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植物根系分泌物与根际营养关系评述 总被引:47,自引:0,他引:47
根系分泌物(root exudates,RE)主要有粘胶、外酶、有机酸、糖、酚及各种氨基酸。不同营养基因型的植物,RE级分明显不同,存在养分和环境胁迫时,植物通过增加粘胶、酶及某些有机酸的分泌量以适应变化的环境。RE也是植物改善根际营养环境的重要手段。RE可改善土壤物理结构,促进矿物风化、提高土壤CEC,影响土壤pH、土壤矿物表面吸附性能及土壤生物学性质。RE还存化根际土壤养分,促进植物对养分吸收 相似文献
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根系分泌物是植物保持根际微生态系统活力的关键因素,也是根际物质循环的重要组成部分,对根际土壤生态环境中的物质循环具有重要的驱动作用。根系分泌物可以刺激微生物生长,增强其活性,加速根际养分循环,增加土壤养分利用率,并在小规模空间引起温室气体通量的变化。此外,它也是植物参与竞争的重要策略,植物通过根分泌物以获取种间长期生存的养分,甚至分泌对自身有害的化感物质来排挤其他植物,实现自我生存,即使存在自毒作用或引起连作障碍等。植物的健康生长依赖于自身与土壤微生物复杂动态群落的相互作用,但是根际微生物群落结构和组成却又受植物物种、植物生长期、土壤性质、功能基因等因素影响,这些因素的动态变化可能导致根系分泌物的多样化,从而形成复杂多变的根系分泌物与植物的关系,进而影响植物的健康生长。目前,对植物根系分泌物的研究是土壤生态学、植物营养与代谢等领域的研究热点,且随着分析技术手段的快速发展,根系分泌物相关研究也逐渐深入,进一步揭示植物与微生物间的协同作用机理对农、林等行业生产具有重要的指导意义。 相似文献
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根际是受根系影响而在物理、化学和生物学性质等方面均不同于土体的极小部分土壤区域.研究表明:植物生长过程中,由于根系的代谢作用而向根外排泄H 或HCO3-,使根际土壤pH发生较大变化.而根际土壤的pH直接影响到土壤养分的活性和生物有效性.故不同植物根际土壤的pH状况可反映出它们对土壤氮、磷、钾养分吸收利用能力的相对大小. 相似文献
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褪黑素调控根系生长和根际互作的机制研究进展 总被引:1,自引:0,他引:1
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外源稀土(RE)可导致根-土界面物理、化学及生物学特性发生根本性变化,特别是根系主导的根际动态过程的变化。如施用不同剂量RE条件下,稀土元素(REE)与根系的相互作用使根系生长、酶活性、细胞质膜透性等受到不同程度的影响。根系生长、酶活性的变化反映了植物可能通过根系形态学、生理学的适应性和非适应性变化机制来改变根系吸收养分、REE及重金属离子的能力,直接影响根际离子进入根系中的含量;而根系细胞质膜透性的变化则反映了植物可能通过根系分泌作用的适应性和非适应性变化机制来改变根系有机酸、质子等的分泌状况,使之作用于根际环境,制约养分、REE及重金属元素在根际的形态转化与迁移分布模式,从而间接影响根际离子进入根系中的含量。本文从外源RE对根系生长状况和酶活性的影响;对根系细胞质膜透性和分泌作用的影响;对根际养分、REE及重金属元素动态的影响;对根系养分、REE及重金属元素吸收分布的影响等4个方面的国内外文献出发,就土壤-植物系统中外源RE作用下根-土界面养分、REE及重金属元素的转化、分布及其植物有效性的响应变化与相关机制做出综述,同时提出目前研究中存在的问题,对今后的研究方向进行展望。 相似文献
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集约化互作体系植物根系高效获取土壤养分的策略与机制 总被引:6,自引:1,他引:5
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植物根系构型即根系在其生长介质中的生长与分布,包括根系长度、根系分支和根系生物量等,能够将植物固定在土壤中并有效吸收水分和矿质养分,直接影响植物的生长和发育。根系构型受多种因素的影响,包括土壤水分、养分和根际微生物,传统方式主要依靠化学肥料增加土壤养分进而改善根系生长,但是化学肥料会对环境造成危害,根际微生物作为植物的“第二基因组”,能够改善初生根、侧根和根毛的发育,促进植物的生长和根际养分吸收,近年来基因组学−代谢组学、基因组学−转录组学等多组学关联技术的应用揭示了微生物的促生机制,为微生物菌剂的开发提供了新思路。基于该领域的研究现状,本文阐述了根际微生物(AMF、PGPR、根瘤菌)对根构型的调控机制包括激素调控、固氮、溶磷、释放挥发性有机化合物四个方面,并描述它们通过这四种机制增加植物根系长度、根系分支,促进根毛发育的调控效应,基于上述结论,植物根际微生物可以有效改善根系生长,但实际应用效果还有待研究,量化不同机制的相对贡献率以及提高微生物菌剂在实际应用中的稳定性是后续研究的重点。 相似文献
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植物的磷素营养和土壤磷的生物有效性 总被引:34,自引:0,他引:34
本文介绍了近年来植物磷素营养研究的发展趋势,强调了开展不同基因型作物品种耐低磷机理研究的重要性;阐述了磷有效性品种生产率和根形态的差异、吸收动力学参数与耐低磷的关系、缺磷的酶促适应性,以及作物根系分泌物的作用等。对土壤根际磷有效的影响因素(如根际pH、磷亏缺梯度、有效扩散系数、缓冲力等)进行了综合讨论。 相似文献
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The rhizosphere is the soil zone adjacent to plant roots which is physically, chemically, and biologically different from bulk or non-rhizosphere soil. Adaptative mechanisms of plants influence physical (temperature, water availability, and structure), chemical [pH, redox potential, nutrient concentration, root exudates, aluminum (Al) detoxification and allelopathy], and biological properties (microbial association) in the rhizosphere. These changes affect nutrient solubility, transport, and uptake and ultimately plant growth. Major rhizosphere changes are synthesized and their influence on nutrient availability is discussed. In the last decade, significant progress has been made in understanding the rhizosphere environment and nutrient availability. However, the subject matter is very complex and more research is needed to understand the interaction between the plant, the rhizosphere environment, and nutrient availability. 相似文献
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Iron and phosphorus availability is low in many soils; hence, microorganisms and plants have evolved mechanisms to acquire these nutrients by altering the chemical conditions that affect their solubility. In plants, this includes exudation of organic acid anions and acidification of the rhizosphere by release of protons in response to iron and phosphorus deficiency. Grasses (family Poaceae) and microorganisms further respond to Fe deficiency by production and release of specific chelators (phytosiderophores and siderophores, respectively) that complex Fe to enhance its diffusion to the cell surface. In the rhizosphere, the mutual demand for Fe and P results in competition between plants and microorganisms with the latter being more competitive