Harvest aids did not advance maturity of non-shatter pennycress

Authors: CUBINS, JULIJA - University Of Minnesota; WELLS, SAMANTHA - University Of Minnesota; Gesch, Russell - Russ; JOHNSON, GREGG - University Of Minnesota; WALIA, MANINDER - University Of Nevada; CHOPRA, RATAN - Covercress, Inc; MARKS, M - University Of Minnesota; SWENSON, REBECCA - University Of Minnesota; FRELS, KATHERINE - University Of Nebraska

Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/27/2023
Publication Date: 5/13/2023
Citation: Cubins, J.A., Wells, S., Gesch, R.W., Johnson, G.A., Walia, M.K., Chopra, R., Marks, M.D., Swenson, R.D., Frels, K. 2023. Harvest aids did not advance maturity of non-shatter pennycress. Crop Science. https://doi.org/10.1002/csc2.20979.
DOI: https://doi.org/10.1002/csc2.20979

Interpretive Summary: Pennycress is a new winter annual oilseed crop being developed for production between summer annual crops in the Upper Midwest. Most agronomic research to date has been done with unimproved wild-type pennycress germplasm that is prone to shedding its seed (i.e., seed shatter) prior to harvest. In this two-year field study, a new improved pennycress line (IO217) with reduced seed shattering was used to evaluate the use of chemical desiccation and swathing as harvest aids to hasten seed maturation and harvesting, while reducing seed loss. Seed moisture decreased to the same level by the time pennycress was mature enough to harvest regardless of harvest aid treatment. However, swathing was the most effective method of reducing moisture of overall plant material. Natural maturation of pennycress (i.e., no harvest aid treatment) decreased seed moisture to a harvestable level at the same rate as plants that received harvest aid treatments. Therefore, results indicate that for current pennycress lines with reduced seed shatter, no harvest aid is required. This study also showed that the improved pennycress line (IO217) produced seed yields two-to-six times greater than unimproved pennycress grown in previous studies. Nevertheless, wild weedy traits such as uneven emergence and late maturation were observed in the present study indicating that further genetic improvements are necessary to create pennycress varieties for successful production in the Upper Midwest.

Technical Abstract: Reliance on summer annual crops in the Upper Midwest results in fallow land during the late fall through early spring, providing opportunities to integrate economically-viable winter crops, such as pennycress (Thlapsi arvense L.), onto the landscape. Pennycress has primarily been studied in agronomic settings using unimproved wild type lines prone to seed shatter resulting in significant yield loss if not harvested early. However, plant and seed moisture can be high, complicating harvest and seed storage. A new breeding line with a reduced-shatter mutation made it possible to study the use of harvest aids to reduce plant moisture without the risk of seed loss. The objectives of this study were to quantify the reduction in pennycress seed and biomass moisture after applying a harvest aid and to assess the seed yield, oil content, and crude protein of the reduced-shatter line. This study was conducted over the 2018-2019 and 2019-2020 growing seasons with ‘IO217’ pennycress in Rosemount, MN, USA. Seed moisture decreased to a similar level by harvest maturity regardless of treatment while swathing was the most effective method of reducing biomass moisture. Natural senescence decreased pennycress moisture content to a harvestable level at the same rate as treated plants indicating that a harvest aid is not required at this time. Seed oil content and crude protein values averaged 323 and 188 g kg-1, respectively, which is comparable to values in prior pennycress research. Seed yield was two-to-six times higher than in studies using unimproved pennycress lines. Challenges associated with wild type pennycress lines, such as uneven germination and late maturation, were still prevalent in this study and further genetic improvement will be necessary to ensure successful pennycress production in the Upper Midwest.