Human activities such as combustion of fossil fuels, intensive agriculture and stockbreeding, have significantly altered the global nitrogen cycle in the last several decades, increasing the concentrations of nitrogenous compounds in the atmosphere and rising the consequent N deposition to the global surface by several folds. As N is usually a limiting nutrient in most terrestrial ecosystems, additional N inputs to forest ecosystems may influence the growth, functioning and dynamics of those receiving ...

综述了氮沉降对森林植物的影响。氮沉降对森林植物的影响主要表现在以下6个方面:(1)在一定量范围内的氮沉降有利于植物的光合作用,但过量后则会引起植物的光合速率下降;(2)当植物生长受氮限制时,在一定程度上的氮沉降增加植物生产力,但当氮过量后,氮沉降则使植物的生产力下降;(3)过量的氮沉降导致植物体各种营养元素含量的比例失衡;(4)氮沉降会改变植物的形态结构,集中表现为根/冠比减小;(5)氮沉降会增加植物对天然胁迫如干旱、病虫害和风的敏感性,减少其抵御能力;(6)氮沉降会改变植物组成和降低森林植物的多样性。

The hydrological processes and nitrogen dynamics of a small watershed were studied in a monsoon evergreen broad-leafed forest of Dinghu Shah Biosphere Reserve. The results showed that the hydrology of this forest had distinct characteristics. The nitrogen input by rainfall was 35.57kg·ha-1 and the output in surface runoff was 9.25kg·ha-1 in a year. 4.72kg·ha-1·yr-1 of nitrogen was leached out from the canopy by rain. The nitrogen concentrations in stemflow of different species were different. The regression equations of nitrogen contents in each component of the hydrological cycle and the monthly rainfall were set up.

本文对鼎湖山南亚热带季风常绿阔叶林—黄果厚壳桂(Cryptocarya coneinna)、鼎湖钓樟(Lindera chunii)群落的水文学过程以及水系统中的氮素动态特征进行了初步研究。结果显示：所研究的群落中雨水输入的氮量较高，达35.57kg·ha-1，但渗入土壤及地表径流输出的氮也多，分别为18.28和9.25kg·ha-1·yr-1，输入输出之差为8.04kg·ha-1·yr-1。雨水对林冠的氮素淋溶量为4.72kg·ha-1·yr-1。通过回归分析，发现各类型水中含氮量与降雨量之间存在较显著的直线相关关系。不同树种的树干茎流中氮浓度存有差别。

Nutrient elements are necessary for the sustainability of environment,while exc essive nutrients have potential impacts on the stability of wetland ecosystem,e specially on the dynamics of wetland plant communities.The nutrients in wetland  habitat decide the growth of its plants,and the dominant species and their ric hness of plant communities.Accumulation of nutrients has significant effects on  the primary productivity,biomass and its allocation,and species diversity of wetland plants.Water is the key factor in wetland system,and the fluctuation o f water level affects wetland structure and characteristics.Species composition ,species diversity,and plant community succession all show significant respons es to moisture content and water level fluctuation in wetland.Nutrients and wa ter level fluctuation are the important factors determining the composition,str ucture,and function of wetland ecosystem.Some research proposals in the future  were put forward in the paper.

营养物质是重要的湿地环境控制因子，过量的陆源营养物质和污染物的输入，对湿 地生态系统的稳定性尤其对湿地植物系统的影响尤为明显。湿地生境中的营养物质决定了植 物生长以及植物群落优势种及其丰富性，营养物大量富集对湿地植物初级生产力、生 物量及其分配以及物种多样性都产生明显影响。水是湿地系统的基本生态因子和主要控 制因素，水位变化对湿地结构和特征具有明显的雕塑作用，湿地水分条件和水位的变化 直接影响到湿地植物物种组成、物种多样性和群落演替。本文同时分析了湿地生态系统 的组成、结构和功能对营养物和水位变化的响应，并对未来研究发展提出几点看法。

Abstract：The paper has made detailed summarization of the nitrogen utilization of plants from the the following three parts: the effect of nitrogen on plants growth and development, the physiological and molecular mechanism of the nitrogen utilization in order to provide theotetic guidence for the crop nutritional breeding and improve its nitrogen utilization efficiency.

