Zs. P. Komáromy szerk.: Studia Botanica Hungarica 16. 1982 (Budapest, 1982)
Bohus, Gábor: Some results of systematical and ecological research on Agaricales, IX.
Mycelium thalli without fruit body formation? By reason of observations in the nature a question was stated, whether it is possible that in soils of certain pH-value the spores of some fungus species are still able to germinate and the formation of mycelium thalli takes place, but the fruit body formation in case of such soil chemical reaction does no longer ensue. In order to examine this question experiments were carried on with Agaricus macrosporoides, because this species is able to fructify regularly under experimental conditions. In the earlier experiments related to the above question, the following data had already become known (BOHUS, 1978). 1) Mycelium thallus formation could be observed at a pH between 3.7 and 7.0. 2) In vitro experiments, fruit bodies were observable even at pH 4.2, but this was the lowest value. Fruit bodies grew also in the compost of manure of horses, in culture premises (on the culture media of Agaricus bisporus) . The pH value of the substratum was about 7. In the present experiments it was examined what are the pH limits are between which spore germination still occurs. It was stated that the spores germinate between pH 4.0 and 7.0, but it is possible that a little below pH 4.0 there is still spore germination and the upper limit can be a little higher than pH 7.0. This can be inferred from the fact that the growth of thalli originated from spores germinating at pH 7.0 is more protected than the growth of the control: the radius of the thalli is 2-3 mm when in the case of the control that germinated at pH 5.2 it is ten times more than that. Spores of Agaricus macrosporoides can germinate at about a value of pH 4.0, but mycelium growth can be observed at even pH 3.7. In the experiments presented, the pH of culture media was 4.2 and it proved to be suitable for fruit body formation. To answer the question whether it is possible to attain the fruit body formation in a culture media with a lower pH value than the former an opportunity was offered by the use of ammonium salts of strong acids as nitrogen source. If no CaC03 is used as a chemical binding the acid, the culture media turn sour strongly as a result of the using of ammonium ion, and this creates unfavourable conditions for a number of fungus species. This does not however happened in the case of Agaricus macrosporoides , which is able to grow even in a strongly acidic medium, and the interlacing of the culture medium does ensue. The observed pH values were as follows: on the 47th day of interlacing, 3.35; on the 61th day, 3.7. No fruit body was, however, formed in the thalli during the 90 days' - usual observation period. Since it is a good characteristic of this species that preceding the fruit body formation, a great number of primordia appear in the thalli, it was remarkable in the present examination that below pH 4.0 values there was only one primordium which could be found in one the cultures. It is thus at such low pH values that the mycelium thalli of this species can live in the soil without a result that fruit body formation could take place. On the basis of the example it can be supposed that this is possible also with other species. Festucetum pseudovinae Achillea Artemisia Camphorosmetum annuae 10-15 cm Puccinellietum limo6ae 1 Iii Fig. 3. Fig. 3. Microrelief on a saline pasture on Hortobágy (Hung.)
