Journal of Crop Production and Processing

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mortazavi N, Moradi L. The Effect of Foliar Spraying of Salicylic Acid and Humic Acid on Some Morphophysiological and Ornamental Characteristics of Echinacea (Echinacea purpurea L.). Journal of Crop Production and Processing 2025; 15 (4) :1-16
URL: http://jcpp.iut.ac.ir/article-1-3370-en.html

Extended Abstract:

Introduction: Echinacea purpurea L. a herbaceous perennial plant belonging to the Asteraceae family, is native to North America. Its lower stem leaves are ovate to lanceolate, typically decreasing in width toward the stem apex. The flowers, which can reach up to 15 cm in diameter, display colors such as purple, pink, yellow, and orange, and remain on the plant for approximately 2 to 3 months. Scientific recommendations now include the use of certain chemical compounds, such as salicylic acid (SA), to enhance metabolic activity and overall plant performance. SA plays a pivotal role in regulating key physiological processes, including seed germination, stomatal closure, and inhibition of ethylene biosynthesis. It also increases the rate of photosynthesis, boosts chlorophyll content, and enhances glycolysis. By inhibiting chlorophyll oxidase enzyme activity, SA prevents chlorophyll degradation, thereby improving photosynthetic efficiency. The aim of this study was to investigate the effects of different concentrations and the interaction between salicylic acid and humic acid (HA) on the morphophysiological characteristics of Echinacea. 

Materials and methods: This experiment was conducted during the 2019–2020 growing season at the research farm of the Faculty of Agriculture, University of Zanjan. Two-leaf seedlings (true-leaf stage) were obtained from Zarrin Kesht Company in Urmia and transplanted in May after field preparation, with spacing set at 50 cm between rows and 35 cm between plants within rows. Regular maintenance included weekly morning weeding and irrigation every three days at 8:00 AM. The experimental treatments consisted of four concentrations of SA (0, 100, 200, and 400 mg·L⁻¹) and four concentrations of HA (0, 100, 200, and 400 mg·L⁻¹), applied both individually and in combination. Foliar spraying was initiated 40 days after transplanting, coinciding with active vegetative growth, and was applied at two key developmental stages: the six- to eight-leaf stage and the flower bud formation stage. The study followed a randomized complete block design with three replications, resulting in a total of 48 experimental units.

Results and Discussion: The results demonstrated that the foliar application of SA and HA significantly enhanced several key characteristics. These included anthocyanin content, plant height, number of lateral branches, number of flowers per plant, vase life of cut flowers, flowering stem diameter, relative leaf water content, and total antioxidant capacity. Concurrently, a significant reduction in leaf ion leakage was observed. All these effects were statistically significant at the 1% probability level. These findings align with previous research. Humic acid has been shown to promote growth and increase plant height in crops like pepper by enhancing cell metabolism, improving nutrient absorption through chelation, and boosting leaf nitrogen content. Similarly, SA is known to stimulate growth, particularly under stress conditions, by improving nutrient uptake and photosynthetic activity, as evidenced in studies on basil and marjoram. The flowering-accelerating effect of HA is likely attributable to increased chlorophyll concentration at higher application rates, which enhances photosynthesis and shortens the plant's dormant period. This effect has been observed in species such as purple nightshade. Furthermore, SA application has been reported to promote and accelerate flowering in plants like blue lentil (Leman) and bean, and to increase flower numbers in African violet and button plant, consistent with the results of the present study on Echinacea.
Conclusion: The findings of this study confirm the beneficial effects of HA and SA on the morphological and physiological characteristics of Echinacea purpurea L. Based on the experimental results, the application of SA at concentrations of 200–400 mg·L⁻¹, combined with HA at 100 mg·L⁻¹, is recommended for optimal growth and quality in Echinacea production. Given their low cost, minimal environmental impact, and ability to enhance antioxidant activity, the use of these compounds represents a practical and sustainable strategy to improve overall plant growth, yield, and ornamental value.