Long-term effects of chloropicrin fumigation on soil microbe recovery and growth promotion of Panax notoginseng

Introduction

Panax notoginseng is a precious Chinese medicinal material. Soil fumigation can control soil-borne disease and overcome the continuous cropping obstacles of P. notoginseng. However, chloropicrin (CP) fumigation can kill non-target soil microorganisms and reduce microbial diversity, but the long-time impacts of CP fumigation on soil microbial are less reported.

Methods

We studied the long-term effects of CP fumigation on soil microbes with high-throughput gene sequencing, and correlated the changes in the composition of microbial communities with environmental factors like soil physicochemical properties and soil enzyme activities. This study mainly focuses on the recovery characteristics of soil microbe after soil fumigation by evaluating the ecological restoration of P. notoginseng soil, its sustained control effect on plant diseases, and its promotion effect on crop growth by focusing on the CP fumigation treatment.

Results

The results showed that CP fumigation significantly increased soil available phosphorus (P) to 34.6 ~ 101.6 mg/kg and electrical conductivity (EC) by 18.7% ~ 34.1%, respectively. High-throughput gene sequencing showed that soil fumigation with CP altered the relative abundance of Trichoderma, Chaetomium, Proteobacteria, and Chloroflexi in the soil while inhibiting a lot of Fusarium and Phytophthora. The inhibition rate of Phytophthora spp. was still 75.0% in the third year after fumigation. Fumigation with CP enhanced P. notoginseng's survival rate and stimulated plant growth, ensuring P. notoginseng's healthy in the growth period. The impact of fumigation on microbial community assembly and changes in microbial ecological niches were characterized using normalized stochasticity ratio (NST) and Levins' niche breadth index. Stochasticity dominated bacterial community assembly, while the fungal community was initially dominated by stochasticity and later by determinism. Fumigation with CP reduced the ecological niches of both fungi and bacteria.

Conclusion

In summary, the decrease in microbial diversity and niche caused by CP fumigation could be recovered over time, and the control of soil pathogens by CP fumigation remained sustainable. Moreover, CP fumigation could overcome continuous cropping obstacles of P. notoginseng and promote the healthy growth of P. notoginseng.

Novel Zn(II) Binuclear and Ni(II) 1D Polymeric Coordination Compounds Based on Dianilineglyoxime and Dicarboxylic Acids: Synthesis and Structure

Two coordinating compounds of zinc(II) (1) [Zn2(DAnH2)2(1,3-bdc)2(DMSO)4] and nickel(II) (2) [Ni(DAnH2)(1,4-bdc)(DMF)2]n were obtained based on dianilineglyoxime (DAnH2), 1,3-benzenedicarboxylic acid (1,3-bdcH2) and 1,4-benzenedicarboxylic acid (1,4-bdcH2), where DMSO is dimethylsulfoxide and DMF is dimethylformamide. The molecular and crystalline structure of reported compounds were established by infrared spectroscopy and single crystal X-ray diffraction, and for 1, additionally, the 1H and 13C NMR spectroscopy was used. According to data, the Zn(II) molecular complex is a binuclear and the Ni(II) is a 1D polymer compound.