Sulfur nutrition of deciduous trees

Sulfur in its reduced form (-II) is an essential nutrient for growth and development, but is mainly available to plants in its oxidised form as sulfate. Deciduous trees take up sulfate by the roots from the soil solution and reduce sulfate to sulfide via assimilatory sulfate reduction in both roots and leaves. For reduction in the leaves, sulfate is loaded into the xylem and transported to the shoot. The surplus of sulfate not reduced in the chloroplast or stored in the vacuole and the surplus of reduced S not used for protein synthesis in the leaves is loaded into the phloem and transported back to the roots. Along the transport path, sulfate and glutathione (GSH) is unloaded from the phloem for storage in xylem and phloem parenchyma as well as in pit and ray cells. Re-mobilised S from storage tissues is loaded into the xylem during spring, but a phloem to xylem exchange does not appear to exist later in the season. As a consequence, a cycling pool of S was only found during the change of the seasons. The sulfate:glutathione ratio in the phloem seems to be involved in the regulation of S nutrition. This picture of S nutrition is discussed in relation to the different growth patterns of deciduous trees from the temperate climate zone, i.e. (1) terminated, (2) periodic and (3) indeterminate growth patterns, and in relation to environmental changes.     

CO_2和O_3浓度升高及其复合作用对华山松生长及光合日变化的影响

以生长在沈阳市区内的5年生华山松幼树为实验材料,采用开顶箱法,研究高浓度CO2和高浓度O3下华山松生长变化、光合速率的日变化动态以及日光合总量季节变化,进而了解大气CO2浓度升高、O3浓度升高及其复合作用对华山松光合作用及生长的影响.结果表明,①高浓度O3处理后,华山松20～90 d针叶鲜重、干重增长量以及90 d针叶叶长较对照分别降低45.8%、38.9%和15.3%.主侧枝生长与对照相比无显著差异.高浓度O3降低了华山松日光合总量,处理30 d后,针叶净光合速率均显著低于对照,光合速率日变化曲线表现为双峰型,光合"午休"程度强于对照.②高浓度CO2处理后,华山松针叶鲜重、干重20～90 d增长量分别高于对照41.7%和22.2%,而针叶叶长以及主侧枝长未受显著影响.华山松日光合总量高于对照处理,处理30 d、60 d时,净光合速率普遍高于对照.CO2处理90 d时,日变化曲线由双峰变为单峰曲线,极大缓解了光合"午休"现象.③高浓度O3和CO2复合处理后,针叶干重、鲜重增量均低于对照,表明了复合处理后O3伤害的发生,但针叶干重高于O3单因子处理,这表明高浓度CO2可以一定程度上缓解高浓度O3对华山松针叶生长的抑制作用.针叶叶长,主侧枝生长未见明显效应.复合处理后,针叶净光合速率普遍低于对照,华山松日光合总量低于对照而高于O3单独处理,说明高浓度CO2可以通过减缓O3对植物光合的抑制而减少O3伤害.光合速率日变化曲线表现为双峰型.     

多环芳烃在冬小麦体内的吸收与转运及富集研究进展

多年来以煤炭为主的能源消费结构和经济社会持续发展,导致我国PAHs(多环芳烃)排放量居高不下,直接造成土壤和大气PAHs严重污染.为了探明PAHs在冬小麦体内的积累过程和调控机制,在系统分析PAHs在冬小麦体内的吸收、转运和富集的基础上,重点阐述了冬小麦PAHs根系吸收和叶面吸收影响因素方面的最新研究进展.研究发现:① 小麦根系对PAHs的吸收包括主动吸收和被动吸收两种方式,其中主动吸收是一个载体协助、消耗能量、PAHs与H+共运的过程;被动吸收除了在高等植物中普遍存在的简单扩散外,水-甘油通道也参与了该过程. ② PAHs通过气态、颗粒态沉降到小麦叶面角质层或直接通过气孔进入叶片. ③ 影响PAHs根系和叶面吸收的主要因素包括PAHs理化性质、植物生理状况、环境因素等. ④ 小麦根系吸收的PAHs可以向地上部转运,并且与辛醇-水分配系数(K_OW)、蒸腾速率、土壤中氮的形态和浓度有关.主要问题:① 对于小麦叶片吸收的PAHs向基运输机理有待进一步研究. ② 农田生态系统中冬小麦往往遭受土壤及大气双重污染,根系吸收及叶面吸收分别对其体内积累PAHs的贡献尚不清楚.因此,需关注韧皮部、木质部在PAHs转运中所起的作用;利用同位素示踪、双光子激发显微镜等先进技术观察和跟踪PAHs如何进入小麦以及在小麦叶中的转移和分布,阐明PAHs叶面吸收的微观机理;注重大田试验研究,为揭示冬小麦对PAHs的吸收、积累及调控机理,同时也为有机污染地区生产安全农产品提供重要依据.      

