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1.
为探讨江西铅山红芽芋的耐盐机制,以其组培移栽驯化苗为材料,研究了盐胁迫对其生物量积累、光合特性、荧光特性等抗逆生理特性的影响。结果表明:(1)红芽芋幼苗生物量和根冠比在低盐胁迫下(50 mmol·L-1)得到显著促进,而在高盐胁迫下(100~250 mmol·L-1)受到显著抑制。(2)低盐胁迫幼苗的净光合速率(Pn)、气孔导度(Gs)、气孔限制值(Ls)、水分利用效率(WUE)和瞬时羧化效率(CUE)比对照(0 mmol·L-1)显著增加,细胞间CO2浓度(Ci)比对照显著下降,蒸腾速率(Tr)与对照无显著差异;高盐胁迫幼苗的Pn、Ls、WUE、CUE和Gs较对照显著下降,Ci比对照显著增加。(3)低盐胁迫幼苗的最大荧光(Fm)、PSⅡ潜在光化学效率(Fv/F0)和光化学猝灭系数(qP)比对照显著增加,初始荧光(F0)较对照显著下降,PSⅡ最大光化学效率(Fv/Fm)、PSⅡ实际光化学效率(ΦPSⅡ)、开放的PSⅡ反应中心捕获激发能效率(Fv′/Fm′)和非光化学猝灭系数(NPQ)与对照无显著差异;而高盐胁迫幼苗的F0、Fm、Fv/Fm、Fv/F0、ΦPSⅡ、Fv′/Fm′和qP均较对照显著下降,NPQ比对照显著增加。(4)各盐胁迫幼苗叶片的可溶性蛋白含量以及过氧化物酶、超氧化物歧化酶和过氧化氢酶活性与对照相比先升后降,并以低盐下最高;可溶性总糖和脯氨酸含量均比对照显著增加;丙二醛含量和质膜透性相对值在低盐胁迫下无显著变化,而在高盐下显著增加;叶绿素含量和根系活力在低盐胁迫下无显著变化,而在高盐胁迫后开始显著下降。研究发现,江西铅山红芽芋移栽驯化苗的耐盐阈值为 50 mmol·L-1,其能够诱导提高叶片可溶性蛋白含量和主要保护酶活性,稳定质膜透性、叶绿素含量和根系活力,增加PSⅡ潜在光化学效率,提高PSⅡ的电子传递活性,维持PSⅡ实际光化学效率,有效启动非辐射热能量耗散机制来保护了光合机构,最终提高净光合速率,增加生物量。 相似文献
2.
5种沙地灌木对地下水埋深变化的响应 总被引:2,自引:0,他引:2
研究干旱、半干旱区植物功能性状对地形地貌分异引起的地下水埋深变化的响应,对于揭示我国西北地区植物应对地下水埋深增加的维持机制和开展植被生态恢复建设具有重要意义。以海流兔河流域典型草原生境的5种建群灌木沙柳(Salix psammophila)、乌柳(Salix cheilophila)、柠条(Caragana korshinskii)、油蒿(Artemisia ordosica)和杨柴(Hedysarum laeve)为研究对象,认识其在滩地、丘间-丘顶典型分布和地势抬升条件下,沙地灌木生物量分配、根系分布及其对地下水埋深变化的生理响应特征。研究结果表明:(1)沙柳为深根系植物,生理功能的维持不仅依赖浅层土壤水,而且吸取地下水;乌柳、柠条、油蒿和杨柴为浅根系植物,主要水源是浅层土壤水。(2)在滩地共生条件下,沙柳和乌柳黎明前小枝水势(ψpd)、正午小枝水势(ψm)、气孔导度(gs)、最大光化学量子产量(Fv/Fm)、表观量子效率(Φ)、光饱和点净光合速率(Ps)及光补偿点光量子通量密度(Ic)无显著差异;油蒿和杨柴ψm、gs与Fv/Fm存在显著差异。(3)由丘间-丘顶分布引起地下水埋深不同的条件下,丘间和丘顶沙柳ψpd、ψm、Ps和Ic差异显著,乌柳ψpd和gs差异显著,柠条和油蒿仅ψm差异显著,这几种灌木其它生理性状在丘间和丘顶无显著差异。(4)沙柳生理性状与地下水埋深的相关性分析表明,随着地下水埋深的增加,gs和Ps呈降低趋势,Φ呈升高趋势,Ic没有明显变化。综上所述,不同根系分布的灌木,对地下水埋深变化的响应存在明显差异。研究结果可以为干旱生态系统原生植被恢复的地下水资源管理提供参考。 相似文献
3.
