Salicylic acid-induced changes to growth, flowering and flavonoids production in marigold plants

Abstract

Salicylic acid (SA) is a phenolic phytohormone that acts as a key regulator of the signaling network in plants under abiotic and biotic stresses. Also, SA exerts stimulatory effects on various physiological processes related to plant growth and development. The purpose of this study was to test the hypothesis that exogenous application of SA affects positively the growth and flowering of marigold plants (Calendula officinalis L.) and also induces an increase in total flavonoids content in the inflorescences of this medicinal species. Plants under greenhouse conditions were sprayed with SA (0.00; 0.25; 0.50 and 1.00 mM) for 3 consecutive days. The effects of SA in marigold were evaluated by the following parameters: leaf gas exchange, number of leaves per plant, leaf dry mass, leaf area, chlorophyll content, number of inflorescences per plant, fresh and dry mass of inflorescences and total flavonoid content in inflorescences. Application of SA in this concentration range resulted in linear increases on biomass accumulation, number of inflorescences and flavonoid content. Leaf gas exchange was not altered by SA application. These results showed that SA exogenous application before the reproductive stage resulted in higher biomass production of marigold plants and added significant value to the raw material by increasing total flavonoids content in the inflorescences.