Photosynthetic utilization of radiant energy by CAM Dendrobium flowers

14CO2 fixation was observed in orchid Dendrobium flowers; its rate decreased with the flower development. Chlorophyll (Chl) fluorescence in different developmental stages of flowers was compared to other green plant parts (leaf, inflorescence stalk, and fruit capsule). The photochemical efficiency of photosystem 2 (PS2) (Fv/Fm) of a leaf was 14-21 % higher than that of a mature flower perianth (sepal, petal, and labellum) which had a much lower total Chl content and Chl a/b ratio. A higher quantum yield of PS2 (PS2) than in the mature flowers was observed in all green parts. Flower sepals had higher Chl content, Chl a/b ratio, and Fv/Fm values than the petal and labellum. During flower development the Chl content, Chl a/b ratio, Fv/Fm, and qN decreased while PS2 and qP remained constant. An exposure of developing flowers to irradiances above 50 µmol m-2 s-1 resulted in a very drastic drop of PS2 and qP, and a coherent increase of qN as compared to other green plant organs. A low saturation irradiance (PFD of 100 µmol m-2 s-1) and the increase in qN in the flower indicate that irradiation stress may occur since there is no further protection when the flower is exposed to irradiances above 100 µmol m-2 s-1. A low Chl/carotenoid ratio in mature flower perianth as a consequence of Chl content reduction in the course of flower development suggests a relief of irradiation stress via this mean.     

重金属对盐生草光合生理生长特性的影响

以盐生草幼苗为试验材料,分别设置0(CK)、50、100、200、400μg?g-1的Ni2+、Cu2+处理,研究重金属Ni2+和Cu2+对盐生草光合生理特性的影响.结果表明:盐生草叶片光合色素含量、净光合速率(Pn)、气孔导度Gs、蒸腾速率Tr、PSⅡ最大光化学效率Fv/Fm、非光化学猝灭系数qN及生长指标(株高、地上部干重和鲜重)在50μg?g-1的Ni2+处理时均达到最大值,后随Ni2+浓度继续增加,其叶片叶绿素a、叶绿素b、Pn、Gs、Tr、Fv/Fm、PSⅡ电子传递量子产率ΦPSⅡ、光化学猝灭系数qP、qN及各项生长指标逐步下降并低于对照水平,而细胞间隙CO2浓度(Ci)较对照呈增加趋势.在50μg?g-1的Cu2+处理时,盐生草叶片光合色素含量、Pn、Gs、Tr、Ci、Fv/Fm、ΦPSⅡ、qP、qN及各项生长指标均达峰值;在100μg?g-1Cu2+处理时,光合色素含量、Pn、Gs、Tr、Fv/Fm、ΦPSⅡ、qN及各项生长指标较对照仍有增加,而后随Cu2+浓度继续增加,其叶绿素a、叶绿素b、各光合参数、叶绿素荧光参数及生长指标均逐步降低并低于对照.可见,盐生草Pn在Ni2+胁迫下的下降主要是由非气孔限制所致,而Cu2+胁迫下的下降主要是由气孔限制所致;低浓度Ni2+和Cu2+对盐生草生长具有一定促进作用,过高浓度Ni2+和Cu2+则会通过抑制盐生草叶片叶绿素合成,影响其光合作用,从而抑制植株生长.     

外源ATP对NaCl胁迫下菜豆叶片叶绿素荧光特性的调节

盐胁迫是影响植物生长的主要逆境因子之一,外源ATP被发现可作为信号分子参与植物对逆境胁迫生理反应的调节。为了探明外源ATP在植物盐胁迫响应中的作用,以增强植物对土壤盐渍化的耐性,更好地应用于土壤盐渍化修复。该研究以菜豆( Phaseolus vulgaris)为材料,通过叶绿素荧光技术探讨了外源ATP 对菜豆叶片在NaCl胁迫下叶绿素荧光特性的变化规律。结果表明：在NaCl胁迫下,叶片光系统Ⅱ( PSⅡ)潜在最大光化学量子效率( Fv/Fm)、光适应下最大光化学效率( Fv′/Fm′)、PSⅡ光适应下实际光化学效率[ Y (Ⅱ)]、光化学荧光猝灭( qP)、电子传递速率( ETR)与对照组相比均有显著性下降,而非光化学猝灭( NPQ)和( qN)较对照组有显著性增加,这表明NaCl胁迫导致菜豆叶片光系统Ⅱ光化学效率的下降和光能耗散的增加。而外源ATP(eATP)的处理能有效缓解NaCl胁迫所造成的Fv/Fm、Fv′/Fm′、Y(Ⅱ)、qP、ETR下降和NPQ、qN的上升。该研究结果表明在NaCl胁迫下外源ATP可以有效地提高菜豆幼苗光系统Ⅱ( PSⅡ)的光化学反应效率。     