植物蒸腾导度是表征土壤-植物-大气连续体(SPAC)中植物-大气间水汽传导过程、反映植物水分调控能力的一类重要变量,常见有冠层导度(Gc)、冠层气孔导度(Gs)与叶片气孔导度(gs),明确三者在反映冠层蒸腾过程时的异同或关联性对于理解植物水分利用机制具有重要意义。本研究基于对黄土高原果园苹果树生长季内树干液流(Js)及环境因子的连续观测,计算了Gc、Gs及脱耦联系数(Ω)等变量,并与短期连续观测的叶片气孔导度(gs)比较,分析了Gc、Gs和gs在反映冠层蒸腾特征方面的异同及其关系。结果表明,日变化过程中Gs、gs呈"单峰"型曲线,而Gc则呈"先增后减,午后抬升"的"双峰"型曲线。gs与Gs存在较紧密的线性关系(R2=0.80),但与Gc的线性关系较弱(R2=0.02)。Gc、Gs均随大气水汽压亏缺(VPD)的变化呈现确定的规律,其中,上边界函数呈递减的对数函数关系,平均值则符合先增后减的Log-Normal函数关系(R2>0.95),拐点对应的VPD值分别为1.33和1.16 kPa。在一日内,Gs对VPD变化的响应过程与gs对VPDL (基于叶片温度计算的水汽压亏缺)变化的响应过程总体一致,其一致性高于Gc对VPD变化的响应。整个生长季(4-10月)中果树的Ω平均值为0.12,随着Ω递减,Gc与Gs的线性相关性愈趋紧密,其斜率呈递增趋势,Gc越来越趋近于Gs。研究结果表明,在北方地区,基于树干液流的监测能较准确的推导整株并估算林分的冠层蒸腾导度。与实测gs的变化过程比较,Gs比Gc具有更高的一致性,Gs可以作为描述苹果树水分利用过程响应大气驱动的更为恰当的变量。 相似文献
4.
为深入了解降水格局改变和氮沉降增加对荒漠草原生态系统碳交换的影响机制,于2017年在宁夏荒漠草原设立了降水量变化(减少50%、减少30%、自然降水量、增加30%以及增加50%)和氮添加(0和5 g m-2 a-1)的野外试验,研究了2019年生长季(5-10月份)净生态系统碳交换(Net ecosystem carbon exchange,NEE)、生态系统呼吸(Ecosystem respiration,ER)和总生态系统生产力(Gross ecosystem productivity,GEP)的时间动态,分析了三者与植被组成以及土壤属性的关系。NEE、ER和GEP日动态和月动态均呈先增加后降低,NEE在整个生长季表现为净生态系统碳吸收。0和5 g m-2 a-1氮添加下,减少降水量显著降低了NEE、ER和GEP (P<0.05),增加30%降水量显著提高了三者(P<0.05)。相同降水量条件下,氮添加不同程度地提高了NEE、ER和GEP,且其效应在增加50%降水量时较为明显。净生态系统碳吸收(-NEE)、ER和GEP与群落生物量、牛枝子(Lespedeza potaninii)以及草木樨状黄芪(Astragalus melilotoides)生物量正相关。三者亦随Patrick丰富度指数和Shannon-Wiener多样性指数的增加而增加。本文结果意味着,减少降水量降低了土壤水分和养分有效性、抑制了植物生长,从而降低了生态系统碳交换。适量增加降水量则可能通过提高土壤含水量、刺激土壤酶活性、调节土壤C : N : P平衡特征等途径,促进了植物生长和物种多样性,从而提高了生态系统碳汇功能;氮添加亦促进了生态系统碳交换,但其与降水的交互作用尚不明显,需通过长期观测进行深入探讨。 相似文献
5.
