The effects of UV-B radiation on the content of bioactive components and the antioxidant activity of Prunella vulgaris L. spica during development were studied. The experimental design involved two levels of UV-B radiation intensity (0 and 120 μW cm⁻² nm⁻¹). The results showed that the contents of total flavonoids, rosmarinic acid, caffeic acid and hyperoside, as well as the antioxidant capacities (DPPH^● and ABTS•+ scavenging activities), in the spicas significantly decreased during spica development. The content of salviaflaside in the spicas significantly increased during development. The highest contents of total flavonoids, rosmarinic acid, and caffeic acid and the highest antioxidant activities were found in spicas in the full-flowering stage, while the highest content of hyperoside was found in spicas in the bud stage. In addition, the highest content of salviaflaside was found in spicas in the mature-fruiting stage. UV-B radiation significantly promoted the synthesis of secondary metabolites, increased the contents of the main bioactive components in the three developmental stages of isolated dried spicas, and significantly increased the DPPH^● and ABTS•+ scavenging activities of P. vulgaris spicas in the mature-fruiting stage. Moreover, the total flavonoids content was positively correlated with the DPPH^● and ABTS•+ scavenging activities, and the correlation with the DPPH^● scavenging activity was very strong. This result shows that the highest contents of the main bioactive components in the spicas were not all found in the same developmental stages of P. vulgaris. Our research revealed that the best stage for harvesting P. vulgaris spica was between the bud stage and the full-flowering stage since harvesting at this point provides a higher content of bioactive components and a higher antioxidant capacity, which is relevant for medicinal applications.

The rhizosphere is a critical interface linking plants and soil; however, the mechanisms by which parasitic plants affect host growth through rhizosphere microecological changes remain unclear. This study systematically elucidates how Monochasma savatieri, a hemiparasitic plant, promotes blueberry growth by reshaping rhizosphere microecology. Pot experiments showed that parasitism significantly enhanced urease, sucrase, and soil nitrate reductase activities, improving organic matter decomposition and nutrient transformation efficiency. Concurrently, soil total nitrogen (TN), total phosphorus (TP), and total potassium (TK), along with alkali-hydrolyzable nitrogen (AN) and available potassium (AK), decreased, suggesting enhanced nutrient absorption by roots. At the microbial level, parasitism altered community composition and diversity, enriching functional taxa such as Nitrosomonas, OLB5, and Serendipita. Functionally, pathways related to stress resistance (necroptosis and glutamatergic synapses) were activated, whereas those linked to pathogen colonization (Pseudomonas aeruginosa biofilm formation and tryptophan metabolism) were suppressed. These modifications reduced harmful microbial competition, optimized nutrient cycling and signaling networks, and established a favorable rhizosphere microenvironment for root health. By integrating soil enzyme activity, nutrient dynamics, and microbial functions, M. savatieri systemically improves the rhizosphere microenvironment, ultimately enhancing blueberry growth. This study provides theoretical support for intercropping and management of parasitic plants with blueberries.

Rhizosphere microecology plays a key hub role in resource competition between parasitic plants and their hosts; however, the niche differentiation characteristics of the two within the parasitic interaction network remain poorly understood. In this study, the hemiparasitic plant Monochasma savatieri Franch. ex Maxim and its host plant blueberry (Vaccinium spp.) were used as research subjects to systematically analyze the differentiation characteristics of soil environmental factors and rhizosphere microorganisms within the parasitic system. The results showed that the parasitic relationship did not lead to convergence of the rhizosphere microenvironments between the two plants. The rhizosphere nutrient content of M. savatieri was significantly lower than that of its host blueberry, while soil urease (S-UE) and nitrate reductase (S-NR) activities were significantly higher. Furthermore, significant differentiation was observed in the community structure and function of rhizosphere microorganisms at the genus level. The rhizosphere of M. savatieri directionally recruited specific microbial taxa, including Pseudonocardia and Nitrospira–F, which enhanced soil nitrogen turnover. Meanwhile, pathways related to the bacterial secretion system and biofilm formation were significantly upregulated, facilitating haustorium formation and infection. In contrast, the rhizosphere of the host blueberry directionally enriched taxa such as Bradyrhizobium and Colletotrichum, activating complex pathways involved in xenobiotic degradation, energy compensation, and chemical defense. This study preliminarily elucidates the adaptive symbiotic mechanisms between M. savatieri and its host blueberry, providing a microecological basis for optimizing the artificial cultivation of M. savatieri.