Differences in the progression of successive flowering between summer and autumn ecotype cultivars in common buckwheat (Fagopyrum esculentum moench)

The common buckwheat cultivars "Shinanonatsusoba'' (summer ecotype) and "Miyazakizairai" (autumn ecotype) were cultivated in pots with soil (sandy loam) in summer and autumn at Meijo University, Nagoya. The flowering position in the flower clusters on a plant and their flowering date were investigated. Shinanonatsusoba in summer and Miyazakizairai in autumn had 600 to 850 flowers per plant during the flowering period of about a month. Shinanonatsusoba in autumn and Miyazakizairai in summer yielded fewer seeds. In these cases, Miyazakizairai had remarkably many flowers (more than 2,600) and a long flowering period of four months, but the seed-setting ratio was low. Shinanonatsusoba had few flowers (199) and a short flowering period of half a month, although the seed-setting ratio was high. Miyazakizairai in summer showed three peaks of flowering and the same end time with autumn cropping. Furthermore, (1) continuation of the occurrence of new flower clusters, (2) differentiation of new flower buds on flower clusters that had once ceased flowering, and (3) regrowth of dormant lateral buds were observed at the later stage. Within a flower cluster, a greater number of flowers and a longer flowering period were also evident. Moreover, It is important to note that they showed long intervals of flowering among flower clusters, subflower clusters, or flowers in a subflower cluster. In autumn, Shinanonatsusoba had the same intervals as in summer, but they had only few flower clusters, subflower clusters, and flowers in a subflower cluster.