德国西南部惠格兰牧草区土壤微生物生物量的研究

对德国巴登符腾堡州的惠格兰牧草区施肥与不施肥区土壤微生物量的研究表明：年平均土壤微生物生物量中Ｃ、Ｎ及其流通量不施肥区均高于施肥区。微生物生物量周转率施肥区大于不施肥区,生物量周转时间则是施肥区小于不施肥区。有机肥料的使用可促进微生物的转化能力。生物通过微生物转化的Ｎ素远大于施入土壤的Ｎ素,也大于植物带走的Ｎ素,表明土壤微生物生物量是土壤养分的源与库。     

植物镁素营养的研究进展

总结近些年来有关镁素营养研究应用。详细综述植物对镁的吸收、镁在植物体内的分配与运输、镁的生理作用、植物体内镁与一些元素间的相互作用。     

三江平原小叶樟和毛果苔草中N素营养动态分析

讨论了沼泽湿地优势种小叶樟（Ｃａｌａｍａｇｒｏｓｔｉｓ ａｎｇｕｓｔｉｆｏｌｉａ）和毛果苔草（Ｃａｒｅｘ ｌａｓｉｏｃａｒｐａ）生物量和生长率变化情况,不同生长期各器官中Ｎ素含量及储量动态变化,以及植物对Ｎ素利用和区域养分限制情况。结果表明,两种植物地上生物量生长符合模式ｐ＝γ＋ａｔ＋βｔ＾２,地下生物量符合曲线ｐ＋ａ０＋ｂ０ｔ;受土壤水分、养分、气温和植物本身特点及其对Ｎ素选择吸收作用等多种因素     

植物镁素营养的研究进展

总结近些年来有关镁素营养研究应用。详细综述植物对镁的吸收、镁在植物体内的分配与运输、镁的生理作用、植物体内镁与一些元素间的相互作用。     

红壤微生物量在土壤—黑麦草系统中的肥力意义

研究了红壤微生物量与土壤养分循环及植物生长的内在联系．结果表明,红壤微生物量不仅与土壤有机碳、全氮、有效氮等显著相关,而且与植物干物质产量及吸Ｎ 量也存在着良好的相关性,可作为指示红壤肥力水平和作物产量的重要指标．试验测得的红壤微生物量Ｎ 周转期较短,每年通过微生物周转的Ｎ 素达到微生物量氮含量的１ ．５ 倍到数倍．     

森林土壤氮素可利用性的影响因素研究综述

近几十年来 ,人类对木材、纤维和其他森林资源需求的急剧增加 ,对森林的集约化经营管理成为必然趋势。由于大部分森林生态系统缺乏Ｎ素 ,因此施肥成为经济有效的途径。但是 ,由于森林中的Ｎ肥利用效率低于农业系统 ,且Ｎ肥生产成本较高 ,易造成环境中多余Ｎ素的污染 ,所以需要更有效的经营管理方法。要改进这类方法 ,则必须很好地理解全球各种森林生态系统的Ｎ素循环和Ｎ素可利用性[3 1] 。可利用性养分 (ａｖａｉｌａｂｌｅｎｕｔｒｉｅｎｔ)是指土壤中易被植物吸收同化的养分元素或化合物的数量[4 0 ] ,可以理解为植物利用土壤中易吸收和…     

兰科植物与菌根真菌的营养关系

兰科植物与真菌具有天然的菌根共生关系。兰科植物种子细小,无胚乳,自然条件下只有与适宜的真菌共生才能萌发;兰科植物作为有花植物中最大的科之一,有光合自养、混合营养及完全真菌异养等营养类型。近年研究表明,不同营养类型的兰科植物其菌根真菌常具有一定的差异性,表现出不同的营养作用关系。本文对不同营养类型兰科植物与菌根真菌的营养作用关系的研究进展进行综述,并对兰科植物菌根营养机理、营养关系的变化等进行讨论,以期为兰科菌根营养学研究及菌根技术应用于兰科植物快繁和保育工作等提供参考。     

