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1.
低温对百合鳞茎内源激素含量变化的影响 总被引：3，自引：0，他引：3
以东方百合Siberia和Tiber为试验材料,进行恒温和变温的低温处理,采用高效液相色谱法测定在不同冷藏解除休眠时期赤霉素(GA3)、吲哚乙酸(IAA)、脱落酸(ABA)和玉米素(ZT)4种内源激素含量。结果表明,恒温处理Tiber先解除休眠,同样处理同期种植的百合鳞茎,Tiber比Siberia一般早出苗7 d左右;变温处理比恒温处理ABA含量降低,说明变温处理对百合鳞茎解除休眠有促进作用,可以缩短解除休眠需要的时间,一般变温处理的比恒温处理的早8 d出苗,且变温处理有利于百合生长量的增加,Tiber茎粗和株高分别增加了23.1%、10.1%,同时Siberia分别增加了5.9%和16.6%。变温处理GA3含量Tiber高于恒温处理,Siberia低于恒温处理,品种之间对温度处理的响应有差异。百合鳞茎休眠的解除与IAA/ABA、ZT/ABA、GA3/ABA比值有关,变温Siberia和Tiber的3种比值都在60 d后逐渐升高,说明冷藏60 d可作为鳞茎解除休眠的临界点,为进一步研究百合鳞茎的休眠机理提供了重要线索。 相似文献
2.
干旱是主要的环境胁迫因子之一,对林木影响非常广泛和深刻。我国自20世纪80年代开始,对林木抗旱性及其机理进行了大量的研究,并且取得了一定的研究成果,然而到目前为止,仍然很难定量地证实树木的一些生理参数的一种或任何一种组合可以实质性地改善树木的耐旱行为。水力结构理论形成于20世纪70年代,引入我国仅仅10 a时间。它是指植物在特定的环境条件下,为适应生存竞争的需要所形成的不同的形态结构和水分运输供给策略。从树木水力结构理论的理论基础、主要参数、树木水力结构和木质部空穴与栓塞化的关系,以及关于水力结构的国内外研究现状进行了详细介绍,并且对树木的水力结构与抗旱性的关系进行了探讨,认为树木木质部的空穴与栓塞化在水分亏缺解除以后的恢复能力与树木的抗旱性密切相关,并针对我国的树木水力结构研究现状提出了一些建议。 相似文献
3.
以百合品种“西伯利亚”为材料,研究了低温和赤霉素（GA3）处理对百合鳞茎休眠解除过程中形态和碳水化合物含量的影响,以及不同温度条件下鳞茎不同部位内源GA3含量的变化。结果表明：低温（5℃）和0.15 g·L-1 GA3处理35 d时芽长与鳞茎高比值为67.954%,芽生长点位于鳞茎直立高度约2/3处,解除休眠所需天数最少;鳞茎在0~14 d时淀粉降解最快,第35天时可溶性总糖和还原糖含量最高。低温处理的内层鳞片和芽内源GA3含量变化显著,且温度越低,变化越明显。低温条件下内层鳞片和芽的内源GA3含量较高,上升趋势最为明显;而外层鳞片和根的GA3含量水平较低,变化趋势较小。可见,顶芽和内层鳞片可能为整个鳞茎休眠解除活动的中心。 相似文献
4.
花椒品种抗冻性比较研究 总被引：8，自引：1，他引：7
秦安1号、油椒和大红袍是甘肃省花椒主产区的主要栽培品种。对其一年生休眠枝在不同低温（0～-40℃）处理不同时间（24～72 h）,通过测定相对电导率、超氧物岐化酶（SOD）活性和丙二醛（MDA）含量,对花椒品种休眠枝的抗冻性进行了比较研究。结果表明,各品种休眠枝的相对电导率和MDA含量从低到高均依次为:秦安1号＜油椒＜大红袍,品种间差异性均达到显著水平（P＜0.05）;SOD活性秦安1号略高于油椒,二者差异性虽未达到显著水平,但均显著高于大红袍（P＜0.01）;相同温度下,3品种休眠枝的相对电导率、MDA含量均随低温持续时间的延长而升高,大红袍休眠枝上升更加明显。SOD活性均随处理时间的延长而降低。引起各花椒品种休眠枝低温伤害的临界温度范围为-15～-20℃。从相对电导率、MDA含量和SOD活性的变化综合分析,供试的3个花椒品种中,秦安1号的抗冻性最强,油椒次之,大红袍抗冻性最弱。 相似文献
5.