为研究不同CO2浓度升高和氮肥水平对水稻叶绿素荧光特性的影响,利用由开顶式气室(OTC)组成的CO2浓度自动调控平台开展田间试验。以粳稻9108为试验材料,CO2浓度设置CK(对照,环境大气CO2浓度)、C1(CO2浓度比CK增加160 μmol/mol)和C2(CO2浓度比CK增加200 μmol/mol)3个水平;氮肥设置低氮(N1:10 g/m2)、中氮(N2:20 g/m2)和高氮(N3:30 g/m2)3个水平。结果表明,在低氮条件下,与CK相比,C1处理使拔节期的Fo上升4.8%(P=0.031);C2处理使拔节期的Fo上升6.3%(P=0.015),Fv/Fm下降4.8%(P=0.003),使孕穗期的Fo上升12.7%(P=0.039),Fv/Fo下降18.2%(P=0.039)。在高氮条件下,与CK相比,C2处理使灌浆期的Fm、Fv和Fv/Fm分别下降3.6%(P=0.039)、4.9%(P=0.013)和1.3%(P=0.039)。在中氮条件下,与CK相比,C1和C2处理的影响不明显。在整个生育期内,CO2浓度升高与施氮处理交互作用对水稻叶绿素荧光特性的影响未到达显著水平。研究表明,大气CO2浓度升高使水稻叶片光系统Ⅱ受损,抑制其电子传递能力、电子受体QA氧化还原情况、最大光化学效率和潜在活性,通过适量施氮可以有效地缓解其负面效应。 相似文献
6.
河口感潮沼泽是全球重要的蓝碳生态系统,具有很强的固碳能力。碳收支研究是量化生态系统碳源/汇过程及固碳规模的基础。本研究运用透明箱和不同遮光率布遮盖+红外气体分析仪/气相色谱相结合的方法,模拟不同光照条件,测定闽江河口鳝鱼滩半咸水芦苇沼泽和短叶茳芏沼泽的瞬时净生态系统二氧化碳(CO2)交换量(net ecosystem exchange,NEE)、生态系统呼吸(ecosystem respiration,ER)以及甲烷(CH4)排放通量,并通过对总光合吸收量(gross ecosystem exchange,GEE)与光合有效辐射的拟合以及ER与气温的拟合,外推2个沼泽生态系统CO2气体在月、年尺度上的NEE和ER,评估其年固碳量。2个沼泽生态系统的NEE和ER均具有明显的季节变化,春夏秋季为大气中CO2的汇,而冬季则转化为大气中CO2的源,芦苇沼泽年尺度固碳能力显著高于短叶茳芏沼泽。芦苇沼泽与短叶茳芏沼泽CH4排放通量差异不显著。综合考虑CH4排放,闽江河口鳝鱼滩半咸水芦苇沼泽、短叶茳芏沼泽生态系统年固碳量分别为(5371.52±336.97) g CO2-eq/m2和(2730.32±503.67) g CO2-eq/m2。研究表明:闽江河口半咸水沼泽湿地在年尺度上是一个较强的碳汇,在缓解全球变暖方面发挥着重要的角色。 相似文献
7.
