Exogenous application of succinic acid enhances tolerance of <Emphasis Type="Italic">Larix olgensis</Emphasis> seedling to lead stress

Larix olgensis A. Henry (Changbai larch) is a productive commercial species and good candidate for afforestation in northeast China. It is widely planted in lead-stressed soils which can induce oxidative damage in this plant. Increasing tolerance to lead (Pb) stress is therefore of keen interest. A greenhouse experiment was conducted to identify the biomass, physiological responses and Pb accumulation of L. olgensis seedlings to Pb stress under succinic acid (SA) application and to explore the interaction of exogenous SA applications and stress resistance. L. olgensis seedlings were planted in Pb-stressed or unstressed haplic cambisols in pots. In Pb-contaminated soils the seedlings were treated daily with concentrations of SA solutions at a rate approximately equivalent to 0, 0.04, 0.2, 1.0, or 2.0 mmol kg^?1 of soil for 10, 20, and 30 days, respectively. Pb treatment induced damage in the seedlings and led to the inhibition of biomass accumulation in roots, stems and leaves, and a rise in Pb accumulation in fine roots and leaves. Malondialdehyde (MDA) content and electrolyte leakage in leaves significantly increased while peroxidase (POD) activities, soluble protein and photosynthetic pigment contents in leaves were all reduced. Physiological toxicity was promoted with increasing Pb treatment times. When Pb-stressed seedlings were exposed to SA (especially 10.0 mmol L^?1 over 20 days), the physiological responses for Pb-only were reversed and the biomass of roots, stems, and leaves dramatically increased. SA facilitated Pb uptake in fine roots and leaves but more Pb accumulated in fine roots. The results demonstrate that exogenous SA alleviates Pb-induced oxidative injuries and improves the tolerance of L. olgensis seedlings to Pb stress.     

不同氮水平对中美山杨幼苗生物量、氮浓度及其季节变化的影响1）

在温室内以中美山杨幼苗为材料进行砂培试验,探讨了4种不同氮素浓度（1、4、8、16 mmol/L）处理对中美山杨幼苗生物量分配以及根、茎、叶氮浓度的影响。结果表明：（1）氮素供给浓度显著影响幼苗生物量,7月份和9月份在N16水平下达最大,8月份在N8水平下达最大,从7月份到9月份,叶片中的生物量比例逐渐降低,根系的生物量比例逐渐增加。（2）随着供氮水平的提高,苗木体内根、茎、叶中氮浓度明显增加。生长末期根、茎、叶中氮浓度平均达到生长初期的1．16、1．38、1．03倍。（3）本试验可为中美山杨幼苗培育提供理论依据和技术参考。     

银杏幼苗修复Pb和Cd重金属污染土壤特性

研究重金属Pb2+,Cd2+污染及其复合污染土壤对盆栽银杏幼苗生物量的影响及银杏幼苗对重金属污染土壤中Pb2+和Cd2+的富集特性及土壤修复.结果表明:Cd2+,Pb2+可显著或极显著降低银杏幼苗单株及各器官生物量增量,Cd2+对银杏幼苗生物量增量的抑制作用较Pb2+小,Cd2+-Pb2+复合污染进一步降低了银杏幼苗单株及各器官生物量增量;银杏幼苗体内Pb2+,Cd2+的质量分数和富集系数均表现为根＞茎＞叶,有利于Pb2+和Cd2+向茎、叶部迁移;Cd2+-Pb2+复合污染可促进植株对Cd2+和Pb2+的吸收,且对Pb2+的向上转运能力大于Cd2+,表现出明显的剂量效应和协同作用;银杏幼苗对Cd2+,Pb2+具有较大的积累量,且根中Cd2+,pb2+累积量高于或显著高于茎、叶;Cd2+-Pb2+复合污染下银杏幼苗对Pb2+具有较强的吸收、运输和积累能力;银杏幼苗对Pb,Cd污染土壤的修复潜力较强.     

