Rozkład drewna olszy czarnej Alnus glutinosa (L.) Gaertn. przez grzybnię lakownicy żółtawej Ganoderma lucidum (Curtis) P. Karst. w warunkach laboratoryjnych

Black alder is an important forest−forming species in Poland. Its wood is decomposed by many species of fungi. Ganoderma lucidum (Curtis) P. Karst. is a species of Basidiomycetes which belongs to family Ganodermataceae, order Polyporales. This fungus causes white rot decay of wood in dead and sometimes living alder trees. G. lucidum has been under partial protection in Poland since 2014. It is also red−listed as a rare species (category R – taxa with small populations) on the ‘Red list of the macrofungi in Poland’. The fungus was cut out with a sizeable fragment of wood from the alder stump in Łuków Forest District (eastern Poland) and transported to the laboratory of the Department of Mycology and Forest Phytopathology, Warsaw University of Life Sciences−SGGW. Pure culture of G. lucidum mycelium was obtained from a fragment of fruitbody. The aim of this study was to investigate, through laboratory decay tests, the ability of G. lucidum to degrade alder wood. Sterilization of wood samples (30×20×20 mm) consisted of placing the material in an accelerator and irradiating it with high−energy electrons at a dose of 30 kGy at the Institute of Nuclear Chemistry and Technology in Warsaw. On the next day, wood samples were put into 200 ml flasks with mycelium of G. lucidum on agar−wort medium (2 samples per flask). The flasks were placed in a Heraeus BK 600 incubator for 180 days, with a constant temperature of 22°C and humidity of 80 ±5%. Every 30 days 10 flasks were randomly selected, i.e. 20 samples of alder wood from this experiment. After each incubation period the samples were removed from the flasks, cleaned to remove mycelia and dried at a temperature of 105°C until they reached constant weight. By comparing mass of the samples at the start and the end of experiment in an absolutely dry state, the relative wood mass loss was calculated. After exposure times 180 days, the relative weight loss of alder wood as a result of decay by G. lucidum mycelium was on average 10.88%. The rate of the decay was almost constant during the study period. On some alder wood samples structures resembling fruitbodies of G. lucidum were noticed.