【作者】 沈荔花；

【导师】 林文雄； 郭琼霞；

【作者基本信息】 福建农林大学 ， 作物栽培学与耕作学， 2007， 博士

【摘要】 在最近的几十年，全球范围内的外来植物入侵频率达到了前所未有的水平。近年来，外来入侵植物的化感作用研究虽然取得了较大的进展，但在外来植物生物测试方法、根际土壤微生物特性、化感物质、化感作用的生理生化方面尚有薄弱环节。为此，本研究在了解了加拿大一枝黄花的生物学特征基础上，首先采用生物测试的方法对加拿大一枝黄花的化感作用潜力评价，并运用化感-竞争分离法分析加拿大一枝黄花在不同氮水平下的化感潜力变化。同时，采用土壤农化分析技术和色谱-质谱联用(GC-MS)技术分析了加拿大一枝黄花的土壤微生物学特性与化感物质的分离鉴定，最后运用生理生化分析技术探讨了加拿大一枝黄花化感作用的生理机制。结果如下：1、加拿大一枝黄花鲜叶和枯叶的浸提液均具有化感作用潜力，且与对照一一枝黄花的相应物比较，鲜叶浸提液对绿豆、莴苣、小麦、甘蓝和白菜的化感作用更强。在供试的植物受体中小麦对加拿大一枝黄花的化感作用最为敏感。田间抑制圈试验亦证实了加拿大一枝黄花对小麦的强化感抑制作用。2、加拿大一枝黄花随根系延伸距离的增加，其土壤库的化感作用逐渐减弱。随着氮营养水平的下降，加拿大一枝黄花对小麦所施加的化感抑制作用与资源竞争都有所增强，特别是在资源有限时(如低氮条件下)化感作用能力增强，是资源竞争的1.7倍。3、加拿大一枝黄花对根部土壤有碱化趋势，土壤微生物的生物量显著增加，有机质含量有所提高，碳源的利用和代谢能力存在显著差异。另外，加拿大一枝黄花对土壤中的真菌生长有抑制作用，对细菌和放线菌生长有促进作用。对微生物生理类群的分析表明，加拿大一枝黄花对根部土壤的反硝化细菌、嫌气性纤维素分解菌和反硫化细菌的生长有抑制效应。而对亚硝酸细菌、好气性自生固氮菌、硫化细菌、氨化细菌和好气性纤维素分解菌的数量及土壤脲酶、脱氢酶、纤维素酶等均有一定的促进作用。4、加拿大一枝黄花化感物质主要存在于氯仿浸膏中，1％氯仿膏的化感抑制作用高达77.02％。其中6个组分在浓度为0.1％时的化感抑制率介于53.2％-64.3％。这些组分中包含了烃类、萜类、酯类和酚、酸类等物质。各化感活性组分之间普遍存在着相互拮抗作用。5、在加拿大一枝黄花化感作用的影响下，小麦活性氧清除系统的SOD、POD和CAT活性下降，导致自由基含量增加，膜质过氧化加剧，营养吸收能力下降，叶绿素含量减少，叶绿素荧光动力学参数改变，光合作用能力减弱，植株生长受抑制，干物质积累减少。更多还原

【Abstract】 In recent decades, the frequency of exotic plants invasions has reached to an unprecedented level. Progresses had been made in allelopathy research of exotic plant invasion, but it is also possible to identify a range of researchable areas that still need attention, such as bioassay, the mechanism of allelopathy expression under environment stresses, rhizosphere biology of alien plant, identifying allelochemicals, searching for physiochemical response in exotic plant allelopathy, etc.In present work, the bioassay method was used to test the allelopahtic effect of Solidago canadensis L. on the target plants in laboratory condition, then the allelopathy of S.canadensis was further detected by allelopathy- competition-separation-based approach under different nitrogen regimes in near natural condition, and rhizosphere biology of S.canadensis was also analyzed through the investigation of soil microbial flora and the allelochemicals in 5. canadensis, which were extracted, separated and identified by GC-MS. Finally, physiobiochemical approach was employed to get first insight into the mechanism of allelopathy in S.canadensis. The results were summarized as follows:1 The extract of fresh and litter leaves of 5. canadensis both showed allelpathic potential, and fresh one was more stronger in the suppression on the the target plants of mungbean, lettuce, wheat, cabbage and pakchoi when compared with the same parts of its counterpart, Solidago decurrens Lour. In all target plant tested, wheat was the most sensitive receiver to extracts from the fresh and litter leaves of S. canadensis. Based on field trial using the method of radial area from the base of donor plant, S. canadensis also performed higher allelopathic potential in the suppression on wheat.2 The allelopathic potential of the rhizosphere soil was weaker when its distance from the surface of the root of S. canadensis was increased. It was indicated that S. canadensis had higher ability in the resource competition and exhibited its increasing allelopathic potential in the suppression of the target plant wheat as N supplies was decreased in the cocultured system, showing the allelopathic potential of 5. canadensis was 1.7 times as high as its resource competition especially in lower N supplies,.3 S. canadensis caused greater reduction on the number of fungi compared with control Solidago decurrens Lour. The reverse was true on bacteria and actinomycetes. Further analysis indicated that the root exudates from S. canadensis promoted the number of nitrite bacteria, aerobic azotobacter, sulphate reducer, ammonifier and aerobic cellulose-decomposer. But the growth of denitrifier, anaerobic cellulose-decomposer and desulphate reducer were inhibited by the invasive alien weed. The invasive plant, S. canadensis also increased the activities of soil enxyme as urease, dehydrogenase, cellulose etc.4 It was found that the allelochemicals most existed in the chloroform cream of 5. canadensis. The inhibition rate was 77.02% at chloroform cream of 1% concentration. Six groups of chloroform cream showed inhibition rate of 53.2%-64.3% at the 0.1% concentration. These groups contained the compounds as hydrocarbon, terpenoid, ester, hydroxybenzene and acid matter. The synergism and antagonistic relationship were evaluated among those allelopathic compounds.5 The allelopathy of S. canadensis significantly decreased the activities of protective enzymes such as SOD, POD and CAT in wheat, consequently increased the contents of free radical contents, decreased the uptake of nutrients from the enviroment and reduced the chlorophyll concentration, thereby, weakened the photosynthesis and inhibited the growth of wheat seedlings.更多还原