摘要:为探究马铃薯与玉米复合种植对化感物质积累与细菌群落结构的影响，分析轮作、间作缓解连作障碍的机制，本研究以马铃薯连作、玉米连作、马铃薯||玉米间作、马铃薯-玉米轮作第8年的土壤为对象，利用GC-MS测定土壤中化感物质含量，并采用Illumina Miseq高通量测序技术对土壤细菌16Sr DNA V4-V5区域进行测序，分析土壤中细菌多样性和群落结构的变化，并对化感物质和优势菌属进行相关性分析。结果表明：玉米连作和马铃薯连作会导致化感物质的积累，玉米连作土壤积累了更多的油酸、亚油酸、花生酸、木焦油酸等脂肪酸，马铃薯连作土壤积累了更多的硬脂醇、二十烷醇等脂肪醇类物质。轮作降低了大部分化感物质的积累，间作降低的化感物质种类相对轮作较少。不同种植方式下土壤细菌群落结构发生了显著变化，相对于连作，间作和轮作Ace指数和Chao指数显著升高。在门水平上，轮作土壤放线菌丰度显著高于马铃薯连作土壤，间作土壤拟杆菌门丰度显著低于玉米连作土壤，两种连作土壤中酸杆菌门丰度都较轮作显著升高。在属水平上，一些有益细菌如节杆菌属、溶杆菌属等在复合种植土壤中相对丰度更高。通过相关性分析发现土微菌属、小梨形菌属与脂肪醇类物质呈显著正相关，黄杆菌属、溶杆菌属、微杆菌属等与脂肪酸类物质呈显著负相关。马铃薯与玉米复合种植降低了化感物质在土壤中的积累，从而抑制了土壤细菌丰度的降低，提高了有益菌属丰度，消减了连作障碍。
关键词:马铃薯/
玉米/
连作障碍/
轮作/
间作/
化感物质/
土壤细菌
Abstract:To investigate the effects of potato and maize compound planting on allelochemicals accumulation and bacterial community structure, soil samples from continuous potato cropping, continuous maize cropping, potato and maize intercropping, and potato-maize rotation were collected in the eighth year of the experiment. Allelochemicals extracted from the soil were determined by GC-MS. Then, Illumina Miseq high-throughput sequencing technology was used to sequence the 16Sr DNA V4-V5 regions of soil bacteria to analyze changes in soil bacterial diversity and community structure. The results showed that:1) continuous cropping of maize and potatoes led to the accumulation of allelochemicals, 2) continuous maize cropping caused soil to accumulate more fatty acids such as oleic acid, linoleic acid, eicosanoic acid, and lignoceric acid, and 3) potato continuous cropping produced soil with more accumulated fatty alcohols such as 1-octadecanol and 1-eicosanol. Rotation reduced the accumulation of most allelochemicals, and the number of allelochemicals that were reduced by intercropping was smaller than that by rotation. The soil bacteria community structure changed significantly among different planting patterns. Compared with continuous cropping, intercropping and rotation had higher Ace and Chao indices. At the phylum level, the abundance of Actinobacteria was significantly higher under rotation than under continuous cropping of potato, the abundance of Bacteroides was significantly lower under intercropping than under continuous cropping of maize, and the abundance of Acidobacteria was significantly higher under both potato and maize continuous cropping than under rotation cropping. At the genus level, some beneficial bacteria such as Arthrobacter and Lysobacteria were relatively more abundant in compound planting soils. Through correlation analysis, it was found that the abundances of Pedomicrobium and Pirellula genera were significantly positively correlated with fatty alcohols, and that of Flavobacterium, Lysobacteria, and Microbacteria genera were significantly negatively correlated with fatty acids. Compound planting of potato and maize reduced the accumulation of allelochemicals in the soil, thus inhibiting reduction in soil bacterial abundance, increasing the abundance of beneficial bacteria, and ameliorating the issues associated with continuous cropping.
Key words:Potato/
Maize/
Continuous cropping obstacle/
Rotation/
Intercropping/
Allelochemical/
Soil bacteria
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