Effect of Mycorrhizal Fungi on Leaf Yield, Root Colonization Percentage and Some Features of Stevia Rebaudiana Root in a Soilless Culture System

Stevia (Stevia rebaudiana) is a source of strong, natural and free of calorie sweetener that is mainly used in industries and pharmacy. With respect to the importance of this plant, extracting sweetening compounds from this demands production of considerable biomass. Therefore, the effects of mychorrhizal fungus on some characteristics of Stevia’s root organ were studied in a factorial experiment based on completely randomized blocks with 4 replications conducted in a greenhouse at Mohghegh Ardebili University in 2014. The first factor included Imma & Angel and Novell nutrient solutions; the second factor included the Planting bed that consisted of Leaf composts vermicompost, and Peat and perlite, and finally, third factor included the inoculation with mychorrhizal fungus and control treatment. The results showed that the highest percentage of root colonization with mycorrhizal was associated with the Novella nutrient solution and vermicompost planting bed, the maximum length of myrrhizae roots and dry weight of the mycorrhizal roots of the Imma & Angel solution and the vermicompost planting bed. In addition, Novell in vermicompost planting bed yielded the largest Leaf dry weight, root volume, root surface and root length after inoculation with mychorrhizal fungus. The largest, root dry weight was observed in case of Imma & Angel solution in vermicompost medium (inoculated with mychorrhizal fungus).