Effects of Cadmium Stress on Leaf Chlorophyll Fluorescence and Photosynthesis of Elsholtzia argyi—A Cadmium Accumulating Plant

A hydroponic experiment was conducted to investigate the effects of cadmium (Cd) on chlorophyll fluorescence and photosynthetic parameters on a Cd accumulating plant of Elsholtzia argyi. Four weeks-seedlings of E. argyi were treated with 0 (CK) 5, 10, 15, 20, 25, 30, 40, 50 and 100 μmol L^?1 Cd for 21days. Fv/Fo, Fv/Fm, qP, ΦPSП, ETR and Fv′/Fm′ were significantly increased under low Cd (5–15 μmol L^?1 for Fv/Fo, Fv/Fm and qP, 5–10 μmol L^?1 for ΦPSП, ETR and Fv′/Fm′) stress, and these parameters were similar to control under Cd ≤ 50μmol L^?1. All above parameters were significantly decreased at 100 μmol L^?1 Cd. Compared with control, Pn was significantly (P < 0.05) increased under 5–30 μmol L^?1 Cd. However, 50 and 100 μmol L^?1 Cd significantly (P < 0.05) reduced it. Gs and Tr were substantially decreased at 50–100 and 40–100 μmol L^?1 Cd, respectively. Ci was significantly increased at 50 and 100 μmol L^?1 Cd. High Cd-induced decrease of Pn is not only connected to stomatal limitation but also to the inhibition of Fv/Fo, Fv/Fm, ΦPSП, qP, ETR and increase of NPQ. Maintain chlorophyll fluorescence and photosynthesis parameters under its Cd tolerance threshold were one of tolerance mechanisms in E. argyi.     

转C4光合酶基因水稻的CO2交换和荧光特性

用转PEPC、PPDK、NADP-ME、PEPC+PPDK酶基因水稻(Oryza sativa L.)及原种为材料 ,研究了光合作用对光照、温度、CO2的响应和光抑制条件下的叶绿素荧光特性,结果如下: 1.转C4光合酶基因水稻的饱和光合速率比原种高,其中转PEPC、PEPC+PPDK双基因水稻的光饱和点比原种高200 μmol*m-2*s-1,饱和光合速率比原种分别高51.6%和 58.5%;转PEPC基因水稻的羧化效率比原种高49.3%,CO2补偿点降低26.2%;在高温(35 ℃)下,转PEPC基因水稻的光合速率比原种高17.5%.2.经光抑制处理8 d后,转PEPC、PEPC +PPDK酶基因水稻的PSⅡ光化学效率(Fv/Fm)和光化学猝灭(qP)下降20%- 30%,非光化学猝灭(qN)增加了约30%;但原种的Fv/Fm和qP下降了5 0%多,qN变化不明显,表明转C4光合基因水稻耐光抑制能力增强.这些结果为用生物技术提高水稻光合效率研究提供了新的依据和途径.     

不同光照度下水蕨配子体叶绿素荧光特性的研究

以模式植物水蕨的两性配子体和雄配子体为材料,研究了不同光照度下蕨类植物配子体叶绿素荧光参数的差异,探讨水蕨配子体光系统Ⅱ(PSⅡ)对不同光照的响应规律.结果表明:同一光照度条件下,水蕨两性配子体的实际光化学效率(Ф_(PSⅡ))和潜在光化学效率(F_v/F_m)均高于雄配子体,但无显著差异,此时两者间的光化学猝灭系数(q_p)和非光化学猝灭系数(q_N)值也无显著差异;在4 000 lx光照条件下,两性配子体PSⅡ驱动的电子传递速率(ETR_(PSⅡ))显著高于雄配子体.随着光照度的增加,水蕨两性配子体的Ф_(PSⅡ)、ETR_(PSⅡ)和q_p值逐渐增加,且在4 000 lx光照下显著增加,但F_v/F_m和q_N值无显著变化;而雄配子体的Ф_(PSⅡ)、ETR_(PSⅡ)、F_v/F_m、q_p和q_N值均呈先增后减趋势,但各光照处理间无显著差异.研究发现,水蕨两性配子体PSⅡ的活性相对比雄配子体高;两性配子体和雄配子体的光保护能力相似;光照度对水蕨雄配子体的光合能力没有显著影响,而4 000 lx的光照度对水蕨两性配子体的生长最有利.     