矿质营养对生长素代谢影响的研究现状与展望

植物从环境中吸收的矿质元素直接参与植物生理代谢,植物内源激素对植物生理代谢具有重要的调节作用,矿质营养与植物内源激素的相互关系一直是植物营养研究的重要内容。生长素是植物五大内源激素之一,对细胞的分裂和伸长具有重要的调节作用。本文从矿质营养对IAA的量及分布,矿质营养对IAA合成,矿质营养对IAA运输,矿质营养对IAA的转化等方面对矿质营养与生长素的关系的研究进展进行了概述,并对矿质营养与生长素的关系的进一步研究进行了展望。     

与高等植物吸收(NO_3)~-/(NH_4)~+、(PO_4)~(3-)和K~+有关的膜转运蛋白编码基因的分子生物学研究现状

高等植物对土壤中营养元素的吸收是其一切生命活动过程的基础,尤其在营养元素缺乏的状态下,更与其抗营养饥饿等特性息息相关。兼于土壤中Ｎ、Ｐ、Ｋ元素缺乏的严重性与普遍性,以及Ｎ、Ｐ、Ｋ对高等植物生长和发育的重要性,有关高等植物吸收营养元素的膜转运蛋白编码基因的分子生物学研究已引起有关学者的高度重视。ＮＯ－３／ＮＨ＋４、ＰＯ３－４与Ｋ＋膜转运蛋白均有低亲和力和高亲和力系统（ＬｏｗＡｆｉｎｉｔｙＴｒａｎｓｐｏｒｔｅｒ＆ＨｉｇｈＡｆｉｎｉｔｙＴｒａｎｓｐｏｒｔｅｒ）。对ＰＯ４３－和Ｋ＋而言,低亲和力系统是组成性表达的系统,在正常营养状态下对根系吸收营养起重要作用。而高亲和力系统是受营养缺乏而诱导表达的系统,对于植物的抗逆性、耐营养饥饿至关重要。迄今为止,与之有关的基因的全长ｃＤＮＡ或全基因已在几种植物中被克隆。此外,对基因的表达特性亦有广泛研究。本文简要概述这三大营养元素的膜转运蛋白编码基因的分子生物学研究现状。     

矿质营养对生长素代谢影响的研究现状与展望

植物从环境中吸收的矿质元素直接参与植物生理代谢,植物内源激素对植物生理代谢具有重要的调节作用,矿质营养与植物内源激素的相互关系一直是植物营养研究的重要内容。生长素是植物五大内源激素之一,对细胞的分裂和伸长具有重要的调节作用。本文从矿质营养对ＩＡＡ的量及分布,矿质营养对ＩＡＡ合成,矿质营养对ＩＡＡ运输,矿质营养对ＩＡＡ的转化等方面对矿质营养与生长素的关系的研究进展进行了概述,并对矿质营养与生长素的关系的进一步研究进行了展望。     

Environmental and plant community determinants of species loss following nitrogen enrichment

Global energy use and food production have increased nitrogen inputs to ecosystems worldwide, impacting plant community diversity, composition, and function. Previous studies show considerable variation across terrestrial herbaceous ecosystems in the magnitude of species loss following nitrogen (N) enrichment. What controls this variation remains unknown. We present results from 23 N-addition experiments across North America, representing a range of climatic, soil and plant community properties, to determine conditions that lead to greater diversity decline. Species loss in these communities ranged from 0 to 65% of control richness. Using hierarchical structural equation modelling, we found greater species loss in communities with a lower soil cation exchange capacity, colder regional temperature, and larger production increase following N addition, independent of initial species richness, plant productivity, and the relative abundance of most plant functional groups. Our results indicate sensitivity to N addition is co-determined by environmental conditions and production responsiveness, which overwhelm the effects of initial community structure and composition.     

