热带落叶树降香黄檀次生韧皮部薄壁组织细胞超微结构的季节变化

研究了ＵＶ－Ｂ辐射对广东省南亚热带森林木本植物九节、鸭脚木、猴耳环、半枫荷、山乌桕入绿化树种大叶合欢幼苗生长的影响。实验结果表明,ＵＶ－Ｂ辐射降低叶片光合色素的含量;显著降低幼苗的净光合速率、蒸腾速率和气孔导度;降低干物质的增长;抑制大叶合欢幼苗要根瘤的形成。     

UV-B辐射对几种木本植物幼苗生长和叶绿体超微结构的影响

在实验室条件下研究了UV－B辐射对广东省南亚热带森林中5种木一植物九节,鸭脚木,猴耳环,半枫荷,山乌桕和绿化树种大叶合欢的幼苗形态和细胞超微结构。特别是叶绿体超微结构的影响。结果表明,UV－B辐射抑制幼苗主根伸长和减少侧根数,抑制茎伸长,减少叶数和叶面积。UV－B辐射破坏叶片细胞膜细胞,特别是叶绿体膜结构,但不同种受影响的程度不同,所表现的症状也不完全相同,鸭脚木的质膜收缩,导致质壁分离;鸭脚木,半枫荷和猴耳环的叶绿体膨胀,前二者的甚至破裂,鸭脚木的质膜收缩,导致质壁分离;鸭脚木,半枫荷和猴耳环的叶绿体膨胀,前二者的甚至破裂;鸭脚木和半枫荷的类囊体膨胀粘连;猴耳环的线粒体出现空泡化,半枫荷和猴耳环的叶绿体内大的淀粉粒增多;鸭脚木和山乌桕的叶绿体内或膜上黑色颗粒增多,鸭脚木的线粒体膜上也出现黑色颗粒。     

补增UV—B辐射对香蕉叶片光合作用和叶氮在光合碳循环组分中分配 …

补增UV -B辐射的香蕉叶片光下呼吸速率 (Rd)和不包括光下呼吸的CO2 补偿点 (г ) ,分别为0 .33μmol·m- 2 ·s- 1 和 46.5μl·L- 1 ,较对照植株分别高 5.6%和 1 0 .0 %。在较高CO2 浓度 (>340 μl·L- 1 )条件下的An/θp关系最初直线部分斜率 ,即表观量子产率 (αA)为 0 .0 2 3± 0 .0 0 7,而补增UV B辐射处理的植株则降低 1 3.0 % ,光能转换效率 (δ)亦降低 2 8.6% ,表明UV B辐射明显降低αA 和δ。在高θp(1 1 0 0 μmol·m- 2 ·s- 1 )和Ci<2 0 0 μl·L- 1 条件下 ,对照植株的An/Ci关系为An =0 .0 2 8Ci 1 .44,补增UV B辐射处理的植株则为An =0 .0 2 1Ci 1 .0 1 ,UV B辐射降低羧化限制速率。最大羧化速率 (Vcmax)和电子传导速率的光饱和值 (Jmax)亦较低 ,补增UV B辐射的叶片 ,叶氮在Rubisco的分配系数 (PR)和叶氮在生物力能学组分的分配系数 (PB)分别较对照低 8.1 %和 3.0 % ,叶氮分配到类囊体膜捕光色素蛋白组分的则略见增高 ,UV B辐射降低叶氮在光合循环组分的分配     

田间增加紫外线（UV）辐射对大豆幼苗生长和光合作用的影响

 两个增加的UV(UV-AB,280～400nm)辐射强度分别相当于大气臭氧减少3.6％和5.1％时增加的UV-B辐射。UV辐射增强明显降低大豆的株高、叶面积、干重、水分含量和叶绿素含量,大豆生长受抑程度随人工UV光源照射时间和强度增加而增强,是增加UV辐射剂量的累积效应,叶绿素b的降幅大于叶绿素a,表明UV辐射对大豆幼苗捕光色素的破坏较严重。同时,增加UV辐射还使大豆幼苗的表观光合速率、蒸腾速率、水分利用效率、气孔导度下降,作用效果与辐射强度正相关。与生长等比较,UV辐射条件下,冠／根比值减少幅度不大。分析认为,大豆幼苗生长和光合能力的下降可以使植物避免或减轻UV辐射的进一步伤害,对植物适应UV辐射有利。     

