Inducing sporulation in different strains of Alternaria solani

Summary

Ultraviolet light induced abundant sporulation in two, out of the three strains ofAlternaria solani studied. Scraped cultures produced larger number of spores than unscraped ones. Ten seconds' exposure was found optimum for maximum sporulation. The optimum temperature of incubation subsequent to irradiation was 20°C. Young cultures were more responsive to ultraviolet light than the older ones. However, old cultures were more tolerant to a greater time of exposure than the younger ones. Intense ultraviolet light greatly reduced or even completely inhibited sporulation whereas low intensity of ultraviolet light was less effective in inducing sporulation. More irradiations than one greatly enhanced sporulation which reached its maximum with four irradiations. Spore length was considerably influenced by the age of the mycelium, temperature of incubation and the intensity and number of irradiations.