Effects of elevated CO2 concentration on growth and water usage of tomato seedlings under different ammonium/nitrate ratios

Increasing atmospheric CO2 concentration is generally expected to enhance photosynthesis and growth of agricultural C3 vegetable crops, and therefore results in an increase in crop yield. However, little is known about the combined effect of elevated CO2 and N species on plant growth and development. Two growth-chamber experiments were conducted to determine the effects of NH4^＋/NO3^- ratio and elevated CO2 concentration on the physiological development and water use of tomato seedlings. Tomato was grown for 45 d in containers with nutrient solutions varying in NH4^＋/NO3^- ratios and CO2 concentrations in growth chambers. Results showed that plant height, stem thickness, total dry weight, dry weight of the leaves, stems and roots, G value （total plant dry weight/seedling days）, chlorophyll content, photosynthetic rate, leaf-level and whole plant-level water use efficiency and cumulative water consumption of tomato seedlings were increased with increasing proportion of NO3- in nutrient solutions in the elevated CO2 treatment. Plant biomass, plant height, stem thickness and photosynthetic rate were 67%, 22%, 24% and 55% higher at elevated CO2 concentration than at ambient CO2 concentration, depending on the values of NH4^＋/NO3^- ratio. These results indicated that elevating CO2 concentration did not mitigate the adverse effects of 100% NH4^＋-N （in nutrient solution） on the tomato seedlings. At both CO2 levels, NH4^＋/NO3^- ratios of nutrient solutions strongly influenced almost every measure of plant performance, and nitrate-fed plants attained a greater biomass production, as compared to ammonium-fed plants. These phenomena seem to be related to the coordinated regulation of photosynthetic rate and cumulative water consumption of tomato seedlings.     

植物中锌同位素的研究进展

锌同位素是示踪植物中锌地球化学的重要手段,详细了解植物中锌同位素的分馏过程是探究其生物地球化学的关键。本文对目前研究程度较高的超富集植物、普通植物的锌同位素分馏成果进行了系统的总结,发现二者锌同位素分馏趋势基本一致,即相比于培养液或土壤的同位素组成,植物根部相对富集锌的重同位素,而植物地上部(如茎、叶等组织器官)相对富集锌的轻同位素。对于能够引起植物发生锌同位素分馏的因素归纳如下:(1)植物根部相对富集锌的重同位素,是土壤中锌的形态、根部对锌的吸收方式、细胞表面吸附共同作用的结果;(2)植物木质部对锌的向上运输,会随着传输距离的增加而使地上部组织器官相对富集锌的轻同位素;(3)大气沉降也可能导致叶片富集锌的轻同位素。     

Effects of used lubricating oil on two mangroves Aegiceras corniculatum and Avicennia marina

