Interactive Effects of Arbuscular Mycorrhizal Inoculation with Nano Boron, Zinc, and Molybdenum Fertilization on Stevioside Contents of Stevia (<i>Stevia rebaudiana</i>, L.) Plants

Stevia (Stevia rebaudiana, L.) is receiving increasing global interest as a diabetes-focused herb associated with zero-calorie stevioside sweetener glycoside production. This study was conducted to determine whether the arbuscular mycorrhiza (AM), as a biofertilizer integrated with nano boron (B), zinc (Zn), and molybdenum (Mo), would improve stevia growth and stevioside content. A factorial experiment with four replicates was conducted to evaluate the effect of AM at 0, 150, and 300 spore/g soil and three nano microelements B at 100 mg/L, Zn at 100 mg/L, and Mo at 40 mg/L on growth performance, stevioside, mineral contents, and biochemical contents of stevia. Results indicated that the combination of AM at 150 and B at 100 mg/L significantly increased plant height, number of leaves, fresh and dry-stem, and herbal g/plant during the 2019 and 2020 growing seasons. Chlorophyll content was increased by the combination between AM at 150 spore/g soil and B at 100 mg/L during both seasons. Stevioside content in leaves was increased by AM at 150 spore/g soil and B at 100 mg/L during the second season. In addition, N, P, K, Zn, and B in the leaf were increased by applying the combination of AM and nano microelements. Leaf bio constituent contents were increased with AM at 150 spore/g soil and B at 100 mg/L during both seasons. The application of AM and nano B can be exploited for high growth, mineral, and stevioside contents as a low-calorie sweetener product in stevia