Influence of Organic and Conventional Management Systems on Carrot Performance and Implications for Organic Plant Breeding

Authors: COLLEY, MICAELA - Organic Seed Alliance; DAWSON, JULIE - University Of Wisconsin; ZYSTRO, JARED - Organic Seed Alliance; HOAGLAND, LORI - Purdue University; LIOU, MICHAEL - University Of Wisconsin; MYERS, JAMES - Oregon State University; SILVA, ERIN - University Of Wisconsin; Simon, Philipp

Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/30/2024
Publication Date: 3/4/2025
Citation: Colley, M., Dawson, J., Zystro, J., Hoagland, L., Liou, M., Myers, J., Silva, E., Simon, P.W. 2025. Influence of organic and conventional management systems on carrot performance and implications for organic plant breeding. Crop Science. 150: 65-85. https://doi.org/10.21273/JASHS05459-24.
DOI: https://doi.org/10.21273/JASHS05459-24

Interpretive Summary: A significant portion of U.S. carrot production is grown under organic crop management, and that portion continues to rise. But there has been little research comparing crop productivity under organic management to that under conventional management. To address this shortcoming, root yield and carrot top growth at early, mid- and late-season for 36 cultivars and breeding lines was compared in Indiana and Wisconsin for four years. These field productivity characteristics were relatively similar for carrots grown with organic and conventional management, but the productivity and top growth for several of the cultivars did consistently differ across years and locations in comparing these two management system effects on carrot growth. This indicates that while carrot growth and yield was similar in these two contrasting management systems, testing of new cultivars should be carried out to inform growers about their expected performance. It also indicates that there is an opportunity for carrot breeders to develop cultivars better adapted to these two management systems. This research is of interest for all carrot growers, seed companies, processors and marketers.

Technical Abstract: Organic carrot producers need varieties adapted to organic farming systems and local environments, that also hold qualities that address production challenges. Weed competition is a challenge in organic carrot production as germination is slow and erratic resulting in slow canopy establishment compared with other horticultural crops. Organic producers rely on costly mechanical and hand weeding methods for weed management. To inform future plant breeding and testing strategies for improvement of carrot for organic systems the current study evaluated top growth measurements and yields in multi-environment trials in Wisconsin (WI) and Indiana (IN), across four years under organic and conventional management. Results revealed variation in genotypes for top height and width at 30 days after planting and 60 days after planting, as well as root and top weights at harvest demonstrating the potential to breed for improved crop establishment as well as yield. Results indicated that selection under conventional growing conditions would likely correlate to improved performance in organic conditions, however when possible genetic gains could be realized more quickly by selecting directly under organic management. A comparison of the ranking of variety performance and stability of performance across the range of growing environments also demonstrated that there are instances when varieties perform similarly across management systems while other genotypes differ in response in organic compared with conventional environments. A key implication is that differences in variety performance in organic versus conventional systems is highly complex with significant higher order interactions and contextual of the location, year, and genotype.