UV-B辐射对香蕉光合作用和不同氮源利用的影响

生长在NO3^--N、NH4^--N和NH4NO3－N的香蕉叶片有相近似的最大光合速率,UV－B辐射引起生长在不同氮源的香蕉叶片光合速率、表现量子产率和光肥利用效率的降低。UV－B辐射使生长在不同氮源的植株叶面积干重和叶氮含是降低。生长在NH4^--N的植株Vcmax和Jmax均较生长在其它氮源的高。UV－B辐射引起生长在NH4^-N的植株Vcmax和Jmax降低较相同处理的NO3^-－N和NH4NO3－N植株明显,表明生长在NH4^ －N的香蕉对UV－B辐射更加敏感。UV－B辐射改变植株的叶片的碳氢比和碳氮比。经过UV－B辐射处理的NH4^ －N生长植株的碳氮生长在NO3^--N和NH4NO3－N的低。UV－B辐射可能改变植株对不同氮源的吸收利用,从而引起碳氮代谢和酸碱调节的变化。UV－B辐射降低叶氮在Rubisco和生物力能学组分的分配系数,可能使这些组分合成减少,使叶片光调节的变化。UV－B辐射降低叶氮在Rubisco和生物力能学组分的分配系数,可能使这些组分合成减少,使叶片光合速率下降。结果表明,生长在不同氮源的香蕉植树对UV－B辐射有不同响应,NH4^ -N有利于主要光合参数增高,但其对UV－B辐射亦最为敏感。氮供应受限制或植株生长在中性盐如NH4NO3－N则对UV－B辐射不甚敏感。     

NaCl胁迫对4种豆科树种幼苗生长和K~+、Na~+含量的影响

以合欢、刺槐、国槐和皂荚4种豆科树种盆栽实生幼苗为试验材料,研究了NaCl胁迫下4个树种幼苗的生长、耐盐临界浓度和Na+、K+含量的变化,并对其耐盐性进行了比较.结果表明:NaCl胁迫抑制了4个树种幼苗的生长,苗木的干物质积累量减小、根冠比增大,尤其对合欢和皂荚的影响较大;以相对干质量降至对照组50%时的NaCl浓度作为生长临界NaCl浓度(C50)指标,4个树种的耐盐强弱顺序为:刺槐(5.0‰)>国槐(4.5‰)>皂荚(3.9‰)>合欢(3.0‰);随NaCl浓度的增加,各树种幼苗根、茎、叶中Na+含量逐渐增加,K+含量先增加后减小(合欢根除外),而K+/Na+差异较大.相同浓度NaCl胁迫下,幼苗器官的Na+分布为根>茎>叶,K+因树种和NaCl浓度不同而各异,以叶片中较多,K+/Na+为叶>茎>根.NaCl胁迫下,刺槐的K+含量和K+/Na+较高,地上部分Na+含量较低,幼苗干物质量大,耐盐性较强;而合欢的K+/Na+较小,高浓度NaCl胁迫下地上部分的Na+含量较高,幼苗干物质量小,耐盐性较差.苗木地上部分对K+的积累和根部对Na+的滞留是影响豆科树种耐盐性能的主要因素.     