Membrane Injury and PSⅡ Inactivation in Some Subtropical Woody Plants Induced by Photooxidation

Leaf discs from the pot-cultured seedlings of tree species and understory shrub species in a natural subtropical forest were treated with methyl viologen (MV) solution under low light or high light illumination. The degradation of chlorophyll and the leakage rate of electrolytes through membrane were enhanced by the increasing MV concentration and prolonged time of treatment. Membrane injury was more serious than oxidative bleaching of chlorophyll under the same condition. When leaf discs were subjected to short term (1 h) exposure of MV-photooxidation in high light (1 300 μmol·m-2·s-1), a pronounced decrease of Fv/Fm, ФPSⅡ and qp, as well as △A505, △A320 and ratio of qp/qN were observed in all tested species, which were accompanied by the increase of qN, KD and Fo. It demonstrated that photooxidation led to PSⅡ inactivation expressing in the reduction of the number of PS Ⅱ centre undergoing a stable charge separation and efficiency of the primary photochemical efficiency and noncyclic electron transport of PS Ⅱ. Partial excitation energy might dissipate via the useful nonphotochemical fluorescence quenching, but the lowering of △A505 was not consistent with the elevation of qN. Understory shrub Psychotria rubra Poir., Ardisia quinquegona BI. Showed more susceptibility to photooxidation than the upper canopy tree species Schima superba Gardn. et Champ., Castanopsis fissa (Champ.) ex Benth. ) Rend. et Wils. and Syzygium rehderianum Merr. et Perry.     

不同品种美国山核桃叶绿素荧光参数日变化的研究

以湖南省永州市冷水滩采穗圃中的美国山核桃为试材,研究了叶绿素荧光参数的日变化规律。结果表明:初始荧光(Fo)、最大荧光(Fm)、PSII原初光能转化效率(Fv/Fm)、光合量子产额(Yield)、光化学猝灭系数(qP)、非光化学猝灭系数(qN)和表观电子传递速率(ETR)均存在着明显的日变化。其中Fv/Fm、Fm、Yield、qP均呈先下降后上升的趋势,在中午强光下降低到最低值;qN则呈先上升后下降的趋势,在中午时分达到峰值;Fo呈下降趋势,部分品种傍晚稍有回升,但仍比早晨低;ETR日变化呈双峰曲线。不同品种间Fv/Fm、Yield、ETR、qP、qN对光强和温度的响应也存在着明显差异,可作为鉴定品种耐光抑制能力大小的指标。     

Effects of Strong Light and Active Oxygen on Photosynthesis in Soybean

With the use of chlorophyll fluorescence technique, it was found that the net photosynthetic oxygen evolution rate decreased after strong light (2 000 μmol· m-2·2-1 ) treatment for two hours in soybean ( Glycine max L. ) leaves. The chlorophyll fluorescence parameters, Fm/Fo, Fv/Fm, ФPSII, qp and qN decreased along with the increase of light intensity. In strong light, exogenous active oxygen H202、·OH and 'O2 were harmful to soybean leaves. The destruction of 'O2 and·OH to leaves was most evident, as was shown that Fv/Fm and PS H decreased significantly. The antioxidants DABCO, mannitol, ascorbate and histidine protected the leaves, but weakly, from strong light. In darkness, the SOD inhibitor sodium diethyldithiocar- bamate (DDC) had no significant effect on Fm/Fo and Fv/Fm, but NAN,, the ascorbate peroxidase (APX)inhibitor, significantly decreased Fm/Fo, Fv/Fm and ФPS II. In strong light, however, beth DDC and NaN3 reduced the above-mentioned fluorescence parameters, but NaN3 was more effective than DDC. The results suggested that photoinhibition did take place in soybean leaves under strong light, and it was related to active oxygen in vivo.     