Effects of calcium, boron and nitrogen fertilization on the growth of teak (Tectona grandis) seedlings and chemical property of acidic soil substrate

Many teak plantations are established on acidic soils with low nutrient availability. There is also poor documentation of nutrient budgets for teak, therefore, a pot experiment with optimal hybrid regression design (Roquemore R311A) was implemented with calcium, boron and nitrogen treatments with teak seedlings (Tectona grandis L.f.) planted in acidic lateritic red soil substrate. Seedling growth, biomass production and root development, and soil pH, and exchangeable Ca and Al concentration were measured. Plant height, root collar diameter, biomass of leaves, stems and roots, root volume, taproot length, number of lateral roots of teak seedlings were significantly and positively correlated with soil exchangeable Ca, pH and Ca/Al molar ratio, and negatively correlated with exchangeable Al. All growth traits were significantly affected by calcium, nitrogen and their interaction, but B fertilizer and other interactions had insignificant effects. To effectively cultivate teak seedlings in acidic soil substrates, 1.68 g kg⁻¹ quicklime (CaO) and 0.65 g kg⁻¹ urea was suggested to be added to neutralize soil acidity, and enhance soil exchangeable Ca content and Ca/Al molar ratio. Urea should not be added without quicklime.     

水杨酸对盐胁迫下大豆生长和渗透调节能力的影响

砂基培养大豆,盐胁迫下进行水杨酸处理,NaCl和SA处理的预定浓度分别为0 0(对照)、100 0、100 0.3、200 0、200 0.3mmol/L。结果表明:SA处理后提高盐胁迫下大豆Pro、SS、AA和叶绿素含量;增强根系活力、硝酸还原酶(NR)活性。综合各项生长和生理指标表明,SA处理有利于增加渗透调节能力,减缓水分胁迫,缓解盐害;且SA对NaCl 100mmol/L处理的大豆生长缓解效应优于NaCl200mmol/L胁迫的。     

Impacts of competition and nitrogen addition on plant stoichiometry and non-structural carbohydrates in two larch species

Previous research has shown that competition between plants can have differential effects on leaf stoichiometry and non-structural carbohydrate(NSC) in different environments.However,little attention has been given to understanding these effects on non-photosynthetic organs,particularly of deciduous tree species.Here we assess the impact of competition on below and aboveground biomass,stoichiometry,nutrient composition and NSC in pure and mixed forests of two Larch species,Larix kaempferi and L.olgensis under nitrogen(N) addition.Nitrogen enrichment did not result in stronger intraspecific competition for both species and L.olgensis benefited from the presence of L.kaempferi under different N levels.Stems kept relatively stable C/N compared to roots and branches in response to competition,while N addition imposed stronger impacts on N/P of different organs rather than competition.In contrast to stable C concentrations,starch and soluble sugar concentrations were more easily impacted by competition and the addition of nitrogen.Competition forced L.kaempferi and L.olgensis to allocate more carbon into storage by increasing their starch concentration and starch/soluble sugar of stems under competition.However,no significant differences in stoichiometry and NSC concentration between intra-and interspecific competition were found.NSC and nutrient pools of L.kaempferi stems,branches and coarse roots consistently declined due to competition regardless of N addition.Coarse and fine roots of L.kaempferi accumulated more N when in competition with L.olgensis than with a conspecific neighbor under N addition.Our results show that NSC was more sensitive to competition relative to stoichiometric traits(N and P) of non-photosynthetic organs.     

淹水胁迫对两种栎树生长的影响

对纳塔栎、南方红栎的2 a生苗在深度淹水约20 cm、浅度淹水(完全水饱和)、对照3种水平下持续76 d的生长进行研究,其中又以抗涝性极强的落羽杉作为参照.主要测定了各树种的生物量和株高,并对外部形态特征及叶片内部解剖结构的变化进行了观察.结果表明:浅淹没有造成苗木死亡,深度淹水第49天南方红栎开始出现枯死植株,第76天纳塔栎出现轻微受害症状,落羽杉没有出现受害症状.与各自对照相比,浅淹水平对落羽杉、纳塔栎的高生长及生物量的累积均具有促进作用,且对落羽杉影响较显著,而对南方红栎影响不显著;深淹水平对落羽杉、纳塔栎的'高生长及生物量的累积影响不显著,但对南方红栎具有显著的抑制作用.同时,发现淹水对落羽杉、纳塔栎的叶片解剖性状影响不显著,而深淹水平下,数据显示南方红栎的叶片内部细胞间隙明显增大.综合表明两种栎树都具有较强的耐水性,而纳塔栎更优于南方红栎,仅次于落羽杉.     

