Reductive soil disinfestation (RSD) and soil fumigant chloropicrin (SFC) are two common agricultural strategies for the elimination of soil-borne pathogens. However, the differences in soil environmental factors, soil bacterial microbiome, and root performance between SFC and RSD are poorly understood. In this study, three soil treatments, untreated control (CK), SFC with 0.5 t⋅ha^–1chloropicrin, and RSD with 15 t⋅ha^–1animal feces, were compared. We evaluated their effects on soil environmental factors, bacterial community structure, and root activity using chemical analysis and high-throughput sequencing. RSD treatment improved soil composition structure, bacterial diversity, and root performance to a greater extent. Carbon source utilization preference and bacterial community structure were strikingly altered by SFC and RSD practices. Bacterial richness, diversity, and evenness were notably lowered in the SFC- and RSD-treated soil compared with the CK-treated soil. However, RSD-treated soil harbored distinct unique and core microbiomes that were composed of more abundant and diverse potentially disease-suppressive and organic-decomposable agents. Also, soil bacterial diversity and composition were closely related to soil physicochemical properties and enzyme activity, of which pH, available Na (ANa), available Mg (AMg), available Mn (AMn), total Na (TNa), total Ca (TCa), total Cu (TCu), total Sr (TSr), urease (S-UE), acid phosphatase (S-ACP), and sucrase (S-SC) were the main drivers. Moreover, RSD treatment also significantly increased ginseng root activity. Collectively, these results suggest that RSD practices could considerably restore soil nutrient structure and bacterial diversity and improve root performance, which can be applied as a potential agricultural practice for the development of disease-suppressive soil.

Reductive soil disinfestation (RSD) is an effective method to inhibit soilborne pathogens. However, it remains unclear how RSD combined with different types of organic materials affects the soil ecosystems of perennial plants. Pot experiments were conducted to investigate the effects of RSD incorporated with perilla (PF), alfalfa (MS), ethanol, and acetic acid on soil properties, enzyme activities, microbial communities and functions, and seedling growth. Results showed that RSD-related treatments improved soil properties and enzyme activities, changed microbial community composition and structure, enhanced microbial interactions and functions, and facilitated seedling growth. Compared with CK, RSD-related treatments increased soil pH, available nitrogen, and available potassium contents, sucrase and catalase activities, and decreased soil electric conductivity values. Meanwhile, RSD-related treatment also significantly reduced the relative abundance of Fusarium while increasing the relative abundance of Arthrobacter , Terrabacter , and Gemmatimonas . The reduction was more evident in PF and MS treatment, suggesting the potential for RSD combined with solid agricultural wastes to suppress pathogens. Furthermore, the microbial network of RSD-related treatment was more complex and interconnected, and the functions related to carbon, nitrogen, sulfur, and hydrogen cycling were significantly increased, while the functions of bacterial and fungal plant pathogens were decreased. Importantly, RSD-related treatments also significantly promoted seed germination and seedling growth. In summary, RSD combined with solid agricultural wastes is better than liquid easily degradable compounds by regulating the composition and function of microbial communities to improve soil quality and promote plant growth. IMPORTANCE: Reductive soil disinfestation (RSD) is an effective agricultural practice. We found that RSD combined with solid agricultural wastes is better than that of liquid easily degradable compounds, may improve soil quality and microbial community structure, inhibit the proliferation of pathogenic bacteria, and contribute to the growth of replanted crops. Thus, RSD combined with solid agricultural wastes is more effective than liquid easily degradable compounds.

Root exudates contain plant metabolites secreted by the roots into the soil, such as ginsenosides secreted by the ginseng root. However, little is known about ginseng root exudate and its impact on the chemical and microbial properties of soil. In this study, the effect of increasing concentrations of ginsenosides on the chemical and microbial properties of soil was tested. Chemical analysis and high-throughput sequencing techniques were used to evaluate the soil chemical properties and microbial characteristics following exogenous application of 0.1 mg·L⁻¹, 1 mg·L⁻¹, and 10 mg·L⁻¹ ginsenosides. Ginsenosides application significantly altered soil enzyme activities; SOM-dominated physicochemical properties were significantly reduced which altered the composition and structure of the soil microbial community. In particular, treatment with 10 mg∙L⁻¹ ginsenosides significantly increased the relative abundance of pathogenic fungi such as Fusarium, Gibberella and Neocosmospora. These findings indicate that ginsenosides in root exudates are important factors that may lead to increased deterioration of soil during ginseng cultivation and provided new research direction for the subsequent study on the mechanism of interaction between ginsenosides and soil microbial communities.

