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对盆栽烟草外源添加不同浓度植烟土壤提取物质(T1:40μg·mL-1;T2:120μg·mL-1;CK:蒸馏水对照),探讨植烟土壤提取物质对烟草生长及土壤细菌多样性的影响。结果表明,植烟土壤提取物处理使烟株生长受抑制,且随处理浓度的增加受抑制程度显著提高,具体表现为烟株变矮,叶面积变小,光合作用能力降低,且烟草的保护酶系统受到破坏,丙二醛含量随处理浓度加大而增加,T2处理的丙二醛含量是对照的3.44倍。对外源添加物质处理后烟草根际土壤微生物T-RFs分析发现,在对照检测到17个门24个纲,T1处理有14个门21个纲,T2有10个门17个纲;丰富度指数的变化也和门纲的变化一致,随着处理浓度的增加而显著降低。可见外源添加物质处理后,根际土壤细菌群落减少,多样性水平下降。对各处理的根际土壤微生物T-RFs变化与烟株生长变化进行相关性分析表明,在外源添加物质处理的土壤中存在较多的负相关T-RFs片段,且这些片段中较多为病原菌;而正相关的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微生物。本研究结果显示,在外源添加植烟土壤提取物质处理下,烟草的生长受抑制,烟草根际土壤的微生态受到破坏,且随浓度的提升而加重。因此,连作土壤中自毒物质的富集是造成烟草连作障碍的主要原因。关键词烟草连作障碍根际细菌自毒作用T-RFLP
The effects of tobacco extracts from tobacco growing soil on the growth of tobacco and the bacterial diversity of soil were investigated by adding different levels of tobacco extract (T1: 40μg · mL-1; T2: 120μg · mL-1; CK: distilled water) Impact. The results showed that tobacco plant growth was inhibited by tobacco soil extract treatment, and the degree of inhibition was significantly increased with the increase of treatment concentration. The results showed that the tobacco plants became shorter, the leaf area became smaller and the photosynthesis ability decreased, and the protection of tobacco The enzyme system was destroyed, the content of malondialdehyde increased with the increase of treatment concentration, and the content of malondialdehyde in T2 treatment was 3.44 times of the control. T-RFs analysis of tobacco rhizosphere soil microorganisms showed that there were 24 phylum of 17 phylum in the control group, 21 phylum of 14 phylogenetic tree in T1 and 17 phylum of 10 in T2. The abundance index The changes are also consistent with the changes in the Meniscus, with the increase of treatment concentration decreased significantly. It can be seen that after treatment with exogenous added substances, the bacterial community in rhizosphere soil decreased and the diversity decreased. Correlation analysis of the T-RFs in rhizosphere soil and the growth of tobacco plants showed that there were more negative T-RFs fragments in the soil supplemented with exogenous substances, and more of these fragments were pathogenic bacteria ; While the positively correlated T-RFs fragments mainly exist in the control soil, among which there are more microorganisms related to soil nutrient cycling. The results of this study showed that the growth of tobacco was inhibited and the micro-ecology of tobacco rhizosphere soil was destroyed under the exogenous added tobacco soil extract, which aggravated with the increase of concentration. Therefore, continuous enrichment of autotoxins in soils is the main reason for continuous cropping obstacles. Key words tobacco continuous cropping obstacle rhizosphere bacteria autotoxicity T-RFLP