韩国的乡村林木处于偏远村庄附近,单独的树木或一片树林,往往构成风水因素。乡村林木也有野生动物生境的功能,有益于农业生物多样性。本文中,乡村林木分为4种类型(天然林、半天然林、半人工林、人工林)23个主要树种(优势种或次优势种)。赤松(Pinus densiflora)在50个地点是优势种,光叶榉(Zelkova serrata)在45个地点为优势种。乡村林木立地植物共分125科、519属、1081种。尽管乡村林木占地面积极小,占100 000 km2韩国国土面积的0.00278%,但这种生态系统具有重要的生物多样性和生境保护功能。乡村林木不仅是保育生物多样性的一个基础,还能为韩国提供生态系统服务。 相似文献
6.
广州华侨新村低密度住宅区庭院的树木和景观研究* 总被引：1，自引：0，他引：1
对广州华侨新村低密度住宅区庭院树木的组成、结构、空间格局、树木与生境的关系,以及私人庭院树木与公共绿地的不同特点进行了研究。结果表明:华侨新村庭院树木的种类多样性很高,共有114个树种。与广州城市行道树相比,华侨新村的乡土树种和果树比例较高。在调查的树木中84.75%的树木没有结构损伤现象,只有1.5%的树木生长较差。私人庭院内的树种较为分散,有45种树木为每个庭院仅一棵的单生种,有67.1%的庭院其树种在5种或以上。树木在街道的空间分布则有相对集中的趋势。庭院的大小是影响树木生长的重要条件,在有限空间的庭院内种植过多的树木是造成树木和环境关系紧张的重要原因。 相似文献
7.
本文分析了西格陵兰Disko湾的表层沉积物硅藻,发现并统计了分属于39个属的78个硅藻种及其变种。应用对应分析方法,对Disko湾表层沉积硅藻组合进行了分类:组合Ⅰ为Fragilariopsis cylindrus-Fragilariopsis oceanica组合,主要分布在西格陵兰Disko湾南部的近岸和外海处;组合Ⅱ为Detonula confervaceae休眠孢子-Thalassiosira nordenskioeldii组合,都分布在Dis-ko湾北部海域。其中,根据海流等环境要素的不同,组合Ⅰ又可进一步划分为两个亚区:组合Ⅰa为F.cylindrus-F.oceanica-Pauliella taeniata组合,主要分布于沿岸海区;组合Ⅰb为F.cy-lindrus-F.oceanica-Thalassiosira antarcticavar.borealis休眠孢子-Thalassiosiracf.antarcticavar.borealis组合,分布于外海区域。 相似文献
8.
中国区域经济发展收敛的空间计量分析 总被引：13，自引：2，他引：11
通过空间计量经济学经济收敛标准分析方法的扩展,就中国240 个地级及以上城市的经济增长收敛性展开讨论。运用Moran's I 探讨中国区域经济空间相关模式与集聚,发现1990-2007 年间人均GDP水平显示出强烈的全局正自相关,且局部空间结构相对稳定,各城市要脱离原来的集群有一定困难。文章指出收敛标准分析存在错误方程设定,空间计量分析方法是合适的。空间计量分析结果表明中国城市间存在绝对β收敛,与非空间模型相比收敛速度显著提高且可信,空间因素在区域经济增长与收敛过程中起到重要作用。但敏感性分析显示,绝对收敛的同一稳态以及在空间上并不稳健。从机制看,中国城市间同时存在新古典增长理论和新增长理论所强调的趋同机制。最后,对促进绝对收敛的区域政策进行了讨论,并提出通过模拟经济收敛过程,是判断区域政策有效性的重要工具。 相似文献
9.
