Seedling emergence traits of susceptible (S) and resistant (R) blackgrass subpopulations isolated from a single non—target-site resistant (NTSR) population were studied in controlled conditions. The seedling emergence of the R subpopulation was lower and slower than that of the S subpopulation, especially at low temperature and deep burial. The burial depth inhibiting final emergence by 50% for the R subpopulation was significantly lower than that of the S subpopulation at low temperature. The present study revealed that under suboptimal conditions the NTSR loci conferring herbicide resistance were correlated with a fitness cost in relation to seedling emergence traits. The results suggest that deep soil cultivation and delayed sowing of autumn-sown crops can hamper germination of the R more than of the S subpopulation and thus potentially reduce the prevalence of the R subpopulation in the blackgrass population.

Nomenclature: Blackgrass, Alopecurus myosuroides Huds. ALOMY.