How stable isotopes may help to elucidate primary nitrogen metabolism and its interaction with (photo)respiration in C3 leaves

Intense efforts are currently devoted to elucidate the metabolic networks of plants, in which nitrogen assimilation is of particular importance because it is strongly related to plant growth. In addition, at the leaf level, primary nitrogen metabolism interacts with photosynthesis, day respiration, and photorespiration, simply because nitrogen assimilation needs energy, reductant, and carbon skeletons which are provided by these processes. While some recent studies have focused on metabolomics and genomics of plant leaves, the actual metabolic fluxes associated with nitrogen metabolism operating in leaves are not very well known. In the present paper, it is emphasized that (12)C/(13)C and (14)N/(15)N stable isotopes have proved to be useful tools to investigate such metabolic fluxes and isotopic data are reviewed in the light of some recent advances in this area. Although the potential of stable isotopes remains high, it is somewhat limited by our knowledge of some isotope effects associated with enzymatic reactions. Therefore, this paper should be viewed as a call for more fundamental studies on isotope effects by plant enzymes.     

不同基因型甘蔗种质资源的表型遗传多样性

为探明甘蔗原种和地方种的遗传多样性和亲缘关系,以期筛选出优良甘蔗种质和优良杂交亲本.该研究对18份甘蔗原种和地方种的14个数量性状进行了表型遗传多样性分析.结果表明：通过14个数量性状的变异系数(coefficient of variance,CV)和性状之间的相关分析,18份甘蔗原种和地方种的数量性状遗传变异主要来自甘蔗蔗糖分、单茎重、叶宽、茎径和纤维分;对14个数量性状进行主成分分析提取获得了4个主成分因子,分别命名为“品质因子”、“生长因子”、“成熟度因子”和“光合因子”,主成分因子累积贡献率达83．482％;进一步通过对主成分因子开展综合评价分析,获得数量性状综合表型高于平均水平的10份材料,依次为 Sampana→甜圪塔→合庆草甘蔗→桂林竹蔗→坦桑尼亚→芒戈→古芝蔗→大岛再来→托江红→春尼;聚类分析基于不同的遗传距离可将18份种质聚为5个类别,潜在的优良杂交组合是 Sampana 和甜圪塔或 Sampana 和合庆草甘蔗,表明在甘蔗遗传育种亲本选择上既要考虑各性状主要因子的互补,又要保持一定的遗传距离.该研究认为,在甘蔗育种工作中,利用因子分析法进行表型遗传多样性分析,将更加有助于亲本和杂交组合的选择.     

不同基因型甘蔗种质资源的表型遗传多样性

植物的碳、氮、磷化学计量特征能反映植物对土壤营养元素的利用效率,岩溶区植物经过长期的进化形成了自身独特的生理生态和生态化学计量特征,通过岩溶区植物叶片碳、氮、磷化学计量可以揭示岩溶生态系统各组分之间的养分循环规律.该研究在桂林毛村岩溶区次生林中选择3个20 m×20 m 的样方,采用多元统计方法分析了岩溶区森林12种典型植物叶片共186个样品的碳、氮、磷的生态化学计量特征,研究它们之间的相互关系,探讨碳、氮、磷化学计量学在岩溶生态系统中的生态指示作用.结果表明：(1)虽然岩溶区石灰土氮和磷的含量较高,但由于其有效性低,植物对养分的吸收和利用缓慢,岩溶区石灰土植物的生长仍然受到 N 和 P 的共同限制;(2)由于岩溶区植物叶片中 N 和 P 的含量显著偏低导致较高的 C∶N 和 C∶P 值(C∶N 的平均值为80．86;C∶P 的平均值为639．65);(3)利用 N∶P＜14表明氮受限制,N∶P＞16表明磷受限制,14＜N∶P＜16表明 N 和 P 共同限制的标准判断植物叶片受 N 或 P 的限制在岩溶区不完全适合;(4)元素间相关性分析表明,叶片的 C 和 N 呈极显著负相关关系(P ＜0．01),C 和 P 呈显著负相关关系(P ＜0．05),N 和 P之间呈现极显著正相关关系(P ＜0．01).这体现了植物体内两营养元素含量需求变化的相对一致性.研究结果有助于了解岩溶区森林植物的适生机制及其生态地球化学过程,可为岩溶区生态治理提供理论依据.     

