【作者】 张义飞；

【导师】 杨允菲；

【作者基本信息】 东北师范大学 ， 生态学， 2011， 博士

【摘要】 退化草地生态系统的恢复和重建是世界各国的热点问题。吉林省西部草地盐碱化环境严重,其植被恢复面临巨大困难,有必要依靠其他技术手段辅助、促进植被的恢复进程,而菌根技术即是实现这一目标的重要手段。因此本研究开展了吉林西部盐碱化草地羊草根际土壤的AM真菌资源调查,AM真菌化羊草的耐盐性的室内和室外实验,以期能为应用丛枝菌根真菌技术恢复和重建盐碱化羊草草地提供理论依据和技术支持。主要研究结果如下:主要研究结果如下:1.吉林省盐碱化草地中羊草AM真菌资源分布研究表明,从吉林省西部草原优势种羊草根围采集的45个土样中分离出AM真菌4属11种。其中Glomus属8种,占总种数的72.42%,Acaulospora属1种, Paraglomus属1种,Scutellospora属1种。AM菌对羊草根系的侵染频度为30-76%,侵染程度为4-36%,,羊草根系土壤中（20g）孢子密度为6-280个。土壤pH与侵染频度、程度和种丰度之间存在负相关关系。2.群落生物多样性与AM真菌对羊草根系的侵频度和侵染强度负相关,但与星星草或寸草苔根系侵染情况无关。AM真菌对植物群落多样性的影响可能与其对强竞争力物种的侵染状况有关。群落生物量随AM真菌对群落根系侵染能力的增加而增加。充分证明了AM真菌-植物共生体促进了干物质积累,改善了植物的生长状况。这种生物量增加效应主要体现在AM-羊草共生体上。随盐碱程度的不断加深,菌种丰度不断下降,由纯羊草草地的5个AM菌种,减少到重度盐碱化群落中的G. mosseae和G. geosporum两个菌种。但广布菌种G. mosseae始终是各个群落的优势菌种。土壤营养元素和有机质的增加提高了AM真菌物种丰度、孢子密度和侵染能力,但土壤pH值和电离率的增加降低了AM真菌物种丰度、孢子密度和侵染能力。AM真菌的侵染能力表现出显著的季节动态变化,除了与气候因素相关外,还可能与雨季中过高的土壤水分有关。3.当羊草植株面临较高的盐胁迫时,菌根效应显著存在;AM真菌-羊草共生体显著降低了羊草的盐胁迫效应,充分证明了AM真菌-植物共生体对植物在逆境中生存的重要性。无论有无盐胁迫,AM真菌极大改变了植物生物量的地上地下分配比例。菌根羊草将更多的光合产物分配到根系,相对增加的根系将比无菌根羊草植株具有更强的水分和营养元素吸收和传输能力,从而能为菌根植株拓展更为广阔的资源空间和生存机会。与AM真菌共生后,羊草体内一直维持较高的N、P浓度,但随着盐胁迫的加大,该优势逐渐减少。菌根羊草Ca²⁺离子含量在低盐条件下高于非菌根羊草。K⁺离子含量在中高盐条件下高于非菌根羊草。接种AM真菌后,菌根羊草一直维持着较低的Na⁺和Cl^-离子含量。菌根羊草P/Na⁺比在低盐条件下高于非菌根羊草;而K⁺/Na⁺比在中高盐条件下高于非菌根羊草。随着盐胁迫的增加,菌根羊草对磷的依赖性逐渐转换为对钾的依赖性。4.土壤磷水平、盐胁迫和接种AM真菌对羊草生物量和离子含量产生复杂影响,也影响着AM真菌与羊草之间的共生关系或寄生关系。增加土壤P营养水平,显著降低了非菌根羊草根系的Na⁺含量,提高了羊草地上部分的P/Na比,降低了NaCl对非菌根羊草的盐胁迫效应。土壤磷营养水平影响AM真菌能否改善羊草生长。无盐胁迫低磷土壤中羊草的菌根生长效应接近于零。随土壤磷营养水平的增加,AM真菌对羊草生长的促进作用增强,对P的依赖性降低。受盐胁迫的AM真菌-羊草共生体关系随着土壤磷水平的增加,由互惠共生关系逐渐转变为寄生关系。5.AM真菌G. mosseae和G. geosporum能够在重度盐碱土中侵染羊草根系,并且该共生体改善了移栽苗的存活率、生长和分蘖。将植物-AM真菌共同体重新引入后,能够促进裸碱斑的植被恢复,驱动该恢复向初始物种群落演替。在重度盐碱土壤中,AM真菌能够显著减少羊草Na⁺和Cl^-离子含量,促进N、P、Ca²⁺和K⁺吸收。AM真菌加强了植物对营养元素的选择性吸收,从而降低盐碱胁迫对生长的影响。在三年的实验中,菌根化植物一直保护较高的根茎比。菌根化植株重新分配的根茎比可能是保证重度盐碱化土地上植被成功恢复的一个重要因素。室内盆栽实验和野外移栽实验均表现出AM真菌成功侵染羊草根系,表明裸碱斑中非菌根羊草的自然侵染率较低是由于土壤中缺乏AM真菌繁殖体。更多还原

