STUDIES ON THE CULTIVATION OF PSATHYRELLA ATROUMBONATA Pegler: AN INDIGENOUS EDIBLE MUSHROOM

ABSTRACT

Studies on the cultivation of Psathyrella atroumbonata Pegler were carried out. The mushroom grew satisfactorily on three agar media tested. The optimum temperature for the growth of the mushroom was 25⁰C while the best pH for its growth was between 6 – 8. The mushrooms grew well in all spawn materials tested (Sorghum, Pennisetum and Zea mays). Supplementation of the spawn materials with calcium carbonate and calcium sulphate promoted mycelial growth and reduced the number of days for complete colonization of the materials. The mushroom was able to utilize glucose better than other carbon sources tested. The three organic nitrogen sources supported mycelial growth better than inorganic nitrogen sources tested. Thiamine was found to be the best vitamin for mycelial growth while asparagine supported the best mycelial growth out of the five amino acid tested. Carbon to nitrogen ratio of 4:1 supported the highest mycelial growth while the ratio above this level reduced the mycelial growth. Nitrogen to carbon ratio of 4:1 also supported good growth. Psathyrella atroumbonata Pegler adapted readily to the non-wood substrate tested. It could utilize a wide range of substrates for mycelial growth and sporophore formation. It gave maximum mycelial extension on oil palm fruit fibres and corn cobs with an average of 12 days for complete colonization of the substrates. The longest period was observed on corn husks with an average of about 20 days for complete colonization. The first sporophore appeared on rice straw after 96 days of inoculation with the spawn while it took 108 days for sporophore to emerge on corn stems. There was mycelial formation on corn cobs, corn husks, and guinea corn shafts but there was no sporophore formation on them. There was temperature change in the substrate during cultivation. The temperature rose steadily during the fermentation and decomposition of the substrate to 31.2⁰C, and dropped to about 26.6⁰C before the emergence of the sporophore. Many contaminants were found associated with the substrates used for cultivation. These contaminants were mostly moulds, and their effects ranged from delay to complete inhibition of sporophore formation. Application of casing enhanced sporophore formation and reduced the number of days for sporophore emergence. Supplementation of substrates with wheat bran, NPK, urea and soyabean meal at different levels had no significant effect on the mushroom yield. Nutritional evaluation of P. atroumbonata showed that the mushroom is very rich in protein, crude fibre and ash. It has low lipid and low sugar content. The nutrient composition was affected by the stage of development. Most of the nutrients were maximum at the immature stage and decreased during further development of the mushroom. Psathyrella atroumbonata contains some secondary plant products, including alkaloids, saponins and tannins. The presence of these plant products indicate the potential medicinal value of this mushroom.