低温胁迫下外源有机酸对长白落叶松幼苗生理生化特性的影响

根据东北林区森林凋落物淋洗液中草酸、柠檬酸和苹果酸的浓度范围,用不同浓度的上述3种外源有机酸溶液叶面喷施长白落叶松幼苗,再置于4℃下进行低温胁迫,研究有机酸对低温逆境条件下长白落叶松幼苗多种生理生化指标的影响,探讨低温胁迫下外源有机酸对苗木抗寒性的调控机制。结果表明:适当浓度的3种有机酸均降低低温胁迫后长白落叶松的质膜透性和MDA含量,不同程度提高SOD,POD,APX和CAT等多种抗氧化酶活性及脯氨酸和可溶性蛋白含量,减缓叶绿素的下降趋势。外源有机酸能通过促进长白落叶松体内保护酶活性提高,降低膜脂过氧化程度,增强渗透调节能力和细胞清除活性氧的能力,最终明显提高其低温抵御能力。3种有机酸对上述生理生化特性的影响强弱表现为:柠檬酸>苹果酸>草酸,适宜的最佳使用浓度为5.0mmol.L-1。     

盐胁迫对楝树6个家系实生苗生长的影响

对楝树6个家系幼苗在0,2‰,4‰,6‰和8‰Na Cl单盐胁迫下的苗高、地径、根幅、主根长、根鲜质量、茎鲜质量、叶鲜质量、根干质量、茎干质量、叶干质量和总生物量等11个性状进行测定和分析表明,楝树6个供试家系之间耐盐能力存在差异,不同质量分数Na Cl单盐胁迫对同一家系的多个性状影响显著。上述11个性状有随Na Cl胁迫质量分数增大而降低的趋势,但各家系之间差异较大。根冠比则基本呈现出随Na Cl胁迫质量分数增大而增大的趋势。     

密度对乐昌含笑幼苗养分积累的影响

以1年生乐昌含笑(Michelia chapensis)实生苗为试验材料,采用盆栽法,在美植袋中分别种植1、2、4、8株幼苗(密度Ⅰ、Ⅱ、Ⅲ和Ⅳ),研究密度对乐昌含笑幼苗N、P和K养分含量和贮量的影响。结果表明:不同密度乐昌含笑各器官对养分富集的能力均为KNP。乐昌含笑幼苗的N含量在各器官为叶根枝干的规律;P和K含量在密度Ⅳ下分别为枝根干叶和根叶枝干,其余密度为叶根枝干。乐昌含笑幼苗的N、P和K贮量随密度增大而增加,且根的养分贮量最大,枝的最小。     

Influence of different nursery container media on rooting of Scots pine and silver birch seedlings after transplanting

Scots pine (Pinus sylvestris L.) and silver birch (Betula pendula Roth.) seedlings were grown in containers filled with growth media based on medium-textured sphagnum peat, coarse perlite and fine sand. The seedlings were then planted into fine and coarse sandy soils in 2.2 l pots, which were subjected to two water-content treatments (only one for birch). After the seedlings had grown five weeks in a greenhouse, rooting into the surrounding soil and shoot growth were measured. Addition of perlite and sand to peat medium slightly affected rooting; thus suggesting minor effects on seedling establishment. However, nitrogen concentration of the seedlings varied between growth media and correlated positively with rooting into the soil. The particle size and water content of the soil affected considerably rooting of the seedlings. Seedling height at the time of planting did not affect rooting or shoot growth. The fact that the fewest out-grown roots occurred in the dry fine sandy soil, suggests that dry soil together with high strength and resistance to root penetration reduce rooting and water uptake by container seedlings most and may thus cause water and nutrient stresses to seedlings after outplanting.     

I-69杨苗期生长及营养特性的研究

杨树是重要的速生树种,在我国长江中下游平原地区发展具有重要意义。1983年对杨树的黑杨派良种I-69杨(Populus deltoides cv.“Lux”)苗期生长与营养特性的研究,旨在培育和选择优质苗木,为杨树用材林定向培育的造林设计提供科学依据。     

铝胁迫对千年桐吸收和运输微量元素的影响

为探索千年桐体内微量元素对不同梯度铝胁迫的响应机制,分析铝胁迫下微量元素在根系和叶片间吸收和运输的规律,以土培和水培的1年生千年桐苗木为研究对象,在不同供铝水平下,测定千年桐苗木根系和叶片中微量元素(Fe、Mn、Cu、Zn)的含量。结果表明,铝处理显著促进盆栽苗根系微量元素的吸收,而对水培苗根系微量元素的吸收则表现为无显著作用或抑制作用,表明同一植物在不同生境下会形成不同的耐铝机制;微量元素在苗木不同器官的分配方式不同,千年桐盆栽苗吸收的微量元素除Mn外多集中在根系,而水培苗则除Fe外多集中在叶片;铝胁迫也会影响微量元素在苗木不同器官间的运输,如在铝浓度低于0.290 mmol·L^-1时,会促进水培苗Zn元素从根向叶的运输,而当铝浓度高于0.290 mmol·L^-1时,则会抑制Zn元素的向上运输。铝处理对千年桐盆栽苗和水培苗微量元素的影响有较大差异,与水培苗相比,盆栽苗在土壤原生环境下具有较好的抗性。因此,在今后的胁迫试验中,除了考虑植物自身的抗逆性,还要考虑原生环境的作用。     

