Diversity of Arbuscular Mycorrhizal (Am) Species in Acacia Nilotica Subsp. Cupressiformis (J.L.Stewart) Ali & Faruqi. Under Arid Agroecosystems of Western Rajasthan
Arbuscular mycorrhizal (AM) fungi associated with Acacia nilotica subsp. cupressiformis (kabulikikar, ramkanta and ramkati babul) were assessed for their qualitative and quantitative distribution from five districts of Rajasthan. A total of two species of Acaulospora, two species of Gigaspora, fourteen species of Glomus, three species of Sclerocystis and two species of Scutellospora were recorded. A high diversity of AM fungi was observed and it varied at different study sites. Among these five genera, Glomus occurred most frequently.Glomus fasciculatum, G. aggregatum, and G. mosseae were found to be the most predominant AM fungi in infecting A. nilotica subsp. cupressiformis. G. fasciculatum, Sclerocystis was found in all the fields studied, while Gigaspora species and Scutellospora species were found only in few sites. The more number (22) of AM fungal species were isolated and identified from Pali whereas, only thirteen species were found from Nagaur. The total three species of Sclerocystis were identified, Sclerocystis sinuosa reported from Jodhpur, Nagaur, Sikar, Pali and Sirohi. The spore density was varied between 178 to 500 propagules (100 g-1) soil. The per cent root colonization was varied (48 to 79 %) from place to place.The pH of study area was ranged between 8.01 to 8.65; EC was recorded from 0.10 to 0.44 (dSm-1); per cent OC ranged from 0.27 to 0.39 and available P content varied from 3.44 to 5.48 mg kg-1 for A. nilotica subsp. cupressiformis. A significant correlation of AM population was observed with root colonization and per cent organic carbon while other variables studied had a non-significant correlation with total AM population.