Effect of bentonite on biochemical traits and relative water content of summer savory (Satureja hortensis) under different soil moisture levels

In order to investigate the effect of bentonite application in different soil moisture levels, an experimental factorial study was performed on summer savory in a completely randomized design with two factors and three replications in the greenhouse of Department of Horticultural Science, Ferdowsi University of Mashhad. The first factor was the application of bentonite at 3 levels (0, 50, and 100 g/kg soil) and the second factor was the different levels of soil moisture at 3 levels (50, 75, and 100% of field capacity). The results showed that drought stress reduced plant height, relative water content and fresh and dry biomass of shoots in summer savory, while the use of bentonite improved the mentioned traits. During drought stress, fresh and dry root biomass, root length, electrolyte leakage, antioxidant activity, total phenol, and proline content were on the rise. The use of bentonite improved these traits. At the highest level of drought stress, the use of bentonite (50 g/kg soil) reduced electrolyte leakage (22.45%) and proline content (58.33%) in the plant. Also, the relative water content in bentonite application (50 and 100 g/kg soil, respectively) at the highest level of drought stress increased by 20.75% and 22.76%, respectively, compared to the control. In general, the results of this study showed that the application of 50 g of bentonite per kg of soil in drought stress conditions had a better effect on the studied traits and its use in these conditions is recommended.