In recent years, with the frequent global occurrence of harmful algal blooms, the use of plant allelopathy to control algal blooms has attracted special and wide attention. This study validates the possibility of turning water dropwort into a biological resource to inhibit the growth of harmful Microcystis aeruginosa blooms via allelopathy. The results revealed that there were 33 types of allelopathic compounds in the water dropwort culture water, of which 15 were phenolic acids. Regarding water dropwort itself, 18 phenolic acids were discovered in all the organs of water dropwort via a targeted metabolomics analysis; they were found to be mainly synthesized in the leaves and then transported to the roots and then ultimately released into culture water where they inhibited M. aeruginosa growth. Next, three types of phenolic acids synthesized in water dropwort, i.e., benzoic, salicylic, and ferulic acids, were selected to clarify their inhibitory effects on the growth of M. aeruginosa and their mechanism(s) of action. It was found that the inhibitory effect of phenolic acids on the growth of M. aeruginosa increased with the increase of the exposure concentration, although the algae cells were more sensitive to benzoic acid than to salicylic and ferulic acids. Further study indicated that the inhibitory effects of the three phenolic acids on the growth of M. aeruginosa were largely due to the simultaneous action of reducing the number of cells, damaging the integrity of the cell membrane, inhibiting chlorophyll a (Chl-a) synthesis, decreasing the values of F₀ and F_v/F_m, and increasing the activity of the antioxidant enzymes (SOD, POD, and CAT) of M. aeruginosa. Thus, the results of this study indicate that both culture water including the rich allelochemicals in water dropwort and biological algae inhibitors made from water dropwort could be used to control the growth of noxious algae in the future.

Research is lacking on the health risks of antibiotics and antibiotic resistance genes (ARGs) in water dropwort grown in livestock wastewater. Our results showed that antibiotics from livestock wastewater were absorbed and bioaccumulated by water dropwort. The concentration of antibiotics was higher in the roots than in the stems and leaves. The health-risk coefficients of antibiotics in water dropwort were below the threshold (<0.1), indicating that in this case study, the consumption of water dropwort used to purify livestock wastewater was safe for humans considering accumulated antibiotics. ARGs were closely correlated between livestock wastewater and water dropwort, with the results showing that all 13 ARGs detected in the livestock wastewater were also found in the water dropwort. Tetracycline resistance genes were more abundant than the other ARGs in both the livestock wastewater and water dropwort. The estimated daily intake of ARGs in water dropwort for humans ranged from 2.06 × 10⁶ to 7.75 × 10¹² copies g⁻¹_, suggesting the potential risk of intaking ARGs in water dropwort cannot be ignored. Although the safety of consuming water dropwort used to purify livestock wastewater, considering accumulated antibiotics and ARGs, was assessed in this study, more studies should be conducted to ensure we fully understand the health risks.

Canna, the sole member of the Cannaceae family, is widely cultivated as an ornamental plant for its decorative flowers and foliage and is also a potential tuber crop due to its high starch content. This study sequenced, assembled, and analyzed the complete chloroplast (cp) genomes of three common Canna species with distinct leaf colors (green, purple, and variegated). The four cp genomes ranged from 164,427 to 164,509 bp in length, had a GC content of 36.23–36.25%, and exhibited identical gene content and codon preferences. Each genome contained 130 genes, including 110 unique genes (78 protein-coding genes, four of unknown function, four rRNAs, and 28 tRNAs), 18 duplicated genes located in the IR regions (six protein-coding genes, two of unknown function, four rRNAs, and eight tRNAs), and two trnM-CAU genes in the LSC region. SSR and long-repeat showed differences in long repeats numbers and distributions among the four cp genomes, highlighting potential molecular markers for Canna species identification and breeding. Comparative analysis showed high conservation across Canna cp genomes. Phylogenetic analysis confirmed a close relationship between Cannaceae and Marantaceae and supported a [Musaeceae (Cannaceae + Marantaceae)] clade as a sister group to Costaceae. The cp genome data generated in this study provide valuable insights for developing molecular markers, resolving taxonomic classifications, and advancing phylogenetic and population genetic studies in Canna species.

Plant selection plays a critical role in phytoremediation. However, previous research has focused on comparing different plant species but has ignored different cultivars. Here, a laboratory experiment was performed to analyze the nitrogen (N) and phosphorus (P) removal performance of different cultivars of Oenanthe javanica, which are widely employed for phytoremediation in China. Seven cultivars were planted on simulated livestock wastewater with high N and P content prepared with compounds for 22 days in two artificial climate chambers with different temperatures. N and P contents were monitored to estimate the nutrient removal performance of the cultivars. ‘Suzhou Yuanye’ had the highest N removal ability at room temperature (45.33 ± 1.92%) and under cold stress (39.63 ± 2.15%) in 22 days, and it could also remove P effectively (99.32 ± 0.33% at room temperature and 77.50 ± 0.08% under cold stress). ‘Yixing Yuanye’ performed the best in P removal (97.90 ± 2.89% at room temperature and 99.57 ± 0.61% under cold stress). ‘Liyang Baiqin’ performed well in N removal only at room temperature (44.30 ± 1.03%). ‘Suqian Jianye’ had low removal efficiencies for both N and P. From the biomass and N content, we could conclude that the high N removal efficiency of ‘Suzhou Yuanye’ is due to high N assimilation of the plant. However, ‘Yixing Yuanye’ did not show higher P assimilation ability than other cultivars. Taken together, the selection of cultivars is important for phytoremediation projects using O. javanica, and ‘Suzhou Yuanye’ is much more suitable for phytoremediation than other cultivars.

The expansion of the livestock industry has led to an increase in biogas slurry discharge, which contains high levels of nitrogen (N) and phosphorous (P). Struvite precipitation is an effective method for the recovery of N and P from biogas slurry, and the recovered N and P can be applied as a slow-release fertilizer in agricultural production. To form an industrial chain for struvite recovery and application in agriculture, we investigated the factors affecting struvite recovery from biogas slurry generated on a pig farm and evaluated its efficacy as a fertilizer. The N and P recovery efficiency was higher when magnesium chloride (MgCl₂) was used as a magnesium (Mg) source compared with magnesium oxide (MgO), and the optimal reaction conditions were pH 10, a reaction time of 20 min, a stirring rate of 200 rpm, and a Mg/P/N ratio of 1.2:1.0:1.0, which achieved N and P recovery rates of 81.83% and 99.67%, respectively. To further investigate the commercial utility of using struvite recovered from biogas slurry as a fertilizer, the growth and content of nutrients in two common vegetables in China were measured. The vegetable quality-related parameters of bock choy (Brassica chinensis) improved as the proportion of struvite in the fertilizer increased. Fresh weight, soluble sugar, and soluble protein increased by 194.47%, 46.13%, and 82.42%, respectively. The quality-related parameters of water celery (Oenanthe javanica (Blume) DC.) increased with an increasing proportion of struvite (27.90 mg·g⁻¹ soluble sugar and 42.20 mg·g⁻¹ soluble protein). The application of struvite precipitated from biogas slurry in plant cultivation shows great potential and lays a solid foundation for the resourceful recovery and utilization of biogas slurry.