Oyster mushroom on substrate C80 + WB20 has highest yield and biological efficiency, significantly higher than that on substrates R80 + WB20 and WS80 + WB20. Oyster mushroom on substrates C45 + R45 + WB10 and C30 + R60 + WB10 gave significantly higher yield and biological efficiency (BE) than that on substrate R80 + WB20, and on substrates C40 + WS40 + WB20 and C30 + WS50 + WB20 gave a significantly higher yield and BE than that on substrate WS80 + WB20. Addition of cotton seed hull significantly increased mushroom weight compared to sole rice straw or wheat straw substrate. The mushroom yield and biological efficiency on non-sterilized substrate was not significantly different from that on sterilized substrate, with much lower average yield per flush (Table 3).