Document Type : Research Paper


1 Department of Horticulture, Gorgan University of Agricultural Science and Natural Resources

2 Associated professor, Gorgan University of Agricultural Sciences and Natural Resources, study field: Medicinal plant

3 Arak University


A ‎factorial experiment based on the randomized complete design with six replications was performed. The ‎work ‎was done in a greenhouse under hydroponic and conditions in two consequential experiments. Endophytic ‎fungi ‎isolated from yew (at three levels of control- without Endophytic fungi, TB20, TB2-3), foliar treatment ‎with ‎melatonin (at three levels of control- without melatonin, 0.5 μM melatonin tablets and 0.5 μM Thymus ‎vulgaris ‎extract) and three salinity levels (without Salinity, medium salinity 8mM and high salinity 15 mM were ‎the ‎treatments of the present experiments. In both experiments, the first foliar spraying took place 7 days and the ‎first ‎irrigation with salinity water was done10 days after planting of the seedling. Based on the results of previous ‎work, a ‎growth cycle of three months was considered to obtain sufficient biomass. A positive effect of melatonin and endophytic fungi on the improvement of plant growth (one to ‎two ‎times) characteristics under salinity stress. Nevertheless, the best growth conditions were observed in low ‎salinity ‎levels using thyme extract and TB20 endophytic fungus. Most traits including plant height, fresh weight, ‎and dry ‎weight of different parts of stevia plant in non-saline conditions along with thyme extract and ‎endophytic ‎fungus TB20 were at their highest and showed an increase of approximately 1.5 times compared to ‎the control. ‎Since the use of melatonin and endophyte, especially TB20, significantly reduced the growth ‎limitations of stevia ‎in saline conditions, it is suggested that the proposed treatments are used in the cultivation of ‎stevia under saline ‎conditions.‎