Molecular Soil Biology 2025, Vol.16, No.1, 37-44 http://bioscipublisher.com/index.php/msb 39 3 Effects of Cultivation Environment on the Content of Active Components in Leonurus japonicus 3.1 Effects of soil type and nutrients The active substances in Leonurus japonicus, especially carnosine, are significantly affected by soil type and composition. Moderate or slightly alkaline soil acidity is beneficial for nitrogen metabolism in plants, thereby promoting the synthesis of nitrogen-containing compounds such as sage alkaloids (Cheng et al., 2022; Zhang et al., 2022). In addition, trace elements such as manganese, copper, and zinc have a positive effect on alkaloid synthesis, and appropriate supplementation of these elements can improve the level of medicinal components in plants (Shen et al., 2002; Tian et al., 2021; Jiao et al., 2022). The organic matter in the soil provides continuous nutrients for plants and contributes to the accumulation of flavonoids and phenolic substances. Applying compost or organic fertilizer can enhance the content of these components and improve the antioxidant capacity of plants (Xu, 2006). 3.2 Effects of climatic conditions (temperature, humidity, and light) Temperature, humidity, and light intensity are directly related to the formation of effective substances in Leonurus japonicus. When the daytime temperature is between 20 ℃ and 30 ℃, the photosynthetic efficiency of plants is higher, which is conducive to the synthesis of photosynthetic pigments and secondary metabolites such as flavonoids and alkaloids (Shang et al., 2014). Excessive or insufficient temperature can inhibit metabolic activity and lower the levels of active ingredients. The stronger the light intensity, the higher the synthesis ability of flavonoids and phenolic acids, which helps to enhance antioxidant performance. However, excessive light exposure can easily generate oxidative stress, which can actually affect plant health (Shen et al., 2002; He et al., 2018). Humidity can also affect the formation of active ingredients. Appropriate air humidity is beneficial for the accumulation of essential oils and alkaloids, while excessive dryness or humidity can lower their quality (Tan et al., 2018). 3.3 Effects of water and fertilizer management Excessive watering can dilute the active ingredients, while moderate drought stress can stimulate the plant to synthesize more alkaloids, a typical defense response (Shen et al., 2002). Maintaining stable soil moisture promotes root development, improves nutrient absorption efficiency, and has a positive effect on the production of active ingredients (Xu, 2006). The method of fertilization is equally crucial. Moderate application of nitrogen fertilizer can increase the content of nitrogen-containing alkaloids such as leonurine and carnosine. However, excessive nitrogen fertilizer can inhibit the accumulation of flavonoids and phenols, so fertilization needs to be balanced (Kuchta et al., 2013). The combination of organic and inorganic fertilizers has the best effect, promoting plant growth and increasing the content of medicinal ingredients (Xu, 2006). 4 Physiological Responses of Leonurus japonicus to Environmental Stress 4.1 Effects of environmental stress on the growth of Leonurus japonicus When Leonurus japonicus is under environmental stress, its growth will be significantly worse. During drought, the leaves of the plant will become smaller and the stem will not grow high, so the whole plant will grow slowly. Because water shortage affects its photosynthetic efficiency, the ability of plants to absorb and use water decreases (Shang et al., 2014). Excessively high or low temperatures can also disrupt plant metabolism, weakening enzyme activity, damaging cells, reducing plant vitality, and delaying flowering (Zhang et al., 2022). This can affect the harvest time and quality of the medicinal material. If the soil lacks nutrients such as nitrogen, phosphorus, and potassium, Leonurus japonicus's root system will likely develop poorly, and its leaves will become lighter in color. This is due to reduced chlorophyll synthesis and decreased photosynthetic efficiency. Appropriate nutritional supplementation can alleviate these problems and
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