Survey of Herbicide-Resistant Weed Biotypes Across Intensive Cereal Production Areas Using Bioassay and Molecular Markers

Abstract

Survey of herbicide-resistant weed biotypes across intensive cereal production areas was conducted using bioassay screening and molecular marker analysis to assess the extent and mechanisms of resistance evolution. Field populations of dominant weed species were collected from major cereal-growing regions with a history of repeated herbicide use. Greenhouse dose–response bioassays were performed to evaluate survival, growth reduction, and resistance levels against commonly used herbicide modes of action. Results confirmed the widespread occurrence of resistant biotypes exhibiting variable degrees of tolerance, with several populations showing multiple resistance patterns. Molecular characterization using target-site gene sequencing and PCR-based markers revealed the presence of known resistance-conferring mutations as well as evidence of non-target-site resistance mechanisms. Enhanced metabolic detoxification and reduced herbicide uptake were implicated in certain populations lacking target-site alterations, indicating complex resistance evolution. Spatial analysis of surveyed fields showed clustering of resistant biotypes in high-input cereal systems, highlighting strong selection pressure associated with continuous herbicide reliance. The integration of bioassay and molecular approaches provided robust confirmation of resistance status and mechanistic diversity. The study underscores the rapid adaptation of weed communities under intensive management practices and emphasizes the need for diversified weed control strategies. These findings support the implementation of integrated herbicide resistance management programs combining chemical rotation, cultural practices, and molecular monitoring for sustainable cereal production systems.