Action Spectrum between 250 and 800 Nanometers for the Photoinduced Inhibition of Spore Germination in Pteris vittata

An action spectrum between 250 and 800 nm for the inhibitionof red-light-induced germination of spores in the fern Pterisvittata was determined on the Okazaki Large Spectrograph. Theresultant spectrum showed prominent peaks of effectiveness atabout 370, 440 and 730 nm and a minor peak in the neighborhoodof 260 nm. Next, a brief red light irradiation was given immediatelyafter the monochromatic irradiation to cancel the inhibitoryeffect caused by simultaneously formed P_R. This resulted ina complete disappearance of the peak at 730 nm and considerabledecrease of other peaks in the shorter wavelength region exceptat 260 nm. Further correction of the latter spectrum by consideringthe transmission spectrum of a spore coat revealed that 260nm light acted more effectively than lights of 370 and 440 nm.The inhibitory effect of UV light on spore germination was nullifiedby subsequent irradiation with red light for 24 h or darknessfor 48 h followed by a brief red irradiation, indicating thatthe inhibitory action of UV light was ascribable to a blue-ultraviolet light-absorbing pigment. ⁴Present address (KT) and permanent address (MF): Botany Department,Faculty of Science, University of Tokyo, Hongo, Tokyo 113, Japan. (Received July 30, 1983; Accepted November 21, 1983)