Effect of water potential on fruit body formation of Lentinula edodes in sawdust-based substrate

The influence of substrate water potential (ψ) on the growth and fruiting of three genotypes of shiitake (Lentinula edodes) was investigated. A slight reduction of ψ (-0.5 MPa) stimulated mycelial and colony growth on liquid, agar, and sawdust-based substrates. L. edodes has been found to grow well at a ψ around -0.5 MPa, which corresponds to a moisture content around 55%. A small decrease in ψ at the final vegetative growth phase had positive effects on flush quantity. The substrate ψ was significantly affected by the interaction between genotypes and spawn run time. The ψ of well-colonized mature substrate was -0.7MPa before and -4.0MPa after the fruiting. The ip rose again to -0.7 MPa during rapid absorbance of water by soaking, and this rise was repeated during the second and third flushes. It is suggested that the water-holding capacity of a substrate is related to culture maturity. Excellent water-providing capacity (higher ψ) is expected in the substrate of well-matured cultures with a high density of mycelial colonization.