STUDIES ON SCLEROTIAL DISEASES OF THE RICE PLANT

Abstract

1. The present paper deals with the morphology and pathogenicity of Sclerotium Oryzae-sativae SAWADA collected from Southern China.2. The size of sclerotia of the fungus produced on potato decoction agar was somewhat diverse according to the localities. It was 266.60-1666.25×266.60-1199.70μ (Mean 741.981±12.674μ in length, 585.354±8.295μ in width) for the “Amoy” (_??__??_) culture strain, 333.25-1732.90×266.60-1466.30μ (Mean 784.137±13.060μ in length, 572.520±8.635μ in width) for the “Tankuei-t'sun” (_??__??__??_) culture strain, and 266.60-1466.30×266.60-1333.30μ (Mean 731.317±14.193μ in length, 547.696±9.327μ in widtn) for the “Fui Sha Wai” (_??__??__??_) culture strain.3. The size of constituent cells of the sclerotia was 11.10-28.86×11.10-26.64μ (Mean 20.468±0;357μ in length, 17.716±0.341μ in width) for the “Amoy” (_??__??_) culture strain, 11.10-24.42×11.10-22.20μ (Mean 18.559±0.366μ in length, 16.583±0.357 in width) for the “Tan-kuei-T'sun” (_??__??__??_) culture strain and 13.32-28.86×11.10-28.86μ (Mean 20.091±0.366μ in length, 17.227±0.333 in width) for the “Fui Sha Wai” (_??__??__??_) culture strain.4. The pathogenicity of the fungus to the leaf sheath of rice plant (Miisinriki variety) differed according to the culture strains. Among these culture strains tested, the “Fui Sha Wei” (_??__??__??_) culture strain was the strongest and the “Amoy” (_??__??_) and the “Tan-kuei-t'sun” (_??__??__??_) culture strains were second to it. In comparison to the “Amoy” culture strain, the “Tan-kuei-t'sun” culture strain was somewhat weaker in the pathogenicity.