Florpyrauxifen-benzyl (FPB) is an important postemergence rice herbicide. This study tested the potential for seed production in an FPB-resistant barnyardgrass population. A barnyardgrass population (NL) collected from a rice field in eastern China was highly resistant to FPB with a GR₅₀ dose (the FPB dose causing a 50% reduction in fresh weight of aboveground parts) of 50.2 g ai ha^–1. No significant differences in the percentages of surviving seedlings after treatment with different doses of the herbicide were found between F₁ lines collected from F₀ plants surviving a 36 g ai ha^–1 FPB treatment and those collected from nontreated control F₀ plants. Additionally, no significant differences were found in the rate of surviving seedlings after treatment with varying doses of FPB among the F₂ lines collected from F₁ plants that survived varying doses of FPB. At a constant temperature of 30 C, seeds from different F₁ and F₂ lines showed germination percentages of 85% to 92.0% and 68.3% to 89.0%, respectively. In the absence of competition, plants from the NL population surviving 0–144 g ai ha^–1 FPB showed no significant differences in plant height, dry weight of aboveground parts, effective accumulated temperature (EAT) from sowing to seed maturation, seed production per plant, or 1,000-seed weight. In the susceptible population (HJ), plants surviving 18 g ai ha^–1 FPB showed no significant differences compared to the nontreated control plants of the same population for the above variables. This is the first report of FPB-resistant barnyardgrass in China. Barnyardgrass seedlings that survived FPB application showed a higher potential for accumulating in the soil seedbank and negatively affecting rice.

Nomenclature: Florpyrauxifen-benzyl (FPB); barnyardgrass, Echinochloa crus-galli (L.) P. Beauv.; rice, Oryza sativa L.