In order to develop a single light source which can be used both for moth control and flower inhibition in chrysanthemum, effects of blue (463nm), green (519nm), yellow green (576nm), yellow (597nm) and red light (646nm) LEDs on the flowering and the cut flower characteristics of chrysanthemum were investigated. As irradiance increased, the days to flower budding increased except under blue light. Yellow green and yellow LED had flower inhibiting effect equivalent to red LED. There was no difference in the crown bud number and the occurrence of abnormal flower irrespective of the light quality and irradiance. Next the, effects of night break and continuous lighting treatment by yellow LED on the flowering and cut flower characteristics of the chrysanthemum were investigated. There were significant differences in the cut flower characteristics except for the blade number on the neck in these treatments ; there was no practical problem with night break or continuous lighting. The minimum irradiance strength enough for flower inhibition in the continuous lighting treatment was about 80 mW m−2 that was half in night break treatment. Therefore, it is considered that yellow LED can be used as single light source for both moth control and flower inhibition in chrysanthemum.
illuminated culture
light-emitting diode
long day treatment
regulation of flowering
spectral quality of light