Calendula ( Calendula officinalis L.), commonly known as pot marigold, is a globally valued flower recognized for its ornamental appeal, edibility, and diverse bioactive properties. In the present study, the effects of foliar application of salicylic acid (SA) at different concentrations (50–200 mg/L) were evaluated under greenhouse conditions. The effect on various vegetative and floral growth parameters, along with their effect on phytochemical content, antioxidant activity, antimicrobial activity, and α ‐amylase inhibition activity of the flowers, was evaluated. The results showed that foliar spray of SA at a concentration of 100 mg/L was most effective for vegetative and floral growth, leading to improved plant height, leaf area, plant spread, flower weight, and flower size in comparison to the control. The 200 mg/L SA treatment resulted in the highest levels of total phenolics, flavonoids, and carotenoids, as well as the highest antioxidant capacities (DPPH and ABTS + assays). The α ‐amylase inhibition and antimicrobial activities were observed to increase at higher concentrations of foliar spray of SA. The HPLC analysis of phenolic compounds revealed that rutin was the predominant phenolic compound in calendula flowers, with the highest concentration of 1064.65 µg/100 mg recorded for treatment T 3 (150 mg/L SA). This investigation underscores the efficacy of salicylic acid foliar application as a viable approach to improve agronomic performance and nutraceutical quality in calendula, presenting significant implications for its application in functional food, pharmaceutical, and ornamental sectors.
Samkaria et al. (Sat,) studied this question.