ABSTRACT

 Yield, heavy metal and nutritional evaluation oiPleurotus ostreatus (Jacq.) P. kumm and Pleurotus pulmonarius (Fries). Quel, cultivated successfully conducted. Living trees ofD. edulis, M. indica and T. cfricana were fell and made into logs of 18cm using Electric wood-saw (EWS) model; Elect. 1710, Japan. Inoculation holes of3cm x 15mm diameter were made hexagonally on each log with high speed drills (HSD) of 5 drill bit in respect to log size. Inoculation was done by inserting 15g ofgrain spawn of P. ostreatus and P. pulmonarius into 2/3 of the holes, following incubation. Results showed that pinheads ofP. ostreatus were first noticed in D. edulis, followed by T. africana and finally in M. indica log substrates, after 9, 10 and 12 days ofinoculation respectively and followed the same trend in P. pulmonarius after 11, 13 and 15 days accordingly. Yield (g/kg) of P. ostreatus and P. pulmonarius was determined by weighing fresh fruit bodies after harvesting. Maximum yield of P. ostreatus and P. pulmonarius was recorded in M. indica (245.8lOOg/kg) and T. africana (156.0967g/kg) log substrates respectively. While both mushroom strains gave lowest yield in D. edulis. Results from heavy metal (mg/kg) analysis showed that P. ostreatus and P. pulmonarius cultivated on M. indica had the highest Zn, Cd, Cu and Pb accumulations. Appreciable amount of all the vitamins analyzed in both mushroom strains as affected by D. edulis was recorded compared to M. indica and T. africana. Proximate composition (%) ofP. ostreatus and P. pulmonarius did not follow a regular trend across the various log substrates. Minerals such as Na, K, Mg, Ca and P. concentrations of both mushroom species grown on D. edulis logs were higher than those of M. indica and T. africana while Bioactive compound (%) contents of both mushrooms were found to be higher with respect to T africana log substrates. Yield, heavy metal and other nutritional parameters investigated in P. ostreatus and P. pulmonarius with respect to the various log substrates were significant (P<0.05) while Fe and Riboflavin concentrations of both mushrooms were not significant (P>0.05). It is therefore crucial to harness the use ofM. indica and T. africana logs in the commercial production of P. ostreatus and P. pulmonarius respectively, having supported their highest yield. In the same vein, D. edulis logs should be adopted in the cultivation of P. ostreatus and P. pulmonarius in demand for nutrient-rich mushrooms.