Recruitment biology of cleavers (<i>Galium</i> spp.) populations in western Canada

Abstract Two species of cleavers, Galium aparine L. and spurium L., are known to inhabit croplands in western Canada. The latter is the more abundant two species. An increased abundance these over most recent decades warrants a comprehensive understanding their developmental phenology cause this increase. This study aimed identify base temperature emergence characteristics spp. across different populations from A thermal gradient plate experiment was conducted using five G. collected various Saskatchewan (SK) Alberta (AB) locations. One reference sample also included. common garden six determine characteristics. germination identified 2 C for all 4 G . median 8.34 C, whereas had similar 6.5 C. Despite characteristics, field revealed differences between populations’ initiation (150 250 growing degree days [GDD]) time 50% (275 470 GDD) spring. Highly variable among years within year (200 600 GDD 2013 100 200 2014) were observed during fall, probably due moisture availability. Cumulative fall very low (1% 9%) compared with spring (2% 17%). Overall, provides evidence periodicity populations, both which may be significant factors contributing seasonal success