【Abstract】 Vegetation restoration is one of the most common and effective ways to combat soil degradation and prevent adjacent areas from further encroachment in many of the degraded regions. However, the poor water availability and nutrient supply are stressful for seed germination and/or seedling establishment in severely damaged areas. Successful revegetation with AM fungi has been reported in many degraded regions. To assess the role of AM fungi in vegetation restoration on saline-alkaline grassland, and provide theoretical and technological surpports, we conducted several researches with Leymus chinensis （Trin.） Tzvel, which included the investigation on the AM fungi resources surrounding roots of L. chinensis in saline-alkaline grassland, the indoor and outdoor experiments on the influence of AM fungi on saline-alkaline resistance of L. chinensis. The main results showed as below:1. From the 45 samples of saline-alkaline agrassland in western Jilin Province, we collected and identified 11 AMF species belonging to 4 genera. There were 8 species of Glomus, 72.42% of all speices, 1 species of Acaulospora, 1 species of Paraglomus, and 1 speices of Scutellospora. The AM colonization rates were between 30-60%, infection intensities were between 4-36%, and the spore densities were in 6-280 spores per 20 g soil surrounding roots of L. chinensis. There were negative relationships between pH of soil and colonization rate, infection intensity or species aboundance.2. There were negative relationships between species diversities and colonization rate and infection intensity of AM fungi to L. chinensis roots, but no relationship to CR and II of AM fungi to roots of Puccinellia tenuiflora or Carex duriuscula. These results showed that the influence of AMF to community diversity might be intermediated by their effects on species with high competitive ability. The community biomass increased by the increasing of AMF coloniation to roots, which suggested that the AMF-plant symbiosis impoved the accumulation of dry matter, and plant growth. This improvement of biomass mainly performed by AMF- L. chinensis symbiosis. As the saline-alkaline condition became intensive, the AMF species richness decreased, which from 5 species in pure L. chinensis community to 2 （G. mosseae and G. geosporum） in seriously saline-alkaline communities. However, the G. mosseae was always the dominant species in all communities. The AM fungi species number and spore density significantly increased with the increasing of nutrient concentration and organic matter content of soil, but decreased with the increasing of pH and electric conductivity of soil. There were significantly seasonal changes of colonization ability of AM fungi, which might resulted by the climate or soil moisture.3. The mycorrhizal growth response （MGR） was high when plants of L. chinensis were under intensive salt stress. The salinity response （SR） was significantly dereased by AMF- L. chinensis symbiosis. Therefore, the AMF- L. chinensis symbiosis was important for plant survival under salt stress. The biomass allocated to aboveground and belowground was changed by AMF wherever under salt or non salt environments. Mycorrihal L. chinensis allocated more biomass to roots, which enhanced the ability of absorbing and transfering water and nutrients. After colonized by AMF, the L. chinensis maintained higher N and P concentration, however, this advantage decreased by the increasing salt stress. There were higher Ca²⁺ concentration under low salt stress, and higher K⁺ concentration under middle and high salt stress in mycorrihal L. chinensis. The concentrations of Na⁺和Cl^- were both lower in mycorrihal L. chinensis. Under high salt condition, the K⁺/Na⁺ of mycorrihal plant was higher than that of non-mycorrihal plants, however, under lower and non salt conditions, it was P/Na⁺ of mycorrihal plant that higher than that of non-mycorrihal plants. The results indicated that the saline-resistant ability of mycorrihal plants was increased by mycorrhizal P response （MPR） under lower salt stress, but by mycorrhizal K response （MKR） under high salt stress.4. The effects of P, salt stress and AM inoculation on biomass and ion contents of L. chinensis were complicated, which also influence the transformation of mutualism and parasitism of AMF- L. chinensis symbiosis. With the increase of P, the Na⁺ content of non-mycorrihal plants significantly decreased, and P/Na increased. As a result, the salinity response （SR） dereased for the non-mycorrihal plants. Under the salt stress condition, the mycorrihal growth response increased with the increasing P concentration, but decreased with the increasing P concentration without salt stress. The relationship between AMF and L. chinensis changed from mutualism to parasitism when the P supply of soil increased.5. The G. mosseae and G. geosporum could inoculate the L. chinensis in bare saline-alkaline soil. The improvement of survival, growth and asexual reproduction of inoculated plants indicated that the plant-AM fungi mutualism could improve the reestablishment of vegetation in bare saline-alkaline soil, drive the vegetation restoration to a community dominated by original species. Association with AM fungi increased the absorption of N, P, K⁺, Ca²⁺, but decreased Na⁺ and Cl^- uptake under saline-alkaline stress. The AMF enhanced the ability of plant to absorb nutriets from soil, which helped reduce the negative effect of salt stress on plant growth. Plants inoculated with AM fungi accumulated significantly higher root/shoot ratio than non-inoculated plants, which suggested that the significant higher root/shoot ratios of inoculated plants growing in three years might be a more important contributor for the successful establishment of plants under severe salt stress. The successful colonization by AM fungi under same severe saline-alkaline soil in both pot and field experiments implicated that the low natural colonization of non-inoculated plants in bare saline-alkaline land was resulted from the absence of propagules of AM fungi.更多还原