Synergistic Effects of Mycorrhizal Inoculation and Nutrient Management on Stevia Yield and Quality in Hydroponic Culture

Stevia rebaudiana Bertoni, a perennial herb, has garnered significant attention for its diterpene glycosides, natural sweeteners approximately 250 to 300 times sweeter than sucrose. These glycosides, concentrated in the plant's leaves, not only serve as a low-calorie alternative to traditional sweeteners but also exhibit notable antimicrobial properties, making Stevia a promising candidate for both the food and pharmaceutical industries. In order to study the effect of mycorrhiza fungi on some growth characteristics of the stevia herb under inoculum conditions with Arbuscular mycorrhizal fungi(AMF)Arbuscular mycorrhizal fungi, a factorial experiment based on randomized complete block design with four replications was conducted at University of Mohaghegh Ardabili. The first factor was Imma & Angel and Novella nutrient solutions; the second was planting bed including leaf composts, vermicompost, and biolan (peat & perlite); and third factor involved inoculation with mycorrhiza (Glomus Musea). The control fungi indicated that the highest percentage of stevioside (16.45%) was related to vermicompost planting bed under conditions of invocation with mycorrhizal in harvest for the Imma and Angel nutrient solution. The maximum percentage of Rebaudioside A (7.57%) was related to vermicompost planting bed under conditions of invocation with mycorrhizal in harvest for the Novella nutrient solution. Further, the greatest levels of Rebaudioside C were obtained under the same conditions, with the difference that in the case of this glycoside, the leaf composts planting bed showed a higher percentage. Then, the highest leaf fresh weight, leaf dry weight, and number of main branches were obtained for the Novella nutrient solution in vermicompost planting bed under inoculation with mycorrhiza. Finally, Mycorrhizal inoculation in vermicompost beds with the Novella nutrient solution resulted in the greatest plant height. Conversely, the Imma & Angel nutrient solution in leaf compost beds, when combined with mycorrhizal inoculation, produced the tallest plants. The positive impact of AMF on plant growth was evident in the quantitative and qualitative improvements observed across various measured parameters.