An outdoor experiment was set up to investigate the effects of used lubricating oil(5 L/m~2)on Aegiceras corniculatum Blanco. and Avicennia marina(Forsk)Vierh.,two salt-excreting mangroves.A.marina was more sensitive to used lubricating oil than A. corniculatum and canopy-oiling resulted in more direct physical damage and stronger lethal effects than base-oiling.When treated with canopy-oiling,half of A.corniculatum plants survived for the whole treatment time(90 d);but,for A.marina,high mortality (83%)resulted from canopy-oiling within 3 weeks and no plants survived for 80 d.Base-oiling had no lethal effects on A.corniculatum plants even at the termination of this experiment,but 83% of A.marina plants died 80 d after treatment.Forty days after canopy- oiling,93% ofA.corniculatum leaves fell and no live leaves remained on A.marina plants.By the end of the experiment,base-oiling treatment resulted in about 45% ofA.corniculatum leaves falling,while all A.marina leaves and buds were burned to die.Lubricating oil resulted in physiological damage to A.corniculatum leaves,including decreases in chlorophyll and carotenoid contents,nitrate reductase,peroxidase and superoxide dismutase activities,and increases in malonaldehyde contents.For both species,oil pollution significantly reduced leaf,root,and total biomass,but did not significantly affect stem biomass.Oil pollution resulted in damage to the xylem vessels of fine roots but not to those of mediate roots.     

土壤添加亚砷酸钠对大豆生长和植株氮、磷、钾含量的影响

利用土壤盆栽实验,研究了0、5、10、30、50、100mg·kg^-1的土壤加砷水平对大豆生长和氮、磷、钾养分含量的影响.结果表明,当土壤加砷水平达到50mg·kg^-1时,大豆出现中毒症状,叶片皱缩,叶色变暗,叶缘焦枯,植株矮化,成熟延迟.大豆株高随加砷水平的提高而降低,并呈极显著的负指数相关关系.土壤加砷达到10...     

Uptake, translocation, and debromination of polybrominated diphenyl ethers in maize

Uptake, translocation and debromination of three polybrominated diphenyl ethers (PBDEs), BDE-28, -47 and -99, in maize were studied in a hydroponic experiment. Roots took up most of the PBDEs in the culture solutions and more highly brominated PBDEs had a stronger uptake capability. PBDEs were detected in the stems and leaves of maize after exposure but rarely detected in the blank control plants. Furthermore, PBDE concentrations decreased from roots to stems and then to leaves, and a very clear decreasing gradient was found in segments upwards along the stem. These altogether provide substantiating evidence for the acropetal translocation of PBDEs in maize. More highly brominated PBDEs were translocated with more difficulty. Radial translocation of PBDEs from nodes to sheath inside maize was also observed. Both acropetal and radial translocations were enhanced at higher transpiration rates, suggesting that PBDE transport was probably driven by the transpiration stream. Debromination of PBDEs occurred in all parts of the maize, and debromination patterns of different parent PBDEs and in different parts of a plant were similar but with some differences. This study for the first time provides direct evidence for the acropetal translocation of PBDEs within plants, elucidates the process of PBDE transport and clarifies the debromination products of PBDEs in maize.     

Remediation effect of compost on soluble mercury transfer in a crop of Phaseolus vulgaris

We studied the dynamics of mercury (Hg) transfer in Phaseolus vulgaris plants grown in soil with Hg-doped compost at the maximum levels permitted by Colombian law on organic amendments. Quantitative evaluation of transfer was made in different plant organs: roots, stem, leaves, pods and seeds. Matrix effect was determined in doped soil assays, using soil with and without addition of compost. Results showed that the use of organic matter reduced Hg transfer to the plant and the amount transferred was differentially distributed to the organs. We observed an inverse relationship between concentration and distance from the body to the root. It was evident that transfer was mediated by quantitative factors; the greater the presence of mercury in soil, the larger the amount that will be transferred. Results also indicate the remedial effect of compost and the presence of a barrier, at the root level, against mercury translocation to the plant aerial parts.     

Remediation effect of compost on soluble mercury transfer in a crop of Phaseolus vulgaris

We studied the dynamics of mercury (Hg) transfer in Phaseolus vulgaris plants grown in soil with Hg-doped compost at the maximum levels permitted by Colombian law on organic amendments. Quantitative evaluation of transfer was made in different plant organs: roots, stem, leaves, pods and seeds. Matrix effect was determined in doped soil assays, using soil with and without addition of compost. Results showed that the use of organic matter reduced Hg transfer to the plant and the amount transferred was differentially distributed to the organs. We observed an inverse relationship between concentration and distance from the body to the root. It was evident that transfer was mediated by quantitative factors; the greater the presence of mercury in soil, the larger the amount that will be transferred. Results also indicate the remedial effect of compost and the presence of a barrier, at the root level, against mercury translocation to the plant aerial parts.     

