The goal of this study was to identify factors determining weed species composition in soyabean crops in Hungary, where its expanding production faces difficult weed problems. The abundance of weed flora was measured in 262 fields across the country, along with 38 background variables. Using a minimal adequate model containing 24 terms with significant net effects, 21.6% of the total variation in weed species data could be explained. Plot location (edge vs core position, the single site variable in our analysis) was found to be the most important explanatory variable that was followed by a set of environmental (temperature, precipitation, altitude, soil texture, pH, Ca, K, Na and humus content), cultural (cultivar maturity, organic manure, fertiliser P and N, row spacing) and weed management (flumioxazin, pendimethalin, dimethenamid, propaquizafop, bentazone, quizalofop-p-ethyl, quizalofop-p-tefuril, linuron, thifensulfuron) factors. Variation partitioning revealed that environmental variables accounted for about four times more variance than cultural and about two and half times more than weed management variables. Chenopodium album, Ambrosia artemisiifolia, Hibiscus trionum, Echinochloa crus-galli and Convolvulus arvensis were the most dominant and frequent weeds, but their abundance was influenced by different factors. The responses of weed species to the studied variables provide new information about their ecological behaviour, and our findings also can be used to develop better weed management strategies.

Stachys annua (L.) L.– a typical annual weed species in stubble fields – was the most important melliferous plant in the Carpathian Basin during the 19th century. The agricultural intensification led to a drastic decline in the species, and previous efforts for its cultivation were unsuccessful due to its unevenly germinating seeds. This study aims to identify an effective method for overcoming the primary seed dormancy of S. annua. In laboratory experiments, we evaluated the effects of moist stratification for 4 weeks (in cold/warm sand) as well as using a gibberellic acid (GA) solution (250 mg/L) on seed germination under two light-temperature regimes (a “constant” regime at 20°C in continuous darkness, and a “fluctuating” regime with 14 h light at 20°C followed by 10 h dark at 10°C). Our results indicate that freshly matured seeds were mostly dormant at maturity. Gibberellic acid has a substantial role in breaking seed dormancy and can help substitute for the cold requirement. The best combination consisted of a GA treatment following a short (4 weeks) warm stratification, which led to a high (98%) germination rate in darkness at 20°C. The results indicate that, under natural circumstances, the seeds of S. annua require a longer period for their primary dormancy to be released. Our findings can establish the basis for the development of a dormancy-breaking technology to achieve uniform germination allowing future cultivation of the plant in bee gardens and arable fields.