Evaluation of wheatstraw, sawdust, banana fronds, maize cobs and cotton hulls substrate combinations for Pleurotus ostreatus cultivation.

Abstract The yield and quality of oyster mushroom is largely dependent on the chemical and nutritional content of the substrate. The objective of the study was to determine the effect of different individual substrates and substrate combinations on the perfomance of P.ostreatus for growth and sustainable development of the mushroom cultivation industry in Zimbabwe. Various individual substrates used as treatments, selected for the cultivation of oyster mushrooms were, wheatstraw, cotton hulls, sawdust, maize cobs and banana fronds each of 1kg and replicated 4 times. Various substrate combinations, also used as treatments were, cotton hulls and wheatstraw, cotton hulls and sawdust, cotton hulls and maizecobs, cotton hulls and banana fronds in the ratio 1:1. Each combination weighed 1kg and was replicated 4 times.Compound substrates perfomed much better in terms of biological efficiency and spawn run compared to individual substrates. The highest biological efficiency (76%) and spawn run(17 days) were obtained from combining cotton hulls and sawdust. Spawn run was fastest(12 days) for cotton hulls and wheatstraw combination. Analysis in terms of economic return, revealed that mushroom production was most profitable using cotton hulls and sawdust as substrate with a benefit-cost ratio of 5.7 compared to other combinations of agricultural residues. In terms of spawn run, yield and economic return, combining cotton hulls and sawdust is highly recommended for farmers involved in the cultivation of Pleurotus ostreatus to satisfy increasing consumer demand, whilst decreasing pressure on limited natural resources and preventing ecosystems degradation.