THE RELATION BETWEEN RED AND BLUE OR FAR-RED LIGHTS IN THE NIGHT-INTERRUPTION OF THE PHOTOPERIODIC TUBERIZATION IN BEGONIA EVANSIANA

Effects of night-interruption on the aerial tuber formationof Begonia evansiana Andr. were investigated. Among coloredlights tested, red light was most effective to reduce the photoperiodicresponse. It inhibited tuberization almost completely at lowintensities. The red lightaction was partially reversed by subsequentblue or far-red irradiation under the 12-hour daylength, andthe relation between the red and the blue or far-red lightswas reversible. No reversal, however, was observed under the8-hour daylength. The inhibitory action of red light remainedunchanged on irradiating with red, blue or far-red light beforethe night periods. ¹Present address: Department of Horticulture, Purdue University,Lafayette, Indiana, USA