【作者】 吴文祥；

【导师】 林文雄；

【作者基本信息】 福建农林大学 ， 作物栽培学与耕作学， 2010， 硕士

【摘要】 本文以自毒物质为主线,对烟草根际土壤的化感潜力进行评价,通过GC-MS初步分离和鉴定烤烟根际土壤物质,然后通过外源添加烤烟根际土壤提取物质(通过大孔树脂D101收集)和对羟基苯甲酸(GC-MS鉴定的物质)的试验模拟烟草连作,研究烤烟根际土壤提取物质和对羟基苯甲酸对烟草的生理生化响应,同时采用T-RFLP技术研究外源添加物质对烟草根际微生物的影响,验证酚酸对烟草的自毒作用并探讨外源添加物质和微生物是何如协同产生连作障碍。主要结果如下:烤烟根际土壤化感潜力评价表明,烤烟根际土壤含有极性自毒物质,这些物质主要存在于酸性部分,随着浓度的变化对莴苣和烟草的生长表现高抑低促的现象。GC-MS的结果表明,烤烟根际土壤含有大量的有机酸,其含量是对照的50倍,在酸性部分检测到已被报道为化感物质的苯甲酸、对羟基苯甲酸、香草酸和香草醛等物质。苯甲酸、对羟基苯甲酸、香草酸和香草醛的生物测试表明,苯甲酸、对羟基苯甲酸对烤烟幼苗具有较强的抑制作用,而香草酸、香草醛则次之。外源添加物质处理的试验表明:第一、烤烟根际土壤提取物质和对羟基苯甲酸都会对烤烟的生长发育起着直接的影响,与自毒作用的相关系数分别为0.82、0.79,对烤烟的毒害主要表现在对烤烟根系伸长的抑制和侧根数量的减少,叶绿素、光合作用的降低,保护酶体系的破坏,及植株钾的缺乏。第二、对外源添加物质处理下的微生物和自毒作用相关性分析表明,烤烟土壤提取物质和对羟基苯甲酸处理下的烟草根际土壤微生物有42个T-RFs与自毒作用呈负相关极显著,10个T-RFs与自毒作用呈正相关。在外源添加物质处理下的烟草土壤中存在较多的正相关的T-RFs片段,在这些片段中存在许多病原菌如斯氏小小梨形菌、普氏立克次氏体,厌氧菌如双酶梭菌、阿根廷梭菌;而负相关的T-RFs片段主要存在于对照土壤中,其中有较多与土壤营养元素循环相关的细菌,如与碳元素循环相关的Porphyrobacter tepidarius、Blastomonas natatoria,与氮元素循环相关的欧洲亚硝化单胞菌,与硫元素循环相关的地热脱硫肠状菌、死海外硫红螺菌,以及一些改善土壤质地的菌如海洋斯瓦尼氏菌和抑菌的微生物如短小芽孢杆菌、苏云金芽孢杆菌等。综上所述,烤烟土壤中存在自毒物质,这些自毒物质会阻碍烟草的生长,另外会使土壤微生态失衡,从而导致烟草的连作障碍,而外源添加物质的试验则验证了这一过程,同时也验证了酚酸在烤烟连作障碍中起着重要的作用。更多还原

【Abstract】 To study the autotoxic substances of the tobacco rhizospheric soil, some experiments such as evaluation on the allelopathic effect of the rhizospheric soil in cropping sequence for different years, separation and identification of substances extracted from rhizospheric soil under flue-cure tobacco were conducted in this study. At the same time, another experiment ,in which tobacco soil substances (collected by Macroporous resin of D101) and hydroxybenzoic acid were added to the soil under tobacco planted in the pot, was conducted to study how the exogenous substances including tobacco soil substances and hydroxybenzoic acid affect the tobacco and the change in the microorganism by T-RFLP to further confirm the autotoxic effect of hydroxybenzoic acid on tobacco and procedure for the continuous cropping obstacle of tobacco caused by the autotochemicals and microorganism . The results were summarized as follows:The results of the evaluation on allelopathic effect of tobacco rhizosphere soil showed that there were some acidic polarity autotoxic compounds in the soil which could inhibit the growth of the tobacco and lettuce at high concentrations and promoted it at low concentrations. The analysis of GC-MS indicated that the tobacco rhizospheric soil contained lots of organic acids which were 50 times to the control and some compounds such as benzoic acid ,hydroxybenzoic acid ,vanillic acid and vanillin reported as allelochemicals were detected in the soil samples. The result of bioassay showed that benzoic acid, hydroxybenzoic acids had higher inhibitory effect on tobacco than vanillic acid and vanillin. The results of the exogenous-adding-experiment showed that both tobacco soil substances and hydroxybenzoic acid had influence on the growth of tobacco directly, including inhibiting the elongation of roots and decreasing the lateral roots, chlorophyll contents, photosynthesis intensity and potassium level as well as destroying the protective enzymes in tobacco. The correlative analysis of microorganism mediated by exogenous-adding-substances with autotoxic effect showed that there were 42 negatively and significantly related common T-RFs and 10 positively related common T-RFs. There were more positively correlative T-RFs in the soil mediated by exogenous-adding-substances and many pathogens such as Pirellula staleyi, Rickettsia prowazekii, anaerobes such as Clostridium bifermentans,Clostridium argentinense were found in them. The soil of CK had more negative T-RFs and many microorganism of soil nutrition cycle such as Porphyrobacter tepidarius related to nitrogen cycle, Desulfotomaculum geothermicum、Ectothiorhodospira marismortui related to sulfur cycle were found in the negative T-RFs, at the same time, other microorganism such as Shewanella related to improvement of soil texture, Bacillus pumilus、Bacillus thuringiensis related to restrict the pathogen were found also.Accordingly, author strongly suggested that the soil under tobacco contain autotoxic substances which could inhibit the growth of the tobacco and destroy the balance of soil micro-system, and then led to the continuous cropping obstacle of tobacco. The procedure of the continuous cropping obstacle of tobacco caused by autotoxic substances and microorganism resulted by autotoxic substances was confirmed by the exogenous-adding-experiment and the experiment also confirmed that phenolic acid played an important role in continuous cropping obstacle of tobacco.更多还原