Uptake and accumulation of copper by roots and shoots of maize(Zea may L.)

The effects of different concentrations of copper sulfate on rootand shoot growth of maize(Zea mays L.) and the uptake and accumulation of Cu2+ by its roots and shoots were investigated in the present study. The concentrations of opper sulfate (CuSO4.5H2O) used were in the range of 10-5-10-3mol/L. Root growth decreased progressively with increasing concentration of Cu2+ in solution. The seedlings exposed to 10-3 mol/L Cu exhibited substantial growth reduction, yielding only 68% of the root length of the control. The shoot growth of the seedlings grown at 10-5-10-4 mol/L Cu2+ were more or less than the same as the control seedlings. The leaves treated with 10-3 mol/L Cu2+ were obviously inhibited in shoot growth. The fresh and dry weights both in roots and shots decreased progressively with increasing Cu2+ concentration.This fits well with the above mentioned effects of copper sulfate on root growth. Zea mays has considerable ability to remove Cu from solutions and accumulate it. The Cu content in roots of Z. Mays increased with increasing solution concentration of Cu2+. The amount of Cu in roots of plants treated with 10-3, 10-4 and 10-5 mol/L Cu2+ were 10, 8 and 1.5 fold, respectively, greater than that of roots of control plant. However, the plants transported and concentrated only a small amount of Cu in their shoots.     

Nickel accumulation and its effect on biomass, protein content and antioxidative enzymes in roots and leaves of watercress (Nasturtium officinale R. Br.)

In order to understand its response towards nickel stress,watercress(Nasturtium officinale R.Br.) was exposed to nickel(1-25 mg/L) for 1,3,5 and 7 days.The accumulation and translocation of nickel were determined and the influence of nickel on biomass,protein content and enzymatic antioxidants was examined for both roots and leaves.It was determined that N.officinale could accumulate appreciable amounts of Ni in both roots and leaves.Nickel accumulated particularly in the roots of plants.Biomass increased at low nickel concentrations but certain measurable change was not found at high concentrations.Under stress conditions the antioxidant enzymes were up-regulated compared to control.An increase in protein content and enzyme activities was observed at moderate exposure conditions followed by a decline at both roots and leaves.The maximum enzyme activities were observed at different exposure conditions.Our results showed that N.officinale had the capacity to overcome nickel-induced stress especially at moderate nickel exposure.Therefore,N.officinale may be used as a phytoremediator in moderately polluted aquatic ecosystems.     

Deep-time patterns of tissue consumption by terrestrial arthropod herbivores

A survey of the fossil record of land-plant tissues and their damage by arthropods reveals several results that shed light on trophic trends in host-plant resource use by arthropods. All 14 major plant tissues were present by the end of the Devonian, representing the earliest 20 % of the terrestrial biota. During this interval, two types of time lags separate the point between when tissues first originated from their earliest consumption by herbivorous arthropods. For epidermis, parenchyma, collenchyma and xylem, live tissue consumption was rapid, occurring on average 10 m.y. after the earliest tissue records. By contrast, structural tissues (periderm, sclerenchyma), tissues with actively dividing cells (apical, lateral, intercalary meristems), and reproductive tissues (spores, megagametophytes, integuments) experienced approximately a 9-fold (92 m.y.) delay in arthropod herbivory, extending well into the Carboniferous Period. Phloem similarly presents a delay of 85 m.y., but this incongruously long lag-time may be attributed to the lack of preservation of this tissue in early vascular plants. Nevertheless, the presence of phloem can be indicated from planar spaces adjacent well-preserved xylem, or inferred from a known anatomy of the same plant taxon in better preserved material, especially permineralisations. The trophic partitioning of epidermis, parenchyma, phloem and xylem increases considerably to the present, probably a consequence of dietary specialization or consumption of whole leaves by several herbivore functional feeding groups. Structural tissues, meristematic tissues and reproductive tissues minimally have been consumed throughout the fossil record, consistent with their long lags to herbivory during the earlier Paleozoic. Neither angiosperm dominance in floras nor global environmental perturbations had any discernible effect on herbivore trophic partitioning of plant tissues.     