增强UV B辐射对喜树生理指标及喜树碱含量的影响

喜树(Camptotheca acuminata Decne.)隶属于蓝果树科(Nyssaceae)喜树属(Camptotheca),为抗癌药物喜树碱的主要资源,提高喜树碱的积累以满足临床需求是喜树碱开发的重要途径。该研究运用UV B辐射对2年生喜树进行每天8 h辐射处理,对1年生喜树分别设置每天2 h、4 h、6 h和8 h的辐射处理,连续处理12 d后分别测定各处理喜树叶的叶绿素、MDA、游离脯氨酸 (Fpro)含量和SOD活性,以及幼叶、幼枝和根中喜树碱含量,分析UV B辐射对喜树生理指标和次生代谢物的影响,以揭示喜树碱为喜树适应UV B辐射逆境的防御产物。结果显示：（1）2年生喜树经UV B每天8 h辐射处理12 d后,叶绿素含量较对照显著降低,而MDA、Fpro和喜树碱含量均增加,说明每天8 h UV B辐射对2年生喜树产生了较强的胁迫伤害。（2）1年生喜树经UV B辐射处理12 d后,随着每天UV B辐射时间的增加,叶绿素含量不断降低,Fpro含量显著增加;每天2~6 h处理的MDA含量与对照无显著差异,但总体随处理时间增加呈上升趋势;每天8 h UV B辐射的MDA含量较对照显著增加;SOD活性随每天处理时间的延长呈先下降、后上升、再下降的变化趋势,说明每天8 h的UV B辐射对一年生喜树也产生了胁迫伤害。（3）1年生喜树幼叶、幼枝和根中喜树碱含量随着每天UV B辐射时间的延长均呈递增趋势,而且每天8 h辐射处理的喜树碱含量均最高,其中幼叶和幼枝中喜树碱含量显著高于根中含量。实验结果表明,增强UV B辐射对喜树造成了一定的伤害,而喜树通过改变生理以及次生代谢机制,以进一步产生喜树碱来响应增强UV B的胁迫。     

NaC1胁迫对4种豆科树种幼苗生长和K+、Na+含量的影响

以合欢、刺槐、国槐和皂英4种豆科树种盆栽实生幼苗为试验材料,研究了NaC1胁迫下4个树种幼苗的生长、耐盐临界浓度和Na+、K+含量的变化,并对其耐盐性进行了比较.结果表明:NaC1胁迫抑制了4个树种幼苗的生长,苗木的干物质积累量减小、根冠比增大,尤其对合欢和皂荚的影响较大;以相对干质量降至对照组50%时的NaC1浓度作为生长临界NaC1浓度(C50)指标,4个树种的耐盐强弱顺序为:刺槐(5.0‰)＞国槐(4.5‰)＞皂荚(3.9‰)＞合欢(3.0‰);随NaC1浓度的增加,各树种幼苗根、茎、叶中Na+含量逐渐增加,K+含量先增加后减小(合欢根除外),而K+/Na+差异较大.相同浓度NaC1胁迫下,幼苗器官的Na+分布为根＞茎＞叶,K+因树种和NaC1浓度不同而各异,以叶片中较多,K+/Na+为叶＞茎＞根.NaC1胁迫下,刺槐的K+含量和K+/Na+较高,地上部分Na+含量较低,幼苗干物质量大,耐盐性较强;而合欢的K+/Na+较小,高浓度NaC1胁迫下地上部分的Na+含量较高,幼苗干物质量小,耐盐性较差.苗木地上部分对K+的积累和根部对Na+的滞留是影响豆科树种耐盐性能的主要因素.     

低温胁迫和解除对4种阔叶幼苗生理特征的影响

以台湾相思(Acacia confusa)、火棘(Pyracantha fortuneana)、银合欢(Leucaena glauca)和葛藤(Pueraria lobota)幼苗为试验材料, 研究其在人工低温6 ℃胁迫下的生理变化。结果表明: 随着低温时间的延长, 台湾相思和葛藤幼苗的叶绿素总含量下降, 分别在低温胁迫48 h和72 h达最小值, 比对照显著减少13%和27%。银合欢和火棘先升后降, 其中银合欢72 h时显著减少25%; 台湾相思、火棘和葛藤幼苗的脯氨酸含量均先增后降, 在低温胁迫48 h分别比对照显著大41%、47%和29%, 银合欢为升-降-升, 各低温阶段与对照无显著差异; 台湾相思和葛藤幼苗的可溶性蛋白质含量显著上升后下降, 火棘和银合欢显著上升, 均在低温胁迫24 h 增加最快, 分别比对照显著大196%、86%、105%和72%; 台湾相思和火棘幼苗的可溶性糖含量先升后降, 在48 h达最大值, 分别比对照显著大27%和83%, 银合欢和葛藤持续上升, 在72 h达最大值, 分别比对照显著大46%和28%; 台湾相思、火棘和银合欢幼苗的SOD活性先升后降, 葛藤持续上升, 且在各个低温胁迫处理时间均显著高于对照; 4 种幼苗的丙二醛(MDA)含量均持续上升, 在72 h达最大值, 分别比对照大46%、54%、8%和165%。主成分分析表明, 低温下幼苗抗寒能力顺序为: 银合欢>葛藤>火棘>台湾相思。     

