Electrical Stimulation of Shiitake Logs


There are several methods to initiate the fruiting.

There is the introduction of light, The decrease in humidity or temperature, and the reduction of the CO2 level. All these four factors will stimulate pinhead formation.

But there might be another method.

The authors of today’s research article found that stimulating logs with 50,000 volts almost doubled the yield of shiitake.

Here is how they did it.

The logs were inoculated two years before the experiment and covered with a blackout curtain to maintain the moisture content.

The pulsed voltage was applied via a needle electrode with a 3 mm diameter driven 7 cm into the logs.

Figure 1: Experimental setup for pulsed voltage stimulation of the log [1].

The voltage was applied with a typical duration of 0.2 μs with an amplitude of, for example, 52 kV and 13 amps, respectively.

Figure 2: Typical waveforms of the applied voltage and the current through the log at 50 kV applied voltage [1].

For the control group, the authors got almost no yield for the first season. For the second season, they found 105g per log. For the third season, again, no yield. In the four and final seasons, they got 60g per log, leading to a total of 167g per log.

If the logs were stimulated 1x with 50,000 volts, the authors found in the first season 73g per log. For the second season, 118g per log. 20g per log for the third season and 111g per log in the fourth and final season.

If the logs were, therefore, stimulated with 50,000 volts, the total yield was 322g per log. An increase of 92% compared with the control group.

Figure 4: Total weight of shiitake for various electrical stimulation conditions [2].

The authors then increased the volts to 100,000 volts and got the following results. 61, 144, 24, and 90g per log for the four seasons, with 319g per log total.

The further increase to 125,000 volts led to a decrease. Applying this high voltage, the authors found
an overall yield of 243g per log.

The third season (autumn) had the lowest yield when comparing all four experiments. Which was addressed by the authors by stating that the used shiitake species mainly fruits in the spring.

Interestingly enough, the pattern is only found in the control group, while applying electrical stimulation on the logs seems to break the pattern for the first season.

The authors then compared 1x stimulation with 50x stimulation and found the following yields.

For the 1x stimulation, only 8 out of 15 logs produced mushrooms with an average of 73g per log. The maximum yield per log was 300g.

Figure 6: Difference in the yield of shiitake based on the number of 50 kV applied voltage treatments received (here one-pulse stimulation) Total weight of shiitake for various electrical stimulation conditions [1].

If the logs were stimulated 50x, all of the logs produced mushrooms with an average yield per log greater than 73g and a total yield of 322g per log.

Figure 7: Difference in the yield of shiitake based on the number of 50 kV applied voltage treatments received (here 50-pulse stimulation) Total weight of shiitake for various electrical stimulation conditions [1].

While this experiment showed that electrical stimulation increases the mushroom yield in log cultivation, there are still, in my opinion, some questions that should be further investigated.

1. What happens between 0 volt and 50,000 volts?

Meaning, what is the minimum voltage which has to be applied to stimulate the growth of the mushrooms?

2. What happens between 1x and 50x stimulation?

What is the minimum number of pulses that have to be applied to decrease the deviation in the mushroom formation?

3. What happens if we are stimulating before every season?

Can we even further increase the yield, and/or can we overcome the drop in yield in season three?

Despite these questions, it is good to see that applying this method increases the yield of log cultivation and pushes the economics more in your favor.

More about the economics of shiitake log cultivation can be found in the following video, which you will find here on the left. If it is not there, I recommend until then the video on the right. In it, I talk about the influence of the environment on the mushroom yield for log cultivation.

Take care and catch you in the next one.



[1] 📝Takaki, K.; Yoshida, K.; Saito, T.; Kusaka, T.; Yamaguchi, R.; Takahashi, K.; Sakamoto, Y. Effect of Electrical Stimulation on Fruit Body Formation in Cultivating Mushrooms. Microorganisms 2014, 2, 58-72. https://doi.org/10.3390/microorganisms2010058, https://creativecommons.org/licenses/by/3.0/

[2] Own chart based on [1]