Functional traits of poplar leaves and fine roots responses to ozone pollution under soil nitrogen addition

Concurrent ground-level ozone（O₃） pollution and anthropogenic nitrogen（N） deposition can markedly influence dynamics and productivity in forests.Most studies evaluating the functional traits responses of rapid-turnover organs to O₃ have specifically examined leaves,despite fine roots are another major source of soil carbon and nutrient input in forest ecosystems.How elevated O₃ levels impact fine root biomass and biochemistry remains to be resolved.This study was...     

大气中CO2体积分数升高对污染土壤中Cu、Cd形态分布及其生物活性的影响

采用OTC-1型开顶式培养箱,模拟研究了CO2体积分数升高对2种小麦的生长以及根际、非根际中Cu和Cd形态分布的影响.结果表明,CO2体积分数的升高显著提高了小麦地上部和地下部生物量,降低了小麦根际和非根际的pH值.临麦2号和宁麦8号小麦地上部干重分别增加了36.9%和25.2%,地下部干重则分别增加了55.1%和59.7%.此外,CO2体积分数升高对不同重金属形态分布的影响随小麦品种和重金属种类的不同而异.在高CO2体积分数条件下,可交换态(F1)Cu和Cd含量显著提高,其中临麦2号根际土壤可交换态Cu和Cd含量分别较对照增加10.6%和29.6%,宁麦8号根际土壤可交换态Cu和Cd分别较对照增加11.0%和20.3%;碳酸盐结合态(F2)Cu和Cd均有所降低,其中宁麦8号和临麦2号根际Cu降低均达极显著(分别降低73.6%和50.0%);铁锰氧化物结合态(F3),有机结合态(F4)和残渣态(F5)Cu和Cd在CO2体积分数升高情况下变化较小.同时CO2体积分数升高还显著增加了2种小麦地上部和地下部铜累积量,增加了临麦2号地上部和地下部镉累积量和宁麦8号地上部镉累积量,但对宁麦8号地下部镉累积量无显著影响.     

Uptake and accumulation of copper by roots and shoots of maize (Zea mays L.)

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作物生长和氮含量对土壤-作物系统CO2排放的影响

为探讨作物生物学特征对土壤-作物系统CO₂排放的影响,本研究基于逐步收割法和静态暗箱-气相色谱技术,以冬小麦和水稻作物为研究对象,采用盆栽和大田试验的方法,在作物生长的主要生育期原位测定了土壤-作物系统CO₂排放速率,同时测定了作物生物量和氮含量.研究结果表明:①土壤-作物系统CO₂排放在生长季内呈现动态变化,土壤-水稻系统CO₂排放高于土壤-冬小麦系统.②作物暗呼吸速率与生物量呈显著线性相关.③作物暗呼吸系数(R_d)的季节变化可以用植株氮含量来描述.冬小麦R_d与N含量的关系可用线性方程R_d=0.0124N-0.0076(R²=0.9879,p<0.001)表示;水稻R_d与N含量的关系可用二次方程R_d=0.0085N2-0.0049NR²=0.9776,p<0.001)表示.④作物根系的参与极大地促进了土壤呼吸.冬小麦生长季土壤表观呼吸CO₂平均值为247.2 mg·(m²·h)^-1 ,高于未种作物土壤1.78倍,水稻生长季为215.3 mg·(m²·h)^-1 CO₂,高于未种作物土壤的3.38倍.冬小麦根系呼吸系数大于水稻,其根际呼吸对土壤表观呼吸的贡献高于水稻.     

