Growth and Dormancy inLunularia cruciata(L.) Dum.: III. THE WAVELENGTHS OF LIGHT EFFECTIVE IN PHOTOPERIODIC CONTROL

Abstract

Growth and dormancy in Lunularia are controlled by daylength, short-day promoting active growth, long-day or light-break treatment inducing dormancy. Light-breaks of red light are highly effective in inducing dormancy, while irradiation with other wavebands is much less inhibitory to growth. Far-red light given after red irradiation causes substantial reversal of the red-light effect, suggesting strongly that phytochrome is involved in the photoperiodic response mechanism of Lunularia. However, even short(15 sec.) exposures to far-red light alone cause significant growth inhibition, and it is considered possible that far-red irradiation also leads to the formation of some of the P 730 form of phytochrome.