[Response Characteristics of Soil Fungal Community Structure to Long-term Continuous Cropping of Pepper].

This study aimed to clarify the effect of long-term continuous cropping of pepper on soil fungal community structure, reveal the mechanism of continuous cropping obstacles, and provide a theoretical basis for the ecological safety and sustainable development of pepper industry. We took the pepper continuous cropping soil in the vegetable greenhouse planting base of Tongren City as the research object. The diversity and community structure of fungi in farmland soil were analyzed using Illumina MiSeq high-throughput sequencing, the responses of soil physio-chemical properties and fungal community characteristics to long-term continuous pepper cropping were discussed, and the relationships between the characteristics of fungal community structure and environmental factors were determined using CCA and correlation network analysis. The results showed that with the extension of pepper continuous cropping years, the soil pH value and organic matter (OM) content decreased, total phosphorus (TP) and available phosphorus (AP) contents increased, hydrolyzed nitrogen (AN) and available potassium (AK) contents decreased first and then increased, and total nitrogen (TN) and total potassium (TK) contents did not change significantly. Long-term continuous cropping decreased the Chao1 index and observed species index and decreased the Shannon index and Simpson index. The change in continuous cropping years had a significant effect on the relative abundance of soil fungal dominant flora. At the phylum level, the relative abundance of Mortierellomycota decreased with the extension of pepper continuous cropping years, the relative abundance of Ascomycota increased first and then decreased, and the relative abundance of Basidiomycota decreased first and then increased. At the genus level, with the increasing of pepper continuous cropping years, the relative abundance of Fusarium increased, and the relative abundance of Mortierella and Penicillium decreased. In addition, long-term continuous cropping simplified the soil fungal symbiosis network. CCA analysis indicated that pH, OM, TN, AN, AP, and AK were the driving factors of soil fungal community structure, and correlation network analysis showed that pH, OM, TN, TP, TK, AN, AP, and AK were the driving factors of soil fungal community structure, including Fusarium, Lophotrichus, Penicillium, Mortierella, Botryotrichum, Staphylotrichum, Plectosphaerella, and Acremonium. In conclusion, continuous cropping changed the soil physical and chemical properties, affected the diversity and community structure of the soil fungal community, changed the interaction between microorganisms, and destroyed the microecological balance of the soil, which might explain obstacles associated with continuous cropped pepper.

[Effect of applying phosphorus bacteria fertilizer on bacterial diversity and phosphorus availability in reclaimed soil.] / é æ–½ç£·ç»†èŒè‚¥å¯¹å¤åž¦åœŸå£¤ç»†èŒå¤šæ ·æ€§åŠç£·æœ‰æ•ˆæ€§çš„å½±å“.

A located field experiment of applying phosphorus bacteria fertilizer for five years was carried out to study the effects of applying phosphorus bacteria fertilizer on the characteristics of microbial community structure in reclaimed soil. We studied the diversity of bacterial community using 16S rDNA gene sequencing and analyzed the relationship between bacterial community and Olsen-P, alkaline phosphatase. Seven treatments including control, chemical fertilizer, manure, manure and chemical fertilizer, chemical fertilizer and phosphorus bacteria, manure and phosphorus bacteria, and, manure,chemical fertilizer and phosphorus bacteria were conducted. The results showed that the relative abundance of Actinobacteria and Proteobacteria in reclaimed soil was the largest, which was 21.6％-32.2％ and 13.8％-28.9％, respectively. Operational taxonomic units (OTU) number and Chao1 index of the treatment of manure, chemical fertilizer and phosphorus bacteria fertilizer was 809 and 26190, which was the highest. Phosphorus bacteria fertilizer could improve the relative abundance of soil Actinomycetes and Proteobacteria and decrease that of soil Acidobacteria, Thermotogae and Nitrospira, and had stimulatory effect on Nocardioides and Flexibacter. The treatment of manure, chemical fertilizer and phosphorus bacteria fertilizer could improve the Olsen-P and alkaline phosphatase activities in reclaimed soil. Correlation coefficients between Proteobacteria and Olsen-P, alkaline phosphatase were the highest (0.900 and 0.955). To a certain extent, Proteobacteria could be used as the sensitivity index of soil phosphorus availability.