To elucidate the morphological diversity and genetic characteristics of the pollen of Polygonatum species, this study utilized a total of 46 samples encompassing six species and one variety of Polygonatum. Scanning electron microscopy (SEM) was employed to examine the morphological traits of the pollen and to analyze the evolutionary patterns and genetic relationships among Polygonatum species. The results indicate that the pollen grains of the 46 Polygonatum germplasm are uniformly characterized as monads, heteropolar, bilaterally symmetrical, atreme, and possess a mono-sulcus. They were peroblate (P/E-ratio = 0.36–0.42) in shape and medium to large (P = 18.17–27.15 μm, E = 44.11–67.07 μm) in size. And there are four types of exine ornamentation: reticulate, reticulate–perforate, reticulate–rugulate, and reticulate–verrucate. The 46 germplasm resources were classified into four clusters based on the results of a pollen morphology clustering analysis: P. cyrtonema and P. macropodum were grouped into cluster I, P. filipes and P. odoratum into cluster II, P. kingianum and P. kingianum var. grandifolium into cluster III, and P. alternicirrhosum was classified as cluster IV, standing alone. This study tentatively suggests that pollen morphology, particularly pollen size and exine ornamentation, can serve as a valuable reference for the classification, genetic relationship, and evolutionary patterns of the genus Polygonatum.

Polygonatum cyrtonema Hua (PCH) is traditionally recognized as both an edible and medicinal food source. Its rhizomes contain numerous bioactive compounds, notably polysaccharides and flavonoids, which serve as key constituents in functional food development. However, the cultivation of PCH is often hindered by allelopathic effects, which diminish its quality and restrict its industrial application. To mitigate these allelopathic influences, three types of biochars derived from maize straw (MB), rice husk (RB), and tea stem (TB) were applied at concentrations of 0%, 2%, and 4%. Initially, the physicochemical properties of these biochars were characterized, followed by an evaluation of their impact on (1) the synthesis of quality-related components, secondary metabolites, and allelochemicals within PCH rhizomes and (2) the fundamental physicochemical properties and bacterial community structure of the PCH rhizosphere soil. The findings indicated that the application of 4% RB significantly enhanced the content of total polysaccharides by 48.5%, total flavonoids by 30.2%, total saponins by 28.6%, and total polyphenols by 18.3%, while concurrently reducing protein (PRO) and free amino acid (FAA) concentrations in the rhizomes. Non-targeted metabolomic analyses revealed that biochar amendments (1) upregulated metabolites involved in the citrate cycle and galactose metabolism pathways, thereby facilitating energy supply and precursors for polysaccharide biosynthesis; (2) downregulated metabolites involved in the arginine biosynthesis pathway, which is unfavorable for protein and amino acid synthesis; (3) decreased the abundance of six identified allelochemicals, including 5-hydroxy-L-tryptophan and andrographolide, with the most pronounced effect observed in the 4% TB treatment (T2); (4) improved soil physicochemical parameters such as pH, soil organic matter (SOM), total nitrogen (TN), and available potassium (AK); and (5) altered the rhizosphere bacterial community by enriching beneficial phyla, notably Myxococcota and Gemmatimonadota. These modifications in soil properties and bacterial community composition were closely associated with enhanced rhizome quality and a reduction in allelochemical accumulation. Collectively, the results of this study elucidate the potential mechanisms linking biochar application to allelopathy mitigation, optimization of soil microbial communities, and improvement of PCH rhizome quality. This research provides a theoretical basis for the production of high-quality PCH while concurrently minimizing allelochemical accumulation in its rhizomes.