摘要： 本文对近年来植物对氮素吸收的研究进展进行了详细的阐述，从氮素对植物生长发育的影响、植物对氮素利用的生理机制和分子机制三个方面进行了总结，旨在为植物营养育种提供一定的理论依据，从而实现提高植物氮素利用效率的目的。

The results indicated that nitrogen nutrition supplied at flag leaf initiation could increase the chlorophyll content and photosynthetic rate, delay the senescence and photosynthetic decline of leaf during leaf aging process. At the meantime, nitrogen nutrition made the leaf cytokinin(ZRs) content increase and abscisic acid(ABA) content decrease. Duing leaf aging process, nitrogen treatment could also increase the RuBPcase activity, PS1 and PS2 activity, but the increase of RuBPcase activity was much higher than that of PS1 and PS2 activity. Which relatively increased the rations of RaBPcase activity to PS1 activity and PS2 activity, and improved the balance state between the light reaction and dark reaction of photosynthetic organ. The suplus photosynthetic reductivity produced by light reaction was little. Otherwise, compared with CK, nitrogen nutrition decreased the O 2 Producing rate and the accumulation amount of H 2 O 2 in leaf, and increased the enzymatic activity of active scavenging enzyme SOD and CAT during leaf aging process. It is suggested that nitrogen nutrition probably is mainly by regulating the hormone balance in the leaf cell, and improving the cycling metabolism of the photosynthetic organ. to decline the producing rate and accumulation amount of active oxygen in the leaf, and inhance the activity of active oxygen scavenging enzyems. Which is one important physiological factor that the leaf senescence and the photosynthetic function decline can be delayed regulated by nitrogen nutrition.

研究表明，氮素营养提高了旗叶老化过程中的叶绿素含量和光合速率，延缓了叶片衰老和光合功能衰退，增加了旗叶内细胞分裂素类物质（ZRs）含量，减少了促表激素ABA的累积量。氮素处理使旗叶老化过程中光合机构的RuBPcase活性和PS1、PS2活性均得以增加，但氮素对RuBPcase活性下降的延缓效果更为明显，相对增加了叶片老化过程中RuBPcase活性与PS1和PS2活性的比值，使光合机构光反应与暗反应之间的平衡状况得到改善，过剩还原力减少。此外，氮素营养使旗叶老化过程中超氧阴离子（O 2 - ）的产生速率降低，H 2 O 2 的累积量减少，并提高细胞中活性氧清除酶SOD和CAT的活性。氮素营养可能主要通过调节细胞内的激素平衡，以及改善光合机构的自身运转平衡状况，减少了细胞中对生物体具有强烈伤害的活性氧的产生速率及其累积数量、提高了活性氧清除酶的活力，由此在很大程度上延缓了旗叶的衰老和光合功能衰退，延长了旗叶的光合功能期。

Taking three flue-cured tobacco ( Nicotiana tabacum L.) varieties Y5, Y7, and NC89 as test objects, this paper studied the effects of nitrogen fertilization on their leaf senescence, photosynthetic characteristics, yield, and quality. Increasing nitrogen supply increased the leaf superoxide dismutase (SOD) activity, chlorophyll content, and photosynthetic performance, and decreased the leaf malondialdehyde (MDA) content significantly. Accordingly, the leaf senescence was delayed. Compared with Y5 and NC89, variety Y7 had higher leaf MDA content and lower leaf SOD activity, chlorophyll content, and photosynthetic performance, and thus, its leaves senesced faster. High quality tobacco leaves with higher average price, gross value, superior leaves percentage, and reasonable chemical constituents were harvested under the application of 45 kg N·hm -2 ,compared with applying 60 and 75 kg N·hm -2 . It was suggested that different flue-cured tobacco varieties had obvious differences in their leaf senescence physiological characteristics, and nitrogen fertilization played important roles in regulating their leaf senescence, yield, and quality. Appropriate nitrogen fertilization could improve the quality of tobacco leaves, and achieve higher economic benefits.

