【作者】 李刚；

【导师】 文景芝；

【作者基本信息】 东北农业大学 ， 植物病理学， 2005， 硕士

【摘要】 棚室蔬菜栽培中,连作障碍已成为制约蔬菜生产可持续发展的重要因素,土壤微生物被认为是连作障碍的主要因子,其群落结构组成及其变化在一定程度上反映了土壤的质量及其健全性,同时也是克服连作障碍及其他土壤障碍因子的关键所在。一般而言,一个具有多样性与活性的生物群落的土壤一定具有较丰富的土壤养分。更重要的是,土壤微生物群落结构和组成的多样性与均匀性不仅提高了土壤生态系统的和谐性和稳定性,同时也提高了对抗土壤微生态环境恶化的缓冲能力。 微生物在土壤中分解有机物质形成腐殖质并释放养分,使土壤有机质的分解、合成处于相对平衡状态,这种相对平衡正是靠土壤微生物生命活动实现的。因此微生物不仅转化土壤碳素和固定无机营养形成微生物生物量,而且土壤微生物可矿化有机物质并将植物不能直接吸收的难溶性物质变为可溶性的,从而提高土壤肥力。微生物对肥料效应、土壤肥力有极其重要的影响,土壤微生物生物量的测定已逐渐成为耕作栽培等农业管理措施对土壤肥力影响的灵敏指标。 本试验利用传统的分离培养方法及PCR-DGGE分子标记技术,对不同种植年限和不同施肥处理条件下土壤微生物数量及土壤微生物群落DNA序列进行了研究,得到不同处理条件下的土壤微生物数量、DNA序列的多样性指数、均匀度指数之间的差异,并对影响土壤微生物群落的因素进行了分析,为进一步制定合理的耕作及施肥措施,调整甚至人为的改变土壤中的生物群落,使之保持和谐、稳定健康的状态和功能,提高作物的产量及品质提供科学依据。 通过试验了解到,棚室土壤中微生物种群以细菌为主,其次为放线菌,真菌数量最少。黄瓜根际微生物总量的变化主要表现在细菌数量的变化上。随着棚室土壤连作年限的增加,盆栽黄瓜根际微生物总量呈不明显上升趋势,其中真菌、细菌和放线菌以及氨氧化细菌和亚硝酸细菌的数量均随连作年限的增加而增加,且真菌增加幅度较大,细菌和放线菌增加幅度较小;纤维素分解菌数量则随连作年限的增加而减少。用黄瓜和番茄交替种植18年的棚室土壤盆栽黄瓜,除了根际氨氧化细菌明显低于连作15年的土壤外,根际真菌、细菌、放线菌和好气性纤维素分解菌的数量明显高于黄瓜连作多年的土壤,亚硝酸氧化细菌的数量也与15年黄瓜连作的土壤无明显差异而远远高于连作2年和7年土壤,说明不同作物春、秋季交替种植这一栽培方式更有利于土壤中各种微生物的积累。 同时,在不同施肥处理条件下,主要表现为施用有机肥或有机复合肥混施可大大提高土壤中细菌、真菌、放线菌和氨化细菌、硝化细菌的数量,而反硝化细菌数量则不同程度的减少,施用有机肥或有机复合肥混施的土壤中微生物多样性指数及均匀度指数也较单独施用复合肥及对照土壤高,说明有机肥或有机复合肥混施对于改善黄瓜根际环境、土壤养分的转化以及微生物的生长有较强的促进作用。更多还原

【Abstract】 Obstacles of continuous cropping have became important factors of decreasing vegetable yield, and it inhibit the sustaining development, soil microbes were considered as the leading one in a lot of factors. Because its change and composing of populations can reflect the health and quality of the soil in some degree. At the same time, it was the key of overcoming the obstacles of continuous cropping and other factors of influencing the soil health. Generally speaking, a soil that having diversified and active microbial populations must have relatively abundant nutrient, what’s more, the diversity and evenness of soil microbial populations structure and composing not only enhance the stability and harmony of the soil ecosystem, but also improve the buffering ability for resisting the deterioration of soil entironment.The microbes can decompose the organic matter and then form the humus and release nutrient, and keep the balanceable state of decomposing and synthesizing the organic matters in soil, this kind of state was realized by the vital activity of soil microbes. Therefore, the soil microbes not only transform the soil carbon element and stable inorganic nutrition into microbial biass, but also mineralize the organic matter and transform the hardly dissolved matter that the plant can not absorb directly into soluble matter, by this they can increase the soil fertility, the microbes can produce great influence on soil fertility and fertilizer effect, the determination of soil microbial bioass have gradually became sensitive index of the soil fertility influence by the agricultural management measurement.This experiment studied the number of microbes and the DNA sequence of microbial community in the soil under different fertilization treatment and cropped for different years at different growth periods with traditional isolating and culturing methods and PCR-DGGE molecular marker technology, gained the changes and differences of the number of soil microbe 、 DNA sequence diversity and evenness index, and analyzed the influencing factors that may change the soil microbial community, try to supply the scientific bases for the eatablishing reasonable farming and manage system by adjusting or even altering the structure of soil microbial community by ourselves, keeping the harmonious, stable and healthy state, which will improve plant yield and quality.By the experiment, we got some conclusions:Firstly, bacteria are predominant among all microbes, and variation of bacteria can represent that of microbes. With the years of continuous cropping of cucumber prolonging, total population of cucumber rhizosphere microbes increased slightly, among them, fungi, bacteria, actinomycete, ammonium-oxidizing bacteria and nitrifying bacteria showed increase, and cellulolytic anaerobicbacteria decrease. Results also showed that growing cucumber and tomato in spring and autumn alternately is beneficial for microbes accumulation in the soil.Secondly, under different fertilization treatment ,the number of bacteria、 fungus、 actinomycete、 ammonium-oxidizing bacteria and nitrifying bacteria were mostly improved, but the number of denitrifying bacteria was decreased in some degree when employ the organic fertilization and the mixture of the organic fertilization and composite fertilization; at the same time, the Shannon-weaver index and evenness index of soil samples which were fertilized with the organic fertilizer or the mixture of the organic fertilizer and composite fertilizer are higher than the soil which were fertilized with composite fertilizer or not fertilized. All these results show that the application of organic fertilizer or the mixture of organic fertilizer and composite fertilizer can improve the environment of cucumber rhizosphere and the transformation of soil nutrient, and have the strong ability for advancing the growth of microbes.更多还原