短期增强UV-B辐射对青榨槭幼苗生理特性的影响

在中国科学院茂县生态站选择2年生青榨槭幼苗进行室外盆栽实验,以人工增强0.27 W·m^-2(7.7kJ·m^-2·d^-1)的UV-B辐射剂量,研究模拟当地平流层臭氧削减1%时近地面太阳UV-B的增强对木本植物幼苗生理生态适应性的影响.处理0 d后,移除UV-B处理装置,就地测定气体交换参数和叶绿素荧光参数,并取样测定叶绿素及UV吸收物质含量.结果表明,增强UV-B辐射显著降低了青榨槭幼苗叶片最大净光合速率P_max(对照为6.214,处理为4.42),显著增加叶片暗呼吸速率Rd(对照为0.413,处理为1.29)和光补偿点LCP(对照为21.629,处理为9.861),但对表观量子速率a(对照为0.021,处理为0.032)影响不明显;它降低青榨槭幼苗每日净光合速率和水分利用效率,以及原初光化学效率(F_v/F_m)和实际光化学量子产量(ΦPS∏).此外,增强UV-B辐射使叶片叶绿素a、b含量降低(对照为16.23,.39,处理为13.17,4.93),但对叶绿素b含量影响未达显著水平.增强UV-B处理降低了青榨槭幼苗UV吸收物质含量(对照为0.87,处理为0.79).光合指标、叶绿素荧光指标和叶绿素含量的变化有较好的一致性,表明增强UV-B对青榨槭幼苗的光合作用可能有一定的抑制作用.     

UV-B辐射胁迫对杨桐幼苗生长及光合生理的影响

通过对UV-B辐射胁迫下亚热带典型木本杨桐幼苗的生长及光合生理的研究,探讨植物对于UV-B辐射胁迫的生理响应及适应性机理,进而揭示UV-B辐射变化对亚热带森林树种的影响.实验设置UV-B辐射滤光组、自然光对照组以及辐射增强组,选择亚热带典型树种杨桐(Cleyera japonica Thunb.)幼苗为实验材料.研究结果表明:(1)增强UV-B辐射会降低杨桐幼苗的叶绿素含量,而降低辐射则会显著促进叶绿素的增加,且这种胁迫在时间上具有积累性.(2)增强或降低辐射强度都会抑制杨桐地径的生长,增强辐射会产生更显著的抑制;降低辐射强度会对杨桐幼苗的株高生长产生促进作用,反之,则会抑制其生长.3个测定期数据综合分析显示随着处理时间的加长,这种胁迫作用有减小的趋势.(3)对光响应曲线的分析表明相对于自然光条件下的UV-B辐射,降低其强度对杨桐幼苗光合作用有显著的促进作用,反之则会抑制,不过抑制作用并不显著;对于光合特征参数的分析表明增强或降低UV-B辐射会显著降低杨桐幼苗的光饱和点(LSP)和光补偿点(LcP),而对最大净光合速率(Amax)、表观光合量子效率(AQY)、暗呼吸速率(Rd)影响均不显著,表明辐射胁迫对杨桐幼苗利用光能的效率影响不大,从而也并未对杨桐的光合作用产生显著性的伤害,但是由于森林树种的多年生特性,这种影响将是积累性的或延迟的,UV-B所造成的光合作用或光能利用率的微小变化都可能会积累成长期影响.因此,对森林树种进行长期研究是必要的.     

UV-B辐射增强对马铃薯叶片结构及光合参数的影响

叶片作为植物进行光合作用的主要器官,在长期进化过程中形成了对不同光照环境条件的形态可塑性和相应的适应机制,以保证植物能在变化的、非适宜环境下的生存与繁衍。随着大气臭氧层衰减引起地表UV-B辐射增强,其对植物叶片结构和光合作用的影响显著,但这种气候变化趋势对马铃薯叶片形态结构、光合作用的影响尚不明确。设置增强UV-B辐射2.5 kJm~(-2)d~(-1)(T1)、5.0 kJm~(-2)d~(-1)(T2)、自然光(CK)3个处理,以6个马铃薯品种(系)为材料,研究增强辐射对不同基因型马铃薯叶片结构和光合参数的影响。结果表明:增强的UV-B辐射使马铃薯叶片解剖结构不同程度增厚,叶片厚度增加;叶片气孔和非腺毛的密度增加明显,腺毛有增多倾向。扫描电镜显示处理后的近轴面叶片角质层厚度增加,蜡质晶体增多,但表皮细胞变小且失水萎缩,细胞轮廓模糊;气孔、腺毛及非腺毛附属结构受胁迫影响呈萎缩状态。透射电镜显示处理后的叶肉细胞中基粒类囊体肿胀,结构层次紊乱,胁迫引起细胞质壁分离,细胞壁扭曲并有较多的沉淀物;部分品种过氧化物酶体可见清晰的过氧化氢酶晶体。叶片缩小增厚、腺毛增多、角质层和蜡质增厚、胞内积累过氧化氢酶的形态适应和生理响应并未能有效减少UV-B辐射对光合参数和光合效率的影响,合作88、丽薯6号、师大6号的净光合速率、气孔导度等参数均受到抑制,光能利用效率明显降低,属于UV-B辐射敏感型品种;剑川红21-3、21-1和转心乌3个品种(系)的相关光合特性几乎不受影响,显示云南地方品种具有较强的UV-B辐射耐受性,有待于进一步从生理生化和分子水平探究更多的适应机制。     