以豫烟5号、豫烟7号和NC89为材料，研究氮素对不同品种烤烟叶片衰老、光合特性及产量和品质的影响.结果表明：增施氮素可显著增强烤烟叶片超氧化物歧化酶(SOD)活性，降低丙二醛(MDA)含量，提高叶绿素含量，增强光合性能，从而延缓烤烟叶片衰老.与豫烟5号和NC89相比，豫烟7号叶片叶绿素含量较低，光合性能较弱，SOD活性低，MDA含量高，叶片衰老较快.与60和75 kg·hm -2 施N处理相比，45 kg·hm -2 施N处理的烟叶均价、产值、上等烟比例均最高，且化学品质指标较好，符合优质烟叶要求.表明不同品种烤烟衰老生理特性有明显差异；氮素营养对烤烟叶片衰老、产量和品质有明显的调节作用；适量施氮可提高烟叶品质，获得较高的经济效益.

Although excessive use of N fertilizer can result in the rapid decrease of N use efficiency and other serious environment problems, N fertilizer is yet the most important and largest input in modern rice production. Previous researches have been demonstrated that variation in N use efficiency existed among rice genotypes. Therefore, it is of urgent importance to elucidate the physiological mechanism of rice N absorption and utilization for increasing N use efficiency. In this research, field experiment with 225 kg ha -1 N fertilizer application was carried out in 2006 on the farm of Yangzhou University, Jiangsu province, China. Twelve rice genotypes (six N efficient and six N inefficient) selected from one hundred and twenty rice cultivars grown in Yangzhou during 2004 and 2005 were adopted to investigate the characteristics of N absorption and accumulation. Compared with N inefficient genotypes, N efficient genotypes had more obvious advantages in N absorption rate, the amount and the percentage of N accumulation during the growth phases from elongating to heading and from heading to maturing. And of which the advantage during the growth phase from heading to maturing was particularly significant. Since rice organs aged and the plant physiological functions declined gradually from heading to maturing, the characteristics of rice senescence was then studied to understand the relationships between rice senescence and the N absorption and accumulation, and the N use efficiency. Results showed that, during the period of grain filling, the activities of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) i n flag leaf of N efficient genotypes were obviously higher than those of N inefficient genotypes. Contrarily, content of malondialdehyde (MDA), which is the product of membrane lipid peroxidation, was lower in N efficient genotypes than in N inefficient genotypes significantly. After the stage of full heading, N use efficiency was positively correlated to the activities of SOD, POD, and CAT in flag leaf of rice and negatively correlated to the content of MDA. So it reveals that, at late growth stages of rice, the activities of SOD, POD, and CAT of N efficient genotypes were higher than those of N inefficient genotypes in flag leaves, which could eliminate reactive oxygen species, inhibit the membrane lipid peroxidation and decrease the content of MDA more efficiently in N efficient rice genotypes. Therefore, compared with the N inefficient genotypes, the leaf senescence of N efficient genotypes was relatively slower, which could prolong the functional period of leaves, enhance the organic matter accumulation and improve the efficiency of N absorption and utilization.

选用氮肥利用高效型和低效型具有代表性的 12 个粳稻品种，研究 225 kg hm -2 施氮条件下其氮素吸收积累特性。与氮低效基因型相比，氮高效基因型水稻在拔节至抽穗、抽穗至成熟阶段的氮素吸收速率、氮素积累量和积累比例均具有明显优势，其中以抽穗至成熟阶段的优势尤为显著。该阶段水稻各器官逐渐衰老，植株各项生理功能逐渐衰退，为明了水稻衰老与植株中后期氮素吸收与积累、氮肥吸收利用效率的相互关系，相继研究了花后各基因型水稻的衰老特性。结果表明，齐穗后的不同时期，氮高效基因型水稻的超氧化物歧化酶 (SOD) 、过氧化物酶 (POD) 和过氧化氢酶 (CAT) 活性均显著高于氮低效基因型，而膜脂过氧化产物丙二醛 (MDA) 的含量却要显著低于氮低效基因型水稻。相关性分析表明，水稻的氮肥利用效率与齐穗后剑叶中的 SOD 、 POD 和 CAT 活性呈极显著正相关，而与其剑叶中的 MDA 含量呈极显著负相关。由此说明，与氮低效基因型相比，氮高效基因型水稻生育后期剑叶中用于清除活性氧自由基的 SOD 、 POD 、 CAT 活性较高，能有效阻止高浓度氧的积累和膜脂过氧化作用，降低 MDA 的含量，因而降低叶片的衰老进程，在维持较长光合功能期的同时能增强物质积累，促进植株对氮肥的吸收和利用。

