Swedish substrates suited for circular production of the edible gourmet mushroom maitake

Abstract: A selection of locally sourced substrates were evaluated for hyphal growth and fruiting body production of the edible gourmet mushroom maitake (Grifola frondosa). Hyphal growth was evaluated on a wide range of substrates (30) including different leaves, sawdust and waste from food production and the substrate that performed best was potato peelings, which showed development of a remarkably dense mycelium. Fruiting body production was studied on eight different substrates including enriched sawdust of alder, birch, oak and fir and the residues apple pomace, oat okara, betfor (a feed product based on residues from sugar beets) and a mixture of betfor and deproteinized rapeseed cake. A literature study was performed to determine commonly used cultivation conditions for G. frondosa and these were applied in the fruiting body experiment. Despite problems with mould infection in the cultivation chamber mushrooms could be harvested from the boxes with enriched fir substrate. Other substrates, such as rapeseed and betfor mix, had primordia but these had not reached full size at the end of the project. It appears G. frondosa mycelium thrives on waste products from agriculture and food production, but further work is needed to determine if fruiting body production is possible on these types of substrates. However, fruiting bodies can be produced on enriched fir substrate which is an easily available substrate in Sweden. Also, aspects of circular production, i.e. reusing the spent mushroom substrate in further production, is highlighted in this work.