Chemical soil fumigation (CSF) and reductive soil disinfestation (RSD) have been proven to be effective agricultural strategies to improve soil quality, restructure microbial communities, and promote plant growth in soil degradation remediation. However, it is still unclear how RSD and CSF ensure soil and plant health by altering fungal communities. Field experiments were conducted to investigate the effects of CSF with chloropicrin, and RSD with animal feces on soil properties, fungal communities and functional composition, and plant physiological characteristics were evaluated. Results showed that RSD and CSF treatment improved soil properties, restructured fungal community composition and structure, enhanced fungal interactions and functions, and facilitated plant growth. There was a significant increase in OM, AN, and AP contents in the soil with both CSF and RSD treatments compared to CK. Meanwhile, compared with CK and CSF, RSD treatment significantly increased biocontrol Chaetomium relative abundance while reducing pathogenic Neonectria relative abundance, indicating that RSD has strong inhibition potential. Furthermore, the microbial network of RSD treatment was more complex and interconnected, and the functions of plant pathogens, and animal pathogen were decreased. Importantly, RSD treatment significantly increased plant SOD, CAT, POD activity, SP, Ca, Zn content, and decreased MDA, ABA, Mg, K, and Fe content. In summary, RSD treatment is more effective than CSF treatment, by stimulating the proliferation of probiotic communities to further enhance soil health and plant disease resistance.

The allelopathic autotoxicity of ginsenosides is an important cause of continuous cropping obstacles in ginseng planting. There is no report on the potential molecular mechanism of the correlation between polarity of ginsenoside components and their allelopathic autotoxicity. This study applied a combination of metabolomics and transcriptomics analysis techniques, combined with apparent morphology, physiological indexes, and cell vitality detection of the ginseng hairy roots, through which the molecular mechanism of correlation between polarity and allelopathic autotoxicity of ginsenosides were comprehensively studied. The hairy roots of ginseng presented more severe cell apoptosis under the stress of low-polarity ginsenoside components (ZG70). ZG70 exerted allelopathic autotoxicity by regulating the key enzyme genes of cis-zeatin (cZ) synthesis pathway, indole-3-acetic acid (IAA) synthesis pathway, and jasmonates (JAs) signaling transduction pathway. The common pathway for high-polarity ginsenoside components (ZG50) and ZG70 to induce the development of allelopathic autotoxicity was through the expression of key enzymes in the gibberellin (GA) signal transduction pathway, thereby inhibiting the growth of ginseng hairy roots. cZ, indole-3-acetamid (IAM), gibberellin A1 (GA1), and jasmonoyl-L-isoleucine (JA-ILE) were the key response factors in this process. It could be concluded that the polarity of ginsenoside components were negatively correlated with their allelopathic autotoxicity.

Rusty root rot is a severe disease in ginseng (Panax ginseng C. A. Mey) production caused by Ilyonectria robusta. The severity of the disease may be related to the residual ginsenosides in soil. In order to elucidate the response mechanism between Rg1 treatment and the occurrence of ginseng rust, we performed growth, reproduction and transcriptome analysis on treated Rg1. The results showed that Rg1 significantly promoted the mycelial growth and sporulation compared with the control, and aggravated the disease symptoms of Panax ginseng. A total of 6708 transcripts out of 213 131 annotated genes identified from global transcriptomic analysis were differentially expressed in Ilyonectria robusta grown during the Rg1 treatment. These genes were found to be related to the carbon-nitrogen metabolism, transport and assimilation. Many of these genes were also associated with pathogenicity based on the Phi-base database. Several transcription factors were related to specific biological processes, such as nitrogen utilization. The current results revealed that Rg1 played a major role in the development of rusty root rot by promoting fungal cell growth and affected the expression of genes required for pathogenesis. Rg1 could aggravate the invasion of Ilyonectria robusta on ginseng root, which preliminarily revealed the reason for the aggravation of rusty root rot in ginseng soil-borne.