Advances in Understanding the Effects of pH and Water Depth on B. schreberi Cultivation and Implications for Artificial Propagation

Brasenia schreberi is a nationally protected aquatic macrophyte of substantial ecological value and economic significance, yet its wild populations have declined drastically due to habitat degradation and anthropogenic disturbances. This review systematically synthesizes research progress on the effects of water pH and depth on the growth, ecophysiology, mucilage quality, and community structure of B. schreberi, integrating findings from field surveys and controlled greenhouse experiments to elucidate critical ecological thresholds under combined environmental stressors. Our analysis reveals that natural B. schreberi populations are predominantly distributed in lentic habitats with stable water depths of 0.5-1.5 m (optimally 1.2-1.5 m) and circumneutral to weakly acidic conditions (pH 6.0-7.5). Deviations from these parameters substantially impair plant performance: when water depth exceeds 1.5 m or pH falls below 5.5, photosynthetic efficiency declines, root-to-shoot ratios increase aberrantly, and mucilage thickness decreases significantly. The synergistic critical threshold for population decline was identified at 1.1 m depth × pH 6.3. For artificial propagation, optimal cultivation strategies diverge from wild habitat preferences: maintaining pH at 7.0-7.5 (weakly alkaline) enhances mucilage polysaccharide accumulation and commercial quality, whereas a phenological stage-specific dynamic water-depth management regime (“shallow-deep-shallow-deep”) maximizes vegetative propagation success and yield. This review provides a theoretical framework and parameterized technical guidance for wild population restoration, standardized cultivation, and hydrological regulation in plateau wetland ecosystems. Future research priorities should focus on elucidating the molecular mechanisms underlying pH- and depth-mediated mucilage synthesis, developing precision water quality management systems, and strengthening ex situ germplasm conservation.