坡耕地-桑树系统土壤微生物群落结构的PLFA分析

PLFA analysis showed that the configuration modes of sloping crop-mulberry systems affect the soil microbial community structure

土壤微生物群落对土壤生态环境敏感,能够指示土壤质量变化,决定土壤的生态功能。利用磷脂脂肪酸(PLFA)法分析了不同配置模式的坡耕地-桑树系统对旱坡地紫色土土壤生态系统微生物群落结构的影响。结果表明,种植桑树篱能显著提高土壤Phospholipid-derived fatty acids(PLFA)含量,改善微生物群落结构:T1处理(两带等高桑)土壤微生物的PLFA总量(20.54nmol/g)显著高于CK处理(常规农作);T1处理显著提高了土壤细菌含量,T5处理(两带纵坡桑)土壤中真菌的丰富度相对较高。T1的多样性指数(H')和均匀度指数(J)最高,T2(三带等高桑)的丰富度指数(R)最高。主成分分析表明,第一主成分(PCI)主要包括a17:0、16:1ω5c和17:0等直链饱和脂肪酸和多不饱和脂肪酸,占PC1的58.15%;第二主成分(PC2)包括i12:0 3OH、20:1ω9c和cy19:0ω8c等直链单不饱和脂肪酸和环丙烷脂肪酸,占PC2的77.50%;T1与T2微生物群落结构相似,与CK差别较大。冗余分析(RDA)表明:微生物群落结构主要受全磷、p H、全氮、有机质、硝态氮含量影响;全磷、全氮对支链饱和脂肪酸、G+、细菌等影响较大,p H对G-影响较大。相关性分析表明,径流量与i16:0、10Me17:0、a17:0、18:3ω6c(6,9,12)呈显著正相关,与20:1ω9c呈极显著正相关;泥沙量与i16:0、i17:0呈显著正相关,与18:3ω6c(6,9,12)呈显著负相关,与20:1ω9c呈极显著正相关。

The soil microbial community is sensitive to the ecological environment,and it can indicate changes in soil quality and determine the ecological functions of the soil. Phospholipid-derived fatty acids（ PLFA） analysis was used to study the response of soil microorganisms to different configuration modes of sloping crop-mulberry systems on purple soil.The results showed that planting mulberry hedges significantly increased PLFA levels and improved the soil microbial community structure,when compared with no hedge control. The total PLFA level after T1 treatment（ two belts of contour mulberry） was 20.54 nmol / g,which was 66.99% higher than the control. The number of soil bacteria after T1 treatment also increased significantly. The richness of fungi after T5 treatment（ two belts of vertical mulberry） was relatively higher than that after the other treatments. The diversity and evenness indexes after T1 treatment and the richness index after T2treatment（ three belts of contour mulberry） were the highest among the treatments. Principal component（ PC） analysis showed that 58.2% of PC1 was composed of straight-chain saturated and polyunsaturated fatty acids of a17： 0,16： 1 ω5c,and 17： 0,while 77.5% of PC2 was composed of monounsaturated and cyclo fatty acids of i12： 0 3OH,20： 1 ω9c,and cy19： 0 ω8c. T1 and T2 treatments resulted in similar soil microorganisms that differed from the control. Redundancy analysis showed that the microbial community structure was mainly affected by total soil phosphorus,p H,total nitrogen,organic matter,and soil nitrate content. G ＋,branched saturated fatty acids,and bacteria were mainly affected by total phosphorus and total nitrogen,whereas G- was mainly influenced by soil p H. The amount of runoff was significantly and positively correlated with i16： 0,10Me17： 0,a17： 0,and 18： 3 ω6c（ 6,9,12） at P〈0.05 and positively correlated with20： 1 ω9c at P〈0. 001. The amount of sediments had a significant and positive correlation with 18： 0,i16： 0,and i17 3 ω6c（ 6,9,12） at P〈0.05 and with 20： 1 ω9c at P〈0.001,whereas it had a significant and negative correlation with18： 3 ω6c（ 6,9,12） at P〈0.05.