Advances of studying rice leaf senescence physiology were reviewed in detail for the past 20 years, including the physiological mechanism of rice leaf senescence, the normal indexes of leaf senescence and its dynamic changes during the leaf aging, and some research results of regulating leaf senescence in rice. At the same time, some key aspects in the future were discussed briefly in this research field.

总结了近年有关水稻叶片衰老生理的研究进展，包括水稻叶片衰老的生理机制，衡量水稻叶片衰老的常用生理生化指标及其变化以及水稻叶片衰老调节等研究成果，进而对今后水稻叶片衰老研究中着重应解决的一些问题进行了讨论。

Aims We conducted a field manipulation experiment to examine the underpinning mechanisms of variation in plant leaf functional traits along a nitrogen addition gradient in a mature typical steppe ecosystem in Inner Mongolia. Methods We selected six dominant and sub-dominant plant species for study: Leymus chinensis , Achnatherum sibiricum , Agropyron cristatum , Stipa grandis , Cleistogenes squarrosa and Carex korshinskyi . Together, they account for >90% of the total community aboveground biomass. We examined the effects of N addition on specific leaf area ( SLA ), leaf N content, total chlorophyll content, and chlorophyll a/b ratio.  Important findings Nitrogen addition lessened the N limitation while strengthening light competition among co-existing plant species. Plant species differed significantly in their responses to increased N addition rates. Leymus chinensis showed high plasticity in SLA , leaf N, and total chlorophyll content. Its area-based leaf N content increased linearly with N addition rate. Achnatherum sibiricum showed the highest plasticity in SLA and high mass-based leaf N and chlorophyll content to N enrichment, whereas its area-based leaf N content was relative stable. Compared to L. chinensis and A. sibiricum , A. cristatum had low plasticity in the three leaf functional traits investigated. Both S. grandis and C. korshinskyi illustrated low plasticity in SLA along with low SLA of S. grandis and short stature of C. korshinskyi ,leading to reduced light competitive ability of the two species under N enrichment. Cleistogenes squarrosa had the highest SLA among the six species and a relatively high plasticity in mass-based leaf chlorophyll and N contents. The chlorophyll a/b ratio of C. squarrosa decreased significantly under N treatment, indicating declining light availability.

该文比较了羊草草原群落中包括建群种和优势种在内的6种植物，羊草（ Leymus chinensis ）、西伯利亚羽茅（ Achnatherum sibiricum ）、大 针茅（ Stipa grandis ）、 冰草（ Agropyron cristatum ）、糙隐子草（ Cleistogenes squarrosa ）和黄囊苔草（ Carex korshinskyi ）的比叶 面积(Specific leaf area, SLA )、叶片含氮量和叶绿素含量等叶片功能特性( Leaf functional trait)对氮素添加的响应，旨在探讨草原生态 系统中，不同物种对氮素可利用性改变的响应和适应对策。结果表明：随着氮素添加量的增加，物种对光资源的竞争增强，不同物种在光资源 的竞争策略和竞争力间存在着显著的差异。羊草通过提高 SLA 、单位质量叶片的叶绿素含量和含氮量，使单位面积叶片含氮量和叶绿素含量均呈 线性提高，进而增强了其对光的竞争力。西伯利亚羽茅主要通过提高 SLA 增加光合总面积，来增强自身的光竞争力。冰草在 SLA 和单位质量叶片 的叶绿素和氮含量均有一定的可塑性，但对光的竞争力明显弱于羊草和西伯利亚羽茅。大针茅和黄囊苔草对 SLA 的调节能力较低，加之大针茅 SLA 较低，而黄囊苔草处于群落的下层，这两种植物的光竞争力较弱。糙隐子草具有较高的 SLA ，对单位质量叶片叶绿素和氮含量的调节能力相 对较强，其光竞争力高于黄囊苔草。同时，糙隐子草叶片叶绿素a与叶绿素b的比值沿氮素添加梯度显著降低，进一步证实氮素添加改变了群落 的光环境。

