中文摘要：

连作障碍已成为马铃薯产业发展的主要限制因素，为了探明马铃薯连作障碍的机理，减轻连作障碍对产量的影响，采用大田试验与PCR—DGGE分子指纹图谱技术相结合的方法，研究马铃薯连作对根际土壤真菌种群结构的影响及其生物效应．结果表明：随着连作年限的增加，根际土壤中真菌DGGE图谱的条带数量增加，连作1～5年处理的操作分类单元（OTU）分别比对照（轮作）增加了38．5％、38．5％、30．8％、46．2％和76．9％，说明马铃薯连作使根际土壤中真菌优势种群的个体数明显增多．随着连作年限的增加，各处理间真菌种群结构的相似性越来越低．通过真菌DGGE条带的克隆测序比对发现，随着连作年限的增加，马铃薯根际土壤土传病害病原菌尖孢镰刀菌和茄病镰刀菌的数量明显增加，而球毛壳菌作为一种生防菌，连作5年时数量明显减少．连作使根际土壤中病原真菌种群过渡成为优势种群，根际微生态环境恶化，从而作用于根系，使根系活力和吸收面积下降，最终导致块茎产量大幅度下降．

英文摘要：

Continuous cropping obstacle is one of the main restriction factors in potato industry. In order to explore the mechanisms of potato＇ s continuous cropping obstacle and to reduce the impact on potato＇ s tuber yield, a field experiment combined with PCR-DGGE molecular fingerprinting was conducted to investigate the continuously cropped potato of visible bands in rhizosph fungal population structure and its biological effect in rhizosphere soil of . With the increasing year of potato＇ s continuous cropping, the numbers ere fungal DGGE profiles increased obviously. As compared with that of CK （rotation cropping）, the operational taxonomic unit （OTU） in treatments of one to five years continuous cropping was increased by 38.5%, 38.5%, 30.8%, 46.2%, and 76.9% respective- ly, indicating that potato＇s continuous cropping caused an obvious increase in the individual num- bers of dominant fungal populations in rhizosphere soil. Also with the increasing year of potato＇ s continuous cropping, the similarity of the fungal population structure among the treatments had a gradual decrease. The sequencing of the fungal DGGE bands showed that with the increasing year of continuous cropping, the numbers of the potato＇ s rhizosphere soil-borne pathogens Fusarium oxys-ultimately, the tuber yield decreased markedly.