Submitted to: Industrial Crops and Products
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/30/2012
Publication Date: 1/1/2013
Citation: Gesch, R.W. 2013. Growth and yield response of calendula (Calendula officinalis) to sowing date in the northern U.S. Industrial Crops and Products. 45:248-252. Interpretive Summary: Calendula, which is often referred to as pot marigold, has been grown throughout the world as an ornamental plant. Additionally, extracts from its flowers are used for dyes and for medicinal purposes. However, it has also been discovered that the oil of its seed contains high levels of calendic acid that can be used as a drying agent to substitute for harmful volatile organic compounds (VOC) in products such as paints and adhesives. Crop breeders from Europe have developed calendula varieties specifically for the production of their seeds for oil. Calendula has good potential to be produced in the northern U.S. because it is well adapted to cool temperate climates. Furthermore, there is considerable pressure being placed on chemical manufactures to replace VOCs in many types of products with less harmful and more environmentally-friendly alternatives such as calendula seed oil. However, little information exists on how well calendula performs and how best to produce it in the northern U.S. Therefore, an experiment was designed to determine the best time to plant and harvest calendula, while determining the performance of three different varieties. It was discovered that to optimize seed yield, calendula should be planted in early May and perhaps even as early as mid April when spring wheat is normally planted. The calendula hybrid variety 99276, obtained from Wageningen University in The Netherlands, out yielded the other two varieties that were tested and produced seed yields as high as 2100 lbs/acre. The seed oil content of the three calendula varieties was about 19 to 20% (wt of oil/wt of seed), which is comparable to soybean seed. Because calendula can be planted in early spring and has a relatively short life cycle from planting to harvest, it will make a good crop to rotate with corn and soybean in the Midwest where its production cycle should not interfere with that of corn or soybean. This information will be used to help our research team develop a set of best management guidelines for producing calendula in the northern U.S. It will also benefit the specialty seed industry, crop consultants, and university extension personnel working with producers to grow calendula as an industrial oilseed crop.
Technical Abstract: Calendula (Calendula officinalis L.) seed is a rich source of the conjugated C18:3 fatty acid calendic acid and can serve as a replacement for VOCs in many industrial chemicals such as paints, coatings and adhesives. Calendula is widely adapted to temperate climates and may be a beneficial rotational crop for the northern U.S. where crop diversity is lacking, while potentially providing producers with a new economic opportunity. However, very little is known about its agronomic potential for the U.S. or best management practices for its production. Therefore, a two-year study was conducted in west central Minnesota to evaluate the growth and yield response of calendula to sowing date. One open-pollinated calendula cultivar, Carola, and two hybrid cultivars, 1557 and 99276, were sown at two-week intervals between early-May and mid-June. Final plant population density was greatest for the early-June sowing (139 plants m-2) and declined with earlier or later sowing. Based on the combined analysis of both years, mean seed yield ranged from 1166 to 1839 kg ha-1 and was greatest for the early-May sowing and declined thereafter. Hybrid 99276 gave the greatest seed yield, which was as high as 2380 kg ha-1 for the early-May sowing in 2009. Seed oil content averaged 19.4% and did not vary with sowing date, although Carola had slightly greater oil content at 20.5% than hybrids 99276 and 1557, which were 19 and 18.6%, respectively. The number of days from planting to 50% flowering ranged from 52 to 59 d and from planting to harvest about 103 to 115 d. Results indicate that calendula flourishes well in the northern Corn Belt and can be planted and harvested as early as most cold tolerant small grains making it a potentially attractive rotational crop for this region.