Evaluation of the USDA sweetpotato germplasm collection for tolerance to the herbicide clomazone

Authors: Wadl, Phillip; CUTULLE, MATTHEW - Clemson University; Harrison Jr, Howard; JACKSON, MICHAEL - US Department Of Agriculture (USDA)

Submitted to: Genetic Resources and Crop Evolution
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/11/2020
Publication Date: 4/29/2020
Citation: Wadl, P.A., Cutulle, M.A., Harrison Jr, H.F., Jackson, M.D. 2020. Evaluation of the USDA sweetpotato germplasm collection for tolerance to the herbicide clomazone. Genetic Resources and Crop Evolution. 67(5):1107-1113. https://doi.org/10.1007/s10722-020-00921-8.
DOI: https://doi.org/10.1007/s10722-020-00921-8

Interpretive Summary: Sweetpotato is an important food crop worldwide, with a value in the United States (U.S.) of $750 million dollars annually. Weed management is consistently ranked among the top priorities of the U.S. sweetpotato industry. Weed control is critical in sweetpotato, as yields can be negatively affected with weed pressure. Thus, chemical weed control is needed to effectively manage weeds within plantings. Unfortunately, weed management of sweetpotato in the U.S. can be challenging as there are few herbicides labeled for use on the crop. Clomazone is one of the most widely used herbicides on sweetpotato in the U.S. Tolerance to clomazone has among some sweetpotato cultivars and experimental clones has been previously reported, but there is a lack of information concerning clomazone tolerance for the majority of the USDA sweetpotato germplasm collection. Researchers at the USDA and Clemson University evaluated over 500 sweetpotato accessions for tolerance to clomazone under a recommended rate in a field plot, with the objective of identifying sources of tolerance to clomazone. Clomazone injury ratings indicated that the majority of accessions had either no chlorosis or minor damage, suggesting that a large number of diverse sweetpotato lines are available in the USDA collection that possess resistance to this herbicide. The results reported here provide critical baseline data for future studies of resistance and practical breeding for tolerance to clomazone.

Technical Abstract: Sweetpotato, Ipomoea batatas (L.) Lam., is an important food crop worldwide. Weed management is consistently ranked among the top priorities of the sweetpotato industry in the United States (U.S.). Unfortunately, weed management of sweetpotato in the U.S. can be challenging as there are few herbicides labeled for use on the crop. Clomazone is one of the most widely used herbicides on sweetpotato in the U.S. and is effective in controlling several annual broadleaf weed species and there is interest in developing germplasm that is tolerant to the herbicide. There is a lack of information concerning clomazone tolerance for sweetpotato plant introductions (PIs) that are contained within the germplasm collection of the USDA, ARS, Plant Genetic Resources Conservation Unit (PGRCU). The present study evaluated 564 sweetpotato PIs for tolerance to clomazone under a recommended rate in a field plot, with the objective of identifying sources of tolerance to clomazone. Clomazone injury ratings of the 564 sweetpotato PIs indicated that the majority (N=497 PIs) had either no chlorosis or minor damage. There is ample phenotypic diversity for periderm (skin) and stele (flesh) color and dry matter present within the clomazone tolerant PIs. Additionally, there is sufficient genetic diversity present, as 108 PIs have been characterized and assigned to four genetic clusters with another 81 PIs having high levels of mixed ancestry. The results reported here provide critical baseline data for future studies of resistance and practical breeding for tolerance to clomazone.