生物炭和秸秆还田对微咸水滴灌棉田土壤真菌群落结构多样性的影响

微咸水灌溉增加土壤盐分，改变土壤环境，进而影响土壤真菌的结构和多样性.在长期微咸水灌溉的基础上，分别添加生物炭和秸秆（采用等碳量设计，分别为3.7 t·hm^-2和6 t·hm^-2），探究生物炭和秸秆对土壤理化性质和真菌群落结构多样性的影响.结果表明：与不施生物炭和秸秆（对照）相比，生物炭施用显著增加土壤的pH、全碳、速效钾和速效磷含量，但显著降低土壤电导率，降低幅度为20.71%；秸秆处理显著增加土壤的速效钾和速效磷含量，但显著降低土壤容重和电导率，降低幅度为4.17%和64.50%.生物炭和秸秆处理对真菌群落Chao1指数和ACE指数有增加趋势，对Shannon指数和Simpson指数有降低趋势.土壤优势真菌门类为子囊菌门、被孢霉门、担子菌门、壶菌门和球囊菌门；优势真菌属为毛壳菌属、赤霉菌属、镰刀菌属、Idriella和被孢霉属.施加生物炭和秸秆提高子囊菌门、被孢霉门、担子菌门、球囊菌门和毛壳菌属的相对丰度；但降低壶菌门、赤霉菌属和Idriella的相对丰度.LEfSe分析表明，施用生物炭和秸秆还田降低真菌群落潜在生物标志物数量.RDA结果显示，土壤真菌群落结构与EC_1：5和TN显著相关.微咸水灌溉给土壤带来了不利影响，其中EC_1：5和TN是驱动土壤真菌群落结构变化的主要因子，土壤真菌群落通过生物炭和秸秆对土壤的改良作用来适应盐胁迫环境.

Effects of Biochar and Straw Returning on Soil Fungal Community Structure Diversity in Cotton Field with Long-term Brackish Water Irrigation

Brackish water irrigation increases soil salinity and changes the soil environment, which affects the structure and diversity of soil fungi. In this study, the effects of biochar and straw (3.7 t·hm^-2 and 6 t·hm^-2, respectively) on soil physical and chemical properties and fungal community structure diversity were investigated on the basis of long-term brackish water irrigation. The results showed that compared to the absence of biochar and straw application (control), biochar application significantly increased pH and the contents of total carbon, available potassium, and available phosphorus in soil but significantly decreased the soil conductivity by 20.71%. Straw treatment significantly increased the content of available potassium and phosphorus but significantly decreased the soil bulk density and conductivity by 4.17% and 64.50%, respectively. The biochar and straw treatment showed an increasing trend in the Chao1 index and ACE index of the fungal community but a decreasing trend in the Shannon index and Simpson index. The dominant fungal phyla in the soil were Ascomycota, Mortierellomycota, Basidiomycota, Chytridiomycota, and Glomeromycota. The dominant fungal genera were Chaetomium, Gibberella, Fusarium, Idriella, and Mortierella. Biochar and straw were applied to increase the relative abundance of Ascomycota, Mortierellomycota, Basidiomycota, Glomeromycota, and Chaetomium. However, the relative abundance of Chytridomycota, Gibberella, and Idriella decreased. LEfSe analysis showed that biochar application and straw returning decreased the number of potential biomarkers in fungal communities. RDA results showed that soil fungal community structure was significantly correlated with EC_1:5 and TN. Brackish irrigation had adverse effects on soil, in which EC_1:5and TN were the main factors driving the change in soil fungal community structure. The soil fungal community adapted to a salt-stress environment through the improvement of soil by biochar and straw.