Molecular Soil Biology 2025, Vol.16, No.4, 214-229 http://bioscipublisher.com/index.php/msb 219 and improve the soil's ability to "clean up" toxins (Bossolani et al., 2021; Kong and Lu, 2023; Liu et al., 2025). New materials, such as fly ash, can also effectively reduce pH and sodium content, while improving soil structure and increasing the salt tolerance of crops (An et al., 2024). These improvement measures provide great help for the replanting of "Tongzi" in fallow land. Figure 2 Experimental design of the effect of fly ash saline and alkaline soil amendment materials on soil properties. Blue shading represents increasing the duration of action. Yellow shading represents increasing dosages of amendment materials. Green circles represent flower pots (Adopted from An et al., 2024) 6 Impact on Growth, Yield, and Quality of L. japonicus 6.1 Root development, flowering time, biomass accumulation Soil improvement has a great impact on the root system, growth time and plant weight of L. japonicus. Studies have found that after adding organic fertilizers or microbial agents (such as Bacillus subtilis), the soil nutrients have increased and the organic matter has also increased. These changes allow the roots to grow better and have more branches, and the plants are more capable of absorbing water and nutrients (Alwitwat, 2022; Guo et al., 2025). The improved soil will also make L. japonicus bloom earlier and extend the growth period, so that the plant can accumulate more nutrients and medicinal ingredients (Guo et al., 2025). Some studies have also found that after the microbial structure in the soil improves, the environment around the roots is more suitable for growth, and the biomass of the aboveground part can also increase (Alwitwat, 2022; Guo et al., 2025). 6.2 Yield data comparisons (treated vs. untreated) Many field trials have shown that the yield of L. japonicus after soil improvement is significantly higher than that of untreated ones. For example, after using Bacillus subtilis, the fresh weight and total yield of a single plant can be increased by 10% to 20%. At the same time, it is more efficient in absorbing water (Guo et al., 2025). Methods such as organic fertilizers and biochar can also increase yields, mainly because these materials improve soil fertility and make it easier for roots to absorb nutrients (Alwitwat, 2022). In contrast, the control group did not use any treatment, the soil was easily compacted, there were fewer nutrients, the plants grew slowly, and the yield was naturally low (Alwitwat, 2022; Guo et al., 2025). 6.3 Active compound content (leonurine, alkaloids) under different treatments In addition to making L. japonicus grow better, soil improvement also increases its medicinal ingredients. Studies have shown that after applying organic fertilizers and microbial agents, the content of leonurine and total alkaloids in L. japonicus has increased significantly, with some treatment groups being 8% to 15% higher than the control group (Guo et al., 2025). This increase is mainly due to the fact that the soil nutrients have become more sufficient, the microorganisms have become more active, and the environment around the roots has improved. These factors together promote the synthesis of secondary metabolites in plants (Alwitwat, 2022; Guo et al., 2025). The more suitable the soil pH and the more organic matter, the positive effect on the accumulation of medicinal ingredients, making the quality of L. japonicus better (Alwitwat, 2022).
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