武夷山国家公园不同林地土壤呼吸动态变化及其影响因素 总被引:2,自引:0,他引:2
探明亚热带山岳型国家公园不同林地利用方式下土壤呼吸(Rs)的动态变化规律以及影响因素,对准确评价和预测该区域以国家公园为主体的自然保护地体系的碳收支具有重要的现实意义。以武夷山国家公园为研究对象,利用Li-8100开路式土壤碳通量测定系统对茶园、锥栗(Castanea henryi(Skam) Rehd.et Wils.)林、马尾松(Pinus massoniana Lamb.)林和裸地的土壤呼吸及近地面气温、土壤温度、土壤湿度、土壤养分和土壤微生物碳(MBC)、氮(MBN)进行测定。结果显示:(1)与近地面气温、土壤温度和土壤湿度相同,不同林地的Rs均呈现夏 > 春 > 秋 > 冬的季节动态,Rs的季节均值按大小排序为茶园(3.10 μmol m-2 s-1) > 马尾松(2.96 μmol m-2 s-1) > 锥栗(2.32 μmol m-2 s-1) > 裸地(1.43 μmol m-2 s-1),锥栗和裸地之间、锥栗与马尾松之间均差异显著(P<0.01)。除马尾松林外,其他林地水热因子(近地面气温、土壤温度和土壤湿度)的单因子二次多项式模型对Rs的拟合度最高。水热因子共同建立的复合模型中,土壤温度、湿度的幂-指数模型对茶园Rs的拟合度较高,土壤温度和土壤湿度能够解释Rs变化的80%,马尾松林的Rs较适用于土壤温度、湿度建立的对数函数模型,而三因子线性模型(进入回归法)对锥栗林和裸地的Rs的拟合度最优,R2分别为0.565和0.281。(2)茶园和锥栗林的碳、氮、磷含量均高于马尾松林和裸地,MBN含量茶园 > 马尾松 > 锥栗 > 裸地。茶园的Rs与全磷(TP)、有效磷(AP)、全钾(TK)、速效钾(AK)含量呈极显著(P<0.01)正相关,马尾松林的Rs受TP、TK、AK含量的影响极显著(P<0.01),锥栗林的Rs与TK、AK、MBN含量呈现显著(P<0.05)正相关,裸地的Rs受MBN含量影响较为显著(P<0.05),4种林地土壤呼吸与养分的多元逐步回归方程R2均接近1。综上,茶园和马尾松林土壤呼吸速率较高,且所有林地的土壤呼吸均呈现夏 > 春 > 秋 > 冬的季节动态。温度和湿度与土壤呼吸的相关性强,是水热条件丰富的亚热带山岳地区土壤呼吸季节变化的主导因素,其中武夷山茶园土壤呼吸对水热因子的响应在4种林地中最为敏感。除温度和湿度外,各林地土壤呼吸受P、K元素的影响较大,其中茶园主要受P元素影响,马尾松林地受K元素影响较多。 相似文献
8.
为研究枯落物输入变化对云南松(Pinus yunnanensis)林地CO2释放的影响。本研究于2018年3月至2020年2月,应用枯落物添加和去除实验(DIRT),设置对照(CK)、双倍枯落物(DL)、去除枯落物(NL)、去除有机层和A层(O/A-Less)、去除根系(NR)和无输入(NI)6个处理水平,采用Li-6400便携式光合作用测量仪及TRIME-PICO 64/32土壤温度水分测定仪对不同处理样地每月的CO2通量(Rs)、土壤温度和土壤水分(15cm)进行了测定。结果表明:(1)不同处理样地CO2通量均呈现出明显的月变化,7至8月最高,1至4月最低,平均值表现为Rs (DL)=8.10 μmol m-2 s-1 > Rs (CK)=6.27 μmol m-2 s-1 > Rs (NL)=5.44 μmol m-2 s-1 > Rs (NR)=4.46 μmol m-2 s-1 > Rs (O/A-Less)=3.86 μmol m-2 s-1 > Rs (NI)=2.94 μmol m-2 s-1。(2)与CK相比,DL样地CO2通量升高了29.12%,而去除地上枯落物和地下根系样地CO2通量显著降低,CO2通量平均变幅分别为α(NR)=-28.85%,α(NI)=-53.14%,α(O/A-Less)=-38.46%,α(NL)=-13.29%。(3)不同处理土壤水分和土壤温度均存在显著的月变化(P<0.01),NL和O/A-Less的土壤水分显著低于CK,而其余处理与CK间无显著差异(P>0.05);不同处理间土壤温度表现为NR和NI均显著高于CK,其余处理与CK间无显著差异(P>0.05)。(4)不同处理样地CO2通量与土壤温度呈显著指数相关(P<0.01),与土壤水分在NI和O/A-Less处理中无显著相关(P>0.05);与CK相比,NI、O/A-Less和NL处理的Q10增加,而NR和DL处理的Q10则降低;不同处理林地CO2通量与土壤水热因子双因素模型能更好的解释林地CO2通量的变化。本研究表明枯落物不同处理通过改变土壤碳输入和土壤环境因子从而影响生态系统碳排放,研究结果可为未来气候变化和人为干扰下云南松林的碳循环提供基础数据。 相似文献
9.
