Effects of Silicon and Salicylic Acid on Growth, Yield, Essential Oil, and Phytochemical Characteristics of Thymus vulgaris L.: A Systematic Review of Experimental Studies Study Design

• Ola Adnan Faeaz

  Author

Background: Thymus vulgaris L. is one of the important medicinal and aromatic plants, valued for its essential oil and numerous phytochemical constituents.. Exogenous elicitors, including salicylic acid (SA) and silicon (Si) have been studied as sources to enhance plant productivity, stress resistance and phytochemistry. Objective: To compile the experimental evidences systematically in order to evaluate the effect of Si and SA on growth, yield and essential oil production and phytochemical characteristics of T. vulgaris. Methods: A systematic review was carried out based on the PRISMA 2020 guidelines. Experimental studies that met the inclusion and exclusion criteria and tested Si and/or SA on T. vulgaris were retrieved. The seven studies were eligible. There was significant methodological and outcome variability, thus no quantitative meta-analysis. Results: In general, SA was able to improve the production of growth, biomass, essential oils, phenolic solutions and antioxidant related responses depending on the concentration and environmental stress. Potassium silicate enriched plants had higher biomass and essential oil percentage, and plant response to treatment, influenced by co-application and growing conditions. The conclusions: Si and SA are potential suppliers that are able to increase the productivity and quality of T. vulgaris, but standard factorial experiments and direct combined experiments of both Si and SA are necessary.

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