Overwintering camelina and canola/rapeseed show promise for improving integrated weed management approaches in the upper Midwestern U.S

Authors: Chao, Wun; Anderson, James; LI, XUEHUI - North Dakota State University; Gesch, Russell - Russ; BERTI, MARISOL - North Dakota State University; Horvath, David

Submitted to: Plants
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/12/2023
Publication Date: 3/15/2023
Citation: Chao, W.S., Anderson, J.V., Li, X., Gesch, R.W., Berti, M., Horvath, D.P. 2023. Overwintering camelina and canola/rapeseed show promise for improving integrated weed management approaches in the upper Midwestern U.S. Plants. 12(6). Article 1329. https://doi.org/10.3390/plants12061329.
DOI: https://doi.org/10.3390/plants12061329

Interpretive Summary: Winter hardy oilseed cash cover crops are gaining popularity as part of integrated weed management approaches for suppressing weeds. To understand the relationship (correlations) between winter hardy oilseed crops (winter camelina and canola/rapeseed) and weed suppression in the upper Midwestern USA, field studies were conducted in Fargo, ND and Morris, MN. Field research revealed that winter survival of winter camelina or canola/rapeseed had a direct correlation on suppression of early season weeds. However, planting date of winter oilseed crops affected winter survival in ND and MN, and the optimal planting dates were different between winter camelina and canola/rapeseed. In this study, nine canola/rapeseed lines were identified as freezing tolerant under field conditions and thus are good candidates for breeding commercial canola cultivars adaptable to colder climates.

Technical Abstract: Winter oilseed cash cover crops are gaining popularity in integrated weed management programs for suppressing weeds. A study was conducted at two field sites (Fargo, North Dakota, and Morris, Minnesota) to determine the freezing tolerance and weed-suppressing traits of winter canola/rapeseed (Brassica napus L.) and winter camelina [Camelina sativa (L.) Crantz] in the Upper Midwestern USA. The top 10 freezing tolerant accessions from a phenotyped population of winter canola/rapeseed were bulked and planted at both locations along with winter camelina (cv. Joelle) as a check. To phenotype our entire winter B. napus population (621 accessions) for freezing tolerance, seeds were also bulked and planted at both locations. All B. napus and camelina were no-till seeded at Fargo and Morris at two planting dates, late August (PD1) and mid-September (PD2) 2019. Data for winter survival of oilseed crops (plants m-2) and their corresponding weed suppression (plants m-2 and dry matter m-2) were collected on two sampling dates (SD) in May and June 2020. Crop and SD were significant (p <0.05) for crop plant density at both locations, and PD in Fargo and crop x PD interaction in Morris were significant for weed dry matter. At Morris and Fargo, PD1 produced greater winter B. napus survival (28% and 5%, respectively) and PD2 produced higher camelina survival (79% and 72%, respectively). Based on coefficient of determination (r2), ~50% of weed density was explained by camelina density, whereas =20% was explained by B. napus density at both locations. Camelina from PD2 suppressed weed dry matter by >90% of fallow at both locations, whereas weed dry matter in B. napus was not significantly different from fallow at either PD. Genotyping of overwintering canola/rapeseed under field conditions identified nine accessions that survived at both locations, which also had excellent freezing tolerance under controlled conditions. These accessions are good candidates for improving freezing tolerance in commercial canola cultivars.