丛枝菌根共生体中碳、氮代谢及其相互关系

丛枝菌根共生体(arbuscular mycorrhiza, AM)是丛枝菌根真菌(arbuscular mycorrhizal fungi, AMF)与宿主植物之间形成的互惠共生形式.共生体中的碳、氮交换和代谢影响着宿主植物和共生真菌之间的营养平衡和资源重新分配,在物质和能量循环中发挥着重要作用.宿主植物光合固定的碳输送到真菌内,并且分解和释放真菌所需的生命物质和能量,包括促进孢子萌发、菌丝生长和提高氮等营养元素的吸收;而菌根真菌利用宿主植物提供的碳骨架和能量,发生氮的转化和运输,最终传递给宿主植物供其利用.本文综述了丛枝菌根共生体中碳、氮传输和代谢的主要模式,碳、氮的交互影响和调控机制,以促进丛枝菌根在可持续农业和生态系统中的应用.     

Water, electrolyte and nitrogen balances of fat sand rats (Psammomys obesus) when consuming the saltbush Atriplex halimus

The fat sand rat (Psammomys obesus), a diurnal gerbillid rodent, is able to thrive while consuming only the saltbush Atriplex halimus. This plant has a high ash, nitrogen and water content but low energy yield. We measured the electrolyte, nitrogen (N) and water balances of fat sand rats in captivity when they were offered only A. halimus.
The fat sand rats scraped the outer layers of A. halimus leaves before consuming them. This removed 14.3% to 19.6% of the ash content of the leaves, and thus substantially reduced the electrolyte intake of the fat sand rats. Total urine osmolality ranged between 2739 and 3098 mOsm/kg, with Na+, K+ and CI - comprising 74.3% to 82.5% of the total osmolytes, percentages much higher than those usually found in desert rodents. Water intake was relatively high compared to other rodents because of the high water content of A. halimus. Evaporative water loss averaged approximately 50% of the total water output. Nitrogen requirements were easily fulfilled, even when the fat sand rats did not meet their energy requirements because of the high N content of the plant. Metabolic faecal nitrogen was 70.5 mg-kg-' 75.d-', endogenous urinary nitrogen was 171.9 mg. kg-0'75 d-' and minimal N requirements were 242.3 mg.k g-75d -1 . Minimal N requirements for the fat sand rats were approximately 98% of that expected for a eutherian mammal of its body mass.
It was concluded that fat sand rats can maintain water, electrolyte and nitrogen balances when consuming only A. halimus without producing highly concentrated urine. This is due, in part, to their ability to remove much of the electrolytes before consuming the plant and by producing urine of which Na+, K+ and C1- comprise a large percentage of the total osmolytes.     

Effects of elevated CO2 concentration on seed production in C3 annual plants

The response of seed production to CO(2) concentration ([CO(2)]) is known to vary considerably among C(3) annual species. Here we analyse the interspecific variation in CO(2) responses of seed production per plant with particular attention to nitrogen use. Provided that seed production is limited by nitrogen availability, an increase in seed mass per plant results from increase in seed nitrogen per plant and/or from decrease in seed nitrogen concentration ([N]). Meta-analysis reveals that the increase in seed mass per plant under elevated [CO(2)] is mainly due to increase in seed nitrogen per plant rather than seed [N] dilution. Nitrogen-fixing legumes enhanced nitrogen acquisition more than non-nitrogen-fixers, resulting in a large increase in seed mass per plant. In Poaceae, an increase in seed mass per plant was also caused by a decrease in seed [N]. Greater carbon allocation to albumen (endosperm and/or perisperm) than the embryo may account for [N] reduction in grass seeds. These differences in CO(2) response of seed production among functional groups may affect their fitness, leading to changes in species composition in the future high-[CO(2)] ecosystem.     

