Evaluation of Yield, Yield Component, and Essential Properties of Pot Marigold (Calendula officinalis L.) under Water Stress and Urea

Abstract

To investigate the effect of irrigation and urea levels on some agronomic traits and the essential oil content of pot marigold, a study was conducted in a split-plot based on a completely randomized block design with three replications. The treatments included four levels of irrigation (irrigation after 5, 10, 15, and 20 days) and four levels of nitrogen (0, 80, 160, and 240 kg ha-1 of urea). The plant height, flower number, flower dry weight, number of seeds/head, thousand kernel weight, biological yield, flower essence percentage, and essence yield were measured in pot marigold under different irrigation and nitrogen levels. The results revealed that water stress, nitrogen, and their interaction had a significant effect on all investigated traits. The highest number of flowers/m2, number of seeds/head, thousand kernel weight, biological yield, and grain yield, were observed under simultaneous application of 5-day irrigation interval and 80 kg ha-1 of urea. Furthermore, the maximum flower essence percentage was obtained under the combined application of a 20-day irrigation interval and 80 kg ha-1 of urea. Nonetheless, the highest essence yield was obtained at 5, 15, and 15-day irrigation intervals and 80 kg ha-1 of urea. It was concluded that water stress and nitrogen can affect the yield and secondary metabolite production in pot marigold. Nonetheless, the highest essence yield can be produced under a 15-day irrigation interval and 80 kg ha-1 of urea. However, the highest biological yield and grain yield can be obtained at 5-day irrigation interval and 80 kg ha-1 of urea in pot marigold.