Speaker
Description
Introduction
Weeds represent a major global constraint to crop production, leading to ~10% yield losses annually, across crops and regions (Oerke, 2006). Vulpia myuros (rattail fescue) is an annual grass species with an almost worldwide presence. In recent years, V. myuros has been increasingly observed as a weed in arable crops in Europe and northern America, in particular in crops under reduced tillage practices (Akhter et al., 2020; Büchi et al., 2020). These reduced tillage practices are increasingly followed to conserve soil and reduce time and energy inputs, but these may favour infestation by V. myuros. Vulpia myuros is adapted to dry conditions and could therefore also be favoured by future climates, as most climate change scenarios for Europe predict increasing occurrences of drought. In Europe, V. myuros distribution has increased in the past century, first in semi-natural habitats, and later as an arable weed. It is now widely found in disturbed urban habitats, such as pavement cracks, walls, car parks, green roofs and increasingly in arable fields. However, what is not known is if the arable populations come from opportunistic invasion from those semi-natural populations, or if a particular arable weed ecotype is spreading independently from the semi natural populations. The objective of this current study is to phenotype in uniform conditions 20 populations of V. myuros coming from semi-natural and arable habitats, to assess the amount of phenotypic differentiation between those populations.
Materials and Methods
In summer 2023, we collected seeds from semi-natural and urban populations of V. myuros in the United Kingdom, spanning from the south of England to Scotland. Farmers with V. myuros infestations also contributed to the collection by sending seeds. From those arable and non-arable populations, we selected 20 populations (12 arable, 8 from urban habitats, Figure 1) to run a set of five phenotyping experiments: E1: seed germination, E2. plant development, E3. vernalisation requirements, E4. herbicide response, E5. competitiveness in a gradient of soil fertility (i.e. from pure topsoil to pure sand, with three intermediate mixtures). The data were subjected to uni- and multi-variate analyses, to assess the phenotypic diversity of the different populations, and if the habitats (arable vs non-arable) or the climate of origin played a role in shaping the characteristics of the individuals.
Results and Discussion
We observed significant differences between the 20 populations of V. myuros in terms of seed weight (from in situ collection), number of leaves and height (when grown in topsoil). Seeds coming from urban populations were lighter than arable ones, and the plants were shorter (Figure 1); no significant difference in leaf number was however observed between the two habitat types. No differences in number of leaves between plants grown in soils of different fertility were observed, except for a strong reduction in leaf production in pure sand (60% of the number of leaves produced in the other soils).
Figure 1: A. Locations of the populations analysed, B. Median plant height after 78 days in arable and urban habitats.
We observed differentiation in the phenotype of V. myuros populations of different origins when grown in uniform conditions, but less than what is observed in situ, indicating the presence of phenotypic plasticity for the traits measured here. Genetic analyses are now needed to unravel the evolutionary pathway driving the expansion of Vulpia myuros populations.
N.B. The remaining data are still being collected and analysed but will be ready for presentation during the conference in August.
References
• Akhter, M.J., Jensen, P.K., Mathiassen, S.K., Melander, B. and Kudsk, P., 2020. Biology and management of Vulpia myuros—an emerging weed problem in no-till cropping systems in Europe. Plants 9, 715
• Büchi, L., Cordeau, S., Hull, R., Rodenburg, J., 2021. Vulpia myuros, an increasing threat for agriculture. Weed Research 61, 13-24.
• Oerke, E., 2006. Crop losses to pests. The Journal of Agricultural Science, 144, 31-43.
| Keywords | rattail fescue; intraspecific variability |
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