滤减UV B辐射对烟叶可溶性蛋白、〖HJ*3〗〖HJ*2〗光合色素和类黄酮的影响

在云南玉溪烟区种植烤烟海拔最高（1 806.0 m）的通海县,通过盆栽烤烟K326试验,研究了在滤减自然的太阳UV B辐射强度25%、50%和65%条件下,UV B辐射对烟叶发育过程中可溶性蛋白、光合色素和类黄酮的影响。结果表明：随叶龄增加,可溶性蛋白含量下降,光合色素降解,类黄酮在老叶中积累,蛋白质在生理成熟期对UV B辐射最敏感。与对照相比,减弱UV B辐射处理降低了烟叶类黄酮和可溶性蛋白含量,但光合色素含量上升;较低的UV B辐射降低了叶绿素的降解速度。结果从一侧面说明UV B辐射对烟叶蛋白质的合成是有益的,类黄酮和叶绿素的变化是对UV B辐射变化的适应性反应,类黄酮与蛋白质之间可能存在一定的偶联关系。     

Effects of UV - B Radiation on Seedling Growth of Several Woody Species in the Southern Subtropical Forest

Effects of UV-B radiation (7.2 and 14.4 kJ d-1 m-2) on seedling growth of several woody species in the Southern subtropical forest in Guangdong Province were investigated. The species studied are: Psychotria rubra (Lour.) Poir., Schefflera octophyHa (Lour.) Harms, PitheceHobium clypearia Benth. , Pterospemwm heterophyllum Hance, Sapium discolor Muell. - Arg. and Albizzia lebbeck (L.) Benth. The results demonstrated that the content of photosynthetic pigments of the UV - B treated seedlings was lower than that of the control seedlings. The effect was more significant on content of chlorophylls than that of carotenoids. UV- B radiation markedly lowered net photosynthetic rate, and reduced stomatal conductance and transpiration rate of the seedlings. It also reduced accumulation of dry matter of the seedlings and inhib-ited the formation of root nodules of Albizzia lebbeck seedlings.     

Photoprotection, photosynthesis and growth of tropical tree seedlings under near-ambient and strongly reduced solar ultraviolet-B radiation

Seedlings of two late-successional tropical rainforest tree species, Tetragastris panamensis (Engler) O. Kuntze and Calophyllum longifolium (Willd.), were field grown for 3-4 months at an open site near Panama City (9 degrees N), Panama, under plastic films that either transmitted or excluded most solar UV-B radiation. Experiments were designed to test whether leaves developing under bright sunlight with strongly reduced UV-B are capable of acclimating to near-ambient UV-B conditions. Leaves of T. panamensis that developed under near-ambient UV-B contained higher amounts of UV-absorbing substances than leaves of seedlings grown under reduced UV-B. Photosynthetic pigment composition, content of alpha-tocopherol, CO(2) assimilation, potential photosystem II (PSII) efficiency (evaluated by F(v)/F(m) ratios) and growth of T. panamensis and C. longifolium did not differ between seedlings developed under near-ambient and reduced solar UV-B. When seedlings were transferred from the reduced UV-B treatment to the near-ambient UV-B treatment, a pronounced inhibition of photosynthetic capacity was observed initially in both species. UV-B-mediated inhibition of photosynthetic capacity nearly fully recovered within 1 week of the transfer in C. longifolium, whereas in T. panamensis an about 35% reduced capacity of CO(2) uptake was maintained. A marked increase in UV-absorbing substances was observed in foliage of transferred T. panamensis seedlings. Both species exhibited enhanced mid-day photoinhibition of PSII immediately after being transferred from the reduced UV-B to the near-ambient UV-B treatment. This effect was fully reversible within 1d in T. panamensis and within a few days in C. longifolium. The data show that leaves of these tropical tree seedlings, when developing in full-spectrum sunlight, are effectively protected against high solar UV-B radiation. In contrast, leaves developing under conditions of low UV-B lacked sufficient UV protection. They experienced a decline in photosynthetic competence when suddenly exposed to near-ambient UV-B levels, but exhibited pronounced acclimative responses.     

