Document Type : Research Paper - Medicinal Aromatic Plants
Authors
1 Ph.D. student of horticultural plant production and post-harvest physiology, Department of Horticultural Science and Engineering, Faculty of Agriculture, Tabriz University, Tabriz,
2 Associate Professor, Department of Horticultural Sciences and Engineering, Ahar Faculty of Agriculture and Natural Resources, Tabriz University, Tabriz, Iran.
Abstract
Introduction: Medicinal plants are essential components of both traditional remedies and modern pharmaceuticals, with their raw and processed forms widely utilized in various medical practices today. Iran, endowed with significant natural and geographical advantages, has the potential to be a leading producer, consumer, and exporter of medicinal plants. Among these, Echium amoenum Fisch. & C. A. Mey. is cultivated to maximize the production of its bioactive compounds. However, the growth and yield of such plants are significantly affected by environmental factors, particularly salinity stress, which is prevalent in Iran arid and semi-arid climate. This stress presents a considerable challenge to the production of medicinal plants. Salicylic acid, a plant hormone, offers a promising solution by mitigating the adverse effects of salt stress through the modulation of physiological and biochemical responses, including the upregulation of osmolytes. Furthermore, it enhances the expression of genes involved in the synthesis of phenolic compounds and flavonoids, which are critical for plant adaptation to environmental stressors. This study aims to assess the effects of foliar application of salicylic acid on the morphophysiological traits and essential oil yield of Iranian Borage under salt stress conditions.
Materials and Methods: To investigate the effects of salicylic acid foliar spraying on the vegetative and physiological traits, as well as the essential oil yield of the Iranian Borage, under conditions of salinity stress, a factorial experiment was conducted using a completely randomized design with three replications. The study examined the influence of salicylic acid concentrations (0, 180 and 360 µM) and varying salinity levels (0, 25, 50, 75 mM NaCl) on Iranian Borage. Prior to conducting a factorial ANOVA, the data were assessed for normality and homogeneity of variance.
Results and Discussion: Salinity stress adversely affected all measured parameters of the Iranian Borage, while the application of salicylic acid enhanced their resilience under these conditions. The optimal growth, indicated by the highest fresh and dry weights, increased plant height, and essential oil yield, was achieved with a concentration of 360 µM salicylic acid in the absence of salinity stress. Additionally, the highest levels of phenolic and flavonoid compounds were recorded with 180 µM salicylic acid at a salinity level of 25 mM.
Conclusions: The study demonstrates the beneficial effects of salicylic acid on the growth and biochemical properties of Borage, particularly under varying salinity conditions. Specifically, the application of salicylic acid at a concentration of 360 µM in the absence of salinity stress has been shown to promote optimal plant growth and enhance the production of essential oils. This finding highlights the potential of salicylic acid as a plant growth regulator that can be utilized to improve the quality and yield of medicinal plants. Moreover, under conditions of mild salinity stress, the treatment with 180 µM salicylic acid significantly increases the content of phenolic compounds and flavonoids. These compounds are known for their antioxidant properties and play a crucial role in the plant’s defense mechanisms. The enhancement of these biochemical attributes indicates that salicylic acid not only supports growth but also boosts the plant’s ability to cope with stress, thereby improving its nutritional and medicinal value. Despite the negative impacts of salt stress on plant growth and overall biochemical attributes, the findings of this study underscore the effectiveness of salicylic acid at a concentration of 360 µM in alleviating these adverse effects. The treatment not only promotes plant development but also enhances vital biochemical properties that contribute to the plant’s resilience and adaptability in saline environments. In light of these results, the foliar application of salicylic acid emerges as a cost-effective and practical strategy for farmers and agricultural practitioners aiming to enhance the growth and antioxidant levels of medicinal plants such as Borage. This approach could provide significant benefits in sustainable agriculture, particularly in regions affected by soil salinity, ultimately contributing to improved crop yields and quality.
Keywords
Main Subjects
)