Influence of substrate formulation on some morphometric characters and biological efficiency of Pleurotus ostreatus EM-1 (Ex. Fr) Kummer grown on rice wastes and “wawa” (Triplochiton scleroxylon) sawdust in Ghana

A study was conducted to correlate the stipe length, cap diameter, and growth yield (fresh weight) of the fruiting body of Pleurotus ostreatus strain EM-1 using different rice lignocellulosic wastes and “wawa” (Triplochiton scleroxylon) compost: raw unamended rice straw; rice straw amended with 1% CaCO₃ and 10% CaCO₃; rice straw amended with 1% CaCO₃ and 10% CaCO₃ supplemented with 5, 10, and 15% rice bran prior to bagging; rice straw and rice husk mixture (1:1 w/w) amended with 1% CaCO₃ and 10% CaCO₃ supplemented with 5%–15% rice bran prior to bagging; and wawa sawdust amended with 1% CaCO₃ and 10% rice bran. The experiment was laid out in a completely randomized design in a well-ventilated semi-dark room at 26–28°C and 60%–65% ERH. The fresh weight, length of the stipe, and cap diameter increased differentially in each treatment with an increasing period of composting in the substrates. There was a good coefficient of determination (R²) among stipe length, cap diameter, and biological efficiency (%). The R² among stipe length, cap diameter, and biological efficiency for the different formulated substrates ranged between R² = 0.6346–0.9454 and R² = 0.570–0.9624, respectively. The highest R² was obtained on raw unamended rice straw substrates (stipe length and cap diameter were R² = 0.9454 and R² = 0.9444, respectively), whereas the lowest correlation coefficient among stipe length, cap diameter, and biological efficiency (%) (R² = 0.6346; R² = 0.0570), respectively, was recorded on the rice straw and rice husk mixture substrates. The results show a positive correlation in morphometric growth parameters studied on the different formulated substrates.