In grassland sites dominated by Stipa baicalensis grassland, we imposed six nitrogen levels: N 0 , N 15 , N 30 , N 50 , N 100 and N 150 , respectively. At the various levels of nitrogen deposition, we placed litterbag with leaf, stalk and root litter of S. baicalensis (Sb), Leymus chinensis (Lc), Artemisia frigida (Af) on the experiment plots. Plots were sprayed NH 4 NO 3 in the middle of June and July. The dynamics of C and N during litter decomposition were different. Different decomposition and nitrogen exchange patterns were observed among the three dominant plants studied. The current paradigm suggests close relationships between decomposition rates, C and N content and , C/N ratio. The results contrasted with that. Decomposition time for 95% degradation of litter was 3.79-5.75 years for Sb, 3.12-6.34 years for Lc, and 2.69-6.82 years for Af. The initial nutrient element concentration of litter determined the nutrient release pattern and the amount of the final net element release ratio. Through correlation analysis of litter decomposition and soil physical and chemical properties, we found: litter decomposition to be weakly correlated with NH 4 - -N , NO 3 - -N and soil moisture content. The carbon and nitrogen content of soil microbial biomass was significantly correlated with litter decomposition rate of Af. Thus, microorganisms are the key factor controlling litter decomposition rate of Af. Therefore, in the short term, nitrogen deposition had no significant effect on litter decomposition, only individual level of nitrogen promoting or inhibiting effect on different litter decomposition rate and nutrient releasing. It implied that the effects of N addition on litter decomposition depended on time, organs, and also N addition levels.

对内蒙古贝加尔针茅草原群落开展氮素添加实验,设置6个氮素添加水平,氮素类型为硝酸铵(NH 4 NO 3 ):对照(N 0 ),1.5 g N/m 2 (N 15 )、3.0 g N/m 2 (N 30 )、5.0 g N/m 2 (N 50 )、10.0 g N/m 2 (N 100 )和15.0 g N/m 2 (N 150 )。利用凋落物网袋分解法,研究贝加尔针茅、羊草和冷蒿3种植物不同器官凋落物分解对氮素添加的响应。结果表明:1) 3种植物不同器官凋落物C残留率的季节变化与植物残留率的变化趋势相同,呈释放模式。2)贝加尔针茅各器官凋落物分解95%所需时间为3.79~5.75年。羊草各器官凋落物分解95%所需时间为3.12~6.34年。冷蒿各器官凋落物分解95%所需时间为2.69~6.82年。3)不同植物、不同器官凋落物分解速率对氮素添加响应不同,初始化学组成不是控制凋落物分解的主要影响因子。4)凋落物分解速率与土壤铵态氮、硝态氮和土壤含水量无显著相关性,冷蒿凋落物与土壤微生物量碳氮显著相关。5)本试验进行期间,氮素添加对各器官凋落物分解无一致影响,仅个别施氮水平对不同器官凋落物分解速率及养分释放有促进或抑制作用。在氮素添加背景下,凋落物分解受到时间、分解底物类型及氮素输入水平的共同影响。

Stipa grandis forms zonal plant communities widely distributed in the typical steppe region of the Mongolian plateau. In recent decades, due to the over-utilization, the S. grandis grassland has shown different degrees of degradation. Nitrogen is a limiting factor for plant growth in semi-arid grassland. N addition is beneficial to the recovery of degraded grassland, but research on the influence of N addition to root characteristics of grassland plants is rarely undertaken. In order to study the response of root characteristics of S. grandis to N addition in grassland with different degrees of degradation, two sites (lightly degraded and heavily degraded grassland) were selected in Xilingol typical grassland region of Inner Mongolia, and a 2-year N addition experiment was performed (0,30,50,80 g/m 2 NH 4 NO 3 ). In the heavily degraded grassland, N addition led to a significant increase in root growth of S. grandis . Root length, surface area, volume, root depth and above-ground height were all significantly increased with increased nitrogen input rates, and these measures of plant response were all significantly correlated. In the lightly degraded grassland, however, the root characters of S. grandis were not responsive to N. Comparing the two sites, root diameter in heavily degraded grassland was significantly lower than that in lightly degraded grassland when no N was added. Root length, area, volume, above-ground height and root depth in heavily degraded grassland was significantly higher than that in lightly degraded grassland under high N (80 g/m 2 ) conditions. In heavily degraded grassland, with increased level of soil N, the root system of S. grandis acquires N for development by increasing root length to colonise a greater soil volume.

