An Action Spectrum for Light Induced Sporulation in the Fungus Ascochyta pisi

Abstract

Five-day-old dark-reared colonies were irradiated with monochromatic radiation of known intensity and having a band width of 10 m/i. Wavelengths from 230 to 360 m[mu] inclusive were effective in inducing sporulation but not radiation of longer wavelengths. The action spectrum showed 290 m[mu] radiation to be most effective. Increased effectiveness was also shown at 260 and 230 m[mu]. Radiation at 290 m(i was approximately 5000 times more effective than 360 m[mu] radiation. A possible relationship between the action spectrum and a sporogenic substance (P310) extracted from A. pisi and other fungi is discussed. A crude action spectrum derived from the published results of irradiation studies with Pleospora herbamm (Stemphylium stage) corresponds quite closely to that obtained for A. pisi and it seems likely that the action spectrum for A. pigi will be found to be common to other fungi.