Effect of potassium uptake on the composition of essential oil content in Calendula officinalis L. flowers

Potassium (K) is an important macronutrient and the most abundant cation in higher plants. K has been the target of some researchers mainly because it is essential for enzyme activation such as enzyme of essential oil synthesis. The highest accumulation of essential oil (0.29% and 0.095 g plant^-1) was recorded at the treatment of 173.2 kg ha^-1 compared with control treatment (0.13% and 0.015 g plant^-1). 28 constituents were identified in the essential oil. The main constituents (α-cadinol, Δ-and γ -cadinene) increased with K level. The highest amount of the main constituents [α-cadinol (33.11%), Δ-cadinene (18.41%), and γ -cadinene (9.99%)] was produced from the F treatment (346.4 kg ha^-1). Alcohols were the major constituents of the heavy oxygenated compounds (HOC) of Calendula essential oil in which α-Cadinol represented the highest concentration.