Effects of solar ultraviolet-B radiation,temperature and CO2 on growth and physiology of sunflower and maize seedlings

The effects of solar UV-B radiation, in combination with elevated temperature (4 °C ) and CO₂ (680 L L^-1 concentration, on sunflower and maize seedlings were studied from May to August in 1991 at the research station Quinta de São Pedro in Portugal (38.7°N). The ambient solar radiation of Portugal was reduced to levels of Central European latitudes by using the ozone filter technique. This radiation served as control, while the ambient solar radiation of Portugal was to simulate intense UV-B treatment (+30%). All plants were grown up to 18 days in 4 climate controlled growth chambers simulating a daily course of temperature with T_max=28 °C or 32 °C , resp., and ambient CO₂ concentrations (340 L L^-1); in one chamber the CO₂ concentration was twice as high (680 L L^-1). Under intense UV-B and at 28 °C (T_max) all growth parameters (height, leaf area, fresh and dry weight, stem elongation rate, relative growth rate) of sunflower and maize seedlings were reduced down to 35% as compared to controls. An increase in growing temperature by 4 °C , alone or in combination with doubled CO₂, compensated or even overcompensated the UV-B effect so that the treated plants were comparable to controls. Chlorophyll content, on a leaf area basis, increased under intense UV-B radiation. This increase was compensated by lower leaf areas, resulting in comparable chlorophyll contents. Similar to growth, also the net photosynthetic rates of sunflower and maize seedlings were reduced down to 29% by intense UV-B calculated on a chlorophyll basis. This reduction was compensated by an increased temperature. Doubling of CO₂ concentration had effects only on sunflower seedlings in which the photosynthetic rates were higher than in the controls. Dark respiration rates of the seedlings were not influenced by any experimental condition. Transpiration and water use efficiency (wue) were not influenced by intense UV-B. Higher temperatures led to higher transpiration rates and lower water use efficiencies, resp.. Doubling of CO₂ reduced the transpiration rate drastically while for wue maximum values were recorded.     

Changes in morphological, photosynthetic and physiological responses of Mono Maple seedlings to enhanced UV-B and to nitrogen addition

In the southeast of the Qinghai-Tibetan Plateau of China, Mono Maple is a common species in reforestation processes. The paper mainly investigated the changes in morphological, photosynthetic and physiological responses of Mono Maple seedlings to UV-B radiation, nitrogen supply and their combination. The experimental design included two levels of UV-B treatments (ambient UV-B, 11.02 KJ m⁻² day⁻¹; enhanced UV-B, 14.33 KJ m⁻² day⁻¹) and two nitrogen levels (0; 20 g N m⁻² a⁻¹)—to determine whether the adverse effects of UV-B on plants are eased by nitrogen supply. Enhanced UV-B caused a marked decline in growth parameters, net photosynthetic rate, and photosynthetic pigments, whereas it induced an increase in reaction oxygen species (hydrogen peroxide accumulation and the rate of superoxide radical production) and malondialdehyde content. Enhance UV-B also induced an increase in antioxidant compounds of Mono Maple, such as UV-B absorbing compounds, proline content, and activities of antioxidant enzymes (peroxidase, superoxide dimutase and catalase). On the other hand, nitrogen supply caused an increase in some growth parameters, net photosynthetic rate, photosynthetic pigments and antioxidant compounds (peroxidase, proline content and UV-B absorbing compounds), and reduced the content of reaction oxygen species (H₂O₂ accumulation, the rate of O₂⁻ production) and malondialdehyde content under ambient UV-B. However, under enhanced UV-B, nitrogen supply inhibited some growth parameters, and increased H₂O₂ accumulation, the rate of O₂⁻ production and MDA content, though proline content, UV-B absorbing compounds and activities of POD and SOD increased. These results implied that enhanced UV-B brought harmful effects on Mono Maple seedlings and nitrogen supply made plants more sensitive to enhanced UV-B, though increased some antioxidant activity.     

