Abstract
Weed management remains one of the primary agronomic bottlenecks in organic maize (Zea mays L.) production across the Forest-Steppe zone of Ukraine. This study evaluated the allelopathic potential and phytochemical profiles of aqueous and ethanolic extracts from four winter cover crops—winter rye (Secale cereale L.), hairy vetch (Vicia villosa Roth), white mustard (Sinapis alba L.), and oil radish (Raphanus sativus var. oleiformis Pers.)—against three dominant weed species: redroot pigweed (Amaranthus retroflexus L.), common lambsquarters (Chenopodium album L.), and barnyardgrass (Echinochloa crus-galli (L.) P. Beauv.). High-performance liquid chromatography coupled with tandem mass spectrometry (HPLC-MS/MS) revealed marked variation in allelochemical profiles, identifying high concentrations of benzoxazinoids (DIBOA and BOA) in S. cereale and glucosinolate degradation products alongside phenolic acids in Brassicaceae species. Laboratory bioassays demonstrated that S. cereale and S. alba extracts at 10% (w/v) concentration significantly suppressed weed seed germination and radicle elongation by up to 88.4% and 82.1%, respectively, while exerting negligible phytotoxic effects on maize emergence. In companion field microplot trials, incorporating rye and mustard biomass achieved early-season weed biomass reductions exceeding 64% without impairing maize grain yield. These findings highlight the viability of utilizing allelopathic cover crop residues as integrated bioherbicidal components in sustainable organic maize cropping systems in Eastern Europe.
