Distinct structural, climatic, and soil predictor domains for biomass estimation and flavonoid quality assessment in Epimedium pubescens

Accurate assessment of both biomass production and medicinal quality is essential for the field management of high-value medicinal crops, yet these two targets may not be captured by the same types of field indicators. Here, we examined whether biomass estimation and flavonoid glycoside quality assessment in Epimedium pubescens are supported by distinct predictor domains. The study was conducted under commercial cultivation conditions. Field observations were collected from 254 quadrats. A larger dataset (n = 187) was used for biomass modeling based on non-destructive morpho-structural traits. A subset (n = 67) was used for flavonoid quality modeling, integrating soil, climatic, topographic, and phytochemical measurements. Biomass was more effectively predicted by canopy-related structural traits, and a derived plant volume index provided a practical non-destructive proxy for aboveground biomass. By contrast, variation in flavonoid glycosides was associated mainly with climatic, topographic, and soil factors, particularly altitude, thermal indices, precipitation-related variables, and soil properties, whereas plant morphology contributed little to quality prediction. In addition, individual flavonoid compounds showed distinct association patterns with climatic and soil factors, indicating compound-specific responses under field conditions. Under the present field sampling design, these findings indicate that biomass estimation and flavonoid quality assessment are supported by distinct predictor domains. Because biomass and flavonoid traits were modeled using separate but spatially related datasets, the results should be interpreted as supporting distinct field indicator systems for biomass and flavonoid quality, rather than indicating biological decoupling between biomass accumulation and flavonoid production. Such a dual-indicator strategy may provide a practical, context-dependent framework for field evaluation, site comparison, harvest planning, and management prioritization of medicinal crops under heterogeneous production conditions.