铝对马尾松菌根苗生长及营养元素吸收的影响

以接种褐环乳牛肝菌和未接种的马尾松幼苗为试验材料,采用水培法研究不同浓度铝(Al^3+)处理(0、0.2、0.4、0.8和1.2 mmol·L^-1)对菌根化和非菌根化马尾松幼苗生长、营养元素吸收的影响,揭示菌根化马尾松苗木对Al^3+的适应机制,为减轻马尾松苗木铝毒害现象提供理论和技术依据。结果表明,在相同浓度Al^3+胁迫下,接种褐环乳牛肝菌的马尾松幼苗苗高、生物量、根系形态以及对氮(N)、磷(P)、钾(K)的吸收能力均优于不接种的马尾松苗。马尾松幼苗苗高、干物质量积累以及根系生长随着Al^3+浓度的增大均呈现先升后降再升的趋势,随着Al^3+浓度的逐渐增大,马尾松幼苗根、茎、叶中的N、P、K含量呈现出低促高抑的趋势,根、茎、叶中Al^3+含量的分配为根>茎>叶。Al^3+胁迫下,接种褐环乳牛肝菌的马尾松幼苗,通过改变马尾松幼苗根系结构,促进了幼苗的生长,特别是根系的生长,以及对N、P、K等营养元素的吸收,抑制了根系吸收Al^3+,提高了马尾松幼苗的耐铝能力。     

盐肤木幼苗对铅胁迫的生理响应

[Objective]A greenhouse pot experiment was conducted to evaluate the potential of Rhus chinensis Mill for phytoremediation of lead-contaminated soil.[Method]The response of container seedlings to Pb concentrations (0, 400 and 1 000 mg·kg^-1) in the soil was studied. Seedling growth, chlorophyll, carotenoid, chlorophyll fluorescence, malondialdehyde (MDA), nutrient elements, Pb accumulation and translocation were assessed.[Result]The results showed that R. chinensis did not show visual symptoms of Pb toxicity. Compared to the control, the biomass increased slightly at low concentration (400 mg·kg^-1). Under Pb stress conditions, the root elongation was restrained, while the radial growth of root was promoted and the fine root was developed better. No differences were observed in photosynthetic pigments, chlorophyll fluorescence, and MDA. During the experiment, only small quantity of Pb were uptake by R. chinensis, and most of the Pb absorbed by plants was retained in the roots. However, at the high concentration (1 000 mg·kg^-1), R. chinensis transported metal to the shoots better, and the translocation factor (TF) value was 0.66. Under the Pb stress, oxalic acid of root exudates was increased significantly; while the root could be induced malic acid and citric acid, and the concentration increased with Pb concentration in soil. [Conclusion]R. chinensis was found to have Pb tolerance and phytoremediation potential in Pb-contaminated soils.     

Effects of nickel and copper on growth and mycorrhiza of Scots pine seedlings inoculated with Gremmeniella abietina

