Medicinal Plant Research 2025, Vol.15, No.6, 274-282 http://hortherbpublisher.com/index.php/mpr 276 3.3 Influence of water management and irrigation strategies Water availability directly influences the growth and synthesis of secondary metabolites. The moderate drought stress could induce the expression of biosynthetic genes of phenolic acids and the ABA-dependent signaling pathways, hence promoting their accumulation (Zhang et al., 2024; Zhang et al., 2025). Severe drought and excess moisture stress suppress plant growth, photosynthetic capacity, and the content of both salvianolic acid B and tanshinones. In S. miltiorrhiza, the optimal soil relative water content is in the range of 55%-65%, balancing yield and metabolite quality (Li et al., 2025). 3.4 Integrated effects of light, temperature, and water on metabolic networks Light, temperature, and water interact in determining the metabolic landscape of S. miltiorrhiza. The climatic variables of air temperature, precipitation, and duration of sunshine interact with each other to control the content and composition of bioactive ingredients, which gives rise to specific regional metabolite profiles. The environmental cues orchestrate complex gene expression networks, including key transcription factors such as WRKY and MYB, which integrate multiple signals into the fine-tuning of secondary metabolism. Examples include Yu et al. (2025) and Wu et al. (2025). Understanding such interacting effects is a basic requirement for an optimization of agronomic practices with the aim of improving medicinal product quality. 4 Soil Conditions and Fertilization Management inSalvia miltiorrhizaCultivation 4.1 Effects of soil nutrient levels (N, P, K, and trace elements) on metabolite content Both N and P are critical to the growth of and secondary metabolite biosynthesis in S. miltiorrhiza. The optimum N fertilization, 6-8 g/plant, increases root biomass, tanshinones, and salvianolic acid B, while excess N may decrease photosynthetic efficiency (Xing et al., 2023). Phosphorus exerts a "peaked" effect with an optimal value of 0.625 mmol/L inducing maximum biomass and metabolite accumulation, while deficiency/excess suppresses the growth and biosynthesis of bioactive compounds (Zuo et al., 2025). Potassium availability has been reported to be negatively correlated with salvianolic acid B but positively correlated with tanshinone IIA, indicating a metabolic trade-off. Trace elements including copper and cadmium also regulate metabolite content; copper positively affects tanshinone IIA, and cadmium enhances salvianolic acid B in S. miltiorrhiza (Hou et al., 2024) (Figure 1). 4.2 Influence of organic and inorganic fertilizers on metabolic pathways Organic fertilizers, especially traditional Chinese medicine residues, greatly enhanced plant growth and accumulation of both phenolic acids and salvianolic acid B, and they improved soil microbial diversity and health. Inorganic fertilization with NPK resulted in increased biomass and the levels of some metabolites, though high dosages of chemical fertilizer have been found to lower the tanshinone content and have a negative impact on soil health. The use of biofertilizers like Bacillus and microalgae had positive results in improving root biomass and bioactive compound contents due to the enrichment of beneficial microbes in the soil and reduction of heavy metal uptake (Wu et al., 2021; Wei et al., 2022). 4.3 Effects of soil physicochemical properties (pH, texture, organic matter) Hence, soil pH and organic matter content along with soil texture become the critical determinants of metabolite accumulation. The contents of Salvianolic acid B and tanshinone IIA increased with the increase in pH and OM of the soil (Hou et al., 2024). Better root development, indicative of superior structural and organic conditions of the soil, attained frequently by organic amendments, contributes to good secondary metabolism (Wang et al., 2024). Certain soil amendments help in the reduction of heavy metal contamination, especially Cd and Pb, thus improving metabolite accumulation and plant health (Wu et al., 2023). 4.4 Optimization strategies combining fertilization and irrigation Balanced fertilization, integrated with optimized irrigation at the soil relative water content of 55-65%, ensures the maximization of yield with regard to metabolite quality (Li et al., 2023; 2025). Site-specific fertilization based on soil testing and predictive modeling resulted in a well-matched nutrient supply and optimal use of resources (Liu et al., 2022). Organic/inorganic fertilizers, combined in proper irrigation and soil amendments such as
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