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.     

Variations in Growth, Photosynthesis and Defense System Among Four Weed Species Under Increased UV-B Radiation

Weed tolerance of UV-B radiation varies with species, and the radiation could affect weed ecology and management. Variations In growth, photosynthesis and defense system among four important agronomic weeds, Abutllon theophrastl Medlk, Amaranthus retroflexus L., Digitaria sanguinalis （L.） Scop and Chloris virgata Swartz, under Increased UV-B radiation （ambient and increased radiation at 2.7, 5.4 and 10.8 kJ.m^-2.d-1） were studied In the greenhouse experiment. After 2 weeks of radiation, the shoots＇ dry mass decreased with increasing UV-B radiation except for D. sanguinalis. The reduction in biomass was the result of changes in morphology and physiology. Higher levels of UV-B treatment decreased the leaf area, plant height, net photosynthetic rate and chlorophyll contents, while it increased the contents of wax and UV-B absorbing compound in all species, except for A. retroflexus, which did not increase significantly. The activity of superoxide dismutase, catalase, ascorbate peroxide and the content of ascorblc acid changed differently among the weed species as UV-B radiation increased. D. sangulnalls was the most tolerant and A. retroflexus the most sensitive to increased UV-B radiation. The results also show that the two grass species （D. sanguinalis and C. virgata） were more tolerant to UV-B radiation than the two broadleafed species （A. theophrasti and A. retroflexus）. The UV-B absorbing compound and leaf wax played Important roles against UV-B damages in the two grass weeds. The overall results suggest that weed community, competition and management will be altered by continuous ozone depletion.     

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.     

Effect of Cerium on Photosynthetic Pigments and Photochemical Reaction Activity in Soybean Seedling Under Ultraviolet-B Radiation Stress

Effects of cerium (Ce) on photosynthetic pigments and photochemical reaction activity in soybean (Glycine max L.) under ultraviolet-B (UV-B) radiation stress were studied under laboratory conditions. UV-B radiation caused the decrease in chlorophyll content, net photosynthetic rate, Hill reaction activity, photophosphorylation rate and Mg²⁺-ATPase activity. Ce (III) (20 mg L⁻¹) could alleviate UV-B-induced inhibition to these photosynthetic parameters because values of these photosynthetic parameters in Ce (III) + UV-B treatment were obviously higher than those with UV-B treatment alone. Dynamic changes of the above photosynthetic parameters show that Ce (III) could slow down the decrease rate of these photosynthetic parameters during a 5-day UV-B radiation and quicken the restoration during recovery period. The final restoration degree of five parameters mentioned above in leaves exposed to low level of UV-B radiation (0.15 W m²) was higher than that exposed to high level (0.45 W m²). Correlating net photosynthetic rate with other four parameters, we found that the regulating mechanisms Ce (ΠΙ) on photosynthesis under various level of UV-B radiation were not the same. The protective effects of Ce (III) on photosynthesis in plants were influenced by the intensity of UV-B radiation.     

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.     

Influence of ultraviolet-B radiation on photosynthetic and biochemical characteristics of a mangrove Rhizophora apiculata

Changes in photosynthesis and biochemical constituents were studied in R. apiculata seedlings grown under solar and solar enhanced UV-B radiation, equivalent to 10, 20, 30, and 40 % stratospheric ozone depletion. The seedlings grown under 10 % UV-B radiation showed an increase of 45 % net photosynthetic rate (PN) and 47 % stomatal conductance, while seedlings grown under 40 % UV-B radiation exhibited a decrease of 59 % PN with simultaneous elevation of 73 % intercellular CO2 concentration. Effects of UV-B on contents of lipids, saccharides, amino acids, and proteins were significant only at high doses of UV-B radiation. The concentration of anthocyanin was reduced with increasing doses of UV-B. The reverse was true with phenols and flavonoids.