地黄连作障碍严重，合理轮作是目前解决地黄连作障碍问题的首选模式。轮作中发现，油菜对地黄的化感作用严重影响了地黄的生长发育，造成产量减低、品质下降、病害严重。本项目以地黄为受体，生物测定为检测跟踪手段, 通过浸提、萃取、硅胶柱层析分离方法及气相色谱-质谱(GC-MS)鉴定方法, 分离鉴定油菜根系分泌物和根际残茬腐解土壤中抑制地黄生长发育的化感物质；分析化感物质对地黄生长发育变化的作用机理；了解化感物质对地黄根际微生物种群的抑制或促进作用，阐明油菜茬口种植地黄造成严重减产的作用机理，以期探寻解决油菜/地黄轮作障碍消减的调 控策略与途径。

Continuous cropping obstacle problem of Rehmannia glutinosa is more severe. Efficiency rotation is the preferred patterns to solve Rehmannia glutinosa continuous cropping obstacles. it is discovered that the previous rape stubble soil will inhibit Rehmannia glutinosa growth, resulting in its quality and yield declination. In this study, bioassays using Rehmannia glutinosa as receptor were conducted as detecting and tracking method, through extraction, silica gel column chromatography, gas chromatography-mass spec-trometry(GC-MS) method, to isolate and identify allelochemicals which inhabit R. glutinosa growth but can be decayed by rape root root exudates or substances in the rhizosphere; to study allelopathy effects of rape and mechanism of allelochemicals to Rehmannia glutinosa growth, to know more about promotion and inhabitation effects of allelochemicals on rhizosphere microbial population. In order to clarify the reason of causing serious Rehmannia glutinosa yield reduction after rape stubble, and search the new thought and strategies to solve the problems of rape-Rehmannia glutinosa rotation.

本研究项目的结果包括三个方面的内容：（1）初步完成了油菜根系分泌物化感物质的鉴定。（2）提取不同浓度的油菜土壤浸提液，进行了地黄的生物活性检测和生理生化分析，以及对产量的影响。（3）对油菜茬地黄根际的微生物优势菌群进行筛查，初步得出此优势菌群的种类。在第一方面，利用GC-MS技术进行分离鉴定，初步确定其主要包括烃类、醇类、酯类和酸类化合物，且烃类和醇类化合物的相对含量较高，说明油菜苗期的根系分泌物主要以结构较简单的直链或支链烷烃为主。不同浸提剂提取的油菜期根系分泌物化感物质种类基本相同，但含量有些变化，乙酸乙酯试剂提取更充分。在第二方面，提取油菜茬土壤浸提液对地黄进行生物活性检测。结果表明，随着油菜茬土壤浸提液的化感累加作用，地黄幼苗生长、根系长度、根系活力等生长性状以及SOD、POD的含量均有显著变化。地黄生长的所有指标（除MDA外）的化感效应指数为负值，化感效应均表现为抑制作用。说明油菜根系分泌物对地黄生长的化感累加作用没有选择性，生产上需避免油菜与地黄的轮作，或采用化感弱的油菜品种进行轮作。在第三方面，根系分泌物中含有的一些物质,如粘胶类物质,可改变土壤的颗粒状态,从而影响根际土壤的碳组分和含量。随着油菜根系生育期的延伸，油菜分泌物的增加，土壤的放线菌数量略有增加，土壤真菌数量增加幅度最大。