Abstract
This study evaluated the effect of coffee waste compost supplementation on the growth, yield, biological efficiency, and nutritional composition of oyster mushroom (Pleurotus ostreatus) cultivated on wheat straw substrate. Four substrate treatments were prepared: T0 (100% wheat straw as control), T1 (25% coffee waste compost + 75% wheat straw), T2 (50% coffee waste compost + 50% wheat straw), and T3 (75% coffee waste compost + 25% wheat straw). Results showed that moderate incorporation of coffee waste compost significantly improved mushroom growth and productivity. The shortest spawn running time (15.2 ± 0.3 days), earliest pinhead initiation (20.1 ± 0.4 days), highest number of fruiting bodies (38.6 ± 1.2 per bag), maximum fresh yield (1.84 ± 0.03 kg/bag), and highest biological efficiency (92.4%) were recorded in Treatment T2. In contrast, Treatment T3 showed delayed mycelial growth, reduced yield, and lower biological efficiency, likely due to excessive concentrations of caffeine and phenolic compounds that inhibited fungal development. Nutritional analysis further revealed that mushrooms cultivated on coffee waste-amended substrates had improved protein, crude fiber, ash, and fat contents, with T2 showing the highest crude protein content (27.2%). The findings indicate that moderate supplementation of coffee waste compost enhances substrate utilization, mushroom productivity, and nutritional quality, while excessive supplementation negatively affects fungal growth. Therefore, the use of 50% coffee waste compost with wheat straw is recommended as an effective and sustainable substrate formulation for oyster mushroom cultivation