<Emphasis Type="Italic"> Picea</Emphasis> seedlings show apparent acclimation to drought with increasing altitude in the eastern Himalaya

Abstract We measured plant structural and physiological responses of two sympatric Picea species, Picea likiangensis (Franchet) E. Pritzel var. balfouriana and Picea asperata Masters var. retroflexa to altitude close to the treeline in the eastern Himalaya. Most measured tree characteristics differed between different altitudes, between different ages, and between shaded and un-shaded treatments. Both P. likiangensis and P. asperata had lower foliage area/stem cross-sectional area ratios, smaller specific leaf areas, higher root mass/foliage area ratios, and less negative ¹³C at 3,900 m than at 3,600 m altitude, and in the un-shaded treatment than in the shaded treatment. The 7- and 9-year-old seedlings also showed lower foliage area/stem cross-sectional area ratios, higher root mass/foliage area ratios and less negative ¹³C than younger seedlings. Shading resulted in an increase of biomass accumulation at all altitudes. A close relationship, independent of altitude, was observed between ¹³C and specific leaf area, suggesting that internal resistance could limit CO₂ diffusion to the site of carboxylation. The results indicate that, in spite of greater water availability, trees at higher altitudes show quite a number of apparent acclimations to drought.     

Differential Accumulation of Volatile Organic Compounds by Leaves and Roots of Two Guianese Philodendron Species,P. fragrantissimum Kunth and P. melinonii Brongn.

Leaf and root essential oils of two closely related but ecologically distant Philodendron species were extracted in natural conditions in French Guiana and analysed by GC/MS to i) describe the blends of volatile organic compounds (VOCs) produced by those species and ii) analyse species and environment‐based variations in extracts composition. A total of 135 VOCs were detected with a majority of aliphatic sesquiterpenes. P. fragrantissimum produced mainly β‐bisabolene (on average 29.12% of the extract) as well as α‐ and β‐selinene (14.52% and 17.50%, respectively) while in P. melinonii, four aliphatic sesquiterpenes could alternatively be the main component: (E)‐β‐farnesene (up to 91.42% of the extract), germacrene‐D (73.74%), β‐caryophyllene (51.63%) and trans‐α‐bergamotene (41.26%). A significant effect of species and organs on extracts composition was observed while the environment (sun exposure) only affected the relative proportions of monoterpenes and sesquiterpenes in roots of P. melinonii. These results are discussed in the light of the potential role of leaf and root terpenes in Philodendron species.     

A review of belowground biomass allocation and its response to global climatic change in grassland ecosystems北大核心CSCD

Biomass allocations between aboveground and belowground organs provide pivotal information for connecting aboveground productivity and belowground carbon sequestration. As accurate measurement of belowground biomass is essential for determining the biomass allocation, we first reviewed the methods in quantifying belowground biomass and their merits. We then presented the major advances on plant biomass allocations between aboveground and belowground organs, as well as the potential drivers such as precipitation, warming, atmospheric CO2 concentration, and nitrogen deposition. We finally provided a list of challenges in studying belowground biomass allocation for the future. This review has important implications for studies on carbon cycling in grassland ecosystems under the changing climate.     

Germination and seedling establishment of two annual grasses on lichen-dominated biological soil crusts

Biological soil crusts dominated by lichens are common components of shrub-steppe ecosystems in northwestern US. We conducted growth chamber experiments to investigate the effects of these crusts on seed germination and initial seedling establishment of two annual grasses; the highly invasive exotic Bromus tectorum L. and the native Vulpia microstachys Nutt. We recorded germination time courses on bare soil and two types of biological soil crusts; one composed predominantly of the lichen Diploschistes muscorum (Scop.) R. Sant. (lichen crust) and the other comprised of an assortment of lichens and mosses (mixed crust). Final germination on the lichen crust for both grass species was about a third of that on the bare soil surface. Mean germination time (MGT) was 3–4 days longer on the lichen crust compared with the bare soil. In contrast, there was no difference in germination percentage or MGT between the mixed crust and bare soil, and results were similar for both grass species. For both species, root penetration of germinating seeds on the lichen crust was lower than on the bare soil or mixed crust surfaces. The combined effects of the lichen crust on germination and root penetration resulted in an overall reduction in seedling establishment of 78% for V. microstachys and 85% for B. tectorum relative to the bare soil treatment. Our results clearly demonstrate that lichen-dominated biological soil crust can inhibit germination and root penetration, but the extent of these effects depends on the composition of the crust. Responsible Editor: Tibor Kalapos     

基于AFLP分析用吴茱萸叶高质量DNA的提取

目的：研究吴茱萸叶基因组DNA的提取方法,以用于扩增片段长度多态性（AFLP）分析。方法：设计了一种改良CTAB法：以石英砂代替液氮研磨;抽提前用不溶性PVP结合酚形成络合物,然后用缓冲液除去;抽提中加入Vc。将改良CTAB法所提吴茱萸叶DNA与传统的SDS法、CTAB法所提DNA进行比较。利用植物的核糖体DNA（rDNA）保守序列设计引物行PCR扩增鉴定吴茱萸DNA及其质量。并确定提取方法中最佳样本含量和β-巯基乙醇浓度。结果：改良CTAB法提取石虎、疏毛吴茱萸总DNA呈白色,A260/A280为1.721~1.886,DNA分子完整,约20kb左右,PCR扩增条带清晰、明亮,无杂带和脱尾。并确定0.10g为最佳样本量,2.0%为最佳β-ME浓度。结论：石英砂研磨简便、迅速、均匀,该实验所建立的改良CTAB法可有效避免次生代谢物的氧化褐变,是一种小量、快速提取吴茱萸叶DNA优化方法。     

