Application And Equipment Development Of DC High-Voltage Pulsed Electric Field In Promoting The Growth Of Shiitake Mushroom

Shiitake mushroom is a valuable edible mushroom with long-standing reputation in China,and its demand and export volume are among the highest in the world.With the growth of population,the pressure of shiitake mushroom production is increasing,and how to improve the yield of shiitake mushroom has become an urgent problem.The application of high voltage electric field treatment as a combination of physical technology and biology is becoming more and more mature in the fields of enhancing plant drought resistance,seed vigor,promoting seed germination and plant growth,and preserving the freshness of fruits.The main raw materials of shiitake mushroom sticks are agricultural by-products,and they are gradually becoming an important way to cultivate shiitake mushroom production because of their easy availability of raw materials and simple cultivation.In this paper,a high-voltage pulsed DC power supply is developed based on the biological effect of electric field,and the mushroom sticks are pulsed to stimulate the mushroom,and the high-voltage pulsed electric field is applied to the mushroom production performance.Firstly,circuit design,parameter calculation,device selection and simulation optimization were carried out for each circuit of the high-voltage power supply,and the performance test of the power supply was conducted after the power supply was made to ensure that the performance of the power supply met the standard for application in subsequent experiments.Subsequently,three-factor four-level orthogonal experiments were designed with voltage,frequency and number of pulses as variables to investigate the effect of high-voltage pulsed electric field on the production performance of shiitake mushroom sticks,and the main research contents are as follows:(1)A high-voltage pulsed DC power supply was developed.The control module,rectifier filter circuit,Buck circuit,inverter circuit,voltage doubling rectifier circuit,driver circuit and feedback circuit were designed,calculated and the devices were selected.In the rectifier filter circuit,Buck circuit and inverter circuit,the diodes,switching tubes,capacitors and inductors are mainly calculated and selected;in the multiplier rectifier circuit,Multisim simulation is used to optimize the capacitor capacity;the high-frequency transformer is designed in three aspects: core material,core shape and winding parameters,and the corresponding enameled wire is selected after the cross-sectional area of primary and secondary windings is calculated.The winding is done by using Multisim.Multisim was used to simulate and optimize the parameters of each circuit after the above design was completed.The final performance test of the high-voltage power supply showed that the maximum output voltage of the high-voltage power supply was 20.8 k V and the output current was 20 m A.(2)In this experiment,the high voltage pulsed electric field has a significant promotion effect on mushroom fresh weight,cap diameter,stalk length and the number of mushroom emergence,among which 15 k V has the best promotion effect in each experimental group.When the voltage was 15 k V,frequency was 500 HZ,and the number of pulses was 1000,the pulsed electric field promoted the average fresh weight,stalk length and number of mushroom emergence of shiitake mushroom to the greatest extent,with 14.45%,12.96% and 19.23%increase respectively compared with the blank control group;when the voltage was 15 k V,frequency was 500 HZ,and the number of pulses was 500,the pulsed electric field promoted the average cap diameter to the greatest extent compared with the blank control group.The maximum promotion effect was achieved at 15 k V,frequency 300 HZ and 500 pulses,with an increase of 8.63% compared with the blank control;at 20 k V,frequency 300 HZ and 500 pulses,the maximum promotion effect was achieved at 20 k V,frequency 300 HZ and 500 pulses,with an increase of 5.83% compared with the blank control.In conclusion,the best treatment combination to enhance the production performance of shiitake mushroom stalk was 15 k V,frequency 500 HZ,and number of pulses 1000.