Effects of Salicylic Acid and Microorganisms on Morphological and Physiological Characteristics (Satureja hortensis L.) under Drought Stress.

Objective: As a critical limitation of plant growing, drought stress has always received a lot of attention from botanical researchers. This study intends to investigate the role of salicylic acid and the Mycorrhiza and Azotobacter bio-fertilizer on Satureja hortensis L. under drought stress. Materials and Methods: Salicylic acid and bio-fertilizers have been shown to improve drought tolerance in growing plants. To evaluate the synergistic effect of salicylic acid, Azotobacter chroococcum bacteria, and arbuscular mycorrhizal fungi under drought stress (-3.5 atm: W1), (-6.5 atm: W2), and (-10 atm: W3), a 2-year (2016 to 2018) field experiment was organized based on split-plot factorial statistical in a randomized complete block design, with three replicates. Results: The main findings of this study showed that the combinable use of bio-fertilizers and salicylic acid diminished the disadvantageous effects of drought stress. Co-application of bio-fertilizers and salicylic acid significantly increased chlorophyll a and b (22% and 31.5%), carotenoid (30.7%) contents, aerial fresh (38.3%) and dry (64.1%) weights, root fresh (55.8%), and dry (45%) weights, auxin (15%), percentage of essential oil (30.7%) in S. hortensis while it decreased the proline content (48.8%) under severe stress as compared to the control groups, which confirmed the efficacy of this approach and its role in drought tolerance. Conclusion: The results demonstrated that this new suggested treatment could effectively alleviate drought stress symptoms and improve S. hortensis growth under spreading drought conditions and limited water resources. [ABSTRACT FROM AUTHOR]