三七根系分泌物在连作障碍中的生态效应及缓解机制研究

The continuous cropping obstacle of Panax notoginseng has always been a bottleneck problem for its sustainable development. The ecological effect of root exudate is closely related with its continuous cropping obstacle. Due to the previous research is more general, the ecological effect of root exudate of Panax notoginseng is not clear and the formation mechanism of continuous cropping obstacle is not known, which make the lack of the effective measures to alleviate continuous cropping obstacle. This project intends to develop a controlled trial, using the illumineMiSeq high-throughput sequencing technology and conventional soil physical and chemical detection technology, to research the function of Panax notoginseng root exudate to soil physical and chemical propertiesof main planting soil types, and the soil microbial diversity; to explore the effect of root secretion on the soil micro ecological environment. At the same time, we will carry out the physiological response research of allelo chemicals intimidation of Panax notoginseng on its root secretion, and combined with the results of former research of root secretion allelopathic effect, to elucidate the ecological effect of Panax notoginseng root secretion, and to explore the mechanism of root exudate in continuous cropping obstacle of Panax notoginseng. Also based on the above research, further clear the effect of biochar and plant ash to alleviate continuous cropping obstacles and to control root rot. Through evaluation of the allelopathic effect and soil micro ecological environment, we will discuss the mechanism of it relieves continuous cropping obstacle and controls root rot, and provide technical support forthe final solution of continuous cropping obstacle of Panax notoginseng.

三七的连作障碍问题一直是困扰其可持续发展的瓶颈问题，其根系分泌物产生的生态效应与其连作障碍密切相关。但以往的研究较为笼统，致使三七根系分泌物的生态效应不明确，连作障碍的形成机制不清楚，从而缺乏缓解三七连作障碍的有效措施。本项目拟通过开展受控试验，运用illuminaMiSeq高通量测序及常规土壤理化检测等技术手段，研究三七根系分泌物对三七主要种植土壤类型土壤理化性状及土壤微生物多样性的作用，探讨其对土壤微生态环境的影响；同时开展三七对其根系分泌物胁迫的生理响应研究，并结合前人对根系分泌物化感效应的研究结果，阐明三七根系分泌物的生态效应，探究三七根系分泌物在三七连作障碍中的作用机制。并在以上研究基础上，进一步明确生物炭和草木灰缓解三七连作障碍和控制根腐病的效果，并通过对其进行化感效应及土壤微生态环境作用的评价，探讨其缓解三七连作障碍、控制根腐病的机制，为三七连作障碍的最终解决提供技术支撑。

三七根系分泌物产生的生态效应与其连作障碍密切相关，但连作障碍的形成机制尚不清楚。本项目通过受控试验，开展了三七根系分泌物对土壤理化性状、土壤微生物多样性影响以及三七对其根系分泌物化感自毒物质胁迫的生理响应等研究，并就消减三七根系分泌物作用来缓解三七连作障碍的措施与作用机理进行了探讨。研究表明：1.种植三七后，pH值是土壤微生物的重要影响因素，红壤种植三七后土壤易富营养化和严重酸化，主要致病真菌镰刀菌属等丰度大幅增加，有益细菌乳酸杆菌属等丰度大幅降低，微生物群落结构和功能遭受严重破坏；2.三七根系分泌物积累，使三七根系活力和根部细胞渗透调节能力下降，抑制根系对养分和水分吸收，影响光合机能，抗病能力下降。较大的根系分泌物浓度严重影响三七产量和品质。根系分泌物积累使土壤严重酸化，促使镰刀菌属等致病菌丰度增加，而鞘脂单胞菌属等有益菌丰度降低，改变微生物群落结构；3.采用生物炭和草木灰间隔三七根际和非根际土壤，可使三七根际土壤向“细菌型”转化，恢复三七根际土壤微生态环境；生物炭和草木灰可调节土壤pH，显著降低连作土中酸杆菌门的丰度，增加对病原菌有拮抗作用的芽孢杆菌属；同时使连作土细菌群落多样性和丰度显著提高，维持三七根际土壤微生态平衡。.本项目取得的主要研究进展和重要结果为：1.土壤pH值是土壤微生物的重要影响因素；2.红壤种植三七后土壤重度酸化，其中三七根系分泌物积累是导致土壤酸化的重要因素，土壤酸化后土壤微生态平衡被破坏，有害真菌增加，有益细菌减少，土壤由“细菌型”向“真菌型”转化；3.添加生物炭、草木灰后改变了土壤pH环境，使得被破坏了的土壤微生物群落结构得以重建，改善了土壤的微生态环境，从而起到了缓解三七连作障碍的效果。研究成果可为缓解三七连作障碍提供重要解决方案。.项目研究发表论文11篇，其中SCI收录6篇；培养硕士研究生2人；项目组人员晋升副高级职称4人。