不同剂量UV-B辐射对冬小麦幼苗形态及生理指标的影响

UV-B辐射增强对植物的影响效果存在差异,即使是同一物种的不同品种之间也存在差异。本研究以对UV-B不同耐性的2个冬小麦品种科遗26和泰山269为材料,比较了品种间及UV-B的剂量间的形态指标、生物量及生理指标的差异。结果表明:高剂量UV-B处理抑制了株高、叶色、茎数、鲜质量、光反应系统Ⅱ(PSⅡ)最大光化学效率(Fv/Fm)和光合速率,促进了丙二醛、类黄酮含量的增加及相对电导率的提高,2个品种的趋势基本相同,但泰山269的变化幅度大于科遗26,说明泰山269比科遗26敏感;低剂量的UV-B对株高、叶色、茎数、鲜质量表现出促进的趋势,对类黄酮的促进作用较大,对Fv/Fm、丙二醛及相对电导率的影响相对较小。     

陆生植物体内酶系统对UV-B辐射增强的响应

臭氧层减薄导致地表中波紫外线UV-B(280～320 nm)辐射的增强,UV-B辐射能量远高于可见光,且能被植物体内蛋白质和核酸等生物大分子吸收.酶是植物体内起催化作用的一类蛋白质,酶的数量和活性对UV-B辐射增强有强烈的响应.本文将近年来增强UV-B辐射对植物体内酶影响的研究工作进行了综述.主要包括抗氧化酶、核酮糖-1,5-二磷酸羧化酶、硝酸还原酶和谷氨酰胺合成酶.并就今后该方面的研究提出建议.     

不同灌水量下限对高羊茅绿期及抗寒性生理指标的影响

采用盆栽试验的方法,研究了秋末冬初不同灌水量下限\[分别占田间持水量(FC)的80%、70%、60%、50%\]对高羊茅绿期及抗寒性生理指标的影响.结果表明：在冬季低温条件下,80%和70%FC灌水处理使高羊茅叶片相对含水量、保护酶(SOD、POD和CAT)活性、叶绿素、可溶性糖和游离脯氨酸含量维持在较高水平,丙二醛含量和电解质外渗率降低,高羊茅的抗寒性增强.80%FC灌水处理分别较70%、60%和50%FC处理的草坪草绿期延长4、22和28 d,到达枯黄休眠的时间最晚,完成返青的时间最早.综合考虑节水和提高水分利用效率等多种因素,70%FC灌水处理为高羊茅秋末冬初季节最佳的灌水下限.     

不同小麦品种对UV-B辐射增强响应的生理特性差异

研究了大田条件下模拟增强UV-B辐射（500 KJ·m^-2,相当于昆明地区臭氧层减少20%）对10个小麦品种生理指标的影响以及小麦对UV B辐射响应的种内差异.结果表明,10个供试小麦品种中有6个品种的叶绿素含量显著下降,叶绿素a降低的程度大于叶绿素b,从而导致叶绿素a/b的比率下降.UV-B对小麦叶片内MDA和类黄酮的影响也具有种内差异,有5个品种的MDA含量显著上升, 2个品种的MDA含量显著下降;4个品种的类黄酮含量显著增加,2个品种的类黄酮含量显著减少.叶绿素和类黄酮含量变化与MDA含量均呈显著负相关关系,类黄酮与小麦UV-B抗性之间存在密切联系.     

