【作者】 张贵云；

【导师】 徐国华；

【作者基本信息】 南京农业大学 ， 植物营养， 2013， 博士

【摘要】 丛枝菌根(Arbuscular mycorrhiza, AM)是植物根系与AM真菌(AM fungi, AMF)形成的一种互惠共生体,是自然生态系统中一个重要的组成成分。AMF能促进植物养分吸收,改善植物水分代谢,增强植物抗逆性,改善土壤理化性状,提高植物产量。农业生态系统中AMF多样性丰富,并以独特的群落结构发挥其功能。田间AM的形成与作用发挥的好坏,与相关的农业管理措施,如耕作方式、种植方式以及肥料施用等密切相关。本研究针对传统农业措施对资源、环境和粮食安全等造成不利影响的现状,利用茵根微生态理论和技术,对现代不同农业措施条件下(如保护性耕作、水稻旱作、无害化有机肥)的AMF群落结构和侵染效应的影响进行研究分析,旨在为现代农业管理措施的推广应用提供理论指导,从而更好地发挥AM在农业生产上的增产潜力,促进农业的可持续发展。主要研究结果如下：1.分析了位于江苏盐城的长期水稻旱作栽培条件下的AMF群落结构特征,发现其AM真菌可分3个属,18个种,其中球囊霉属(Glomus)有11个种,无梗囊霉属(Acaulospora)有2个种,盾巨孢囊霉属(Scutellospora)有1个种,尚有4个未知种；三个水稻旱作处理的AMF物种丰度均高于水作处理,但它们的优势种基本一致。地球囊霉(G. geosporum)、摩西球囊霉(G. mosseae)和沾屑球囊霉(G. spurcum)为水作处理0-20cm土层和旱作处理0-40cm土层的优势种,聚丛球囊霉(G. aggregatum)为水作和旱作处理20-80cm土层的优势种。2.深入分析了长期水稻旱作和水作田AMF的时空分布规律,发现同一土层旱作处理的AMF孢子密度均高于水作处理,大小依次为覆膜>裸露>覆草>水作；各处理均随土层加深,孢子密度逐渐降低。水作处理中AMF孢子主要集中在0-20cm土层,20-80cm土层的孢子密度显著降低,旱作处理下层孢子密度虽然也有降低趋势,但明显高于水作处理,尤其覆膜处理20-40cm土层的孢子密度比0-20cm土层还高。大麦季AMF孢子密度高于水稻季,且随作物生育期延长,大麦的AMF孢子密度趋增,而水稻的AMF孢子密度趋减；在大麦田,旱作与水作处理0-20cm土层的孢子密度差异不显著,在水稻田旱作覆草和旱作裸露两个处理0-20cm土层的孢子密度显著高于旱作覆膜和水作处理。对根系AM侵染率做了比较分析,结果表明大麦AM侵染率显著高于水稻AM侵染率；旱作处理的AM侵染率显著高于水作处理,其中,旱作覆膜处理的AM侵染率显著高于旱作覆草和旱作裸露两个处理。3.分析了以上长期试验水稻田土壤的环境因子与AMF孢子密度和AM侵染率的相关性,发现0-20cm土层的土壤有机质、温度、速效P、含水量及pH值不同,这些因子对AMF的发育和侵染均有一定影响。孢子密度与AM侵染率随土壤有机质含量,尤其是土壤水分含量的提高呈显著的下降趋势,但与土壤pH值、土壤温度间则呈一定程度的正相关,覆膜处理表层(0-20cm)高磷土壤环境对AMF的产孢和侵染具有一定的抑制作用。AMF孢子密度、AM侵染率与水稻产量呈不同程度的负相关,而与大麦产量呈显著正相关。分析认为,旱作处理中影响AMF侵染的关键因子是土壤水分。4.分析了位于山西临汾的长期免耕(15年以上)和传统耕作小麦田的AMF多样性特征,发现其AM真菌分为3个属,12个种,包括球囊霉属(Glomus)7个种,无梗囊霉属(Acaulospora)1个种,盾巨孢囊霉属(Scutellospora)2个种,尚有2个未知种。免耕和传统耕作处理的AMF优势种相同,均为摩西球囊霉(G. mosseae)、地表球囊霉(G. versiforme)和聚丛球囊霉(G. aggregatum),且摩西球囊霉和地表球囊霉主要出现在上层土壤,聚丛球囊霉主要在下层土壤。5.调查分析了长期免耕和传统耕作小麦的AMF时空分布规律,发现免耕处理的AMF物种丰度显著高于传统耕作处理,三个免耕处理间的AMF物种丰度基本一致；免耕处理和传统耕作处理的AMF物种丰度均随土层加深而逐渐降低。免耕处理的AMF孢子密度显著高于传统耕作处理,尤以免耕深松处理为高,但与其它两个免耕处理相比差异不显著；不同土层的AMF孢子密度不同,传统耕作20-40cm土层孢子密度低于0-20cm土层,但免耕处理20-40cm土层的孢子密度均稍高于0-20cm土层；40cm土层以下,所有处理的AMF孢子密度均明显降低,160cm土层以下没有发现AMF孢子；另外,100cm土层以下,所有处理都只有1个AMF物种出现,为聚丛球囊霉(G. aggregatum)。6.分析了小麦不同生长时期AMF侵染率和孢子密度的季相变化规律,结果显示免耕处理的AM侵染率和AMF孢子密度在小麦不同生长时期均显著高于传统耕作处理,免耕深松处理的AM侵染率和孢子密度显著高于免耕免压和免耕少压两个处理；侵染率在小麦拔节期达到最高,而孢子密度在小麦收获期达到最高。7.分析了不同免耕条件下土壤环境因子与AMF孢子密度和AM侵染率的相关性,结果表明土壤容重与AMF孢子密度和AM侵染率呈显著负相关,而土壤有机质与孢子密度和AM侵染率呈显著正相关。本研究中,免耕处理的土壤容重明显降低,有机质含量提高,这两个因素提高了土壤的保水性和透气性,有利于小麦根系AM的形成。8.通过盆栽试验,发现单施有机肥对摩西球囊霉(G. mosseae)及其寄主植物玉米的生长发育等有明显的影响,且影响程度随有机肥水平的改变而发生变化。当有机肥施用量<2.0g/kg时,接种处理的AM侵染率、AMF孢子密度、玉米株高、叶绿素含量、生物量以及磷含量均高于或显著高于相应水平的不接种处理,且随有机肥水平的提高而逐渐增高。然而,当有机肥施用量>2.0g/kg时,接种AMF处理的各项指标则与不接种处理相当或显著低于不接种处理。9.通过有机肥和等量氮磷钾无机肥对比试验,研究了两者对摩西球囊霉(Gmosseae)及其寄主植物生长发育的影响。结果显示,有机肥对AM侵染率、玉米株高以及生物量均有明显的影响。有机肥处理的AM侵染率和玉米生物量均显著高于无机肥处理,证明有机肥中的有机质部分(包括微量元素等其他营养成分)发挥着重要作用。以上研究结果表明不同农业措施对土壤AMF的群落结构产生了显著的影响。其中,南方水稻旱作和北方免耕覆盖处理对AMF的重要影响因素都是改善了土壤的水分状况和通气性,从而促进了AMF的繁殖、侵染及其寄主植物的生长发育；而施用有机肥对AMF的影响则表现为,有机肥含量较低时对AMF生长有促进作用,而含量较高时则有抑制作用。采用不同农业技术措施,适度调控表层土壤养分,有助于AMF的丰度和侵染效率的提高,从而促进农业的可持续发展。更多还原

【Abstract】 Arbuscular mycorrhizal (AM) symbiosis is a plant-microbe association between some Glomeromycota fungi and the roots of more than80%of land plants. AM fungi (AMF) are rich in diversity in agricultural ecosystem, playing a vital role based on their unique community structure. AMF improve plant growth by increasing the supply of immobile soil nutrients, notably P, enhancing tolerance or resistance to soil pathogens and abiotic stresses, and by improving the soil structure. Agricultural management factors such as tillage methods, cultivated forms, types and amounts of fertilizers applied may have severe impacts on the AMF community structure. In this study, the micro-ecology theory and technology of mycorrhiza were adopted to investigate the effects of new agricultural practices, such as conservation tillage, rice cultivated in aerobic soil and use of harmless organic fertilizer, on community structures and inoculation rates of AMF. The experimental methods and main results were summarized as follows:1. In order to learn the community structure, spatial and temporal distribution of AMF in rice paddy soils, a field investigation