Potential genetic variation of flowering time in late-summer type cultivar of buckwheat (Fagopyrum esculentum Moench) in Kyushu region [Japan]

Most of the cultivars of buckwheat (Fagopyrum esculentum MOEINCH) in Japan are classified into two ecotypes ; summer and late-summer types. The summer type cultivars are mainly distributed in regions of high latitude (37-45 whereas the late-summer type cultivars are distributed in regions of low latitude (31-34, the former being assumed to have differentiated from the latter. It has been reported that the summer type cultivars are non-sensitive to day length unlike the late-summer type cultivars. We carried out the present experiment to analyze the process of phylogenetic differentia-tion of the summer type cultivars from the late-summer type cultivars, with emphasis placed on the genetic changes in flowering time and seed yield in the long-day summer and the short-day autumn seasons in Tsukuba, Ibaraki (Lat. 36North) (Table 1 and Fig. 1). The summer type cultivars did not exhibit any variation in the flowering time in either seasons. However, the late-summer type cultivars grown in the summer season showed remarkable variations in the flowering time ranging from early to late (Fig. 2) along with a drastic decrease in seed yield (Table 2).