以大针茅为建群种的草原是蒙古高原典型草原地带广泛分布的地带性植物群落。近几十年来,由于不合理的利用,大针茅草原出现不同程度的退化。氮素是半干旱草原植物生长的限制性因素,氮素的添加有利于退化草原的恢复,但在氮素影响下草原植物根系特征变化的相关研究很少。本研究分别选取内蒙古锡林郭勒典型草原区的轻度退化和重度退化草地,进行氮素添加实验(0,30,50,80 g/m 2 ),研究在不同退化程度的草地中大针茅根系特征对氮素添加的响应。结果表明,在重度退化草地中,氮素的添加显著促进了大针茅的根系生长和地上部分生长,根系长度、面积、体积、深度以及地上高度均随氮素添加量的增加而显著增加,根系长度、面积、体积呈极显著正相关关系,根系深度与地上高度呈显著正相关关系;轻度退化草地中大针茅根系特征对氮素添加的响应不显著。比较2个样地,在无氮素添加的条件下,重度退化草地中大针茅的根系直径显著低于轻度退化草地;在高氮素(80 g/m 2 )添加条件下,重度退化草地中的大针茅根系长度、面积、体积、地上高度与根系深度显著高于轻度退化草地。重度退化草地中土壤氮素的增加,促使大针茅根系主要通过增加根系长度扩大在土壤中的空间分布。

The photosynthetic characteristics and seed yields of sudangrass response to different topdressing nitrogen fertilizer including six different nitrogen application rates of 0, 150, 300, 450, 600 and 750 kg·ha -1 and the fixed proportion (3∶4∶3) were studied by single factor randomized trials using Sorghum sudanense ‘Xinsu No.2’. The results showed that photosynthesis rate (P n ), stomatal conductance (GS), transpiration rate (T r ) significantly increased with increasing of nitrogen fertilization application rate in a certain range. The values of P n , T r , GS in heading stage were significantly greater than that in grain filling stage and heading stage. Excessive nitrogen fertilizer could inhibit the photosynthetic during growth period. The results confirmed that SPAD value can fully reflect the chlorophyll contents. The SPAD value significantly increased with increasing of nitrogen fertilization application rate if the nitrogen fertilizer rate was less than 450 kg·ha -1 . Nitrogen fertilizer could effectively improved thousand seeds weight, grains per spike, and also significantly increased sudangrass seed yield in a certain range. However, the seed yield significantly decreased with the increasing of fertilizer. The seed yield was maximized (3 815 kg·ha -1 ) at the level of 600 kg·ha -1 nitrogen application. In combination with photosynthetic characteristics and seed yield of sudangrass, the best nitrogen application rate was 600 kg·ha -1 .

以新苏2号苏丹草(Sorghum sudanense ‘Xinsu No.2’)为试材, 采用单因素完全随机区组设计, 在拔节、孕穗和灌浆期追施氮肥, 以揭示施氮对苏丹草叶片光合生理特性及种子产量性状的影响。结果表明, 追施氮肥可显著提高苏丹草叶片光合速率、气孔导度和水分利用效率, 当追肥超过600 kg·hm -2 时, 在拔节期和抽穗期对光合速率产生抑制作用。随追肥量增加SPAD值随之增大, 追肥量超过450 kg·hm -2 后, SPAD值增幅较小或不增加。追施氮肥可有效增加种子千粒重、穗粒数, 从而使苏丹草种子产量明显增加, 然而, 追施氮量增加, 落粒率升高, 产量增幅明显减小, 追氮150与300 kg·hm -2 时, 产量增幅分别达23.7％和32.2％, 而追氮750 kg·hm -2 时, 产量增幅仅为3.9％, 追施氮肥600 kg·hm -2 时, 可获最大种子产量3 815 kg·hm -2 。综合苏丹草光合生理指标及产量性状的变化认为, 追肥量为600 kg·hm -2 为最佳, 此时光合速率最大, 并可获得最大种子产量。

