Effects of Septoglomus viscosum inoculation on biomass yield and steviol glycoside concentration of some Stevia rebaudiana chemotypes

There is growing interest in the medicinal properties of Stevia rebaudiana Bertoni, due to its ability to produce zero-calorie sweeteners, steviol glycosides (SGs). Inoculation of the roots with arbuscular mycorrhizal fungi (AMF) is a method used to improve the production of secondary metabolites by many plant species, but its effects on S. rebaudiana have not been extensively studied, especially in open field conditions in Italy. Therefore, a field experiment was conducted to study the effects of the fungus Septoglomus viscosum on the leaves and secondary metabolites of three micropropagated stevia chemotypes (L1, L2 and L3) over three years. Our results indicate that the establishment of symbiotic relations between AMF and stevia plants of selected chemotypes improved leaf yield, because the mycorrhizal (MIC) treated plants had a better tendency to regrowth, especially L1 and L3, which had survival rates of 80 % and 90 %, respectively. MIC treatment also had positive effects in terms of SG production, which was not significant in terms of concentration, but was significant in terms of production.