超富集植物蜈蚣草在中国的地理分布及其生境特征 总被引：7，自引：0，他引：7
根据本研究小组多年来对我国南部近20个省、市(区)的调查,结合前人的文献资料,编制了蜈蚣草在中国的分布图,总结了蜈蚣草对日照、水分、热量和土壤等因素的生态适宜性。研究发现,蜈蚣草在中国主要分布在秦岭以南的热带、亚热带地区。蜈蚣草生长需要的水热条件为:年均温高于10℃、1月均温大于0℃、7月均温大于20℃、≥10℃积温超过3800℃、无霜期不短于200天和年降水量大于500 mm。冬季的低温(1月均温和无霜期)可能是蜈蚣草进一步向高纬度分布的主要限制性因素。蜈蚣草对土壤pH的适应范围较宽。本研究结果为蜈蚣草的引种及其在植物修复中的潜在应用价值的确定提供了科学依据。 相似文献
10.
《中国沙漠》2016,(3)
种子萌发特性是荒漠植物适应干旱的重要策略。红砂(Reaumuria soongarica)是典型耐旱植物,但目前缺乏从群体角度探讨其种子萌发特性和其局部适应性关系的报导。在25、4、-20、-40℃下,分别对来自于甘肃、宁夏和新疆的17个地区红砂种子进行发芽试验,检测不同群体在萌发时间、萌发率和发芽势上的差异,并用world-clim的气象数据分别对不同群体的萌发率和发芽势进行了相关性分析。结果表明:低温贮藏会削弱红砂种子的休眠、缩短红砂种子的初始萌发时间和萌发持续时间。经不同温度贮藏,红砂种子萌发率的变化不显著,其变化主要来自于不同群体间的差异,而且萌发率与其生存环境的温度和降水量显著相关。红砂种子的发芽势在-40℃温度贮藏后显著提升,呈现爆发型萌发,说明超低温储藏能极大消除红砂种子的生理休眠。此外,红砂种子的发芽势和环境温度显著相关。红砂种子的萌发特性表现出其对干旱生境的局部适应性,这一结果有助于深入理解荒漠植物对干旱环境的生态适应性机理,并为红砂在荒漠植被恢复中的推广提供理论和数据支撑。 相似文献
11.
厘清驱动植物物候变化的气候因子对评估全球变化对生态系统的影响具有重要意义。针对欧洲与北美地区木本植物的控制实验表明春季物候变化主要受冷激、驱动温度和光周期影响,但这3个气候因子是否对东亚地区木本植物的春季物候存在相似的作用仍需验证。论文选取了5种典型木本植物(迎春Jasminum nudiflorum、连翘Forsythia suspensa、荚蒾Viburnum dilatatum、玉兰Yulania denudata与东京樱花Cerasus yedoensis),利用生长箱对冬季休眠枝条的展叶过程开展了控制实验。实验设置了3种驱动温度(12 ℃、15 ℃、18 ℃)、3种冷激(3 d、38 d、59 d)以及2种光周期(10 h、14 h)处理,并利用分层贝叶斯模型建立了展叶始期与各影响因子间的关系。结果表明,驱动温度每升高1 ℃导致展叶始期提前2.6 ~ 9.0 d,但展叶始期的温度敏感度随温度和冷激天数的增加而减弱。冷激也是影响木本植物展叶始期的重要因子。与冷激处理3 d相比,冷激处理59 d使展叶始期提前20.3 ~ 66.6 d,但随冷激天数增加,展叶始期对冷激响应的敏感度减弱。光周期延长对展叶始期具有提前效应,但总体小于驱动温度与冷激的影响。光周期由10 h延长至14 h后,展叶始期提前0.3 ~ 12.9 d,且在低冷激处理时光周期的效应更明显。这些结果为理解近几十年来春季物候变化及其对增温的响应提供了科学依据。 相似文献
12.
