Growth and yield response of calendula (Calendula officinalis) to sowing date in the northern U.S.

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 volatile organic compounds 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 hybrids, 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 1839kgha−1 and was greatest for the early-May sowing and declined thereafter. Hybrid 99276 gave the greatest seed yield, which was as high as 2380kgha−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 59d and from planting to harvest about 103 to 115d. 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.