Influence of day length on stem growth, flowering, morphology of flower clusters and seed set in buckwheat (Fagopyrum esculentum Moench)

Hiroyasu Michiyama¹, Keiji Tsuchimoto¹, Ken-ichiro Tani¹, Tatsuya Hirano¹, Hisayoshi Hayashi² and Clayton Campbell³

¹ Faculty of Agriculture, Meijo University, Tenpaku-ku, Nagoya 468-8502, Japan ² Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8572, Japan ³ Kade Research Ltd., Morden, Manitoba, R6M 1E9, Canada

Hiroyasu Michiyama, Keiji Tsuchimoto, Ken-ichiro Tani, Tatsuya Hirano, Hisayoshi Hayashi and Clayton Campbell. 2005. Influence of day length on stem growth, flowering, morphology of flower clusters and seed set in buckwheat (Fagopyrum esculentum Moench) Plant Prod. Sci. 8: 44-50

Abstract: The effects of day length on main stem growth, flowering, morphology of flower clusters and seed-set were examined in three buckwheat cultivars Shinanonatsusoba (summer eco-type), Miyazakizairai (autumn eco-type and BLO 1999 ( a long cluster line which usually develops DM clusters at Kade Research Ltd., Canada). Long-day treatment prolonged the stem elongation period, elevated the first flowering node, delayed the first flowering day, increased the number of nodes, flower clusters and flowers on the main stem, and decreased the increase rate of flowering-cluster number, the number of seeds and the seed-set ratio on the main stem. It also increased the frequency of DM clusters, the length of the flower clusters and the number of sub-flower clusters per cluster in Shinanonatsusoba and Miyazakizairai as well as in BLO 1999. The effects of day length varied among the growth parameters and there were three types of responses to day length. The difference between the summer and autumn eco-type cultivars in the response to day length was elucidated in four groups of parameters:(1) main stem elongation; (2) first flowering node and first flowering day; (3) increase rate of flowering-cluster number on the main stem; and (4) the number of seeds and seed-set ratio.

Key words: Buckwheat, Day length, Eco-type, Flower cluster, Flowering, Growth, Seed-set