The variation of nutrient elements contents and pH value between rhizosphere and non-rhizosphere soils of 5, 10, 15, and 20-year-old Artemisia sphaerocephala were studied. The results revealed the following conclusions: 1) With the extension of growing period, N and P in rhizosphere soil increased, the highest enrichment rate of ammonium and P were 91.15% and 127.30%, respectively. 2) Cu had negative enrichment, which decreased with the extension of growing period. The contents of other micronutrients were higher in rhizosphere than that in bulk soils. For example, Mn accumulated significantly in rhizosphere with the extension of growing period, and the highest enrichment rate 85.24% which appeared in 20 year-old A.sphaerocephala growing soil. 3) There were obvious acidification in rhizosphere of 15 and 20 year-old A.sphaerocephala , however, there was no obvious change in rhizosphere of 5 and 10 year-old A.sphaerocephala . 4) There was rhizosphere effects correlated with different nutrient elements in soil.

分别选取建植5、10、15和20年的白沙蒿( Artemisia sphaerocephala ), 研究其根际与非根际土壤中营养元素含量及土壤pH值的变化。结果表明, 1)随建植年限的增加, 白沙蒿根际土壤有效N、P含量增加, 铵态氮和有效磷的最大富集率分别为91.15%和127.30%;2)有效Cu表现为负富集, 其在根际的含量随建植年限的增加而降低, 其它有效微量元素均表现出根际含量大于非根际, 其中有效Mn随年份增加有明显积累, 在20年株龄富集率达到最高值, 85.24%;3)5、10年株龄沙蒿根际pH无明显变化, 15、20年株龄白沙蒿根际土壤表现出明显的酸化作用;4)土壤有效元素间的相关性存在明显的根际效应。

Photosynthesis is closely related to crop growth and yield, and higher photosynthetic rate of leaves is one of the important factors for high crop yield. The study explored the changes of photosynthetic indexes of the leaves at different flowering nodes in high-yield mung bean varieties Jilü 2 and An 9910, and low-yield varieties Chifeng and Tailai adopted in the summer planting region，thus to clarify the physiological characteristics affecting seeds yield and photosynthetic performance of the leaf in mung bean at the late growth stage. The results showed that after flowering, the leaves gradually aged, the net photosynthetic rate (Pn), transpiration rate (T r ), stomata conductance (G s ), chlorophyll and soluable protein contents of its functional leaves gradually declined, but the intercellular carbon dioxide concentration (C i ) of the leaves tended to rise, specific leaf weight tended to decline-rise-decline. The photosynthetic capacities of the leaves appeared to decline from the upper nodes to the lower nodes. Compared with low-yield varieties, the leaves of Jilü 2 and An 9910 had a longer functional period, declining slowly in chlorophyll and soluable protein contents and maintaining higher photosynthetic capacity at the late growth stage, which provided a good physiological foundation for higher amount of accumulated photosynthates . Further analysis indicated, there were significant positive correlations between seed yield and average net photosynthetic rates of leaves at flowering nodes(r = 0.999), and between net photosynthetic rate and the contents of chlorophyll and soluble protein at the late growth stage. In summary, at the crucial stage of yield formation, maintaining higher chlorophyll content and photosynthetic capacity of functional leaves, and delaying leaf aging have important action for increasing crop yield.

