Evaluation of Black-jack (Bidens pilosa L.) substrate for the production of Oyster (Pleurotus ostreatus) mushroom

Using commonly used agricultural byproducts as a substrate for cultivating mushrooms is challenging due to their high cost. Finding economically viable alternative substrates with a high biomass return, particularly for mushroom production like P. ostreatus, is essential. The aim of this study was to determine the feasibility of the weed (Black-jack straw) for oyster mushroom cultivation. Oyster fruiting bodies were obtained from mushroom growers in Mekelle city, Ethiopia. Mycelial culture was secreted via tissue culture and it was used as inoculum for spawn development. The substrates were chopped, weighed (500 g dry weight of substrate), and sterilized. The substrates were packed in polyethylene bags, inoculated with 4% (w/w) spawn. The five treatments, consisting of various blends of Black-jack and wheat straws, were arranged in completely randomized design with triplicates. The highest average total yield (351 g/bag) and biological efficiency (70.20%) were obtained from 100% Black-jack straw. However, lower yield (199 g/bag) and biological efficiency (39.80%) were obtained from 100% wheat straw. Higher (8.78 cm) mean cap diameter and higher (3.48 cm) mean stipe length were recorded from 75% wheat straw + 25% Black-jack straw and 50% wheat straw + 50% Black-jack straw. This study revealed that the best substrate for overall mushroom yield and biological efficiency was 100% Black-jack. Therefore, the Black-jack straw can be considered as low-cost substrate to effectively substitute wheat straw for the cultivation of oyster (Pleurotus ostreatus) mushroom in the studied area.