UV-B辐射增强对芦苇光合生理及叶绿体超微结构的影响

在UV-B辐照增强条件下,研究不同辐照梯度对芦苇光合特性、光合色素含量及叶绿体超微结构的影响. 结果表明: 与自然光照相比,UV-B辐照增强显著降低芦苇叶片净光合速率、气孔导度、蒸腾速率,且随辐照强度增大,降低程度加剧,胞间CO₂浓度升高,光合效率显著降低;与自然光照相比,UV-B辐照增强显著降低芦苇叶片光合色素含量(包括叶绿素a、叶绿素b、总叶绿素和类胡萝卜素),且随辐照强度增大,降低程度加剧;UV-B辐射增强条件下,叶绿体超微结构遭到破坏,表现为叶绿体结构变形,类囊体片层排列稀疏紊乱、膨胀甚至模糊不清,并且UV-B辐射强度越大,损伤越大,高强度UV-B辐射对叶绿体超微结构的影响大于低强度辐射.     

多蒴灰藓对强紫外线照射的生理响应

将多蒴灰藓(Hypnum fertile)置于紫外辐射下照光3周,研究了紫外辐射对多蒴灰藓的损害及其生理响应。结果表明： 与对照(自然环境)相比,多蒴灰藓的叶绿素和类胡萝卜素含量均随紫外辐射时间的延长而减少,MDA含量却明显增加,SOD、POD和CAT活性也相应增加;增加紫外辐射量会引起多蒴灰藓的氧化胁迫,其能通过增加抗氧化酶的活性来减轻这种胁迫。     

Combined effects of enhanced UV-B radiation and nitrogen deficiency on the growth,composition and photosynthesis of rye (Secale cereale)

The interactive effects of N-deficiency and enhanced UV-B radiation on growth, photosynthesis and pigmentation of rye were studied. The plants were grown for 5 weeks in growth chambers with high (700 mol m^-2 s^-2) irradiance levels. A 30% difference in UV-B at plant level was achieved by using different thicknesses of UV-B transparent Plexiglass. One half of the plants received optimal N nutrition, while the other received half of this dose. Both enhanced UV-B and N deficiency strongly decreased production (from 24–33%). The combined effect was additive (no interaction) on most parameters, including total dry weight production which was 52% lower than in the control series. Significant interaction was found on the root/shoot ratio. While reduced N supply induced an increase in the ratio at normal UV-B irradiation, under the increased UV-B, N deficiency had no effect on the root/shoot ratio. The reduced biomass due to UV-B was clearly correlated to a reduction in photosynthesis. At optimal N supply the plants increased the production of protective pigments in response to UV-B, but at reduced N supply this response was lacking. The increased N content of the high UV-B/high N plants could be a result of increased flavonoid production as well as changes in light penetration in the canopy.     

Effects of UV-B radiation on photosynthetic reactions in Rhizophora apiculata

Influences of UV-B radiation on Rhizophora apiculata were studied in terms of chlorophylls, their presence in protein complexes of the chloroplast, PS I and PS II photochemical activities, in vitro absorption spectrum of the chloroplast, in vivo leaf fluorescence and UV absorbing compounds. The seedlings were exposed to the various levels of UV-B radiations, equivalent to 0 (control), 10, 20, 30 and 40% stratospheric ozone depletion of the study area. The low doses of UV-B (10 and 20%) increased the reaction centre chlorophyll (10 and 8%) and activities of PS-I (98 and 39%) and PS-II (77 and 38%) respectively; whereas, 30 and 40% UV-B treatments decreased the reaction centre chlorophylls by 11 and 33% and PS II activity by 0 and 20%; while PS I activity did not show any inhibitory effect. Chloroplasts isolated from control and 10% UV-B treated plants exhibited the same level of absorption at 676 nm. In vivo leaf fluorescence was found to be diminished with UV-B radiation and at the 10% UV-B, variable fluorescence was promoted significantly by 10%. The content of UV-absorbing compounds was progressively enhanced with doses of UV-B radiation along with higher absorption at 276 and 330 nm.     