以夏播区高产绿豆品种(系)冀绿2号、安9910和低产品种(系)赤峰绿豆、泰来绿豆为材料，对其衰老过程中开花节功能叶片的光合参数变化进行了研究。结果表明，绿豆开花后，随着叶片的衰老，各功能叶片净光合速率(P n )、蒸腾速率(T r )、气孔导度(G s )、叶绿素含量、可溶性蛋白质含量逐渐下降，叶质重表现出降低—增大—降低的变化趋势，同一时期不同开花节叶片的光合性能自上而下逐渐降低。不同品种间存在显著差异，冀绿2号和安9910叶片功能期长，叶绿素和可溶性蛋白质降解较慢，生育后期仍具有相对较高的光合性能，这为其积累较多的光合产物提供了生理基础。进一步分析表明，绿豆产量与花后开花节叶片的平均净光合速率呈极显著正相关，叶片净光合速率又与叶绿素、可溶性蛋白质含量呈极显著正相关。综合分析表明，在绿豆开花结荚期间，保持较高的叶绿素含量和功能叶片的光合生产能力，延缓叶片衰老，对籽粒产量形成具有重要作用。

The hydroponic method was used to study the photosynthetic characteristics of navel orange “No.52” seedlings under Cu stress. The study shows that chlorophyll (Chl.) content under 0.1 mmol・L -1 of Cu increases significantly, but decreases under 5 mmol・L -1 , 20 mmol・L -1 and 40 mmol・L -1 of Cu. Carotenoid content decreases with increasing Cu concentration. Net photosynthetic rate and light saturation point reduces under Cu stress as Cu concentration exceeds 5 mmol・L -1 . 0.1 mmol・L -1 of Cu improves, but 5 mmol・L -1 and 20 mmol・L -1 of Cu decrease transpiration rate and stomatal conductance of orange. These parameters do not change significantly under 40 mmol・L -1 of Cu. At the same time, high Cu concentration (5 mmol・L -1 , 20 mmol・L -1 and 40 mmol・L -1 ) restricts photoreduction activity. The findings indicate that lower Cu concentration improves photosynthesis while high Cu concentration inhabits it.

以“脐橙52”为材料, 采用水培方法, 研究了Cu胁迫对脐橙幼苗光合作用的影响。结果表明, 0.1 μmol?L -1 Cu处理的脐橙叶片叶绿素含量比对照显著增加, 而5 mmol?L -1 、20 mmol?L -1 、40 mmol?L -1 Cu处理使绿素含量下降, 且Cu浓度越高下降幅度越大; 类胡萝卜素含量随Cu浓度增加不断下降。Cu≥5 mmol?L -1 的胁迫造成光合效率降低, 净光合速率、光饱和点下降。0.1 mmol?L -1 Cu处理使脐橙叶片蒸腾速率和气孔导度增加, 而5 mmol?L -1 和20 mmol?L -1 Cu处理使蒸腾速度和气孔导度下降, 40 mmol?L -1 Cu处理的两个指标变化不大。0.1 mmol?L -1 Cu处理叶绿体光还原活性比对照有所增加, 而5 mmol?L -1 、20 mmol?L -1 、40 mmol?L -1 Cu处理叶绿体光还原活性受到抑制。说明低浓度Cu处理可促进脐橙幼苗的光合作用, 而高浓度有明显的抑制作用。

Effects of super absorbent polymers type and dosage and the nitrogen fertilizer on oats yield and hay production in different growth stages were studied with orthogonal design with 3 factors and 3 levels at arid and semi-arid region. The results showed that the influence on oats yield decreasing in the following order: nitrogen fertilizer, super absorbent polymers dosage and super absorbent polymers type. The optimal treatment was Soil Conditioner Warer with dosage of 60 kg·ha -1 and 60 kg·ha -1 nitrogen fertilizer which can increase the yield, yield performance and economic benefit of Avena sativa cv. Qingyan No.1.

试验采用三因素三水平正交设计方法,研究保水剂类型、保水剂用量和氮肥用量在干旱半干旱地区对燕麦( Avena sativa cv. Qingyan No.1)不同生长阶段干草产量和种子产量的影响。结果表明,3种因子在生育期对青燕1号燕麦干草产量影响大小为氮肥用量＞保水剂用量＞保水剂类型,施加抗旱保水剂,保水剂用量60 kg·hm -2 ,氮肥用量60 kg·hm -2 ,可增加种子产量、干草产量、产量构成相关性状指标和种子田经济效益。