Influence of Local Isolates of Arbuscular Mycorrhizal Fungi on Growth and Some Physiological Performance of Zea mays Grown in Calcareous Soil as Affected by Phosphorus Levels

Abstract

Arbuscular mycorrhizal fungi (AMF) are among plant-symbiotic fungi with higher plant roots. The applicability of AMF poses a strategy to minimize the deleterious effect of abiotic stress to enhance plant tolerance. Phosphorus is an essential macronutrient for plants, can cause toxic effects at low levels. Our target was to determine the mitigation effect of local inoculum of AMF on growth and metabolic activity of Zea mays under phosphorus levels. Phosphorus deficiency disturbed physiological performance however, AMF mitigated negative effects by enhancing the dry weight significantly (P < 0.05), P content and alkaline phosphatase in calcareous soil amended with P concentrations (from 15 to 120 mg P kg-1 soil), compared with non-inoculated plant. The maximum H+-ATPase activity was 28.13 µmol Pi-1ngP-1min in leaves of Zea mays in AM- inoculated soil and amended with 60 mg P kg-1soil. AMF enhanced antioxidant enzyme activities, superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX) and glutathione reductase (GR) together with their substrates glutathione (GSH) and ascorbic acid (AA), with concurrent reduction of lipid peroxidation and hydrogen peroxide content. Highest mycorrhizal colonization (88%) recorded in maize grown in 60 mg P kg-1 soil. Established data on morphological characters revealed AMF local isolates belong to four native spores related to genus Glomus, Acaulospora, Scutellospora and Entrophospora. Analysis of the genetic material confirmed that spores were related to Glomus mosseae and Acaulospora spinose. These findings demonstrate that root colonization by local AMP inoculum could ameliorate the phosphorus deficiency in calcareous soils collected from Southwestern coast of Egypt