Medicinal Plant Research 2025, Vol.15, No.6, 274-282 http://hortherbpublisher.com/index.php/mpr 277 biofertilizers or mycorrhizae, enhance plant health, secondary metabolite content, and sustainability (Wu et al., 2021; Wei et al., 2022). Figure 1 Samples collected from five sites (A, B, C, D, and E) in Shandong Province. (a) Physical and chemical properties of the soils. AN: alkaline nitrogen; AP: available phosphorus; AK: available potassium; ACu: available copper; AZn: available zinc; AFe: available iron; AMn: available manganese; SOM: soil organic matter. (b) Contents of soil heavy metals among different soil samples. Cd: Cadmium; Cr: Chromium; As: Arsenic; Pb: Lead; Hg: Hydrargyrum; Cu: Cuprum. Significant differences between soils were indicated by the least significant difference (LSD) test, with different lowercase letters indicating p < 0.05. (c) The five locations where soils were collected and the planting point in Site A where all soils were transported to (Adopted from Hou et al., 2024) 5 Planting Density, Pruning, and Cultivation Patterns inSalvia miltiorrhiza 5.1 Regulation of metabolite accumulation by planting density and light competition The main effects of planting density on secondary metabolite accumulation in plants are light availability and root competition. Although there are very few specific studies with regard to the effect of density in S. miltiorrhiza, some evidence from related research indicates that increasing the planting density will increase the competition for light and nutrients, which may further lower root biomass and the concentration of major metabolites. On the other hand, combined blue and red LED light improves phenolic acid content and growth, and hence optimization of light conditions together with planting density may improve metabolite yields (Zhang et al., 2020). 5.2 Effects of Pruning and trimming on spatial distribution and synthesis of secondary metabolites Although direct studies about pruning in S. miltiorrhiza are scanty, research on the spatial distribution of metabolites shows that different root tissues accumulate different metabolites; hence, cultivation practices that affect the architecture of the root, such as trimming or pruning, might have an effect on the spatial synthesis and accumulation of bioactive compounds. Methods such as MALDI-MSI have visualized these spatial patterns in roots, showing how continuous cropping and management practices of the root system can drastically alter metabolic profiles and their distribution within the root system (Sun et al., 2021). 5.3 Crop rotation, intercropping, and relay cropping patterns Continuous monoculture of S. miltiorrhiza results in the yield and secondary metabolite content declining due to soil fatigue and changes in microbial communities (Sun et al., 2021). Intercropping, especially with sesame, can
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