保护性耕作对西北旱区丛枝菌根真菌及土壤理化性质的影响

Responses of Arbuscular Mycorrhizal Fungi and Soil Physical and Chemical Properties under Different Tillage Practices in Arid Area of Northwest China

在渭北旱塬连续10 a“冬小麦-夏玉米”一年两熟的复种模式下,设置2种保护性耕作处理:免耕和深松耕,并以翻耕作为常规耕作进行对照,研究不同耕作处理下丛枝菌根(Arbuscular mycorrhizae,AM)真菌生物量(真菌孢子数量、菌丝生长密度)、对玉米根系的侵染效果(包括根系侵染率、菌丝密度和丛枝丰度)和群落结构多样性(AlpHa多样性),并将其与土壤的理化性质进行关联分析。结果表明,耕作处理对土壤的理化性质产生影响,粉粒含量:深松耕、免耕>翻耕,pH:翻耕>深松耕、免耕,有机碳和全氮含量:深松耕>免耕>翻耕,速效磷含量:翻耕>深松耕>免耕。免耕和深松耕处理的土壤AM真菌生物量、侵染效果均高于翻耕。关联分析结果表明,土壤pH、有机碳含量和速效磷含量与AM真菌生物量和侵染效果都存在显著相关。高通量测序结果表明,土壤AM真菌属的种类和分子种数量不同(免耕>深松耕>翻耕),球囊霉属Glomus为优势种(99.34%)。OTU结果表明,深松耕处理的土壤AM真菌多样性显著高于翻耕。冗余分析结果表明,土壤有机碳含量、速效磷含量是导致不同耕作处理下土壤中AM真菌群落结构差异的主效土壤环境因子。

The“winter wheat-summer maize”double cropping system was used for 10 consecutive years in Weibei dryland highland.Two conservation tillage treatments of zero tillage and chisel plow tillage were carried out and plow tillage was taken as a control.Arbuscular mycorrhizae(AM)fungi biomass(spore count,mycelial density),infection of maize roots(infection rate,infection density,clump abundance),and community structure under different tillage treatments were determined.The indicators above were correlated with soil physical and chemical properties.The results showed that the long-term tillage measures had effect on the physical and chemical properties of the soil.The silt contents in chisel plow tillage and zero tillage soil were higher than that in plow tillage;the pH in plow tillage was higher than that in chisel plow tillage and zero tillage;the organic carbon content in chisel plow tillage was higher than that in zero tillage,and the organic carbon content in zero tillage was higher than that in plow tillage.The content of total nitrogen in plow tillage soil was higher than that in zero tillage,and total nitrogen in zero tillage was higher than that in plow tillage.The content of available phosphorus in plow tillage soil was higher than that in chisel plow tillage,and the content in chisel plow tillage was higher than that in zero tillage.AM fungal biomass,infection,and community diversity were also affected to varying degrees.Under zero tillage and chisel plow tillage measures,the biomass and infection by AM fungi were higher than those in plow tillage.Correlation analysis revealed that pH value,organic carbon content,and available phosphorus content were significantly correlated with AM fungal biomass and infection.Illumina MiSeq high-throughput sequencing showed that the relative abundance of soil AM fungi was not significantly different at the genus level,but the species and molecular species were different under the various treatments(zero tillage>chisel plow tillage>plow tillage),and Glomus was the dominant species(99.34%).The Operational Taxonomic Unit results showed that the soil AM fungi diversity under chisel plow tillage was significantly higher than that of plow tillage.The results of redundancy analysis showed that soil organic carbon and available phosphorus were the main environmental factors affecting the species composition of AM fungi in different tillage soils.