Scots pine (Pinus sylvestris) seedlings were planted in soil originating from two localities with different background levels of nickel and copper. In addition, some of the seedlings were exposed to additional nickel (20.5 mg Ni/l of soil) or copper (63.5 mg Cu/l of soil), or a combination of both Ni and Cu, via soil without direct shoot exposure during their second growing period. The seedlings were either irrigated with spring water (pH 6) or got only natural rain during the whole field experiment. All seedlings were inoculated with conidia of a shoot‐pathogen Gremmeniella abietina during their third growing season, and harvested the following spring. Lengths of shoots of different year‐classes were used as growth estimates. In roots, the proportion of fungal (assumedly mycorrhizal) biomass was estimated by measuring ergosterol concentration. Guajacol peroxidase activity was measured. Short roots were classified into two groups according to their condition and the composition of the mycorrhizal community was expressed as a proportion of morphotypes in the roots. The seedlings exposed to additional Ni had higher shoot growth than the seedlings in the other treatments. The mean Ni concentration in the roots of seedlings exposed to additional Ni was 79 p.p.m. and in other seedlings 16 p.p.m. Additional Ni also decreased the frequency of clearly senescent short roots and the proportion of the mycorrhizal morphotype with the thinnest mantle. These results indicate that the Ni exposure levels used in this experiment had some positive effects on the seedlings. The relative fungal biomass was about 6% lower (p = 0.0981) in the fine roots of seedlings treated with additional Cu. The mean Cu concentration in the roots of seedlings exposed to additional Cu was 256 p.p.m. and in other seedlings 29 p.p.m. Peroxidase activity, which was used as a general stress indicator in this study, was not affected by any of the treatments. The shoot growth and the relative biomass of fungi in the fine roots were positively correlated in all seedlings, and this correlation was stronger in seedlings exposed to additional Ni that were not irrigated compared with seedlings not exposed to additional Ni that were irrigated. The frequency of asymptomatic infections of G. abietina was positively correlated with the proportion of senescent short roots in the irrigated seedlings but not in not‐irrigated seedlings. The general condition of seedlings may be an important factor for infection by G. abietina when moisture is high enough for the fungi to infect seedlings by conidia.     

Effects of shading and removal of plant parts on growth of Trema micrantha seedlings

Effects of artificial shading and removal of plant parts on growth of Trema micrantha (L.) Blume (Ulmaceae) seedlings were studied. Seedlings were grown in pots in a greenhouse in 45, 30, 10.6, 4.8 and 1.8% of full sunlight. Shading for 60 days had no effect on survival, but it influenced all growth parameters measured. Total biomass decreased with decreasing irradiance, reflecting reductions in dry mass of leaves, stems and roots. In response to shading, allocation of biomass to leaves increased, while allocation of biomass to roots decreased. Specific leaf area, leaf area ratio and leaf mass ratio increased with decreasing irradiance. Decreases in relative growth rate were caused by reductions in net assimilation rate rather than leaf area ratio. Photosynthetic efficiency, as determined by the Fv/Fm ratio (Fv = variable fluorescence, Fm = maximal fluorescence), was unaffected by the shading treatments. Partial removal of leaves, stem or roots did not affect seedling survival. Seedlings responded to removal of plant parts by compensatory growth. Topophysis was observed when the apex was removed: the lateral buds developed only as new plagiotropic lateral shoots; consequently, the decapitated plant ceased height growth and was unable to compete with its neighbors for light.     

不同炼苗密度对桉树轻基质幼苗的影响

通过对5个月生4种不同炼苗密度的尾巨桉优良无性系 DH_32-29幼苗树高、地径及各器官生物量进行调查分析，结果表明：4种不同炼苗密度间苗高无显著差异；而地径差异达到极显著水平，并呈极显著负相关；不同炼苗密度单株间及各器官生物量均差异显著，单株生物量、叶片、茎干与根系的生物量均随炼苗密度增加而降低；考虑到空间利用率、通风保水性及疾病易感程度综合分析，炼苗密度以45株·盘^-1效果最佳。     

大花序桉幼苗营养吸收及分配规律研究

对大花序桉幼苗生物量及营养元素进行测定,结果表明,大花序桉苗木平均单株生物量大小排序为茎>根>叶。幼苗主要营养含量和吸收积累规律为K>N>P>Fe>Mn>Zn>B>Ca>Cu>Mg。大量元素N、P、K贮量最高的部位均为茎,根部和叶中含量相近。大花序桉苗期叶片对主要营养元素N、P和K的吸收分配间存在相互促进的关系;Mg与Ca,Cu与P、K,Zn与N、K、Cu、Fe,Fe与N呈现互相促进关系;Mn与N、Fe、K、Cu,B与P、Cu为相互抑制关系。据此,大花序桉苗期以氮、磷、钾肥为主,其中要求养分K₂O>N>P₂O₅,并有针对性地添加铁肥、锌肥和铜肥。     

水曲柳落叶松混交林中细根空间分布

采用根钻取样方法对年生水曲柳落叶松混交林中细根空间分布状况进行了研究。结果表明,水曲柳落叶松地下生物量的空间分配差异显著。在林分水平上,水曲柳的根生物量密度高于落叶松(分别为4442.3和2234.9g/m3)。两树种在相邻区域中分配的细根生物量较高,表明种间根系竞争较弱。落叶松行间的水曲柳细根生物量密度和根长密度均高于水曲柳行间的落叶松细根,表明水曲柳地下部分具有较强能力。根系的空间分布有利于混交林中水曲柳的生长。图1表4参19。