Echinochloa crus-galli is a highly competitive annual weed distributed across a wide climatic gradient. Appropriate timing is important for successful control, therefore modelling of phenological developmental stages can be a useful tool for a decision support system. Predicting flowering time is also useful to reduce seed production. Phenological development of E. crus-galli plants was studied in a common experiment by the EWRS working group Germination and Early Growth. Sowing was done in October-November 2015 and plant development was studied in the following vegetation season. Seeds from two common populations (Italy (South) and Norway (North)) and 1-3 local populations were sown in 25 cm pots at each of the study sites to monitor emergence. In each pot three plants were preserved for monitoring development using BBCH scale. Soil disturbance and fertilization was performed in March-April 2016. Time required for the plants of different populations to reach certain development stages at different sites was analysed. There was a significant difference in the time required to reach BBCH12 (two leaves unfolded) between the locations, but no differences between the populations, except in Poland. Location was a significant factor for time to reaching BBCH23-25 (3-5 tillers), but no difference was detected among populations except in the location in Italy. However, timing of the onset of flowering (BBCH over 49) was different and was significantly delayed in plants of South population at several locations, while plants of the North population developed faster. This can be explained by quantitative photoperiodicity in E. crus-galli (a short-day plant) that was pronounced in the South population but not in more northern populations. The data will be further used to develop models of early development of E. crus-galli. The possibility of using the cumulative degree-days to model its phenological development is discussed.
