Salicylic acid increases the resistance to some environmental stresses such as drought salt and chilling stress. The experiment was conducted to evaluate the effects of SA (Salicylic Acid) on morphological and physiological characteristics of medicinal pumpkin seedlings under drought stress. A trial was conducted based on completely randomized block design with 5 levels of SA pre-treatment (0, 0.5, 1, 1.5 and 2 mM) and 5 levels of SA foliar spray (0, 0.5, 1, 1.5 and 2 mM) and 3 levels of drought stress, three water deficit levels (90% FC (I1), 70% FC (I2) and 50% FC (I3)) with 3 replications. Drought stress was started at 4 true leaf stage after SA spray. The results showed that SA increased leaf area, number of leaf, number of bud leaf and chlorophyll content, respectively. Stem diameter, plantlet height, shoot and root dry weight and biomass, increased by applying SA in both method application compared to control. Seedling height, shoot dry weight and leaf area, decreased with increasing of drought stress. However, higher salicylic acid concentrations inhibited above physiological characteristics. Results show that pre-treatment and spray of salicylic acid at (2 mM) are suitable to increase drought tolerance during germination and seedling growth on medicinal pumpkin plants under drought stress.

Keywords