广藿香化感自毒作用与根际土壤微生物互作效应研究

发布时间：2018-09-11 08:38

【摘要】：广藿香[Pogostemon cablin (Blanco) Benth.],是唇形科(Labiatae)刺蕊草属(Pogostemon)的重要的芳香化湿类中药植物,原产于越南、马来西亚、菲律宾等东南亚国家,是重要的药用植物。但随着栽培年限的增加,广藿香连作障碍现象明显,表现为地下部分根系腐烂、退化、根部病害严重,地上叶片长势弱、植株生长不良,甚至整株死亡,造成产量和品质明显下降,这些都阻碍了广藿香的规模化生产。因此,对广藿香连作障碍的成因及作用机理的研究意义重大。本文从化感作用及土壤生态学角度入手,研究了广藿香的化感自毒作用的表现和机理,及连作后根际土壤因子及微生物多样性的变化,为实现有效调控广藿香连作障碍提供理论依据和技术支撑。本研究采用盆栽实验的方法,探讨广藿香根、茎、叶水浸液对广藿香盆栽苗的化感自毒作用潜力,结果表明：最高浓度的广藿香不同部位水浸液(1：10)对盆栽苗的自毒作用强弱比较结果是叶根茎；高浓度的根、茎、叶水浸液(1：10)均能使最株高、根长、最大叶长、总鲜重和叶片数的变化量显著下降；与对照相比,浓度为(1：10)的叶水浸液使植株高度降低了99.8%(p0.05)。叶和根水浸液随浓度增加,使盆栽苗叶片的POD和SOD活性先显著升高,后降低。根水浸液(1：25)使SOD含量上升了284.2%,使POD含量上升了99.5%,叶水浸液(1：25)使SOD含量上升了71.2%,使POD含量上升了137.5%。高浓度的叶和根水浸液(1：10)均使广藿香盆栽苗叶片的MDA含量增加,增加值分别为158.3%,和358.3%(p0.05)。本研究采用盆栽实验的方法,探讨广藿香根际土壤水浸液对广藿香盆栽苗的化感自毒作用潜力,结果表明：高浓度的根际土壤水浸液使盆栽苗的株高、根长、最大叶长、叶片数和总鲜重都显著降低,而根长的下降量最明显,为147.1%。中浓度(1：1)和高浓度(纯浓缩物)的根际土壤水浸液使植株总鲜重降低量分别为19.6%和22.7%(p0.05)。在处理浓度为最高浓度(纯浓缩物)时,SOD、POD、MDA的含量分别达到307μg-1FW,1.6μmol g-1FW and3.3μmol g-1FWh-1。本研究采用水培法,探讨已筛选出的8种化感物质对广藿香盆栽苗的化感自毒作用潜力,结果表明：化感自毒潜力最强的是对羟基苯甲酸,在最高浓度(200μM)时,使广藿香组培苗的株高、根长、总鲜重分别降低了77.0%,42.0%和70.0%(p0.05)。对羟基苯甲酸对SOD和POD活性的影响最大,在浓度为(50μM)时,使SOD和POD活性分别升高了101.6%和437.4%。本研究采用t-RFLP技术分析了不同茬次广藿香根际土壤与对照土壤细菌和真菌多样性的变化,结果表明：随着种植年限的增加,细菌的种类和菌群数量逐渐下降,优势度和丰富度均降低；土壤真菌的种类和菌群数量呈先上升后下降的趋势,二茬土壤中有益菌数量降低；土壤因子中全钾和pH是导致微生物多样性变化的主要因子,细菌中的青枯雷尔氏菌(Ralstonia solanacearum)和真菌中的红辣菇菌(Laccaria laccata)是主要致病菌和拮抗菌。
[Abstract]:Pogostemon cablin (Blanco) Benth. [Pogostemon cablin (Blanco) Benth.] is an important aromatic wet herb of Pogostemon (Labiatae). It originates from Vietnam, Malaysia, Philippines and other Southeast Asian countries and is an important medicinal plant. However, with the increase of cultivation years, continuous cropping obstacles of Pogostemon are obvious, showing in the underground part. Root rot, degeneration, root diseases, weak growth of aboveground leaves, poor growth of plants, even the death of the whole plant, resulting in a significant decline in yield and quality, which hindered the large-scale production of Pogostemon cablin. Therefore, it is of great significance to study the causes and mechanism of continuous cropping obstacles of Pogostemon cablin. The allelopathic autotoxicity and mechanism of Pogostemon cablin and the changes of rhizosphere soil factors and microbial diversity after continuous cropping were studied in order to provide theoretical basis and technical support for effective control of continuous cropping obstacles of Pogostemon cablin.
The allelopathic autotoxicity potential of aqueous extracts from roots, stems and leaves of Pogostemon cablin on potted seedlings was studied by pot experiment. The results showed that the highest concentration of aqueous extracts from different parts of Pogostemon cablin (1:10) had stronger or weaker autotoxicity on potted seedlings, and the higher concentration of aqueous extracts from roots, stems and leaves (1:10) could make it possible. The changes of plant height, root length, maximum leaf length, total fresh weight and leaf number decreased significantly; compared with the control, the leaf water extract at the concentration of (1:10) decreased the plant height by 99.8% (p0.05). With the increase of leaf and root water extract concentration, the POD and SOD activities of potted seedling leaves increased significantly first and then decreased. The content of POD was increased 99.5% by 284.2%, 71.2% by leaf water extract (1:25) and 137.5% by leaf water extract (1:10). High concentration of leaf and root water extract (1:10) increased the content of MDA in leaves of potted Pogostemon cabbage seedlings, with an increase of 158.3% and 358.3% respectively (p0.05).
Pot experiments were conducted to investigate the allelopathic Autotoxicity of Pogostemon cablin rhizosphere soil water extract to Pogostemon cablin potted seedlings. The results showed that the plant height, root length, maximum leaf length, leaf number and total fresh weight of Pogostemon cablin potted seedlings were significantly reduced by high concentration of rhizosphere soil water extract, while the root length was most significantly decreased by 147.1%. (1:1) The total fresh weight of plants was reduced by 19.6% and 22.7% (p0.05) respectively by rhizosphere soil water extract with high concentration (pure concentrate). At the highest concentration (pure concentrate), the contents of SOD, POD and MDA reached 307 ug-1 FW, 1.6 ug-1 FW and 3.3 ug-1 FWh-1.
The allelopathic autotoxicity potential of 8 selected allelochemicals on potted Pogostemon cabbage seedlings was studied by hydroponic culture. The results showed that the highest allelopathic autotoxicity potential was p-hydroxybenzoic acid. The plant height, root length and total fresh weight of Pogostemon cabbage seedlings were reduced by 77.0%, 42.0% and 70.0% (p0.05), respectively, at the highest concentration (200 mu). The effect of benzoic acid on SOD and POD activity was the greatest. The SOD and POD activity increased by 101.6% and 437.4% respectively at the concentration of (50 mu M).
The variation of bacterial and fungal diversity in rhizosphere soils of different stubbles and control soils was analyzed by t-RFLP technique. The results showed that with the increase of planting years, the number of bacterial species and flora decreased gradually, and the dominance and richness of soil fungi decreased. In the second cropping soil, the number of beneficial bacteria decreased, total potassium and pH in soil factors were the main factors leading to the change of microbial diversity, Ralstonia solanacearum in bacteria and Laccaria laccata in fungi were the main pathogenic bacteria and antagonistic bacteria.
【学位授予单位】：海南大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：S567.239;S154.3

【参考文献】