Heading behaviour in Japan of Turkish populations of cocksfoot,Dactylis glomerata L.

Summary Ninety-nine populations of cocksfoot collected throughout Turkey were examined for heading behaviour at Sapporo, Japan. In some populations, all the plants produced heads in the year of sowing or in the aftermath of the next year. Much of the Turkish populations, even from the mountainous regions with severe winters, is also distinct in heading behaviour in autumn from the north European types, which fail to head in the year of sowing. This behaviour is related to winter temperatures of the place of origin, with the milder winter tending to result in a higher heading rate. Date of heading is also influenced by the climatic factors of the habitat, especially by the length of the growing period between winter and summer dormancies. Turkish populations provided useful material for the study of flowering habit.