Does GABA increase the efficiency of symbiotic N2 fixation in legumes?

The ability to regulate the rates of metabolic processes in response to changes in the internal and/or external environment is a fundamental feature which is inherent in all organisms. This adaptability is necessary for conserving the stability of the intercellular environment (homeostasis) which is essential for maintaining an efficient functional state in the organism. Symbiotic nitrogen fixation in legumes is an important process which establishes from the complex interaction between the host plant and microorganism. This process is widely believed to be regulated by the host plant nitrogen demand through a whole plant N feedback mechanism in particular under unfavorable conditions. This mechanism is probably triggered by the impact of shoot-borne, phloem-delivered substances. The precise mechanism of the potential signal is under debate, however, the whole phenomenon is probably related to a constant amino acid cycling within the plant, thereby signaling the shoot nitrogen status. Recent work indicating that there may be a flow of nitrogen to bacteroids is discussed in light of hypothesis that such a flow may be important to nodule function. Large amount of γ-aminobutyric acid (GABA) are cycled through the root nodules of the symbiotic plants. In this paper some recent evidence concerning the possible role of GABA in whole-plant-based upregulation of symbiotic nitrogen fixation will be reviewed.Key words: γ-aminobutyric acid, nitrogen fixation, nodule, symbiosis, translocation, signalingNitrogen (N) is major limiting nutrient for the growth of most plant species in different ecosystems. Acquisition and assimilation of N is second in importance only to photosynthesis for plant growth and development. Elemental N is a key constituent of protein, nucleic acids and other vital cellular components. Most plants acquire N from the soil solution either as nitrate or ammonium ions. In addition, some plants can utilize the atmospheric gaseous nitrogen pool through symbiotic associations with species of bacteria, cyanobacteria or actinomycetes that contain the N₂ fixing enzyme, nitrogenase. Clearly, the crucial role that symbiotic plants play in plant growth requires that physiologists understand the biochemical and molecular events that regulate fixation and subsequent metabolism of nitrogen.Symbiotic N₂ fixation is an important process for increasing the plant available N and thereby the growth capacity of legumes. This process results from the complex interaction between the host plant and microorganism.¹ The host plant provides the microorganism with carbon and a source of energy for growth and functions while the microorganism fixes atmospheric N₂ and provides the plant with a source of reduced nitrogen in the form of ammonium. An adequate supply of carbohydrates is an essential requirement of nodule functioning as N₂ fixation is expensive in terms both of energy and carbon for the synthesis of N-products. Sucrose synthesized in photosynthesis and exported to the nodules via the phloem, is the primary fuel for N₂ fixation.² Sucrose can be metabolized in the cytoplasm of infected, uninfected or interstitial cells with organic acids as the end products. Malate is strongly believed to be the major respiratory substrate for bacteroids.³ This dicarboxylic acid is the major energy source for the bacteroids and plant mitochondria, and is used for NH₄⁺ assimilation as carbon skeleton in the glutamine synthetase/glutamate synthase (GS/GOGAT) pathway.⁴ The products of symbiotic N₂ fixation are exported from the nodules to the rest of the host plant where they are incorporated into essential macro-molecules such as amino acids, proteins that drive plant growth, development and yields. According to the fixation products, root nodules are generally divided into two major groupings:¹ (1) indeterminate nodules that are elongate-cylindrical activity that transport fixed N as amides such as alfalfa, pea and clover; and (2) determinate nodules that are spherical with determinate internal meristematic activity that transport fixed N as ureides, such as soybean and common bean. The complex series of events leading to the formation and functioning of the fixation machinery required controlled coordinated expression of both bacterial and host plant genes.     

