The Use of Sawdust Mixed with Ground Branches Pruned from Wax Apple or Indian Jujube as Substrate for Cultivation of King Oyster Mushroom (Pleurotus eryngii)

Abstract

The king oyster mushroom [Pleurotus eryngii (DC.:Fr.) Quél.] is gaining popularity across the world due to its excellent taste, high nutritional quality, medicinal value, and long shelf life. Conventional substrates for king oyster mushroom cultivation consist of sawdust derived from various tree species. Sawdust demand is increasing worldwide, creating a need for alternative materials that can at least partially replace sawdust as substrate for king oyster mushroom. In Taiwan, as in other countries that grow fruit trees, pruned fruit tree branches are an expensive agricultural waste, particularly if they are not recycled or reused. In the present study, we evaluated substrates containing sawdust and different proportions of material ground from pruned wax apple or Indian jujube branches for cultivation of king oyster mushroom. Our results suggested that among all five substrate mixes tested, the best substitute for conventional sawdust (100% sawdust) was a substrate that contained 75% sawdust mixed with 25% materials ground from trimmed wax apple branches (Wax apple 25%). Furthermore, determination of mineral element content, pH, and electrical conductivity (EC) levels of the substrates both before spawn inoculation and after harvesting revealed no significant changes in mineral content, a slight reduction in pH value, and a minor increase in EC levels after cultivation. Taken together, results from this study suggest that agricultural wastes from pruned fruit tree branches can partially replace sawdust as the cultivation substrate for king oyster mushroom.