Timothy L. Cook Raymond S. Bradley Joseph S. Stoner Pierre Francus 《Journal of Paleolimnology》2009,41(1):77-94
Sediments in Lower Murray Lake, northern Ellesmere Island, Nunavut Canada (81°21′ N, 69°32′ W) contain annual laminations
(varves) that provide a record of sediment accumulation through the past 5000+ years. Annual mass accumulation was estimated
based on measurements of varve thickness and sediment bulk density. Comparison of Lower Murray Lake mass accumulation with
instrumental climate data, long-term records of climatic forcing mechanisms and other regional paleoclimate records suggests
that lake sedimentation is positively correlated with regional melt season temperatures driven by radiative forcing. The temperature
reconstruction suggests that recent temperatures are ~2.6°C higher than minimum temperatures observed during the Little Ice
Age, maximum temperatures during the past 5200 years exceeded modern values by ~0.6°C, and that minimum temperatures observed
approximately 2900 varve years BC were ~3.5°C colder than recent conditions. Recent temperatures were the warmest since the
fourteenth century, but similar conditions existed intermittently during the period spanning ~4000–1000 varve years ago. A
highly stable pattern of sedimentation throughout the period of record supports the use of annual mass accumulation in Lower
Murray Lake as a reliable proxy indicator of local climatic conditions in the past.
相似文献
| Pierre FrancusEmail: |
13.
东北地区水稻延迟型冷害时空特征及其与气候变暖的关系 总被引：3，自引：0，他引：3
利用水稻延迟型冷害分级指标和1951-2010 年东北地区101 个气象台站的逐日气温资料,采用累计距平、相关系数、气候倾向率、趋势系数等方法分析东北地区水稻延迟型冷害时空变化特征及其对气候变化的响应。结果表明：蒙东地区西部、吉林东部和黑龙江交界延迟型冷害出现的频率较大,辽宁中南部延迟型冷害出现的频率较小。东北地区严重冷害出现频率高于轻度冷害和中度冷害。轻度、中度、严重延迟型冷害都呈下降的趋势,特别在1994 年后延迟型冷害呈快速下降的趋势,东北地区水稻延迟型冷害与气候变暖有着较好的对应关系,5-9 月平均气温和延迟型冷害呈明显反相关,5-9 月平均气温升高1℃,水稻延迟型冷害减少约45次。 相似文献
14.
1963—2018年中国垂柳和榆树开花始期积温需求的时空变化 总被引：1，自引：0，他引：1
积温需求是决定北半球温带地区木本植物开花时间的主要因子。全球变暖使植物在冬季受到的冷激量减少,可能会改变植物开花的积温需求。气候变化导致的中国木本植物开花始期积温需求的时空变化仍不清楚。有鉴于此,本文基于“中国物候观测网”1963—2018年垂柳（Salix babylonica）和榆树（Ulmus pumila）开花始期数据,利用3种积温算法（GDD、GDDS和GDH）系统分析了两种植物开花积温需求的空间格局和在代表性站点的年际变化,构建了基于冷激日数模拟积温需求的模型。主要结论为：垂柳和榆树开花始期的积温需求在低纬度地区大于中纬度地区。站点多年平均积温需求与冷激日数呈显著的负指数关系,即随冷激日数增加,积温需求降低。时间上,3个典型站点（贵阳、西安和牡丹江）垂柳开花积温需求的变化趋势分别达到1.28~1.41 °C·d/a（P < 0.01）、1.63~1.89 °C·d/a（P < 0.01）和0.12~0.58 °C·d/a（仅GDD算法P < 0.05）,榆树开花的积温需求在贵阳和西安同样显著增加,但在牡丹江变化不显著。冷激日数随时间减少是两个站点积温需求显著增加的主要原因。因牡丹江冬季气温低,冷激日数多且年际变化小,冷激对积温需求变化的影响不显著。基于时空耦合样本建立的冷激日数—积温需求模型对垂柳开花积温需求的模拟效果较好,R2达0.54~0.66。对榆树开花积温需求的模拟效果稍差（R2为0.33~0.64）。就不同算法而言,冷激日数对GDD算法得到的积温需求模拟效果更好。本文为量化植物开花积温需求的时空变化及在气候变化背景下的花期预测提供了重要的科学依据。 相似文献
15.
