Study on the Growth Behavior of Stevia Affected by Biotic and Abiotic Elicitors in Hydroponic Conditions ‎

In order to investigate the effect of some biotic and abiotic elicitors on yield and yield components of stevia plant under different salinity stress, the present study has been perfoemed as a factorial experiment based on the randomized complete design with six replications. It has taken place in a greenhouse under hydroponic and conditions in two consequential experiments. Endophytic fungi isolated from yew (at three levels of control, TB20, TB2-3), foliar treatment with melatonin (at three levels of control, 0.5 μM melatonin tablets, and 0.5 μM Thymus vulgaris extract), and three salinity levels (without salinity, medium salinity 80mM, and high salinity 150mM) have incorporated the present experiments’ treatments. The experimental plants have been investigated based on morphological parameters. In both experiments, results show a positive effect of melatonin and endophytic fungi on characteristics of plant growth’s improvement (one to two times) under salinity stress. Nevertheless, the best growth conditions have been observed in low salinity levels, using thyme extract and TB20 endophytic fungus. Most traits of stevia plant in non-saline conditions along with thyme extract and endophytic fungus TB20 have been at their highest, showing an increase of approximately 1.5 folds, compared to the control. Due to the positive effects of melatonin and endophytes, especially TB20, it is recommended to use melatonin-containing plant extracts as a protective treatment in stevia cultivation in saline conditions.