植烟土壤提取物质对烟株生长及根际土壤细菌多样性的影响

Effects of tobacco-cultivated soil extracts on tobacco growth and bacterial community diversity in rhizosphere soils

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。

Different concentrations（T1： 40 μg.mL-1;T2： 120 μg.mL-1;CK： 0 μg.mL-1） of tobacco-cultivated soil extracts were used to pot-soils to determine the effects of continuous tobacco cropping on tobacco growth and bacterial community diversity in rhizosphere soils.The results indicated that soil extracts significantly inhibited tobacco growth,dwarfed tobacco plant,reduced tobacco leaf area and photosynthesis,and destroyed protective enzymes in tobacco plants.MDA enhancement in tobacco plants was noted.Tobacco MDA in T2 was 2.44 times higher than that in CK.Tobacco growth inhibition was significantly enhanced with increasing concentration of soil extracts.Analysis of T-RFs suggested that 17 plylums and 24 classes rhizospheric bacteria existed in CK soils,14 plylums and 21 classes in T1 soils and 10 plylums and 17 classes in T2 soils.A similar trend was also noted for Margalef index.The results suggested that bacterial community diversity dropped significantly with increasing concentration of soil extracts.Microbial/plant-growth analysis showed that a large proportion of T-RFs derived from soils treated with soil extracts had negative correlations with tobacco growth,and with most T-RFs identified as pathogens.However,a large proportion of T-RFs derived from CK showed positive correlation with tobacco growth,and with several corresponding T-RFs bacteria were involved in soil nutrient recycling.In conclusion thus,tobacco-cultivated soil extracts inhibited tobacco growth,destroyed soil micro-system balance,and reduced bacterial community diversity.The results suggested that soil autotoxic allelochemical accumulation was a major limiting factor in continuous tobacco cropping.