Flower and seed yield and quality traits of marigold (Calendula officinalis L.) in response to winter sowing at different harvest intervals and times in Çukurova conditions

Marigold is a plant native to the Mediterranean region, belonging to the Asteraceae family, and has been cultivated as a medicinal and ornamental plant all over the world for centuries. Due to its long flowering period, it is important to determine the appropriate harvest interval and harvest time. This study was performed in three replications according to randomized complete block design in the Research and Application Area of Çukurova University in 2019-2020 and 2020-2021 growing seasons and the aim was to investigate the influence of different harvest intervals (4, 8, 12 days interval for flowers) and harvest times (8-day interval for seeds) on flower and seed yield and quality traits of marigold. The highest total flower yield (751.98 kg/da; harvest at 4 days intervals) and seed yield (59.56 kg/da; 1st harvest) were obtained in the first growing season. The highest seed fixed oil ratio (12.86%) was obtained in June, and the highest flower essential oil ratio (0.18%) was obtained in May. Of the 38 components in the essential oil, α-Cadinol (22.59-30.10%), δ-Cadinene (9.88-13.79%), τ-Muurolol (6.58-8.20%), γ-Cadinene (4.80-7.15%) and γ-Muurolene (4.15-4.82%) were determined as the main components. Six fatty acids were detected in the seed fixed oil and the main components were determined as α-calendic acid (22.07-49.41%), linoleic acid (28.31-37.85%), and oleic acid (7.18-30.06%). The highest α-calendic acid ratios were detected in June and decreased as the harvests were delayed. As a result, shortening the harvest interval increased the yield by promoting flowering.