An Action Spectrum for Photoinduced Conidium Formation in Alternaria solani (Ellis et G. Martin) Sorauer

Abstract

An action spectrum for photoinduced conidium formation in the fungus Alternaria solani (Ellis et G. Martin) Sorauer was determined by exposing colonies to monochromatic radiation obtained from a diffraction grating monochromator. Reciprocity holds over a wide range of time and dose rate for wavelengths of 242 and 283nm. The most effective wavelength is around 230nm. Three peaks are evident in the action spectrum at around 230, 270 and 285nm, with definite shoulder at about 303nm. Another shoulder is dsicerned at around 240nm. The main trough is at 250 to 260nm. Wavelengths longer than 356nm were not effective in inducing conidium formation even at high dosages given by 6hr continuous irradiation.