Influence of Local Isolates of Arbuscular Mycorrhizal Fungi on Growth and Physiological Performance in Zea mays Grown in Phosphorus-deficient Calcareous Soil

ARBUSCULAR mycorrhizal fungi (AMF) are fungi that form symbiotic relationships with the roots of higher plants. AMF can potentially be applied to enhance plant tolerance to stress and thus minimize the deleterious effects of abiotic stress. Deficiencies in phosphorus, an essential macronutrient for plants, can have negative effects. Our target was to determine the mitigation effect of local AMF inoculum on the growth and metabolic activity of Zea mays at different phosphorus levels (from 0 to 120mg P kg⁻¹ soil). Phosphorus deficiency disturbed physiological performance; however, AMF mitigated associated negative effects, enhanced dry weight significantly (P< 0.05), and increased P and alkaline phosphatase levels in calcareous soil compared with non-inoculated controls. The maximum H⁺-ATPase activity was 28.13µmoL Pi⁻¹ ng P⁻¹ min in the leaves of Z. mays in AMF-inoculated soil treated with 60mg P kg⁻¹ soil. AMF enhanced the activities of the antioxidant enzymes superoxide dismutase, catalase, ascorbate peroxidase, and glutathione reductase together with their substrates glutathione and ascorbic acid, with concurrent reductions in lipid peroxidation and hydrogen peroxide content. The highest mycorrhizal colonization (88%) was recorded in maize grown with 60 mg P kg⁻¹ soil. Established data on morphological characteristics revealed that the local AMF isolates contained four native spores related to the genera Glomus, Acaulospora, Scutellospora, and Entrophospora. Analysis of genetic material confirmed that the spores were related to Glomus mosseae and Acaulospora spinose. These findings demonstrate that root colonization via local AMF inoculum could ameliorate phosphorus deficiency in calcareous soils from the northwestern coast of Egypt.