Zs. P. Komáromy szerk.: Studia Botanica Hungarica 15. 1981 (Budapest, 1981)

Bohus, Gábor: Some results of systematical and ecological research on Agaricales, VIII

two former ones - the substitution of normal atmosphere for C0

2 was successful, because during the COg treatment, lasting for 30 days, caused some changes in the cells of the mycelium. After C0

2 removal, a thick stroma-like mycelium layer developed spreading up to glasá-cover, and no fruit body grew either. Another experiment, closing also with interesting results, was carried out in the same topic. It could be noticed in the earlier examinations that if part of the surface of the cultures was covered with a plastic sponge full of water, the fruit bodies appeared only on the uncovered surface, and not on the plastic sponge in spite of the fact that mycelium did spread over the surface as well. This phenomenon was similar to that when part of the surface of the cultures was covered with water. In the present experiment, the surface of the cultures was fully covered with a plastic sponge full of water, with the exception of the area of 2 cm dia which had been left uncovered as a hole. The situation became unfavourable for the fruit bodies on the surface covered with a sponge, nevertheless, thus numerically 6 (see the photo) did not appear at the hole but at the bottom of the culture vessel, on the lower side of the culture medium, where the carbon dioxide was accumulated. This area can be considered as completely closed at the beginning of fruit body growth since the mycelium interlaces the culture medium to such an extent that the water, poured on the upper surface, remains on the surface without changing in its quantity for weeks, it cannot get downwards. Naturally in the course of fruit body growth, the interlaced culture medium, separated, as a result of a decrease in its volume, from the wall of the vessel. Discussion It could be stated that the mycelium growth, the fruit body formation and the growth of fruit bodies of Agaricus macrosporoides were undisturbed even at a rather high C0

2 concentration. At the time of the appearance of the fruit body a CO2 concentration of 1.65% was measured, but carbon dioxide does not effect as inhibitor for fructification even at a higher concentration, fruit bodies can appear and grow in a space without ventilation, moreover, at the bottom of the vessels in hermetically closed situation. Compared the observations on Agaricus macrosporoides with for example that of Pleurotus ostreatus

, it can be stated, that the C0

2 tolerance of mycelium naturally extends to a higher percentage at Pleurotus ostreatus

, since it can interlace the hard wood where C0

2 can accumulate in a considerable amount. There is, however, an essential difference in the CO2 tolerance of the fruit bodies

. In cultivation of Pleurotus ostreatus

. owing to the C0

2 sensitivy of the fruit bodies, the keeping of the C0

2 content of the atmosphere at a low level causes a problem; if we cannot succeed in this, the quantity of the production is not satisfactory. This is well indicated by the investigations of SCHÂNËL, KÖZLIK & JABLONSKY (1974) according to which Pleurotus ostreatus in an atmosphere without ventilation, when the diffusion of gases was arrested, did not produce fruit bodies and at CO2 concentration of 0.012% half the quantity of fruit bodies grew than that produced at 0.0068% CO2 concentration. As against this, the fruit body production of Agaricus macrosporoides is much less Influenced by CO2 concentration, this species is more resistive to C0

2

. Ecologically, the advantage of the C0

2 tolerance of this fungus is understandable. Its habitat is in prairie environments where in the more or less dense soil the CO2 content can increase considerably. In heathy soils values as high as even 1.5% were found (ROMELL 1928). In the air layer above the soil surface, the C0

2 concentration is, of course, considerably lower than that. Nevertheless, the fruit body production of Agaricus macrosporoides seems to be accustomed to the higher CO2 concentration. This fact is supported by the experimental observation, that the fructification of the fungus takes place in the soil when the water content of the soil decrease simultaneously with a favourable air temperature. Examination about the dispersion of the fructification of mycelium thalli Record production of soil inhabiting macrofungi can be observed under especially favourable weather conditions. On the basis of our experiments, described below, it can be supposed that a part of mycelium thalli of an area belonging to the identical species and congested reserve food,