On spectral dependence for maturation of apothecia in Sclerotinia trifoliorum Erik.

Abstract

In order to determine the effective spectral region for stimulating maturation of apothecia of Sclerotinia trifoliorum Erik., sclerotia embedded in sterilized soil were irradiated through coloured cellophane films in a green house under natural conditions or irradiated continuously by fluorescent lamps with glass filters. Radiation filtered throught colourless, blue, green or yellow cellophane films was effective in stimulating maturation of apothecia, while the radiation filtered through red cellophane was not. On the other hand, in the experiment with coloured fluorescent lamps not only red but also green and yellow lamps had no stimulative effect on maturation of apothecia. Studies with glass filters which cut off all radiations shorter than the wavelength designated for each filter indicated that near-ultraviolet radiation between 300 and 390nm stimulated apothecial maturation, whereas wavelengths longer than 390nm were not effective. From these results it can be concluded that the sporulation response to light of this fungus is similar to that of the fungus sensitive to near-ultraviolet radiation, and the effective radiation under green and yellow cellophane is due to transmission bands in near ultraviolet region.