The purpose of our study was to better understand seed germination ecology of the spring annual short-lived Olimarabidopsis pumila, which grows in the Gurbantonggut Desert, China. Seeds underwent after-ripening at 4, 20 ± 2 (room temperature) and 30 °C. After dormancy was broken, germination capacity was a function of temperature and presence of light. For the temperature range studied (4–30 °C), germination capacity was significantly higher between 15 and 25 °C than at temperatures above or below them. Alternating temperatures of 20/10, 25/10 and 25/15 °C were favorable for germination. Although GA3 did promote dark germination of seeds, GA3 did not replace light for germination. Seeds germinated to >75% if light exposure time was over 8 h and temperature and moisture conditions were favorable. Seeds were able to germinate at relatively low water potentials (83% at ?0.41 MPa), but decreasing water potentials produced detrimental effects on germination percentage and rate. Thus, dormancy characteristics and germination behavior of O. pumila seeds ensure that germination occurs in the desert only when soil moisture conditions are favorable for seedling establishment and survival. 相似文献
16.
Mingjun Zhang Lei Dong Shengjie Wang Aifang Zhao Fang Qiang Meiping Sun Qiong Wang 《地理学报(英文版)》2014,24(5):833-844
Based on the radiosonde data observed at 14 stations in Southwest China from 1960 to 2010, as well as the corresponding surface air temperature, the long-term change of free-air 0℃ isotherm height in Southwest China and the relationships between surface air temperature and 0℃ isotherm height are discussed. The results indicated that the spatial distribution of 0℃ isotherm height is generally related with latitude, but the huge massif or plateau may complicate the latitude pattern. The two main regimes influencing the spatial patterns of 0℃ isotherm height in Southwest China are latitude and huge massif. The annual 0℃ isotherm height has increased by 35 m per decade in the recent decades, which is statistically significant at the 0.001 level. Generally, the increasing trend can be examined for each seasonal series, especially in winter （53 m per decade）. The diversity of trend magnitudes for annual and seasonal series can also be detected at a spatial view, but generally 0℃ isotherm height correlated well with surface air temperature. 相似文献
17.
Gufu Oba Inger Nordal Nils C. Stenseth Jrn Stave Charlotte S. Bjor Josphat K. Muthondeki William K. A. Bii 《Journal of Arid Environments》2001,47(4):499
In the arid zone of central Turkana, north-western Kenya, where soil salinity affects 15–20% of the rangelands, growth performances of trees planted in saline soil rehabilitation trials have not been evaluated. Tree-planting trials have emphasised exotic species over indigenous ones. However, advantages and disadvantages of promoting exotic tree species have not been examined. The current study was aimed at evaluating growth performance of seven exotic and nine indigenous tree species used in saline soil rehabilitation trials. The tree species were established from 6-month-old saplings using microcatchments (FT1) from 1988 through 1990 and pitting treatment (FT2) from 1989 through 1992. The soils in FT1 and FT2 treatments were moderately to highly saline. The exotic tree species produced greater cover and volume during the first year (FT1) but by the second year, production was not sustained due to greater mortality (FT1 & FT2). The indigenous species in general had higher survival rates. Relative growth rates (RGR) of exotic and indigenous species did not differ (FT1 & FT2). Tree mortality was negatively correlated with RGR for exotic species in FT1 but not for indigenous ones. However, changes in plant performance were not in response to salinity alone. Rather, water scarcity superimposed on soil salinity might have influenced plant growth performance. Greater water and salinity stress and subsequently greater mortality in exotic species provided a more convincing reason for promotion of indigenous tree species. In the future, knowledge of salinity distribution and selection of indigenous species to match this will be a better way of rehabilitating sites affected by soil salinity in the arid zone of central Turkana, north-western Kenya. 相似文献
18.
