Influence of LED light quality ratios on the physiological regulation of Lentimula edodes mycelial growth and color conversion stage

This study aims to investigate the effects of different light qualities on mycelial growth and color conversion in Lentimula edodes factory cultivation. LED plant filler lamps were utilized to supplement the light for Lentimula edodes mycelial growth and color conversion stages. Mycelial growth and physiological indexes were measured to analyze the influence level of light quality on different growth stages of mycelia. Taking Lentimula edodes 'L808' as the test material, eight treatments of light quality were set at 25 ℃, including red light, blue light, green light, yellow light, red-green light 1:9, red-green light 6:4, red-blue light 3:7 red-blue light 7:3, and dark conditions were set as the control in the mycelial growth stage, while the white light was set as the control in the color conversion stage. The mycelial growth conditions were determined in the mycelial growth and color conversion stages. The dynamic patterns of five kinds of extracellular enzymes were determined in the growth of Lentimula edodes mycelia under different LED light quality environments using linear regression and principal component analysis. The results show that: In the mycelial growth phase, compared with dark treatment (CK₁), the average mycelial growth rate was significantly increased by 12.13% (P < 0.05) under red light treatment, and the activity of carboxymethylcellulase (CMC enzyme) was increased by 66.81% on average, while the ratio of red to blue was 3:7. The average growth rate of mycelia was significantly decreased by 2.62% (P < 0.05), and the average CMC enzyme activity was decreased by 10.46%. In the mycelium color conversion stage, compared with the white light treatment (CK₂), the average laccase activity increased by 19.21% when mycelium transformation was completed on the 54th day of red and blue light 7:3 treatment, while the average laccase activity decreased by 9.50% when mycelium was not transformed under red and yellow light treatment.The dynamics of extracellular enzyme activity showed that compared with CK₁, the enzyme activity was not inhibited under each light treatment from day 25 to day 30 of mycelia growth.The activity of CMC enzyme was positively correlated with the activity of xylanase, and the activity of amylase was positively correlated with the activity of laccase and polyphenol oxidase. CMC enzyme activity was positively correlated with xylanase activity, amylase activity and laccase activity, while the amylase activity was positively correlated with laccase activity and polyphenol oxidase activity. The principal component analysis showed that the red light treatment was ranked the first in the mycelial growth stage, and red-blue light 7:3 treatment was ranked the first in the mycelial color conversion stage. Therefore, the red light was suitable for mycelial growth, and red-blue light 7:3 was suitable for mycelial color conversion in the factory production of Lentimula edodes. The finding can provide a theoretical basis for the selection of LED light quality during growth and the control of light environment under the factory cultivation of Lentimula edodes.