Abstract
Inhibitive effect of some amino acids on sclerotial formation of Rhizoctonia solani (AG-1) was tested. Few or no sclerotia were formed on sulfur containing amino acids, histidine, leucine, isoleucine, tryptophan or tyrosine amended medium. Among these amino acids, leucine was not inhibitive and was merely unuseful for the formation. Inhibitive amino acids limited sclerotium formation and affected scarcely mycelial growth. Although the structural difference between cysteine and serine or homocysteine and homoserine was small, their effects on the formation were completely reverse. Sulfur or sulfhydryl bond could be an inhibitive principle. D-isomers of stimulative amino acids inhibited the formation.
