秸秆连续还田对苏打盐碱水稻土养分及真菌群落的影响

Effects of continuous straw returning on nutrients of soda saline-alkaline paddy soil and fungal community

为探明水稻秸秆长期还田对苏打盐碱土养分状况以及土壤真菌群落结构的影响,采用盆栽试验,设置0(CK)、3.0(RS1)、7.5(RS2)、12.0(RS3)、16.5(RS4)t·hm^(-2)5个梯度秸秆还田量,于连续还田5 a后测定土壤的pH值、有机质、全氮、全磷、全钾、速效养分含量以及真菌的相对丰度、Alpha多样性和群落结构变化。结果表明:秸秆还田显著降低了土壤全氮含量,降幅为20.37%~31.48%;RS1和RS3处理碱解氮含量较CK分别降低11.77%和9.61%;秸秆还田显著提高了土壤的pH值,增幅为9.39%~12.65%;RS4处理的有机质含量较CK增加了11.03%。随还田量的增加,全磷、有效磷和速效钾含量呈显著增加的趋势,均在RS4处理达到了最大值,较CK分别增加15.00%、49.34%、103.81%。总体上秸秆还田对苏打盐碱土起到了改良效果。Illumina MiSeq测序结果表明,还田量3.0 t·hm^(-2)时,Aphelidiomycota、轮虫门以及黄藻门相对丰度与CK分别相差20.40%、1.47%、0.08%;还田量16.5 t·hm^(-2)时,子囊菌门、担子菌门、裂壳菌属、柄孢壳属、腐质霉属以及被孢霉属与CK分别相差52.45%、1.40%、30.70%、16.84%、0.53%、0.44%,表明秸秆还田能够显著提高部分菌门和菌属的相对丰度。秸秆还田显著降低了土壤真菌Alpha多样性,ACE指数、Chao1指数、香浓指数降幅分别为10.86%~25.32%、7.81%~26.32%、0.25%~31.34%。秸秆还田处理改变了真菌的群落结构,其中RS3和RS4处理对其影响更为显著。进一步利用RDA和Mantel test分析表明,全钾(p<0.05)、全磷(p<0.05)、有效磷(p<0.01)、速效钾(p<0.01)以及有机质含量(p<0.01)对真菌群落结构的影响显著。综合分析表明,秸秆还田能够调节土壤的理化性质,从而影响真菌的群落结构。

Five treatments including 0(CK),3.0(RS1),7.5(RS2),12.0(RS3),and 16.5(RS4)t·hm^(-2)were set to investigate the effects of continuous straw returning on nutrients of soda saline-alkaline paddy soil and fungal community structure through a pot experiment.The pH,organic matter,total nitrogen(N),total phosphorus(P),total potassium(K),available nutrient content of soil and relative abundance,Alpha diversity and community structure of fungi were determined after five-years straw returning.The results indicated that the total N content significantly decreased by 20.37%~31.48%with the straw returning,and the available N content in RS1 and RS3 treatments decreased by 11.77%and 9.61%,respectively,compared with CK,and the pH significantly increased by 9.39%~12.65%,respectively.The organic matter content in RS4 increased by 11.03%compared with CK.With increasing straw returning amount,the content of total P,available P and available K showed a trend of significant increase,reaching the maximum values in RS4 treatment,which were increased by 15.00%,49.34%,and 103.81%compared with CK,respectively.Overall,the soda saline-alkali soil was amended by straw returning.Illumina MiSeq sequencing results showed that the relative abundance of Aphelidiomycota,Rotifera,and Anthophyta under 3.0 t·hm^(-2)was 20.40%,1.47%,and 0.08%higher than that of control,and the relative abundance of Ascomycota,Basidiomycota,Schizothecium,Zopfiella,Humicola,and Mortierella under 16.5 t·hm^(-2)was 52.45%,1.40%,30.70%,16.84%,0.53%,and 0.44%higher compared with control,respectively,indicating that straw returning significantly improved the relative abundance of some phylum and genus of fungi.Straw returning significantly reduced Alpha diversity of soil fungi,with the index of ACE,Chao1,and Shannon decreased by 10.86%~25.32%,7.81%~26.32%,and 0.25%~31.34%,respectively.The fungal community structure was markedly changed by straw returning,especially in RS3 and RS4 treatments.Further analysis by Redundancy analysis(RDA)and Mental test indicated the fungal community structure was significantly affected by the content of total K(p<0.05),total P(p<0.05),available P(p<0.01),available K(p<0.01),and organic matter(p<0.01).Comprehensive analysis showed that straw returning influenced the fungal community structure by regulating the physicochemical properties of soil.