Deciphering the quality and yield of heteromorphic seeds of marigold (Calendula officinalis L.) under high temperatures in the Eastern Mediterranean region

• Published in: South African journal of botany 2022-09, Vol.149, p.303-314
• Main Authors: BARUT, Muzaffer, TANSI, Leyla Sezen, BICEN, Gulistan, KARAMAN, Sengul
• Format: Article
• Language: English
• Subjects: botany; Calendic acid; Calendula officinalis; Climate change; dormancy; drought; Fatty acid; fatty acid composition; field experimentation; germination; Global warming; intensive farming; linoleic acid; lipid content; Mediterranean region; oleic acid; Seed heteromorphism; seed oils; Turkey (country)
• ISSN: 0254-6299
• DOI: 10.1016/j.sajb.2022.06.020

•The heteromorphism ratio in marigold seeds varied according to the environmental conditions.•Among the 6 different seed shapes, the highest number of seeds was ring-like at all of the planting dates under high temperatures in the mediterranean region.•High temperature increases the marigold seed oil rate but decreases the oil yield.•Seed oil yield was highest in the balloon-like with spines and ring-like seed shapes.•The stearic acid and oleic acid rates were significantly affected by the heteromorphic seeds. Seed heteromorphism, which has different dormancy and germination behavior, is vital under hostile environments such as high temperatures and drought. Seed morphs of marigold were investigated in order to examine the seed heteromorphism, which correlates with environmental variability. A field experiment was conducted on 3 different planting dates (March 1st, March 15th, and April 1st, 2020) in the hot ecological conditions of the eastern Mediterranean region of Turkey. The results of this study revealed significant variations in the agronomic traits and fatty acid composition of heteromorphic marigold seeds. When the general averages were considered, the highest values for all of the studied traits were obtained from the March 1st planting date, except for the seed oil content. The seed yields and the number of seeds decreased significantly on late plantings that were more exposed to high-temperature stress. Six distinct morphs were found in the marigold seeds, comprising balloon-like, balloon-like with spines, insect-leg, winged, curved, and ring-like. The findings clearly indicated that the seed oil yield was highest in the balloon-like with spines and ring-like seed shapes. The major oil components of the heteromorphic marigold seeds were linoleic acid (37.55%–41.47%), oleic acid (21.04%–27.37%), and α-calendic acid (15.54%–22.09%). The most common seed, ring-like shaped, may play a key role in the intensive agriculture of the plant in terms of some features such as dormancy, dispersal, and cultivation techniques. As a consequence, even if multiple gradual harvests can be made in this region where global warming and climate change is felt more clearly, the marigold plants exhibited fewer capitula for the late planting dates and the ratio of seed heteromorphism changed.