In this study, the spatial distribution and changing trends of agricultural heat and precipitation resources in Northeast China were analyzed to explore the impacts of future climate changes on agroclimatic resources in the region. This research is based on the output meteorological data from the regional climate model system for Northeast China from 2005 to 2099, under low and high radiative forcing scenarios RCP4.5 (low emission scenario) and RCP8.5 (high emission scenario) as proposed in IPCC AR5. Model outputs under the baseline scenario, and RCP4.5 and RCP8.5 scenarios were assimilated with observed data from 91 meteorological stations in Northeast China from 1961 to 2010 to perform the analyses. The results indicate that: (1) The spatial distribution of temperature decreases from south to north, and the temperature is projected to increase in all regions, especially under a high emission scenario. The average annual temperature under the baseline scenario is 7.70°C, and the average annual temperatures under RCP4.5 and RCP8.5 are 9.67°C and 10.66°C, respectively. Other agricultural heat resources change in accordance with temperature changes. Specifically, the first day with temperatures ≥10°C arrives 3 to 4 d earlier, the first frost date is delayed by 2 to 6 d, and the duration of the growing season is lengthened by 4 to 10 d, and the accumulated temperature increases by 400 to 700°C·d. Water resources exhibit slight but not significant increases. (2) While the historical temperature increase rate is 0.35°C/10a, the rate of future temperature increase is the highest under the RCP8.5 scenario at 0.48°C/10a, compared to 0.19°C/10a under the RCP4.5 scenario. In the later part of this century, the trend of temperature increase is significantly faster under the RCP8.5 scenario than under the RCP4.5 scenario, with faster increases in the northern region. Other agricultural heat resources exhibit similar trends as temperature, but with different specific spatial distributions. Precipitation in the growing season generally shows an increasing but insignificant trend in the future, with relatively large yearly fluctuations. Precipitation in the eastern region is projected to increase, while a decrease is expected in the western region. The future climate in Northeast China will change towards higher temperature and humidity. The heat resource will increase globally, however its disparity with the change in precipitation may negatively affect agricultural activities. 相似文献
19.
R.G.W. Ward 《Applied geography (Sevenoaks, England)》1984,4(2):109-133
The paper presents a method for predicting avalanche activity from meteorological data which is suitable for Scottish snow conditions. Two main types of avalanche are distinguished. Direct-action avalanches are the result of fresh snow accumulation and may release after approximately 200 mm of fresh snow has fallen over a period of a few days. They become extremely likely if a further 100 mm falls in a single day. Climax avalanches are the result of strength loss in the snow cover, due either to thawing or persistent cold. Thaws may produce an avalanche after only three or four days with maximum temperatures around 2°C. Alternatively, if maximum temperatures remain below ?4°C for over a week, and especially if cold weather persists for two weeks, slab avalanches of dry snow are likely to occur. Between these two types are several possible avalanche situations in which fresh snow accumulation is combined with high or low temperatures. Topography plays a passive role, and determines where avalanche activity is most likely. Free faces, smooth surfaces and slopes in the lee of major storms respond most rapidly to the onset of avalanche conditions. 相似文献
20.
Land surface temperature (LST) variability results from diversity in urban surface materials over space and time such that locations with impervious urban cover experience higher temperature and larger temperature variation compared to non-impervious cover. There is growing awareness that warmer temperatures in urban locations negatively impact city residents by increasing heat related death and energy usage during heat waves. However, little previous work investigates the linkages between urban tree cover loss events related to invasive species eradication and urban heat trends. This paper examines the variation in LST using Landsat-5 Thematic Mapper (TM) thermal imagery in Worcester County, Massachusetts where over 30,000 trees were removed since 2008 to eradicate the invasive Asian Longhorned Beetle (ALB), most of which existed in urban residential areas. Throughout the study area a 10% loss in tree canopy cover caused a 0.7 °C increase in LST whereas a 10% increase in sub-canopy impervious surface area exposed due to tree loss caused 1.66 °C increase in LST. The Burncoat and Greendale neighborhoods in northern Worcester experienced a combined 48% tree cover loss from 2008 to 2010 due to ALB eradication and an average relative LST increase of 2.4 °C (range 0.6–4.1 °C). Given that areas with an increase in exposed impervious surface produce greater temperature increases than areas of tree loss, future tree replanting efforts may focus on locations that reduce exposed impervious surfaces. 相似文献