**7. Conclusions**

High-voltage electrical stimulation on fruiting body formation in cultivating mushrooms was described. The compact high-voltage pulsed power supplies were developed for the electrical stimulation to promote fruiting body formation on cultivation bed-logs and sawdust substrate (bed-block). The promotion effects of high-voltage stimulation of sawdust-based substrate of *L. decastes* and natural logs hosting *L. edodes*, *P. microspora* and *H. lateritium* were confirmed through the evaluation using a developed compact pulsed power generator. The fruiting body formation of mushrooms increases 1.3–2.0 times in terms of the total weight. The accumulated yield of *L. edodes* for four cultivation seasons was improved from 160 to 320 g by applying voltages of 50 or 100 kV. However, the yield was decreased from 320 to 240 g upon increasing the applied voltage from 100 to 130 kV. The yield of the other types of mushrooms show tendencies similar to those of *L. edodes* when voltage was applied. An optimal voltage was confirmed for efficient fruiting body induction.

Securing profitability of the electrical stimulation is important for the widespread to the mushroom famers. The pulse voltage stimulation systems for improvement of mushroom yield have been developed and sold by some companies. Typical price of the stimulation system is around 5000 USD. The increment of *L. edodes* yield is around 155 g/(1-log, 2-year) at 50 kV. The price of the *L. edodes* is around 20 USD/1-kg at natural-log cultivation in Japan. If the mushroom farmer uses 1612 logs, the initial cost of 5000 USD can be recovered with increment of the mushroom yield.