镉铅复合胁迫下根表铁锰氧化胶膜厚度对美洲商陆富集镉的影响

为了探讨根表铁锰氧化胶膜厚度及共存离子铅(Pb)对美洲商陆富集镉(Cd)影响,采用水培的方法,诱导培育了胶膜厚度具有极显著差异的美洲商陆(低膜美洲商陆、中膜美洲商陆和高膜美洲商陆),分别进行低Cd低Pb、低Cd高Pb、高Cd低Pb、高Cd高Pb等4种不同金属组合的胁迫处理,观察美洲商陆生长状况、测定植株对Cd的富集量、抗胁迫生理活性物质的表达量.结果表明:中膜和高膜美洲商陆侧根发达,新生根较多,高Cd胁迫对根系发育有较强的抑制作用.高Cd条件下,植株对Cd的富集量为高膜美洲商陆中膜美洲商陆低膜美洲商陆,高膜美洲商陆Cd总富集量可达89765.69 mg·kg-1(以干重计).低Cd条件下,植株对Cd的富集量为低膜美洲商陆高膜美洲商陆中膜美洲商陆.高Pb处理,可提高低膜和高膜美洲商陆Cd富集量,但显著降低中膜美洲商陆Cd富集量.根系分泌的可溶性还原糖含量、叶及根部合成的可溶性蛋白含量与根表铁锰氧化胶膜的厚度成正相关.中膜和高膜美洲商陆叶片及根部可溶性蛋白含量还受到不同金属组合胁迫的影响.镉铅复合胁迫使美洲商陆叶片及根部可溶性蛋白含量极显著高于对照组.     

Nickel accumulation and its effect on biomass, protein content and antioxidative enzymes in roots and leaves of watercress （Nasturtium officinale R. Br.）

In order to understand its response towards nickel stress, watercress (Nasturtium o cinale R. Br.) was exposed to nickel (1–25 mg/L) for 1, 3, 5 and 7 days. The accumulation and translocation of nickel were determined and the influence of nickel on biomass, protein content and enzymatic antioxidants was examined for both roots and leaves. It was determined that N. o cinale could accumulate appreciable amounts of Ni in both roots and leaves. Nickel accumulated particularly in the roots of plants. Biomass increased at low nickel concentrations but certain measurable change was not found at high concentrations. Under stress conditions the antioxidant enzymes were up-regulated compared to control. An increase in protein content and enzyme activities was observed at moderate exposure conditions followed by a decline at both roots and leaves. The maximum enzyme activities were observed at di erent exposure conditions. Our results showed that N. o cinale had the capacity to overcome nickel-induced stress especially at moderate nickel exposure. Therefore, N. o cinale may be used as a phytoremediator in moderately polluted aquatic ecosystems.     

施硅对水稻铁膜砷固定和体内砷转运的影响

水稻铁膜对砷(As)的固定及其体内As的转运深刻影响着糙米中As的累积.施硅(Si)能够抑制水稻对As的累积,然而,施Si如何调控铁膜对As的固定和水稻各部位的As向糙米的转运,相关机制目前尚未十分清楚.以As超标土壤中的水稻铁膜为研究对象,通过开展不同Si处理水平的土壤盆栽试验,研究施Si对水稻根表铁膜固定As和各组织器官中As向糙米转运的影响及作用机制.结果表明,Si2(0.66 g·kg^-1)处理显著提高了水稻根系CAT(1.81倍)、SOD(7.98倍)和POD(1.25倍)酶活性,增加了铁膜中的DCB-Fe含量(44.35%),提高了铁膜的表面粗糙度(108.91%),导致铁膜的DCB-As含量明显升高(88.32%);而且,Si2处理显著增加了水稻根中As的累积率,降低了根和叶对As的转运能力,最终导致糙米中As含量的显著降低(53.12%).施Si增强水稻根表铁膜对As固定的原因可归结于Si促进铁膜的形成和增大铁膜的表面粗糙度,而施Si抑制根和叶中As向糙米的转运则可能与Si竞争水稻体内As的转运蛋白,促进As-巯基络合物形成以及增强As液泡区隔化等...