Performance of ACCase-Resistant and ACCase-Susceptible Phenotypes of Sterile Oat <i>Avena sterilis</i> subsp. <i>ludoviciana</i> (Durieu) Nyman under Drought Conditions in the Greenhouse

Abstract

Climate change might benefit water-stress-adapted weeds, further impairing their management. To evaluate the impact of soil moisture regimes on the growth and reproductive behaviour of ACCase-resistant and ACCase-susceptible phenotypes of sterile oat (Avena sterilis subsp. ludoviciana (Durieu) Nyman), a greenhouse experiment was carried out in 2020 and 2021. The factors were soil moisture regimes (100% field capacity (FC) as well-watered, 75% FC, 50% FC, and 25% FC) and ACCase-resistant and ACCase-susceptible phenotypes of sterile oat. Increased drought stress conditions reduced the number of tillers per plant by 34, 55, and 83% and the number of seeds per plant by 36, 61, and 89% in the 75% FC, 50% FC, and 25% FC conditions, respectively, compared to the well-watered treatment. Notably, both phenotypes reacted similarly to water stress, with no interactions between the two factors. Regardless of water stress, the resistant phenotypes produced fewer seeds per plant, indicating fitness costs. However, due to their high plasticity, both phenotypes will still produce seeds even when facing severe water stress conditions. Thus, sterile oat is expected to continue infesting crop fields in the near future, but with ACCase-resistant phenotypes being less successful than susceptible ones in the absence of herbicide application.

Keywords

• drought stress
• seed production
• water regimes
• herbicide-resistant phenotypes