施用棉秆炭连作棉花根际土壤真菌多样性与土壤理化性质及黄萎病的相关性

【目的】研究施用棉秆炭,连作棉花根际土壤真菌群落多样性与土壤理化性质及黄萎病病害的关系,为棉秆的合理利用和防治棉花连作障碍提供科学依据和理论指导。【方法】以棉秆移除(NPK)和棉秆还田(NPKS)为对照,采用常规分析和454高通量测序技术,研究棉秆移除基础上施用常量棉秆炭(22.50 t/hm²,NPKB1)和增量棉秆炭(45.00 t/hm²,NPKB2)条件下,新疆棉花根际土壤真菌群落多样性、理化性质和黄萎病病害发生的相关性。【结果】施用棉秆炭连作棉花根际土壤真菌多样性和理化性质有显著相关性。经过2年的2%棉秆炭的施用显著降低了真菌多样性。真菌NPKS和NPKB2处理OTU丰度分别显著降低了15.63%和46.25%(P<0.05),Shannon多样性指数分别显著降低了11.81%和65.40%。不同用量棉秆炭对子囊菌门和接合菌门真菌数量的影响较大,但菌根真菌数量降低。NPKB2处理土壤中Gibberella、Fusarium和Verticillium等病原真菌数量较NPK处理显著降低。施用棉秆炭显著增加了棉花根际土壤中有机质、速效钾和速效氮的含量,而速效磷的含量则降低;对pH的影响不显著,但显著提高了土壤的电导率。RDA分析中,土壤有机质和速效氮是影响棉花根际土壤真菌群落结构的重要环境因素。与NPK处理和NPKS处理相比,NPKB1处理增加了黄萎病病害发病率和病情指数,NPKB2处理黄萎病病害发病率下降不显著,病情指数分别降低了2.2%和15.0%。Verticillium数量与黄萎病发病率和病情指数呈极显著正相关。施用棉秆炭降低了棉花黄萎病病原菌数量,与NPK处理相比,增量棉秆炭Verticillium数量显著降低了63.83%。与NPK处理和NPKS处理相比,NPKB1处理增加了黄萎病病害发病率和病情指数,NPKB2处理黄萎病病害发病率下降不显著,病情指数分别降低了2.2%和15.0%。【结论】施用棉秆炭降低了连作棉花根际土壤真菌多样性,减少了黄萎病病原菌数量,增加了连作棉花根际土壤养分含量。虽然没有显著降低棉花黄萎病发病率,但有缓解病害发病程度的趋势。

Relationships between Fungi Diversity,Physicochemical Properties and Verticillium Wilt in Continuous Cropping Cotton Rhizosphere Soil with Cotton Stover Biochar

【Objective】 The method of cotton stover incorporation directly affects the physicochemical properties, soil microbial characteristics and occurrence of soil-borne diseases under cotton cultivation, so this project aims to study relationships between continuous cropping cotton rhizosphere soil fungi community diversity and soil physicochemical properties and Verticillium wilt disease in the hope of providing scientific basis and theoretical guidance for rational utilization of cotton stover biochar and the prevention and control of continuous cropping barrier of cotton.【Method】In this study, field trials were conducted to examine the effects of cotton stover biochar on the physicochemical properties, fungal communities, and occurrence of Verticillium wilt disease over 2 years in soil under continuous cotton cropping in Xinjiang, China. The experiment was a factorial design with the four treatments: 1) normal fertilizer with cotton stover removed (NPK); 2) normal fertilizers with powdered cotton stover returned to fields (NPKS); 3) normal fertilizer plus cotton stover biochar applied at 22.50 t/hm² (NPKB1); and 4) normal fertilizer plus cotton stover biochar applied at 45.00 t/hm² (NPKB2).【Result】Compared with NPK and NPKS treatments, fungi diversity was significantly correlated with physicochemical properties in the NPKB1 and NPKB2 treatments. The 454 high-throughput fungal DNA sequencing data showed that the NPKB2 treatment significantly reduced soil fungal diversity in the soil under continuous cotton cropping. As compared to NPK treatments, OTU abundance of fungal decreased by 15.63% and 46.25%(P<0.05)in NPKS and NPKB2 treatments, the Shannon index decreased by 11.81% and 65.40%. Different dosage of cotton stover biochar had a great influence on the number of Ascomycota and Zygomycota, but the number of mycorrhizal fungi was decreased. Analysis of microbial populations at the genus level revealed that the pathogenic fungi, including Gibberella, Fusarium and Verticillium wilt significantly decreased under the NPKB2 treatment. Compared with NPK and NPKS treatments, the NPKB1 and NPKB2 treatments significantly increased soil organic matter (OM), available K and N, whereas available P decreased in the soil. Cotton stover biochar had no significant effect on soil pH, but significantly increased soil electrical conductivity. In RDA analysis, OM and AN were important environmental factors affecting the community structure of soil fungi in cotton rhizosphere. In RDA analysis, OM and AN were important environmental factors affecting the community structure of soil fungi in cotton rhizosphere. Compared with NPK and NPKS treatments, the NPKB1 treatment increased the incidence and disease index of Verticillium wilt. For NPKB2 treatment, no significant decrease was found in the incidence of Verticillium wilt; however, the disease index declined by 2.2% and 15.0%, respectively.【Conclusion】This study showed that cotton stover biochar reduced fungal diversity and the number of Verticillium wilt in rhizosphere soil of continuous cropping cotton, and increased soil nutrient content. Although the incorporation of cotton stover biochar did not significantly lower the incidence of cotton Verticillium wilt but tended to relieve the disease severity.