We determined the interactive effects of irradiance, elevated CO2 concentration (EC), and temperature in carrot (Daucus carota var. sativus). Plants of the cv. Red Core Chantenay (RCC) were grown in a controlled environmental plant growth room and exposed to 3
levels of photosynthetically active radiation (PAR) (400, 800, 1 200 μmol m−2 s−1), 3 leaf chamber temperatures (15, 20, 30 °C), and 2 external CO2 concentrations (C
a), AC and EC (350 and 750 μmol mol−1, respectively). Rates of net photosynthesis (P
N) and transpiration (E) and stomatal conductance (g
s
) were measured, along with water use efficiency (WUE) and ratio of internal and external CO2 concentrations (C
i/C
a). P
N revealed an interactive effect between PAR and C
a. As PAR increased so did P
N under both C
a regimes. The g
s
showed no interactive effects between the three parameters but had singular effects of temperature and PAR. E was strongly influenced by the combination of PAR and temperature. WUE was interactively affected by all three parameters.
Maximum WUE occurred at 15 °C and 1 200 μmol m−2 s− 1 PAR under EC. The C
i
/C
a
was influenced independently by temperature and C
a. Hence photosynthetic responses are interactively affected by changes in irradiance, external CO2 concentration, and temperature. EC significantly compensates the inhibitory effects of high temperature and irradiance on
P
N and WUE. 相似文献
10.
Six months old in vitro-grown Anoectochilus formosanus plantlets were transferred to ex-vitro acclimation under low irradiance, LI [60 μmol(photon) m−2 s−1], intermediate irradiance, II [180 μmol(photon) m−2 s−1], and high irradiance, HI [300 μmol(photon) m−2 s−1] for 30 d. Imposition of II led to a significant increase of chlorophyll (Chl) b content, rates of net photosynthesis (P
N) and transpiration (E), stomatal conductance (g
s), electron transfer rate (ETR), quantum yield of electron transport from water through photosystem 2 (ΦPS2), and activity of ribulose-1,5-bisphosphate carboxylase/ oxygenase (RuBPCO, EC 4.1.1.39). This indicates that Anoectochilus was better acclimated at II compared to LI treatment. On the other hand, HI acclimation led to a significant reduction of
Chl a and b, P
N, E, g
s, photochemical quenching, dark-adapted quantum efficiency of open PS2 centres (Fv/Fm), probability of an absorbed photon reaching an open PS2 reaction centre (Fv′/Fm′), ETR, ΦPS2, and energy efficiency of CO2 fixation (ΦCO2/ΦPS2). This indicates that HI treatment considerably exceeded the photo-protective capacity and Anoectochilus suffered HI induced damage to the photosynthetic apparatus. Imposition of HI significantly increased the contents of antheraxanthin
and zeaxanthin (ZEA), non-photochemical quenching, and conversion of violaxanthin to ZEA. Thus Anoectochilus modifies its system to dissipate excess excitation energy and to protect the photosynthetic machinery. 相似文献
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Recent advances in the study of Kaposi's sarcoma-associated herpesvirus replication and pathogenesis
It has now been over twenty years since a novel herpesviral genome was identified in Kaposi's sarcoma biopsies. Since then, the cumulative research effort by molecular biologists, virologists, clinicians, and epidemiologists alike has led to the extensive characterization of this tumor virus, Kaposi's sarcoma-associated herpesvirus(KSHV; also known as human herpesvirus 8(HHV-8)), and its associated diseases. Here we review the current knowledge of KSHV biology and pathogenesis, with a particular emphasis on new and exciting advances in the field of epigenetics. We also discuss the development and practicality of various cell culture and animal model systems to study KSHV replication and pathogenesis. 相似文献
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RICHARD E. NORRIS 《Botanical journal of the Linnean Society. Linnean Society of London》1991,106(1):1-40
Comprises species occurring mostly in subtidal habitats in tropical, subtropical and warm-temperate areas of the world. An analysis of the type species, V. spiralis (Sonder) Lamouroux ex J. Agardh, a species from Australia, establishes basic characters for distinguishing species in the genus. These characters are (1) branching patterns of thalli, (2) flat blades that may be spiralled on their axis, (3) width of the blade, (4) primary or secondary derivation of sterile and fertile branchlets and (5) position of sterile and fertile branchlets on the thalli. Application of the latter two characters provides an important basic method for separation of species into three major groups. Osmundaria , a genus known only in southern Australia, was studied in relation to Vidalia , and its separation from the Vidalia assemblage is not accepted. Species of Vidalia therefore are transferred to the older genus name, Osmundaria. Two new species, Osmundaria papenfussii and Osmundaria oliveae are described from Natal. Confusion in the usage of the epithet, Vidalia fimbriala Brown ex Turner has been clarified, and Vidalia gregaria Falkenberg, described as an epiphyte on Osmundaria pro/ifera Lamouroux, is revealed to be young branches of the host, Osmundaria prolifera. 相似文献
17.