due to their ability to decompose plant-derived chelators and their proximity to the root surface; however microbial competitiveness is strongly affected by carbon availability. On the other hand, plants are able to avoid direct competition with microorganisms due to the spatial and temporal variability in the amount and composition of exudates they release into the rhizosphere. In this review, we present a model of the interactions that occur between microorganisms and roots along the root axis, and discuss advantages and limitations of methods that can be used to study these interactions at nanometre to centimetre scales. Our analysis suggests mechanisms such as increasing turnover of microbial biomass or enhanced nutrient uptake capacity of mature root zones that may enhance plant competitiveness could be used to develop plant genotypes with enhanced efficiency in nutrient acquisition. Our model of interactions between plants and microorganisms in the rhizosphere will be useful for understanding the biogeochemistry of P and Fe and for enhancing the effectiveness of fertilization. 相似文献
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T. Mimmo D. Del Buono R. Terzano N. Tomasi G. Vigani C. Crecchio R. Pinton G. Zocchi S. Cesco 《European Journal of Soil Science》2014,65(5):629-642
Poor iron (Fe) availability in soil represents one of the most important limiting factors of agricultural production and is closely linked to physical, chemical and biological processes within the rhizosphere as a result of soil–microorganism–plant interactions. Iron shortage induces several mechanisms in soil organisms, resulting in an enhanced release of inorganic (such as protons) and organic (organic acids, carbohydrates, amino acids, phytosiderophores, siderophores, phenolics and enzymes) compounds to increase the solubility of poorly available Fe pools. However, rhizospheric organic compounds (ROCs) have short half‐lives because of the large microbial activity at the soil–root interface, which might limit their effects on Fe mobility and acquisition. In addition, ROCs also have a selective effect on the microbial community present in the rhizosphere. This review aims therefore to unravel these complex dynamics with the objective of providing an overview of the rhizosphere processes involved in Fe acquisition by soil organisms (plants and microorganisms). In particular, the review provides information on (i) Fe availability in soils, including mineral weathering and Fe mobilization from soil minerals, ligand and element competition and plant‐microbe competition; (ii) microbe–plant interactions, focusing on beneficial microbial communities and their association with plants, which in turn influences plant mineral nutrition; (iii) plant–soil interactions involving the metabolic changes triggered by Fe deficiency and the processes involved in exudate release from roots; and (iv) the influence of agrochemicals commonly used in agricultural production systems on rhizosphere processes related to Fe availability and acquisition by crops. 相似文献
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间作作为一种可持续发展的种植模式不仅具有产量和养分获取的优势,而且能够保证粮食安全、降低作物减产风险。在众多间作组合中,豆科禾本科作物间作由于种间促进及生态位互补作用,而在世界范围内被广泛应用。根际是作物-土壤-微生物相互作用的界面,是养分、水分及有害物质从土壤进入作物系统参与食物链物质循环的必经门户,在根际中所发生的生物过程不仅决定着养分的供应量和有效性,而且也影响着作物的生产力和养分利用效率。因此,本文从豆科禾本科间作的根际生物过程角度出发,综述了豆科禾本科间作对根系形态、根际微生物、根系分泌物及其生态效应的研究进展,为豆科禾本科间作体系在修复重金属污染土壤、提高土壤中养分有效性以及植物遗传改良等方面的应用提供理论依据。 相似文献
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Cereal–legume intercropping can promote plant growth (i.e. facilitation) through an increase in the amount of phosphorus (P) taken up, especially in low P soils. The aim of this study was to test the hypothesis that these positive interactions are supported by rhizosphere processes that increase P availability, such as root-induced pH changes. In neutral and alkaline soils legumes are assumed to increase inorganic P availability by rhizosphere acidification due to N2 fixation which benefit to the intercropped cereal. Growth, P uptake, changes in inorganic P availability and pH in the rhizosphere of intercropped species were thus investigated in a greenhouse pot experiment with durum wheat and chickpea either grown alone or intercropped. We used a neutral soil from a P fertilizer long-term field trial