was carried out in the experimental farm of Yancheng Academy of Agriculture Science, Jiangsu province from2006to2007. The soil samples were collected respectively from the plots of a waterlogged soil treatment and three aerobic soil treatments including the ground covered with plastic film, with rice straw mulching and without any mulching. Eighteen AM fungal species belonging to three genera were identified in the soil samples, including11species from Glomus,2species from Acaulospora,1specie from Scutellospora, and4unknown species. The most abundant species of AMF were G. geosporum, G. spurcum and G. mosseae. AMF diversity in aerobic paddy soil was higher than that of waterlogged paddy soil, but the dominant species of AMF, were not altered by water regime in the paddy field. However, the distribution of the dominant AMF species in the soil profile was altered by the water regime. G. geosporum, G spurcum and G. mosseae were the most abundant species in0-20cm layer of waterlogged soil and0-40cm layer of aerobic soil and G. aggregatum was the dominant species in 20-80cm layer of waterlogged and aerobic soil.2. AMF density was significantly higher in the aerobic soil than the waterlogged soil. Among three aerobic soil treatments, plastic film cover resulted highest AMF density. The density of AMF spores gradually decreased from upper layer to lower layer of soil. In waterlogged soil, the spores of AM fungi were mainly distributed in0-20cm soil layer, but the spores of AMF in the20-80cm soil layer in aerobic soil were significantly higher than that of waterlogged soil. It was also observed that both the water regime and plant species affected the root colonization rate. The rice root colonization of AMF was significantly higher in the aerobic soil compared to waterlogged soil. In addition, the colonization percentage of AMF in rice roots grown under aerobic condition was much higher in the treatment with plastic film than with straw mulching and no mulching. The AM colonization in barley roots was significantly higher than that in rice roots.3. The study on the different types of rice cultivated under non-flooded soil showed that the density of AMF spores in host plant rhizosphere correlated significantly with the infection rate of AMF. The cultivation methods significantly affected the contents of organic matter, available P and pH value in0-20cm layer of soils, which had very large effects on AMF’s growth and infection. The spore density and the infection rate of AMF showed a declining trend with the improvement of soil water content and soil organic matter. In contrast, the spore density and the infection rates of AMF to host plants were to some extent positively correlated with soil pH. Phosphorus (P) enrichment on the top layer of soil in plastic film treatment led to the inhibition of the reproduction and infection of AMF. Soil water content was the important influence factor on infection of AMF in aerobic soil.4. A field survey was conducted in a15-years long-term no-tillage wheat area in Linfen, Shanxi to study the effects of no-tillage without compaction, no-tillage with less compaction, no-tillage with subsoiling and traditional tillage on the diversity of AMF.12species from three genus of AMF were identified in the soil samples, including seven of Glomus, one of Acaulospora, two of Scutellospora, and two of unknown species. In addition, G. mosseae, G. versiforme and G. aggregatum were the dominant species in the no-tillage and conventional tillage treatments, G. mosseae and G. versiforme mainly were in the surface layer of soil, and G. aggregatum mainly was in the deep layer of soil.5. AM fungal species richnesses of conservation tillages were significantly higher than that of conventional tillage. There was no significant difference in AMF species richness among three no-tillage treatments. The species richness of AMF differed between different soil layers, and the species richness gradually decreased with the soil layer increases. The