中文摘要：

土壤微生物是土壤生态系统的重要组成部分,长期连作严重影响了作物产量和品质,改变了土壤生态系统过程.试验以不同连作年限马铃薯和倒茬地根际土壤为材料,采用气相色谱和质谱联用技术以及群落水平生理活性（CLPPs）和磷脂脂肪酸（PLFAs）生物标记法,对不同连作年限马铃薯根际土壤化学物质及微生物群落结构、功能进行研究.结果表明,连作马铃薯根际土壤乙酸乙酯浸提的酸、中、碱性相中都有质量分数高达50%左右的邻苯二甲酸二丁异酯和少量的顺式-14-二十九烯;和倒茬相比,长期连作根际土壤酯类、烯烃类和苯类物质都有明显的积累.随连作年限的延长,微生物群落利用碳源的能力呈现先增加后降低的趋势,连作4 a 时最强;而连作10 a 时微生物群落对主要碳源的利用能力总体较弱,以碳水化合物为碳源基质的微生物类群代谢能力显著降低;以碳水化合物、羧酸类化合物和氨基酸为代谢基质的微生物类群组成明显受到抑制.主要磷脂脂肪酸中,以16 ∶1、16 ∶ 0、18 ∶ 2ω6t 和18 ∶ 1ω9c 表征的PLFA 含量较高,不同类型的PLFA 含量随连作时间的增加呈现单峰型变化趋势,连作4 a 时土壤微生物生物量最高;随着连作年限的增加,细菌/ 微生物群落生物量比值升高,而真菌/ 微生物群落生物量比值下降;倒茬种植明显改善了土壤主要微生物群落生物量及结构组成.长期连作产生的邻苯二甲酸二丁异酯及顺式-14-二十九烯积累,可能是导致马铃薯连作障碍的主要化感物质;这些化学物质显著改变了土壤微生物群落结构与功能,连作4 a 可能是马铃薯连作栽培障碍的临界点.

英文摘要：

Soil microorganisms are an important component of a soil ecosystem. Long term continuous mono?cropping of potato was found to have altered the soil eco?system, thus affecting yield and quality of the crop. To confirm the finding, rhizospheric soil samples were collected from potato fields under continuous mono?cropping different in cultivation history and fields under crop rotation ( potato and sesame) for analysis of allelochemicals and community structure and functions of soil microbes using gas chromatography?mass spectrometry( GC?MS) , and the phospholipid fatty acids ( PLFAs) biomarker method, separately. Results show that from the soil samples collected from fields under mono?cropping, the educts extrac?ted with ethyl acetate, despite in what phase, acid, neutral and basic, all contained over 50% of diisobutyl phthalate and some Z?14?twenty?nine dilute, indicating apparent accumulation of esters, olefins and benzene substances in the soil, as compared with the soil under crop rotation. With mono?cropping going on, the soil microbial community displayed a trend, rising in the first 2-4 years, peaking after the 4th years, declining after 7-10 years and lingering in general at a low level after 10 years, in carbon utilization capacity. The groups of microbes living on carbohydrates as carbon source decreased significantly in metabolism and the groups living on carbohydrates, carboxylic acids and amino acid as metabolic substances were apparently inhibited. Among the main PLFAs, those characterized by 16 ∶ 1, 16 ∶ 0, 18 ∶ 2ω6t, 18 ∶1ω9c accounted for a high proportion. Contents of various fractions of PLFA varied with mono?cropping going on, all dis?playing a single peak curve. In the field under 4 years of mono?cropping, the soil biomass was the highest, and the biomass ratio of bacteria/microbial community increased, while the ratio of fungi/soil microbial community declined with mono?cropping going on. In the fields under crop rotation, community structure and biomass of the soil microbes were obvi