水分胁迫对长期UV—B辐射下柚树苗生理特性的影响

水分胁迫下,柚[Citrus maxima(Burm.)Merr.]树苗叶片相对含水量（RWC）、水势（ΨW)、净光合速率（Pn)、可溶性蛋白质和叶绿素（Chl)含量下降,丙二醛（MDA）、脯氨酸（Pro)含量和超氧化物歧化酶（SOD）活性升高,过氧化氢酶（CAT）活性先上升后下降,抗坏血酸过氧化物酶（APX）活性、抗坏血酸（AsA)和还原型谷胱甘肽（GSH）含量明显降低。叶绿素荧光参数中光系统Ⅱ光化学原初效率（Fv/Fm)、光系统Ⅱ电子传递量子效率（ΦPSⅡ）和光化学猝灭（qp)下降,非光化学猝灭（qN)和热能耗散系数（KD）升高。显示膜系统和PSⅡ是水分胁迫的主要抑制位点。抗旱性强的品种具有较高的活性氧清除能力。长期紫外线－B（UV－B）增强辐射能缓解水分胁迫下柚树苗叶片RWC、ΨW、APX活性和GSH、AsA含量下降,但对水分胁迫下的Pro含量、Pn和叶绿素荧光特性作用不明显。初步推测：UV－B和水分胁迫对植物有部分相同的作用机制,都导致植株膜脂过氧化程度加剧和PSⅡ的失活,同时存在各自作用方式的特异性。     

The effects of enhanced UV-B radiation on physiological activity and growth of Norway spruce planted outdoors over 5 years

The responses of Norway spruce [Picea abies (L.) Karst.] to enhanced UV-B radiation during the 5-year treatment performed outdoors have been subjected to ecophysiological and growth analysis. The plants were exposed to UV-B radiation, simulating 17% ozone depletion. Ecophysiological parameters were monitored three times a year on three needle age classes, while growth was analysed at the end of each growth season. Spruce exhibited great variability in the amounts of photosynthetic pigments and methanol-soluble UV-B absorbing compounds, light use efficiency, photosynthesis and respiratory potential. The needle, branch and plant biomass production was not significantly affected during the 5-year treatment. The repeated-measures procedure comparing growth parameters through subsequent seasons, revealed a decrease of branch diameter under enhanced UV-B, which could be interpreted as a cumulative UV-B effect. The effects of UV-B radiation depended on needle development stage, interaction with environmental conditions and stresses. A reduced negative effect of UV-B radiation was observed during the prolonged drought in 2003, which was hypothesised as an alleviating effect. The tolerance of Norway spruce to elevated UV-B was to a large extent due to the high content of methanol-soluble UV-B absorbing compounds that was related neither to environmental conditions, including UV-B dose, nor to the developmental stage of the needles. The current year needles exhibited a tendency to increased production of UV-B absorbing compounds under elevated UV-B radiation. The outdoor study performed under variable environmental conditions showed great complexity of spruce response to enhanced UV-B.     

增强紫外—B对反枝苋形态、生理及异速生长的影响

在田间条件下,模拟西安地区21.6%的臭氧层减薄,研究增强紫外-B辐射 280～320nm,3.18kJ·m-2·d-1 对双子叶阔叶杂草反枝苋 Amaranthusretroflexus 生理、形态及异速生长的影响.结果表明: 1 与对照相比,处理组的叶绿素、类胡萝卜素含量降低,但叶片紫外吸收物质的含量增加; 2 处理组的株高、叶数及单株重有明显降低; 3 株高与单株重的线性关系有较大的偏离,表现在同等株高下处理组的生物量低于对照.这些表明在补充的紫外-B条件下,反枝苋的形态有较大的可塑性,并进一步会影响该植物在群落中的竞争能力.     

增强紫外B辐射对植物及生态系统影响研究的发展趋势

介绍了一些有关紫外B辐射增强对植物及生态系统影响研究的新进展：1．许多研究已深入到分子水平;2．注意到对植物生长调控的研究;3．更加重视对植物防御、修复的研究;4．有关信号传导的研究日渐增多;5．对植物群体及生态系统影响的研究在不断扩大与加深;6．复合效应研究正在升温。推断今后在一段时间内,有关UV－B辐射对植物和生态系统影响的研究不但不会削弱,可能还会加强,特别分子水平的研究会大大增加,今后对群体和生态系统的研究会重视野外和长期效应的观测。我国在这一领域的研究起步晚,但近些年发展得较快,有部分研究已赶上国际研究进展的步伐。     

A morphological and cytological study of Petunia hybrida exposed to UV-B radiation

