Substitution of Light by Indolyl-3-acetic Acid in the Sporulation of Sclerotinia fructigena

Abstract

GROWTH patterns of Sclerotinia fructigena Fries in light and darkness differ markedly. According to Hall1 cultures grown in the dark are characterized by sparse development of aerial hyphae and very little sporulation, while those grown in the light show profuse development of aerial hyphae and much more sporulation. Investigation of the effect of indolyl-3-acetic acid (IAA) on sporulation and growth was carried out. The fungus was grown in Petri dishes on the synthetic medium suggested by Hall1 in a cooled incubator at 25 ± 1° C. Philips daylight fluorescent tubes which emit light of approximately 500 lux were used as the light source and darkness was emulated by Petri dishes kept in the dark in the incubator. Four different concentrations (10, 15, 25 and 50 p.p.m.) of IAA were used in a preliminary experiment and 50 p.p.m. was found to be the most suitable so this concentration was used in later experiments. The percentage of sporulation was calculated by counting under the microscope the tips of hyphae with and without coriidia. The results based on the average often replicates are given in the table.