spore densities in no-tillage treatments were significantly higher than that of conventional tillage treatment. Especially, no-tillage with subsoiling treatment had the highest density of spores in the three conservation tillage treatments. The spore densities of AMF in different layers were also different, and the spore density of20-40cm layer was lower than that of0-20cm layer in the conventional tillage, but it was higher in the no-tillage treatments. The spore density of AMF of all treatments decreased with the increase of soil layer below40cm soil layer, and no AMF was founded below160cm soil layer. There was only one specie of AMF, identified as G. aggregatum in all the treatments below100cm soil layer.6. AM colonization and spore density at different growth stages of wheat in no-tillage soil were all significantly higher than that of conventional tillage soil, and the AM colonization and spore density in no-tillage with subsoiling were significantly higher than those of other two no-tillage treatments. The study results showed that the spore density and colonization of AMF in wheat soil had a seasonal variation. The AM fungal colonization reached the maximum in jointing stage of wheat, and the spore density had a highest value in mature period of wheat.7. The analysis on the relevance of soil environmental factors and the spore density and the infection rates of AMF in long-term no-tillage wheat field showed that the soil bulk density linking to the tillage management was negatively correlated with the spore density and the infection rates of AMF to wheat. In contrast, soil organic matter was positively correlated with the spore density and the infection rates of AMF to host plants.8. In order to evaluate the effect of G. mosseae on maize growth, a pot experiment was conducted by using different organic fertilizer rates (0.0,0.5,1.0,2.0and4.0g kg’soil). There were two AMF treatments (inoculation with G. mosseae,+AM and uninoculated control,-AM) at every organic fertilizer rate. Generally, both inoculated G. mosseae and organic fertilizer significantly improved plant growth. In the inoculated pots, the growth of plant and AM colonization varied with the rates of organic fertilization. The plant height, chlorophyll content, biomass, P uptake, and AM colonization were increased by the increasing of organic fertilizer rate up to2.0g kg1, but decreased or had no significant difference compared to the uninoculated plants at the highest fertilizer rate (4.0g kg-1). The results suggested that optimal organic fertilizer rate was needed to stimulate AM fungi and improve the maximal growth of plant in agricultural systems. 9. The comparative experiments between the organic fertilizer and inorganic fertilizer with the same amount of major nutrients (N, P and K) were conducted to understand the effect of organic matter on AM colonization and growth of maize. The results showed that organic matter played a significant role in promoting the infection rate of G. mosseae, plant height and biomass of maize. The infection rate of AMF and biomass of maize in the organic fertilizer treatments were higher than that of inorganic fertilizer treatment. At the early growing period of maize, the plant height was lower in organic fertilizer treatment than that of inorganic treatment, but it was significantly higher than that of inorganic fertilizer treatments at the late period of maize.Taking together, the effect of the agricultural practices on soil AMF community structure and infection rate was significant. The conservation tillage and non-flooded rice cultivation increased the infection and reproduction of AMF due to improved the soil aeration and water content. Increasing application of either organic or inorganic fertilizers containning P could inhibite the growth of AMF and AM rate in maize. The proper agricultural practices could thus promote the sustainable development of agriculture by moderately adjusting and controlling nutrition of top soil.更多还原