思茅松中幼人工林的生物量碳计量参数

通过开展思茅松中幼人工林样地调查,基于实测数据计算了相关碳计量参数并研究了碳计量参数与相关林分因子的关系.结果表明:1)思茅松中幼人工林生物量转化与扩展因子(BCEF)的平均值为0.5483 Mg·m~(-3)(n=30,95%置信区间:0.5357～0.5609),低于政府间气候变化专门委员会(IPCC)的缺省值.BCEF和平均树高(H)、林分形高(FH)、蓄积量(V)和林龄(A)存在显著负相关(P<0.05).BCEF和平均胸径(D)负相关,但相关不显著(P>0.05).BCEF和N(林分密度)正相关,但相关不显著(P>0.05).BCEF值与林分因子的关系函数拟合效果不佳.2)思茅松中幼人工林生物量扩展因子(BEF)的均值为1.78378(n=30,95%置信区间:1.71714～1.85043),高于IPCC缺省值.BEF和D、H、FH、V和A存在极显著的负相关(P<0.01),与N存在显著的正相关(P<0.05).BEF与A和V的关系以二次曲线函数形式拟合效果较好,与N的关系则以双曲线形式较好,与FH、H和D的关系以幂函数较好.3)思茅松中幼人工林的根茎比(R)均值为0.2400(n=30,95%置信区间:0.2194～0.2606),与IPCC缺省值基本一致.R与D、H、FH、V和A有极显著的负相关关系,与N有显著的正相关关系.R与D、H、FH、V和A的关系以二次曲线的形式拟合效果较好,与N的关系则以双曲线形式拟合较好.     

Influence of inoculation on yield ofAlnus glutinosa in the Netherlands

Summary The occurrence and the infectivity of Frankia, the root-nodule endophyte ofAlnus glutinosa, were studied in different kinds of soil in the Netherlands. Both field and pot experiments indicated that many soils, on which alders have not been grown before, had low numbers of endogenous Frankia or none at all. Inoculation of these soils usually enhanced growth and nodulation of alders.The effect of fertilizer treatments on growth and nodulation ofA. glutinosa were studied in experimental plots. Alders grown in sandy soils, dressed with farmyard manure had the highest yield and the most nodules. The influence of inoculation with homogenates of Sp(+) and Sp(–) nodules and with a pure culture of Frankia AvcIl were studied in pot experiments. The quantity of different kinds of inoculum needed to obtain good growth and nodulation of alder was estimated. The results indicated that addition of a nodule homogenate of 90 g fresh AvcIl Sp(+) nodules is sufficient to inoculate one hectare of nursery soil to produce 10 nodules per plant, while a thousand times larger amount of inoculum is necessary when Sp(–) nodules are used. The limitations and the potentials of using nodule homogenates and pure cultures of Frankia for inoculation in forestry are discussed.     

Kinetics of the light-induced georeactivity of maize roots

Apical root segments of Zea mays L. cv. Orla 264 undergo some geotropic curvature in complete darkness but the curvature increases considerably if prior to geostimulation the segments are given a light pretreatment. If the light treatment is follwed by a dark treatment before the root is geostimulated the light-induced response is not changed by dark periods up to 2 h but declines with longer ones, and disappears completely after 5 h of darkness.     

Regeneration of vascular tissue in wounded pea roots

Severance of the stele of young main roots of pea (Pisum sativum L.) results in formation of a bridge of vascular tissue in the remaining cortex. Cell divisions occur close to the severed vascular tissues on both the proximal and distal sides of the cut within 24 h. Differentiation of new vascular strands subsequently begins in the same locations and progresses from both sides of the wound into the remaining cortex and also back along the original vascular strands. Most of the vascular tissue which forms the bridge through the cortex differentiates in the acropetal direction. Continuous strands composed of single sieve elements bypass the wound somewhat sooner than the first complete xylem strands; the latter in 60–70% of the cases, are present by 3 d. Cambial activity subsequently adds more xylem and phloem. Vascular regeneration is not affected by removal of the epicotyl or the root tip; it is greatly reduced but not prevented by removal of the cotyledons.     

石菖蒲根茎挥发油对稗、鳢肠和水稻的萌发与生长的影响

在实验室和温室条件下,用从石菖蒲根茎中提取的挥发油经减压蒸馏获得的组分四,对稗草、鳢肠和水稻的萌发与生长进行了生物学效应测试。结果表明,在低浓度时促进供试植物的萌发和生长,而在高浓度时则抑制萌发和生长。实验室培养皿条件下,50～400mg／L浓度抑制作用产生并逐渐增加,400mg／L以上达到90％或更高。但是,温室盆钵条件下,3000mg／L时才出现抑制作用,在1000mg／L以下均表现促进作用。