Medicinal Plant Research 2024, Vol.14, No.6, 334-344 http://hortherbpublisher.com/index.php/mpr 336 It is interesting that some fungi living inside plants, known as endophytic fungi, may have the potential to help improve seedling survival rates. Studies have shown that these fungi can not only reduce the incidence of diseases, but also promote seedling growth. Some fungal strains have been found to increase plant size and enhance the content of beneficial compounds in their bodies (Ye et al., 2020). However, this positive effect cannot be stably exerted in all environments, and its effect is greatly influenced by external conditions and strain types. Therefore, it still needs to be carefully evaluated in practical applications. 2.3 Factors influencing growth during in vitro propagation The growth of A. roxburghii is influenced by various factors at the time of tissue culture. One of the most critical factors is the formulation of the culture medium, in which the type and concentration ratio of growth hormone. Wang et al. (2022) found that a reasonable combination of plant hormones like 6-benzylaminopurine (BA), alpha naphthylacetic acid (NAA), and zeatin (ZT) is crucial for inducing bud formation and proliferation. If the hormone concentration is too high or too low, it may lead to slow growth or decreased plant quality. So, in practical operation, maintaining precise balance between hormones is the key to ensuring stable and efficient tissue culture results. Light is also an important factor affecting the growth of tissue culture. Related studies have found that LED light sources with specific wavelengths, especially the combination of red and blue light, can not only promote rapid growth of seedlings, but also significantly enhance the synthesis of beneficial compounds such as flavonoids (Figure 1). This type of light stimulates the expression of related genes, thereby enhancing the medicinal value of A. roxburghii (Gam et al., 2020). Figure 1 Effects of different light conditions on the A. roxburghii morphology; (a): fluorescent light; (b): red; (c): blue; (d): BR (one blue: four red); (e): BRW151 (one blue: five red: one white); (f): BRW142 (one blue: four red: two white). Scale bars = 1 cm (Adopted from Gam et al., 2020) Image caption: The results in the figure indicate that compared to single-wavelength red or blue light, plants grown under BR light exhibit more robust growth, characterized by larger leaf areas, more upright stems, and a greater number of leaves. In contrast, plants treated with red light have thinner and weaker stems, while those under blue light have smaller leaves and restricted morphological development. This figure demonstrates that the combination of blue and red light can promote the growth and biomass accumulation of A. roxburghii, providing experimental evidence for optimizing artificial light cultivation (Adapted from Gam et al., 2020) Some scientists have also tried growing the plants in special systems called continuous immersion bioreactors. These setups keep the plants in liquid and have been shown to increase both plant size and the amount of useful compounds they make (Jin et al., 2017). But, like with other methods, the results can be different depending on how the system is used. More work is still needed to figure out the best setup. 3 Environmental Factors Affecting Transplantation Success 3.1 Temperature and humidity control Temperature and humidity play a big role in whether A. roxburghii seedlings survive after being moved out of the lab. In the beginning, the seedlings lose water easily and get stressed. So, keeping the air humid and steady helps
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