Abstract
Effects of light on the sclerotial formation of two isolates of Rhizoctonia solani Kühn (AG-1, IA) were studied. The irradiation by fluorescent lamp on the mycelia of the isolates increased the number of sclerotial initials and mature sclerotia, although mycelial growth and total weight of sclerotia in a Petri dish were not affected. The irradiation was carried out at several phases of sclerotial differentiation and the promotion was observed at all phases with the most striking effect at hyphal and sclerotial initial phases. The pigmentation of sclerotia during sclerotial maturation was inhibited to some extent by the light, and the tyrosinase activity which catalyzes the melanization decreased concomitantly.
