Proceedings ofthe 9th International Symposium on Buckwheat, Prague 2004 Evolution of Flowering and Ripening Within Inflorescence of Buckwheat Plants, Effect of Reduction of Sinks and Seed Setting of the Two Floral

The evolution of open young flowers, closed flowers, green kernels, brown kernels and aborted kernels was monitored within inflorescence of node lOon the main stem of field grown buckwheat plants submitted to different degrees of removal of inflorescences. The three treatments were: control, complete removal of inflorescences situated on the lateral ramifications of buckwheat plants and partial removal (50%) of inflorescences of the whole plant (main stem and lateral ramifications). In all cases (whatever the treatment) flowers continued to appear within inflorescences during extended period of time and there was a drastic reduction of grain number relative to number of flowers formed. Examination of cumulative curves of development stages confmned clearly that this happened shortly after flowering whatever the moment of flowers appearance within the inflorescences. The low number of kernels was mainly due to early abortion of flower occurring just after flower opening. The treatments of suppression of inflorescences presented a better seed setting than the control treatment by reducing this early abortion rate, major factor of the general very low seed setting of buckwheat plants. Therefore, there was no significant difference for the final mean yield of brown kernels per plant between the plants with removal inflorescences and control plants, in spite of a smaller number of inflorescences. The plants submitted to removal of inflorescences compensated by reducing the abortion rate in the remaining inflorescences. In the source-sink relationship, the sink parameter seemed to be a significant factor. The distribution of the brown kernels through the whole plant and the seed setting appeared to be very similar between the thrum and pin flowers ofbuckwheat plant