Seed base temperature and emergence of selected Echinochloa crus-galli populations

This study aimed to estimate the base temperature (Tb) for germination and to characterize field emergence patterns of eight Echinochloa crus-galli populations collected from maize fields across Europe. Germination tests were conducted at constant temperatures under controlled conditions to estimate Tb using thermal time models, while field emergence was monitored under Mediterranean conditions. Estimated Tb values were generally consistent with previous studies, ranging around 10 °C for most populations, with the lowest Tb observed in France (7.5 °C) and the highest in Latvia (11.5 °C). Anomalously high Tb estimated for the Spanish population (15.9 °C) was attributed to low germination and requires further validation. Field emergence dynamics revealed two main population groups: Central and Northern European populations emerging predominantly during winter, and Southern populations emerging mainly after soil disturbance. Emergence patterns were well described by sigmoid models. These results highlight both similarities in thermal requirements among European populations and clear differences in emergence behaviour, with implications for region-specific weed management strategies.