Song Qin

Background: The large-scale cultivation of dragon fruit ( Selenicereus undatus ) in China faces challenges in sustainable weed management, particularly during the summer season. There is a notable lack of suitable green manure species for mountainous orchards that can effectively suppress weeds while enhancing ecological sustainability. Methods: From March to June 2019, a field trial was conducted in a mountainous dragon fruit orchard in Guizhou Province. A comprehensive evaluation of nine leguminous green manure species was performed using membership function analysis. Agronomic performance and weed-suppression effects were analyzed, with natural grass cover as a control, and correlations with green manure growth traits were examined. Results: Common bean ( Phaseolus vulgaris ), rice bean ( Vigna umbellata ), and bush bean ( Phaseolus vulgaris dwarf cv. ) achieved the highest comprehensive scores (0.71, 0.70, and 0.62, respectively). Intercropping with leguminous green manures significantly reduced weed species richness and diversity. Five species demonstrated weed control efficacy exceeding 90%: bush bean (95.98%), cowpea ( Vigna unguiculata , 95.59%), adzuki bean ( Vigna angularis , 92.32%), rice bean (91.16%), and common bean (90.11%). Correlation analysis indicated that rapid emergence, vigorous early growth, and high fresh biomass were significantly associated with enhanced weed suppression. Conclusion: Common bean, rice bean, and bush bean are recommended as optimal summer green manure species for weed management in mountainous dragon fruit orchards. Rapid emergence and high biomass accumulation are key traits for effective weed suppression. Their prioritized application is advised, with subsequent long-term, multilocation trials recommended to assess their comprehensive ecological and economic benefits.

Uncaria rhynchophylla is an important herbal medicine, and the predominant issues affecting its cultivation include a single method of fertilizer application and inappropriate chemical fertilizer application. To reduce the use of inorganic nitrogen fertilization and increase the yield of Uncaria rhynchophylla, field experiments in 2020–2021 were conducted. The experimental treatments included the following categories: S1, no fertilization; S2, application of chemical NPK fertilizer; and S3–S6, application of chemical fertilizers and green manures, featuring nitrogen fertilizers reductions of 0%, 15%, 30%, and 45%, respectively. The results showed that a moderate application of nitrogen fertilizer when combined with green manure, can help alleviate soil acidification and increase urease activity. Specifically, the treatment with green manure provided in a 14.71–66.67% increase in urease activity compared to S2. Metagenomics sequencing results showed a decrease in diversity in S3, S4, S5, and S6 compared to S2, but the application of chemical fertilizer with green manure promoted an increase in the relative abundance of Acidobacteria and Chloroflexi. In addition, the nitrification pathway displayed a progressive augmentation in tandem with the reduction in nitrogen fertilizer and application of green manure, reaching its zenith at S5. Conversely, other nitrogen metabolism pathways showed a decline in correlation with diminishing nitrogen fertilizer dosages. The rest of the treatments showed an increase in yield in comparison to S1, S5 showing significant differences (p < 0.05). In summary, although S2 demonstrate the ability to enhance soil microbial diversity, it is important to consider the long-term ecological impacts, and S5 may be a better choice.