氮磷添加对荒漠草原植物-凋落物-土壤生态化学计量特征的影响

为明确植物、凋落物和土壤养分含量及化学计量比对土壤中添加多种限制性养分的响应，阐明"植物-凋落物-土壤"连续体化学计量动态及各组分之间的协同作用，以宁夏荒漠草原为研究对象，于2018年开始进行氮（N）、磷（P）养分添加控制试验。试验处理包括对照（CK）、N添加、P添加、NP共同添加4个处理。结果表明：（1） NP共同添加显著增加了荒漠草原植物N和P含量、以及凋落物和土壤P含量，显著降低了荒漠草原植物C：N和C：P、以及土壤和凋落物C：P和N：P。P添加显著增加了荒漠草原植物、凋落物和土壤P含量，显著降低了植物、凋落物、土壤C：P和N：P。N添加分别增加了植物、凋落物N含量和N：P，但对植物N含量影响未达到显著水平。（2） C、N、P含量和N：P大小均表现为植物 > 凋落物 > 土壤，C：N和C：P均表现为凋落物 > 植物。（3） N添加提高了荒漠草原植物对P再吸收效率，降低了荒漠草原植物对N利用效率；P添加提高荒漠草原植物对N再吸收效率，降低荒漠草原对P的利用效率；NP共同添加提高了荒漠草原植物对N和P再吸收效率，降低了荒漠草原植物对N和P利用效率。（4）植物-凋落物-土壤的N、P含量和化学计量比之间显著相关，其中植物N、P、N：P与凋落物和土壤N、P、N：P显著正相关，凋落物P、C：N与植物和土壤C：P、N：P显著负相关。（5）荒漠草原植物和凋落物N较稳定（1/H=0.45和1/H=0.48），而植物和凋落物P、N：P较敏感（1/H=0.80、0.73和1/H=0.81、0.78）。荒漠草原植物生长受N限制，N添加缓解荒漠草原植物N限制，P添加和NP添加加剧荒漠草原植物N限制，荒漠草原植物通过改变养分利用策略和再吸收利用效率适应土壤中N、P含量的变化。     

Patterns of soil and plant nitrogen isotope composition and their relationships with climate factors in Xilingol League,Inner Mongolia,China

Background: Plant and soil nitrogen stable isotope (δ¹⁵N) can integrate several fundamental biogeochemical processes in ecosystem nitrogen dynamics, and reflect characteristics of ecosystem nitrogen cycling.

Aims: We investigated how climate change influenced plant-soil nitrogen cycling by relating soil δ¹⁵N, plant δ¹⁵N and Δδ¹⁵N (difference between soil and plant δ¹⁵N) with climatic factors.

Methods: Field investigation was conducted in temperate grasslands in Inner Mongolia during August 2015. Plant δ¹⁵N, soil δ¹⁵N and Δδ¹⁵N were determined, and their relationships with climatic factors were examined by simple regression analyses and general linear models.

Results: Soil δ¹⁵N was significantly higher than plant δ¹⁵N, and there was a positive linear correlation between them. Soil and plant δ¹⁵N were negatively related with mean annual precipitation (MAP) and positively with mean annual temperature (MAT); conversely, Δδ¹⁵N was positively related with MAP and negatively with MAT.

Conclusion: Soil δ¹⁵N was dominantly controlled by MAT, while it was MAP for plant δ¹⁵N. Climate factors influenced plant δ¹⁵N not only through their effects on soil nitrogen dynamics but also strategies of plant nitrogen acquisition. Thus, compared with plant δ¹⁵N, soil δ¹⁵N can more accurately reflect soil nitrogen dynamics, while plant δ¹⁵N may integrate soil nitrogen dynamics and plant nitrogen acquisition.