Present paper was attempted to investigate the effect of carbon and nitrogen sources on the mycelial growth of several isolate strains of Sclerotinia sclerotiorum(Lib.) de Bary isolated from cucumber, rape and lettuce, and to investigate the relationships between nitrogen forms absorbed and mycelial growth or change of pH of cultural solution.
The results are abstracted as follows:
1. The mycelial growth of cucumber and lettuce isolate strains was usually good on the media tested, but that of rape one was poor.
2. Glucose, sucrose, maltose, soluble starcin and dextrin were good as the carbon sources for mycelial growth of cucumber and lettuce strains, but lactose and glycerin were not so good. Glucose, sucrose and dextrin were good for rape strain.
3. KNO₃, NH₄Cl, NaNO₃, NH₄NO₃ and (NH₄)₂SO₄ as the nitrogen sources for mycelial development of cucumber strain, NH₄Cl, (NH₄)₂SO₄, NH₄NO₃, NaNO₃ and KNO₃ for lettuce strain, NH₄Cl, NH₄NO₃, KNO₃, (NH₄)₂SO₄ and NaNO₃ for rape strain, were poor in the order described. KNO₂, however, was poor for all strains. According to the results, different effect of nitrogen forms, NH₄-N and NO₃-N, on the mycelial growth was not recognized obviously through all strains.
4. Showing the effects of C/N ratio on mycelial development, those of cucumber and lettuce strains were increased logarithmically with being increased the carbon source(glucose) up to 20g/ℓ cultural solution, that of rape strain, was rather inhibited at 10g/ℓ or more than. Amount of carbon source, therefore, seems to act as limiting factor for mycelial growth.
5. Though both nitrogen forms, NH₄-N and NO₃-N, in culture solution were absorbed together in early stage of growth of all strains, absorption amount of NO₃-N was larger than that of NH₄-N, and having nothing to do with absorption of both nitrogen forms, pH of cultural solution was dropped below than initial pH 5.0.
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