Effects of Different LED Light Quality on the Physiological Characteristics and Ultrastructure of Ginseng Seedling Leaves

The present study is mainly aimed at studying the effect of different light quality on the growth of ginseng seedling leaves, to explore the excellent light quality of ginseng factory seedlings, and provide a basis for improving the quality of ginseng seedlings. The experiment set up six groups of treatments, namely white light (W, as a control), blue light (B, 460 similar to 480 nm), red light (R, 615 similar to 635 nm) green light (G, 510 similar to 530 nm) yellow light (Y, 585 similar to 605 nm), red and blue (RB, R/B=4:1), white light as the contrast light source. The study results showed that the leaves of ginseng seedlings grown under different light qualities had obvious changes in appearance, physiological characteristics and cell structure. In the process of leaf area growth, the leaf area under red, blue and white light is larger, next is red light and the smallest under blue light. In the distribution of chlorophyll, the treatment of adding blue light is significantly higher than the control, indicating the Blue light plays a key role in the synthesis of chlorophyll. Moreover, it is the lowest under red light. The electron efficiency of chlorophyll fluorescence is higher under blue, yellow and white light. In terms of stomata characteristics, there is more stomata numbers in green, red and white light, and the area of a single stomata is larger under B and RB light. Through observation of leaf ultrastructure under an electron microscope, it is found that different light qualities significantly impact the cell structure of leaves, mainly in the distribution of mitochondria and chloroplasts and the structure of chloroplasts. White light and blue light have more mitochondria and chloroplasts, and the number of stacks of chloroplast lamella structure is also more compact and rich. In addition, the senescence process of the seedling leaves grown under different light quality also had obvious differences. The B and RB treatment senescence speeds were fast. In summary, different light qualities have different effects on the growth of ginseng seedling leaves, but blue light and red-blue composite light have more excellent characteristics and better physiological parameters. However, in application and practice, it is also necessary to formulate corresponding light quality ratio strategies according to specific needs to achieve the purpose of strong seedlings and high yield.