1980 Volume 49 Issue 2 Pages 251-259
Uncolored detached- and intact-petals of floribunda rose ′Ehigasa′ were subjected to various light treatments. In vitro culture of the detached petals, sucrose concentration of 10 to 20% in medium was favorable to anthocyanin formation. The petals remained colorless in darkness and under irradiation of light excluding UV. Anthocyanins were produced by the irradiation with UV region below 330nm and were increased with increases in duration and intensity of UV irradiation. When the total amount of UV radiant energy was equal, UV irradiation of long duration at low intensity produced considerably more anthocyanins than that of short duration at high intensity. Irradiation with visible light before or along with UV markedly stimulated anthocyanin formation as compared to UV irradiation alone. Furthermore, increased intensity of visible light along with UV irradiation enhanced anthocyanin formation. In the intact petals, UV irradiation in the daytime was more effective for anthocyanin formation than that in the nighttime.