Organic foliar fertilization increases polyphenol content of Calendula officinalis L.

Abstract

With the growing demand for ecological products, a better understanding and optimization of organic agriculture systems is required. Marigold (Calendula officinalis L.) is an important medicinal and ornamental herb, cultivated on large areas in many countries. The present study evaluates total phenolics and flavonoid contents and Free radical scavenging activity of Calendula officinalis L. under organic fertilization with four different foliar fertilizers (Fylo®, Geolino Plants&Flowers®, Cropmax®, Fitokondi®) in a two year study under field conditions.The content of phenolic compounds was increased by the foliar fertilizers used in the experiment. In the first year, the highest content of total phenolics (+51%), total flavonoids (+84%) and Free radical scavenging activity (+43%) were obtained in plants fertilized with Fitokondi if compared with control. In the second year, monthly measurements showed that the highest content of total flavonoids (36.4mg quercetin/g dry weight) and highest Free radical scavenging activity (83%) were registered in September for the Geolino treatment while the maximum total phenolic content (6.7mg gallic acid/g dry weight) was recorded in July. Fertilization, in certain months, led to increases in flavonoid contents and in total phenolics with a maximum of 53%, respectively, 60% under Cropmax treatment, while the Free radical scavenging activity was enhanced particularly by Fitokondi, with 100% compared with control.The selected ecological foliar fertilizers used in this study can thus be used to obtain higher levels of phenolic compounds in marigold.