JOAN VALUÈS MONTSERRAT TORRELL NÚRIA GARCIA JACAS 《Botanical journal of the Linnean Society. Linnean Society of London》2001,137(4):399-407
Fifteen chromosome counts of six Artemisia taxa and one species of each of the genera Brachanthemum, Hippolytia, Kaschgaria, Lepidolopsis and Turaniphytum are reported from Kazakhstan. Three of them are new reports, two are not consistent with previous counts and the remainder are confirmations of very scarce (one to four) earlier records. All the populations studied have the same basic chromosome number, x = 9, with ploidy levels ranging from 2x to 6x. Some correlations between ploidy level, morphological characters and distribution are noted. 相似文献
18.
肝癌中HBV和HCV基因和抗原的分布及意义 总被引:1,自引:0,他引:1
采用原位分子杂交方法检测HCV
RNA及HBV X基因;采用免疫组织化学方法研究HCV核心抗原,非结构区C33c抗原及HBxAg在肝细胞肝癌中的定位及分布.结果表明(1)HCV
RNA、HBV X基因在肝细胞肝癌组织检出率分别为40%(55/136)和82%(112/136).HCV
RNA定位于癌细胞的胞浆内,阳性细胞呈散在、灶状及弥漫分布三种形式;HBV
X基因在肝癌细胞中的分布呈胞浆型、核型及核浆型,阳性细胞也呈上述三种分布形式;(2)HCV
C33c抗原、核心抗原在肝细胞肝癌中的阳性率为81%(133/164)及86%(141/164).C33c抗原定位于癌细胞及肝细胞的胞浆内;核心抗原既定位于癌细胞核中,又可定位于胞浆中.C33c抗原阳性细胞以灶状分布为主;而核心抗原阳性细 相似文献
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H.-R. GREGORIUS 《Biological journal of the Linnean Society. Linnean Society of London》1984,23(2-3):157-165
For a plant selection model with frequency-independent viabilities, fertilities and selfing rates, it is shown that apart from global fixation, for certain parameter combinations a protected polymorphism and facultative fixation (either allele may become fixed according to initial frequencies) may both occur. Facultative fixation requires different selling rates for the dominant and recessive type. Protection of the polymorphism requires resource allocation for male and female function. In this connection the problem of purely genetically caused population extinction is discussed.
For general frequency dependence and regular segregation, the chances for establishment of a completely recessive gene are compared to those of a completely dominant gene. It is proven that the process of establishment of the recessive gene, despite a fitness advantage, may be considerably endangered by drift effects if random mating prevails. The recessive gene may reach the same effectivity in establishment as a dominant gene, only if the recessive homozygote mates exclusively with its own type during the period of establishment. 相似文献
For general frequency dependence and regular segregation, the chances for establishment of a completely recessive gene are compared to those of a completely dominant gene. It is proven that the process of establishment of the recessive gene, despite a fitness advantage, may be considerably endangered by drift effects if random mating prevails. The recessive gene may reach the same effectivity in establishment as a dominant gene, only if the recessive homozygote mates exclusively with its own type during the period of establishment. 相似文献