exhibiting either low (−P) or high (+P) P availability. Phosphorus availability was increased in the rhizosphere of both species, especially when intercropped in −P. Such increase was associated with alkalization. Rhizosphere pH changes could not fully explain the observed changes of P availability though. Low rates of N2 fixation may explain why no rhizosphere acidification was observed. Increases in P availability did not lead to enhanced P uptake but growth promotion was observed for durum wheat intercropped with chickpea in −P soil. Our hypothesis of an increase in inorganic P availability in intercropping as a consequence of root-induced acidification by the legume was not validated, and we suggested that root-induced alkalization was involved instead, as well as other root-induced processes. Thus, the cereal through rhizosphere alkalization may also enhance P uptake and growth of the intercropped legume. Facilitation can thus occur in both ways. 相似文献
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玉米根鞘改变土壤粒径及养分有效性 总被引:3,自引:0,他引:3
Root exudates,microorganism colonization and soil aggregates together form the rhizosheath,a special cylinder of micro-ecosystem adhering to the root surface.To study how the rhizosheath affects soil structure and nutrient distribution,we analyzed the impact of maize rhizosheath on soil particle size and nutrient availability in pot and field experiments.The results showed that there was a significant size decrease of soil particles in the rhizosheath.Meanwhile,the soil mineral nitrogen in the rhizosheath was significantly higher than that in the rhizosphere or bulk soil at tasseling and maturity stages of maize.The contents of Fe and Mn were also differentially altered in the rhizosheath.Rhizosheath development,indicated by a dry weight ratio of rhizosheath soil to the root,was relatively independent of root development during the whole experimental period.The formation of maize rhizosheath contributed to the modulation of soil particle size and nutrient availability.The subtle local changes of soil physical and chemical properties may have profound influence on soil formation,rhizospheric ecosystem initiation,and mineral nutrient mobilization over the long history of plant evolution and domestication. 相似文献
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The chemical, physical and biological processes occurring in the rhizosphere can influence plant growth by modifying root associated microorganisms and nutrient cycles. Although rhizosphere has been widely investigated, little is known about the rhizosphere effect of pioneer plants in soils of periglacial environments. The knowledge of the processes controlling soil–plant relationships in these severe environments may help understanding the ecological evolution of newly deglaciated surfaces. We selected three plants [Helianthemum nummularium (L.) Mill. subsp. grandiflorum (Scop.), Dryas octopetala (L.), and Silene acaulis (L.) Jacq. subsp. cenisia (Vierh.) P. Fourn.] that sparsely occupy deglaciated areas of central Apennines (Italy), with the aim to assess changes between rhizosphere and bulk soil in terms of physical, chemical, and biological properties. The three plants considered showed to have different rhizosphere effect. Helianthemum induced a strong rhizosphere effect through a synergistic effect between root activity and a well adapted rhizosphere microbial community. Dryas did not foster a microbial community structure specifically designed for its rhizosphere, but consumes most of the energetic resources supplied by the plant to make nutrients available. Conversely to the other two species, Silene produced slight soil changes in the rhizosphere, where the microbial community had a structure, abundance and activity similar to those of the bulk soil. The ability to colonize harsh environments of Silene is probably linked to the shape and functions of its canopy rather than to a functional rhizosphere effect.This study showed that the rhizosphere effect differed by species also under high environmental pressure (periglacial conditions, poorly developed soil), and the activity of roots and associated microbial community is decisive in modifying the soil properties, so to create a suitable environment where plants are able to grow. 相似文献