FLOWER INITIATION IN TOTAL DARKNESS IN A QUANTITATIVE SHORT DAY PLANT,

The flowering behavior of two cultural varieties of Fagopyrum esculentum Moench aseptically cultured in total darkness was studied. The effect on the flower initiation of some chemical substances added to sterilized dry seeds was also investigated. Low temperature was found to be more suitable for flower initiation in buckwheat plants. 2-Thiouracil promoted flower initiation at high temperature in total darkness and inhibited it at any temperatures examined under light conditions. Sucrose promoted flower initiation at higher temperatures than 15°. Lithium chloride and peptone inhibited flower initiation only at high temperature. Indoleacetic acid, gibberellin and kinetin had no effect on flower initiation in total darkness. It is postulated that in the flowering response the primary reaction may be connected with the metabolism of sucrose and ribonucleic acid. Since the discovery of flower initiation in total darkness in Raphanus sativus L. by TASHIMA (1), many experiments have been done in total darkness with some success in inducing flowering (2-8). In short day plants such as Pharbitis Nil Chois. (morning glory) and Cuscuta japonica (dodder), it has also been ascertained that they are capable of initiating flower primordia in total darkness, i.e. independently of light condition (9, 10). By using aseptic culture of buckwheat, the present experiments were designed to study the effect of temperature, sucrose and some growth substances on flower initiation in total darkness. MATERIALS AND METHODS The materials used in the present experiments were two cultural varieties of Fagopyrum esculentum Moench, "Shinano No. 1 " and "Hashi-kamiwase". It was reported that all varieties of buckwheat investigated were quantitative short day plants (11). Unless otherwise mentioned, the basic culture medium was a modified WHITE'S medium containing MgS04-7H;>0 260 mg, CafNO,) ^ 411,0 200 mg