The destructive bacterial wilt disease caused by Ralstonia solanacearum leads to substantial losses in pepper production worldwide. Plant-derived pesticides exhibit advantages of high efficiency and broad spectrum when compared to traditional chemical pesticides. Artemisia annua and ‘Tai Jiao’ No. 1 were used as the experimental materials, and treated with 0.75 g·mL⁻¹, 1.5 g·mL⁻¹, and 3 g·mL⁻¹ of A. annua extract and inoculated with R. solanacearum at a concentration of OD600 = 0.1 for 14 days. The inhibitory activity of A. annua extracts against R. solanacearum, as well as the disease index, defense enzyme activities, and defense-related substances contents of pepper seedlings were determined. The results showed that the Minimum Inhibitory Concentration (MIC) of the A. annua extract was 3 g·mL⁻¹. As the concentration of A. annua extract increased, the extent of R. solanacearum cell crumpling intensified, accompanied by a gradual decline in its biofilm-forming ability. On the 14th day after treatment, the disease severity index and incidence rate were significantly reduced when the A. annua extract was applied at concentrations of 0.75 g·mL⁻¹ and 3 g·mL⁻¹. At both the 7th and 14th days after treatment, the application of A. annua extract at concentrations of 0.75 g·mL⁻¹ and 3 g·mL⁻¹ led to enhanced activities of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) in peppers at different stages. Simultaneously, it reduced the levels of malondialdehyde (MDA) and hydrogen peroxide (H₂O₂), effectively scavenging reactive oxygen species and alleviating cellular lipid peroxidation. Furthermore, the extract increased the activities of polyphenol oxidase (PPO) and phenylalanine ammonia-lyase (PAL), as well as elevated the contents of soluble protein, flavonoids, and total phenols, ultimately enhancing the disease resistance of peppers. Considering the development costs, the application of A. annua extract at a concentration of 0.75 g·mL⁻¹ demonstrates great potential for green control measures against bacterial wilt in peppers.

The impact of Bacillus thuringiensis (Bt) corn straw returning on the soil ecosystem has attracted significant attention. In this study, taking the homologous conventional corn 5422 as a control, we explored the effects of Bt corn (5422Bt1 and 5422CBCL) straw return after five consecutive cycles on soil nutrients, enzyme activities, and microbial communities. The results showed that in the 5422Bt1 treatment, the levels of available phosphorus (AP), total nitrogen (TN), and sucrose enzyme (SUC) activities significantly increased. In the 5422CBCL treatment, organic matter (OM), alkaline nitrogen (AN), and AP contents, as well as SUC and acid phosphatase (ACP) activities, significantly decreased, while available potassium (AK) and TN contents significantly increased. Through Illumina high-throughput sequencing, it was found that the OTU abundance of soil fungi and bacteria changed after straw returning, and there were no significant differences in alpha diversity (α-diversity) among the three treatments. Redundancy analysis (RDA) indicated that soil nutrients and enzyme activities also affect the soil microbial communities. In summary, Bt corn straw returning affects soil nutrients, enzyme activities, and the structure of microbial communities. Overall, this study revealed the impact of continuous Bt corn straw returning on the soil ecosystem, providing a theoretical basis for subsequent studies.

Podocarpus macrophyllus is an evergreen tree with significant ornamental, economic, and medicinal value, widely used in landscape gardening and bonsai production. However, systematic research on the optimal substrate ratios required for its efficient cultivation remains relatively scarce. This study compared the effects of two cultivation substrates (SJ1: 80% native soil + 20% fine sand and SX2: 25% native soil + 25% coarse sand + 25% peat soil + 25% coconut coir) on the growth of P. macrophyllus. Soil physicochemical properties and plant physiological and biochemical indices were measured, and the rhizosphere microbial community structure was analyzed using Illumina MiSeq high-throughput sequencing. The results show that P. macrophyllus grown in the SX2 substrate exhibited significantly greater ground diameter, plant height, chlorophyll content, and soluble protein content than those in the SJ1 substrate. Microbial community analysis indicates that the two different substrates had little impact on alpha diversity. In the bacterial community, the dominant phylum in the SJ1 substrate was Acidobacteriota, whereas in the SX2 substrate, it was Pseudomonadota. In the fungal community, Ascomycota was the dominant phylum in both SJ1 and SX2. Redundancy analysis (RDA) reveals that water content and total porosity were the primary factors influencing the bacterial community structure. Based on physiological indicators and microbial community composition, the SX2 substrate was more conducive to the growth of P. macrophyllus in terms of plant height and ground diameter. Therefore, this study provides valuable insights for substrate selection and optimization in the cultivation of P. macrophyllus.

The incorporation of Bacillus thuringiensis (Bt) rice straw into fields may influence the growth of subsequent crops, but its ecological risks for winter vegetables remain largely unreported. Investigating the effects of Bt rice straw extracts on the seed germination and plant growth of pakchoi (Brassica campestris L. ssp. Chinensis Makino var. communis Tsen et Lee) can provide a theoretical foundation for ecological risk assessments. In this study, straw extracts from non-Bt rice (Tianyouhuazhan), homozygous Bt rice (T775), and heterozygous Bt rice (F₁ of T775 hybrid) were used as experimental materials at concentrations of 10, 20, and 40 g·L⁻¹. Results showed that, compared to non-Bt extract, 40 g·L⁻¹ homozygous Bt extract increased seedling height and leaf peroxidase (POD) activity but inhibited catalase (CAT) and root superoxide dismutase (SOD) activities. The 20 g·L⁻¹ extract boosted root CAT activity yet suppressed leaf CAT and POD activities. The 10 g·L⁻¹ extract enhanced root length but reduced leaf CAT and POD activities. The 40 g·L⁻¹ heterozygous Bt extract increased leaf and root POD activity but inhibited germination rate and leaf SOD activity. The 10 g·L⁻¹ extract promoted root length and seedling POD activity but suppressed leaf POD activity. In plant growth assessments, the 10 g·L⁻¹ homozygous Bt extract reduced underground dry weight, and the 10 g·L⁻¹ heterozygous Bt extract inhibited both above and underground dry weight, while the 20 g·L⁻¹ heterozygous Bt extract increased aboveground dry weight. In conclusion, the effects of homozygous and heterozygous Bt rice straw extracts on pakchoi varied with concentration and physiological indices, showing no clear pattern. Optimizing straw return concentrations based on Bt rice variety differences is essential to mitigate ecological risks.