Comparative effect of gamma irradiated and steam sterilized sorghum grains (Sorghum bicolor) for spawn production of Pleurotus ostreatus (Jacq. Ex. Fr) Kummer

Abstract

The efficacy of gamma irradiation and moist heat sterilization of sorghum grains (Sorghum bicolor) for the production of spawns in heat resistant polypropylene bags were assessed. Both methods were tested single (moist heat or irradiated) and combined (moist heat and irradiated). The mycelium colonizing time, rate of colonizing, percentage contamination and mycelia density were parameters investigated. The best treatment was the set of experiment which was steamed and irradiated at a dose of 25 kGy (S+I) which produced a growth rate of 11.8 mm/day, colonized completely in 7 days and had a very thick mycelia density without (0%). The slowest treatment was the set of experiment of non- irradiated sorghum treatment (nI) which produced a mycelium growth rate of 10.0 mm/day, used 13 days to complete colonization and also produced a poor mycelia density owing to high (80%) contamination. The results of this experiment clearly demonstrated that gamma radiations could be used as a substitute of steam sterilization for sorghum spawn production for the cultivation of oyster mushrooms (Pleurotus ostreatus)