Abstract
(1) Recently it has been shown that some plant pathogenic fungi require growth factors for their normal development. The present paper deals with the results of experimental studies on the effects of thiamine and the nitrogen as well as the carbon sources of Stagonospora carpathica Baeum., the causal fungus of the brown spot of broad bean.
(2) In the cultural experiment using the modified Czapek-Dox solution, it has been shown clearly that the present fungus grows easily in the case of vitamin-free, while Ceratostomella fimbriata does not grow in the medium lacking thiamine. Judging from this fact thiamine is recognized to be the dispensable growth-factor for the present fungus.
(3) According to the results of the present experiment, both nitrate and nitrite seem to be good sources of nitrogen for the growth of Stagonospora carpathica BAEUM. Ammonium salts such as ammonium chloride or ammonium sulfate are worthless as nitrogen source for the present fungus, probably because of the dropping in pH value of the medium used, while the salts such as ammonium oxalate or ammonium citrate give the good result for its growth. It is, however, unknown whether the oxalate or citrate acts as carbon source for the present fungus.
(4) The various amino-acids and amides differ in value from each other as nitrogen source for the growth of this fungus. As nitrogen source, tyrosine, glycocoll and asparagine are of use better, but worse in leucine and urea than nitrate. It seems to be doubtless that cystine and thiourea are inadequate nitrogen sources for this fungus.
(5) Judging from the results of the writer's experiment on the present fungus, fructose, arabinose and xylose are most excellent as carbon sources, being followed by glucose, mannose, galactose, sucrose, maltose and starch. As carbon sources lactose and mannitol are not advisable to use and glycerol is not proper for the present fungus.
