Substrates evaluation and effects of ph and nutritional supplementation on production of oyster mushroom (pleurotus ostreatus)
Mushrooms have been grown all over the world for many years because of their culinary, medicinal, bioremediation and biodegradation properties. Lack of locally generated information on substrates for oyster mushroom cultivation has led to over reliance on wheat straw. This is one of the major challenges facing the mushroom sector in Kenya today. Ten different substrates were tested using plastic bag technology in a randomized complete block design (RCBD) experiment to determine their effect on time to pinning, number of caps, average biological efficiency (ABE), pileus diameter, stipe length and flushing interval. Substrates tested were water hyacinth (Eichhomia crassipes), maize cobs (Zea mays), coconut fibre (Cocos nucifera), finger millet straw (Seteria microcheata), banana fibre (Musa sp), sugarcane bagasse (Saccharum officinarum), sawdust (Eucalyptus sp), rice straw (Oryza sativa), bean straw (Phaseolus vulgaris) and wheat straw (Triticum aestivum). The pH of maize cobs, coconut fibre and sugarcane bagasse were adjusted by liming using calcium carbonate to 6.0, 6.5 and 7.0 in order to determine the effect of pH on their productivity. Supplementation with maize germ, wheat bran and rice bran was done on bean, finger millets, rice and wheat straws at 3% dry weight basis to determine their effect supplementation on the productivity of these substrates. Substrates and pH had significant (P::;0.05) effect on average biological efficiency while supplementation had no effect. The average biological efficiency (ABE) varied between the ten substrates from 4.0% on sawdust to 106.2% on bean straw and the time to pinning was from 19.6 days on maize cobs to 39.9 days on water hyacinth. Adjusting the pH of maize cobs, coconut fibre, eucalyptus sawdust and sugarcane bagasse, increased their ABE to between four to tenfold. Supplementation increased the average biological efficiency marginally. Choice of substrate and correct pH adjustment are very important to profitable oyster mushroom cultivation as was observed from the results of this study.