Screening of Potential Arbuscular Mycorrhizal Fungal Isolates for Costus speciosus, a Medicinal Plant in Unsterile Soil

Selection of an efficient Arbuscular mycorrhizal (AM) species for inoculum production is an important step towards adapting mycorrhizal inoculum technology in crop production. In this direction six indigenous AM species were screened, isolated, identified and cultured on two promising host plants of maize and Johnson grass. When host plant had optimum AMF colonization with respective AMF species; Glomus intraradices, Glomus fasciculatum, Glomus microcarpum, Glomus mosseae, Gigaspora margarita and Sclerocystis dussii were inoculated to Costus speciosus sm in unsterilized soil. Overall result revealed that Sclerocystis dussii was most efficient AM Fungus to Costus speciosus sm, a medicinal shrub. There was significant increase in plant height, leaf length, leaf number, total chlorophyll content in leaves and increased stem tubers length, tuber diameter and phosphorus content as compared to control uninoculated plants. However, this enhanced growth response was influenced by other promising AMF species, Glomus fasciculatum and Gigaspora margarita. The underground stem tubers and their phosphorus content increased with the inoculation of Sclerocystis dussii followed by Glomus mosseae and Glomus microcarpum. Therefore, an efficient indigenous Sclerocystis dussii may be made to inoculate on Costus speciosus sm tuber cuttings in an unsterilized soil to get healthy seedling stock.