水分管理对稻田细菌丰度与群落结构的影响

摘要

目前，不同水分管理条件下，从DNA和RNA水平探究长期淹水和间歇灌溉对稻田土壤细菌群落结构的研究还较少。为探明不同水分管理方式下土壤细菌数量和群落结构特征，以长沙县金井长期定位试验为平台，提取土壤微生物 DNA 和RNA，应用荧光定量和限制性片段长度多态性技术和方法分析了两种水分管理方式——间歇灌溉（稻草和无稻草）和长期淹水（稻草和无稻草）对稻田土壤细菌丰度和群落结构的影响。结果表明，间歇灌溉稻田细菌数量高于长期淹水稻田。在DNA水平上，间歇灌溉稻田干土细菌数量达到3.9×1010 copies·g-1，是长期淹水稻田干土的2.18倍；有稻草添加时，间歇灌溉条件下稻田干土细菌数量达到6.1×1010 copies·g-1，是长期淹水稻田干土的2.21倍。在表达水平上，间歇灌溉条件下稻田干土细菌数量达到2.1×108 copies·g-1，是长期淹水稻田干土的2.58倍；有稻草添加时，间歇灌溉条件下稻田干土细菌数量达到2.8×108 copies·g-1，是长期淹水稻田干土的1.13倍。间歇灌溉稻田与长期淹水稻田的细菌种群结构存在差异。在DNA水平上，尽管间歇灌溉稻田多样性指数与长期淹水稻田相近，但优势细菌种群存在差异。而在表达水平上，不仅优势细菌种群存在差异，而且间歇灌溉稻田土壤细菌的多样性显著高于长期淹水稻田。在有稻草添加情况下，间歇灌溉稻田多样性指数为2.49，而长期淹水稻田多样性指数为0.28。总之，水分管理方式对稻田土壤细菌丰度和群落影响显著，间歇灌溉能够提高水田土壤细菌的数量和细菌的多样性，从细菌的丰度和多样性角度考虑，间歇灌溉是稻田较适宜的水分管理方式。%A field plot experiment was conducted on studying the influence of water management on soil bacterial abundance and community in a rice paddy field during the late rice season in Changsha, Hunan Province. The study included four treatments, that were intermittent flooding without straw (IFS0), intermittent flooding with straw (IFS), continuous flooding without straw (CFS0) and continuous flooding with straw (CFS). The results showed that: the density of bacteria in IF soil was higher than that in CF soil at DNA level. The abundance of bacteria was 3.9×1010 copies·g-1 dry soil in IFS0, which was 2.18 times of that in CFS0. The abundance of bacteria was 6.1×1010copies·g-1 dry soil in IFS, which was 2.21 times of that in CFS. At RNA level, the bacteria was more abundant in IF soil than in CF soil. The abundance of bacteria in IFS0 was 2.1×108 copies·g-1 dry soil, which was 2.58 times of that in CFS0. The abundance of bacteria in IFS0 was 2.8×108 copies·g-1 dry soil, which was 1.13 times of that in CFS0. The bacterial structure differed between intermittent flooding (IFS0 and IFS) and continuous flooding (CFS0 and CFS) at both DNA and RNA levels. The diversity index in intermittent flooding (IFS0 and IFS) was similar to that in continuous flooding (CFS0 and CFS) at DNA level, however, the predominant species were different. At RNA level, the diversity index in intermittent flooding (IFS0) was higher than that in continuous flooding (CFS0), it was even more obvious when straw was added. The diversity index in IFS was 2.49, which was higher than that in CFS, which was 0.28. In general, water management dramatically affected bacterial abundance and community structure in paddy soils and intermittent flooding was a better strategy than continuous flooding for rice cultivation.