The main aim of this study was to report the usability of P. purpureum leaf a major substrate for cultivation of oyster (P.ostreatus) mushroom with supplement of different proportion of cotton seed waste. The pure culture of the oyster mushroom was maintained on potato dextrose agar, and the spawn was prepared on yellow colored sorghum and sterilized substrate was inoculated with 10% of the spawn wet basis on dry basis of the substrate. The experimental design constitutes ten treatments on the leaf of elephant grass with ratios of cotton seed wastes (T1-T10) in three replication. Fastest mycelia run was observed on the treatments T4 (70:30) and T8 (70:30), and the slowest mycelia extension were observed on T1 (100:00), days of Inoculation periods on the leaf of elephant grass and T4 at ratios (70:30). Highest fresh weight mushroom 276.2g/100g dry substrate was recorded on T8; highest number of fruits recorded 60(T4), while largest cap diameter (14cm) was recorded on (T5) on the leaf of elephant grass and the highest Stipe length on T6 and T1 (4.5cm). Highest biological efficiency was recorded for T8 (276.2) on leaf of elephant grass .The nutrient content of all the treatments also shows variations and the highest protein were recorded on T3 (40.51%), the highest carbohydrate were recorded on T3 (62.46) on leaf of elephant grass, the least protein contents were recorded on T5 (15.76%) on leaf of elephant grass and on the others treatments intermediate number of food contents were recorded. Even though the leaf of elephant grass and the proportion supplementation of cotton seed waste was varied for all the treatments except on both T1 treatments make 100% p. purpureum dry leaves were made. Over all, the results of the study showed that the P. purpureum leaf supplemented with cotton seed wastes can be gave highest yield and yield related parameters of oyster mushroom. The result of the present study implies to carry out further research on the optimization of P.ostreatus production using two or more type of substrates tested in this experiment.
Keywords: biological efficiency, Cottonseed wastes, Pennisetum purpureum, Pleurotus ostreatus