidant enzymes (superoxide dismutase, peroxidase) IAA oxidase, polyphenol oxidase, acid phosphatase and nutritional status especially P and Zn concentrations. Mycorrhizal inoculation significantly (P ≤ 0.01) increased all the four antioxidant enzymes in both roots and shoots at 45 DAS regardless of Zn levels. All enzyme activities except SOD increased progressively with increasing levels of Zn under M+ and M− conditions. The SOD activity got decreased in roots and shoots at 2.5 and 3.75 mg Zn kg−1. Acid phosphatase activity in M+ roots and shoots were higher in all levels of Zn but the values decreased with increasing levels of Zn particularly in roots. Mycorrhizal fungus inoculated plants had higher P and Zn concentrations in both stages in comparison to non-inoculated plants. Our overall data suggest that mycorrhizal symbiosis plays a vital role in enhancing activities of antioxidant enzymes and nutritional status that enables the host plant to sustain zinc deficient conditions.