Abstract
Quantification of variation for phenotypic traits within and among weed populations facilitate understanding of invasion mechanisms and management tactics. In the Pacific Northwest (PNW), USA, in response to climate change and to improve sustainability, producers are increasingly adopting broadleaf crops and cover crops, but Mayweed chamomile (Anthemis cotula L.) is a significant barrier to diversifying cropping systems because of its abundance and lack of herbicide options for its control. To quantify within-population phenotypic trait variation and heritability, plants (n = 300) from six half-sib families (i.e., seed source plants or mother plants) from each of 10 A. cotula populations (infested farms or sites) in the PNW were grown from seed through the flowering stage in the greenhouse common garden experiment. We measured percent seedling emergence, the initial date of flowering, flowering duration, plant biomass, number of flower heads, floral scent profiles, and other traits on individual plants. Trait variation was high among half-sib families within each population. For example, in two of the populations, percent seedling emergence within 30 days of planting ranged from 5 to 41% and 3 to 53%, respectively. As another example, initial date of flowering in two other populations ranged from 61 to 93 days and 58 to 92 days, respectively. Differences among half-sib families were greatest for flowering period, which differed by a month in most populations, and floral scent profiles. Heritability estimates were higher than 1.0 for most phenotypic traits, indicating that the study plants were more closely related than half-sibs (i.e., included full-sibs or products of selfing). These patterns of phenotypic trait variation are potentially caused by local edaphoclimatic factors and within-field farm management practices, suggesting that management of A. cotula might be challenging and differ within and across farms.
Highlights
Mayweed chamomile (Anthemis cotula L.; Asteraceae) is an annual, bushy, ill-scented, and globally invasive weed that originated in Eurasia to have a wide geographic range and long invasion history (Kay, 1971; Adhikari S. et al, 2020)
As A. cotula in the Pacific Northwest (PNW) mainly occurs in agricultural fields where its range is apparently expanding, genetically based phenotypic variation in the species will allow it to respond to local differences in farm management practices such as types of crop planted (Ogg et al, 1994), continuous cropping (Murphy and Lemerle, 2006), fertilizer (Lemke et al, 2015; Zeng M. et al, 2017), tillage (Ghersa and MartínezGhersa, 2000), mowing and herbicides (Lyon et al, 2017; Hovick et al, 2018)
Adaptation in response to herbicide regimes can introduce requirements for robust weed management tactics (Menalled et al, 2016; Bagavathiannan and Davis, 2018). All these selection pressures are likely to shift as producers adopt cropping systems and management regimes in response to climate change
Summary
Mayweed chamomile (Anthemis cotula L.; Asteraceae) is an annual, bushy, ill-scented, and globally invasive weed that originated in Eurasia to have a wide geographic range and long invasion history (Kay, 1971; Adhikari S. et al, 2020) It has been introduced worldwide, presumably as a contaminant of crop seed and other plant materials (CABI, 2018), and has become abundant especially in Mediterranean-like climates such as in the Pacific Northwest (PNW), USA. Despite increases or stable crop production in recent decades, uncertainties caused by climate change and pest challenges have threatened low-input cereal-based cropping systems and, progressive farmers are responding by adopting climate-change-resilient practices including intercropping and cover crops, fall- and spring-seeded pulses and oilseed Brassica crops into cereal rotations (Eigenbrode et al, 2013; O’Leary et al, 2018) These new crops, are vulnerable to A. cotula because it can outcompete them and there is a lack of compatible herbicides for its management (Lyon et al, 2017). To help understand A. cotula and the management challenges it presents, there is a need to assess systematically the phenotypic traits that contribute to its invasiveness and weediness
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
