Substrate preparation
The substrates consist of sawdust, rice meal and calcium carbonate, CaCO3 in 100:10:0.1-1 ratio. Polypropylene bags were filled with 800 g of substrates with 70% of water (Norouzi et al., 2008) and the bags were tightly closed with neck and cap then sterilized once in hot steam container for 24 hours. The substrate was allowed to cool down before being injected with mushroom spawn. The regular amount of spawn was 3% based on the substrate weight (Kalberer and Kunsch, 1974). The bags were subsequently kept in spawn running room with 75 -85% relative humidity until the formation of primord ia. Then the bags were uncapped and transferred to the fruiting room to allow the normal development of fruit bodies. The bags were kept in bed position on rack (240 cm × 90 cm) at 25°C with a 12 hours photoperiod and 80–90% relative humidity. Adequate ventilation was provided to prevent increase of carbon dioxide gas, CO 2 concentration in the room which will inhibit the fruit body development (Norouzi et al., 2008)