Study on primary spawn medium for shiitake mushroom (Lentinula edodes (Berk) Pegler) under laboratory conditions

Abstract

This study aims to evaluate the effects of the composition and ratio of the medium/substrate on the mycelium growth of the shiitake mushroom (Lentinula edodes (Berk) Pegler) under laboratory conditions. Before production, shiitake mushrooms must go through two stages: primary and secondary varieties. Primary varieties are cultured on agar medium. Secondary varieties are propagated on substrates such as corn cobs or cereal grains. For primary varieties, we arranged 3 formulas. After experimentation, formula 3 (20 g sugar + 250 g potatoes + 0.5 g MnSO₄ + 1.0 g KH₂PO₄ + 20 g agar) gave the best results in terms of colony diameter, mycelium spreading speed and coverage. In formula 3, the colony diameters at the 5^th, 10^th, 15^th, 20^th days after inoculation were 6.3 mm, 13.5 mm, 27.0 mm, 40.5 mm, respectively; the mycelial spread rates were 1.26 mm/day, 1.44 mm/day, 2.70 mm/day, 2.70 mm/day, respectively; the mycelial coverage rates were 7.0%, 15.0%, 30.0%, 45.0%, respectively. Formula 3 had superior mycelial growth, so the time for mycelial coverage of the plate was the shortest, 22 days, and the average mycelial spread rate for the entire process was 2.03 mm/day. For secondary propagation, we have 3 formulas. The results show that formula 1 (35% boiled rice + 69% sawdust + 1% CaCO₃) is the best for secondary propagation. The average mycelium growth rate is 22.3 mm/day; on the substrate, the mycelium grows more slowly, taking 38–44 days to cover the bag; in the air on the agar medium, it only takes 22−28 days.