Abstract
We cultured rose tissues under irradiation of LED and LD at different wavelengths, and examined their effects on the growth and flowering of roses. As a result, flower-bud differentiation was rarely observed under irradiation of red (660 nm) and green (517 nm) LED, but it was enhanced by irradiation of blue (465 nm) and bluegreen (502 nm) LED. In particular, flowering was observed in 76% of the samples irradiated with blue-green LED, which was the highest flowering rate. However, flowering occurred earlier by irradiation of blue LED than by that of blue-green LED, and the flowering position (node position) was lower by the former irradiation than by the latter irradiation. The irradiation of LD (445 nm) demonstrated a higher flowering rate and earlier flowering than the irradiation of LED, but the growth rate was lower by the former irradiation than by the latter irradiation. This may be because there are photoreceptors that absorb blue to blue-green light and induce flower-bud formation. Since the wavelength width of LD is smaller than that of LED, energy for the increase in the growth rate may have been suppressed, and used for the reproductive growth, resulting in the enhancement of flowering.