The aim of this study was to investigate whether the cytoskeleton, and in particular the microtubular system, is affected by enhanced levels of ultraviolet-B (280–320 nm, 9 kJ m⁻² day⁻¹ biologically effective UV-B radiation) radiation in epidermal cells of Petunia x hybrida Vilm, isolated from leaves of plants grown under UV-B radiation and visible light. In addition, morphological changes during development were monitored. In a previous study microtubules were depolymerized and delays in the different stages of the cell cycle were found when protoplasts of Petunia were irradiated with UV-B radiation (Staxén et al. 1993. Protoplasma 173: 70–76). Thus it was of interest to ascertain whether the cytoskeleton would be similarly affected in an intact system. Assuming an effect of UV-B radiation on the microtubular system, we wished to determine whether this could be correlated to concomitant changes in leaf morphology. Plants of Petunia hybrida were grown in greenhouse conditions in the presence or absence of UV-B radiation. During the course of the experiment, samples were taken from young, expanding leaves and from older, fully expanded leaves and prepared for localization and analysis of microtubules from the adaxial epidermal cells. Morphology rather than the cytoskeleton was affected by UV radiation, despite the fact that the epidermal cytoskeleton would most likely be affected, since it is located in the cells which form the first intercepting layer for incident radiation.
Morphological changes under UV-B radiation, as compared to those under control conditions, were reflected in earlier flowering and an increase in leaf number. Cell division was thus stimulated as was also evidenced from the increased leaf area. Our results indicate that the number of stomata differentiated on a leaf area basis was not altered although the number of stomata per epidermal cell was reduced.     

UV-B辐射和Hg2+复合处理对黑小麦生理代谢和生长的影响

在室内,用1.35 w·m-2剂量的UV-B和1.29 mmol·L-1浓度的Hg2+对黑小麦幼苗进行复合处理.结果表明,随处理时间的延长,叶绿素(Chl)、类胡萝卜素(Car)含量和光系统Ⅱ(PSⅡ)电子传递活性下降,SOD活性下降不明鲜;根系TTC还原能力下降;而叶片细胞膜相对透性(El)、丙二醛(MDA)和H2O2含量增加;处理12天后植株高和鲜重下降.MDA和H2O2含量指标,UV-B+Hg2+的复合处理大于Hg2+的单独处理.     

He-Ne激光对增强UV-B辐射后小麦幼苗光合作用的影响

以"晋麦8号"小麦幼苗为研究材料,分别采用He-Ne激光(辐照剂量为5 mW·mm-2)、增强UV-B(辐射剂量为10.08 kJ·m-2·d-1)以及二者的复合辐照进行处理.循坏处理不同天数(4、5、6、7、8 d)后,利用电导仪、低温荧光测定法检测了小麦叶绿体电子传递速率、膜透性和荧光发射光谱的变化;采用紫外分光光...     

CaCl2对UV-B辐射下菠菜叶片光合特性的影响

以丹麦旺盛菠菜为材料,通过UV-B和CaCl2复合处理,测定光合色素含量、Hill反应活力、叶绿素荧光、MDA含量和抗氧化酶活性等参数,探讨了CaCl2对UV-B辐射下菠菜叶片电子传递链和光合膜酶保护系统的影响。结果表明,UV-B处理下,光合色素含量、chl/car、类囊体膜上PSII潜在活性(Fv/Fo)、光化学淬灭系数(qP)、非光化学淬灭系数(qN)、PSII光量子产量(ΦPSⅡ)、原初光能转化效率(Fv/Fm),以及Hill反应活力等降低,chla/chlb和MDA含量升高;喷洒CaCl2可不同程度缓解UV-B的伤害。不同处理下,POD、SOD和CAT活性的变化呈现补偿效应。UV-B强度与菠菜叶片PSII功能受损程度呈正相关,CaCl2则主要通过提高chlb含量、类囊体膜上的光量子产量和POD活性,以缓解伤害。重度UV-B辐射下,CaCl2使chlb含量显著提高可能是导致PSII捕光效率提高的重要因素。     

UV－B辐射增强对长白山五种藓类植物生长的影响

对生长在中国长白山的5种藓类植物——垂枝藓、拟垂枝藓、塔藓、星塔藓和高山金发藓分别以辐射强度为0.2(自然光照,对照)、3.0(紫外线中等辐射强度)和6.0kJ.m-2.d-1(高剂量辐射强度)的UV-B照射40d后,测定其株高、生物量及叶绿素含量.结果表明:中等和高强度的UV-B辐射使拟垂枝藓和塔藓的株高、生物量和叶绿素含量分别下降了32.3%、62.4%、81.3%和21.4%、59.4%、62.8%,其相对生长速率均为负值;高剂量UV-B辐射处理下垂枝藓的生物量稍有上升,而高山金发藓地下部分的生物量增加1倍,但叶绿素含量变化不明显.高山金发藓和垂枝藓抵抗UV-B辐射的能力较强,拟垂枝藓和塔藓对UV-B辐射较敏感.