Evaluation of Kadostim and Humiforte Effects on Some of the Physiological and Biochemical Characteristics of Summer Savory (Satureja hortensis) under Drought Stress

The use of plant growth stimulants can contribute to improving plant yield and resistance to abiotic stresses such as drought stress. In order to evaluate the effect of two biostimulants on some physiological and biochemical characteristics of summer savory under drought stress, this experiment was conducted in the Research, Education and Natural Resources Center of Kermanshah Province as a factorial experiment based on the completely randomized design with 3 replications in 2024. Three factors, including irrigation levels (100, 75 and 50% Evp), Kadostim (0 and 1 in 1000) and Humiforte (0 and 1 in 1000) were used. The results indicated that the drought stress decreased the total chlorophyll and relative water content. In contrast, the drought stress led to significant enhancement of essential oil, total phenol, proline, total soluble sugar, malondialdehyde and electrolyte leakage. Biostimulants treatment caused improvement in all evaluated characteristics. Therefore, the highest total chlorophyll (2.88 mg. g-1 FW) was obtained in 100% Evp with Kadostim and Humiforte. Also, the highest relative water content (86.83%) was in 100% Evp with Kadostim. Although the highest essential oil was obtained in 50% Evp without Kadostim and Humiforte, the highest total phenol, proline and total soluble sugar (12.22 nmol. g-1 FW, 29.67 mg. g-1 FW and 3.92 mg. g-1 FW, respectively) were observed in 50% Evp with Humiforte. Also, Kadostim in 50% Evp irrigation level showed the highest proline (29.25 mg. g-1 FW), total soluble sugar (3.87 mg. g-1 FW) and malondialdehyde (2.9 nmol. g-1 FW). The use of Kadostim and Humiforte could reduce electrolyte leakage by 42.22% and 42.44%, respectively. In conclusion, the application of biostimulants, mainly Kadostim, contributes to improving some biochemical and physiological characteristics of summer savory exposed to drought stress.