A hydroponics assay distinguishes between S-metolachlor tolerant and sensitive sweetpotato cultivars

Authors: CUTULLE, MATTHEW - Clemson University; CAMPBELL, TYLER - Clemson University; FARFAN, MONICA - Clemson University; Wadl, Phillip

Submitted to: HortScience
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/23/2020
Publication Date: 5/21/2020
Citation: Cutulle, M.A., Campbell, T.H., Farfan, M., Wadl, P.A. 2020. A hydroponics assay distinguishes between S-metolachlor tolerant and sensitive sweetpotato cultivars. HortScience. https://doi.org/10.21273/HORTSCI14936-20.
DOI: https://doi.org/10.21273/HORTSCI14936-20

Interpretive Summary: Sweetpotato is an important specialty crop in the United States and consumption has shown a dramatic increase over the past 10 years, and production levels have increased to a level not seen since the 1940s. Effectively managing weeds is a top priority for sweetpotato growers. Three weeds that are of primary concern to sweetpotato producers in the Carolinas are yellow nutsedge, purple nutsedge, and Palmer amaranth. Yield losses can be up to 96 percent with heavy pressure of these three weed species. To manage weeds, sweetpotato growers utilize herbicides, between-row cultivation, mowing, and hand-removal. S-metolachlor is the only herbicide registered in sweetpotato for suppression of yellow nutsedge and provides excellent control of pigweed species; therefore, it is important for sweetpotato growers in the Southeast to plant sweetpotato cultivars that have tolerance to S-metolachlor. Research was conducted by scientists at Clemson University and the USDA, ARS that used a hydroponics system to screen for tolerance to S-metolachlor. Results of the study show that ‘Beauregard’ was approximately 50 times more tolerant to S-metolachlor than ‘Centennial’ was when accessing injury at 25% thresh hold. This assay could be used for screening for S-metolachlor tolerance in a sweetpotato breeding program.

Technical Abstract: Weed Management is an important component of sweetpotato production. Currently, S-metolachlor is the only herbicide registered in sweetpotato that has some suppressive effect on nutsedge species (Cyperus spp.). It is integral that the release of any new germplasm from sweetpotato breeding programs be tolerant to S-metolachlor. Screening for thousands of experimental clones for S-metolachlor in a field trial would be cumbersome. Therefore, screening for tolerant lines might be streamlined in an hydroponics system. Research was conducted to determine if a hydroponics assay could detect differences in S-metolachlor response between a known sensitive sweetpotato cultivar (Centennial) and tolerant sweetpotato cultivar (Beauregard) in 10 days. Results of the study show that ‘Beauregard’ was approximately 50 times more tolerant to S-metolachlor than ‘Centennial’ was when accessing injury at 25% threshhold. No differences were detected in S-metolachlor response between cultivars in the soil-based assay. This assay could be used for screening for S-metolachlor tolerance in a sweetpotato breeding program.