Seasonal Variation in Root Colonization and Rhizosphere Spore Population of AM Fungi in Alkaline Soil

摘要

Arbuscular mycorrhizal (AM) fungi form obligate symbiotic association with many agricultural, horticultural, medicinal, fibre, ornamental, shrubs and tropical trees. AM fungi colonize about 80% of plants existing on the globe. The fungi involved are Glomus, Gigaspora, Acaulospora, Entrophospora, Scutellospora, Pacispora, Diversispora, Paraglomus, Geosiphon, Archaeospora, Kuklospora and Intraspora. These fungi are now placed in a separate new phylum Glomeromycota. They are obligate symbionts and have not been cultured on nutrient media. Improved plant growth of AM-inoculated plants is attributed to increased nutrient uptake especially of phosphorus, production of growth-promoting substances, resistance to plant pathogens and water stress, and synergistic interaction with beneficial soil microbes such as nitrogen fixers and phosphate solubilizers. Obligately mutualistic AM fungi have been studied extensively at a global scale, not only on account of their ability to help plant withstand various kinds of abiotic and biotic stresses but also with their new found role in evolution, ecosystem dynamics, and plant community establishment. The present study revealed that during survey all 19 plant species were found colonized by AM fungi. Nine AM fungal species were found associated with all these plants growing in alkaline soil in Mainpuri district of south-western Uttar Pradesh. These AM fungi included Acaulospora laevis, Gigaspora margarita, Gi. Calospora, Glomus fasciculatum, Gl. mosseae, Gl. aggregatum. Gl. coremoides, Gl. Macrocarpum and Gl. constrictum. The maximum root colonization and spore population of AM fungi were found in Cenchrus sp. followed by Acacia nilotica, Prosopis juliflora, Dalbergia sissoo and Eucalyptus hybrid. The morphology of all AM fungi was also studied during this investigation.