Spatial Variations in Arbuscular Mycorrhizal (AM) Fungi Associated with Carica papaya L. in a Tropical Agro-Based Ecosystem

Studies were carried out on the arbuscular rnycorrhizal status of Carica papaya L. in a tropical agro-based ecosystem. Three geographic localities, Western Ghats, plateau and coastal area from two districts of Goa, India were selected for the study. In all, six sites were selected for the study. In the present investigation, the occurrence of arbuscular rnycorrhizal association was recorded in papaya sampled at all the study sites and was characterized by the presence of hyphae, arbuscules and vesicles. At any given geographical locality, papayas sampled from North Goa recorded a comparatively higher total root colonization and spore density than papayas sampled from South Goa. In general, the papayas sampled from Western Ghats had highest root colonization and spore density of arbuscular mycorrhizal fungi (AMF) followed by plateaus and coastal areas, respectively. Pearson's correlation and backward regression analysis revealed that root colonization and spore density were influenced by pH, E.C., organic carbon, N, P, Zn and Mn. The present study recorded a total of 23 species of arbuscular mycorrhizal fungi belonging to four genera, Acaulospora, Gigaspora, Glomus and Scurellospora. Species richness of arbuscular mycorrhizal fungi for any given geographical locality was higher in semi organically to organically managed farms of South Goa than in conventionally managed farms of North Goa. The present study indicates spatial variations of arbuscular mycorrhizal fungi in Carica papaya L. in a tropical agro-based ecosystem and the fact that numerous factors affect these variations.