草莓叶绿素荧光参数日变化的研究

以草莓（Fragaria ananassa Duch）为材料,研究其叶片叶绿素荧光参数的日变化。在自然光下,草莓叶片的最大荧光（Fm）、PSⅡ光化学效率（Fv／Fm）、PSⅡ光量子效率（Yield）和光化学猝灭系数（qP）从6：00-18：00均先下降后上升,其中在下午14：00最低;而非光化学猝灭系数（qN）先上升后下降,其中在下午14：00最高。表明在中午强光下,草莓叶片遭受了强烈的光抑制,而热耗散是其主要的光保护机制。     

玉米全生育期黄化材料的光合性能分析

通过对玉米(Zea mays L.)黄化材料和2份正常自交系的光合特性、光响应曲线及荧光动力学参数进行分析,结果表明,黄化材料yglm1的净光合速率(Pn)、气孔导度(Gs)和胞间CO2浓度(Ci)均显著低于正常自交系Mo17和RP128,而蒸腾速率(Tr)却显著高于正常自交系;黄化材料的光补偿点、光饱和点、暗呼吸速率及表观量子效率均高于正常自交系Mo17和RP128,但其净光合速率却低于正常自交系;黄化材料的荧光动力学参数初始荧光(Fo)、最大荧光(Fm)、PSⅡ原初光能转换效率(Fv/Fm)、PSⅡ原初光能捕获效率(Fv'/Fm')、PSⅡ光下实际光化学效率(ΦPSⅡ)、光化学猝灭系数(qP)均显著低于正常自交系Mo17和RP128,非光化学猝灭系数(qN)显著高于正常自交系。相对于正常自交系,黄化材料具有较低的电子传递潜力、原初光能捕获效率和转换效率、光能分配及利用率,这可能是导致其净光合能力降低的根本原因。     

草莓叶片光合作用对强光的响应及其机理研究

用便携式调制叶绿素荧光仪和光合仪研究了强光下草莓叶片荧光参数及表观量子效率的变化.结果表明,Fm、Fv/Fm、PSⅡ无活性反应中心数量和Q_A的还原速率在强光下降低,在暗恢复时升高;而PSⅡ反应中心非还原性Q_B的比例在强光下增加,在暗恢复时降低.上述荧光参数的变化幅度均以强光胁迫或暗恢复的前10 min最大.强光下Φ_PSII、ETR和qP先升高后降低,但qN先大幅度降低,然后小幅回升.强光处理4 h后,丰香和宝交早生的表观量子效率(AQY)分别降低了20.9%和37.5%;qE(能量依赖的非光化学猝灭)为NPQ(非光化学猝灭)的最主要成分.强光胁迫下丰香的Fo、Fm、Fv/Fm、Φ_PSII、ETR和AQY的变化幅度均明显比宝交早生小.DTT处理后,草莓叶片的Fm和Fv/Fm明显降低,Fo显著升高.可以认为,依赖叶黄素循环和类囊体膜质子梯度两种非辐射能量耗散在草莓叶片防御光损伤方面起着重要作用,丰香的光合机构比宝交早生更耐强光.     

建兰叶艺品种光合色素含量及叶绿素荧光特性分析

以建兰栽培品种‘八宝奇珍’Cymbidium ensifolium ‘Ba Bao Qi Zhen’为材料,对其正常绿色叶片及黄化变异叶片的光合色素含量、叶绿素荧光参数进行比较。结果表明,‘八宝奇珍’黄化变异叶片的叶绿素总量、叶绿素a 和叶绿素b 含量均显著低于正常绿色叶片,且随着黄化面积的增大呈现递减趋势;黄化变异叶片的初始荧光量(Fo)、最大荧光产量(Fm)、Kautsky 诱导效应最大荧光(Fp)、稳态光适应光化学淬灭系数(qP)以及光适应稳态荧光产量(Ft_Lss)均显著低于正常绿色叶片;PSⅡ原初光能转化效率(Fv/Fm)与正常绿色叶片无明显差异;稳态非光化学荧光淬灭系数(NPQ)高于正常绿色叶片。     

Tolerance of gametophytes of Acrostichum aureum (L.) to salinity and water stress

Tolerance of gametophytes of Acrostichum aureum to NaCl and dehydration was investigated under controlled conditions following the changes in chlorophyll fluorescence parameters (Fv/Fm, qP, qN). Salt tolerance was increased by growing gametophytes in low concentrations of NaCl. However, such treatment could not increase the tolerance of gametophytes to dehydration. Under water stress, a decrease in photochemical quenching (qP) was accompanied by an increase in non-photochemical quenching (qN). Under salt stress, qP also decreased, but qN did not change significantly in salt-hardened gametophytes.     

Visual discrimination between two sexually deceptive <Emphasis Type="Italic">Ophrys</Emphasis> species by a bee pollinator

Almost all species of the orchid genus Ophrys are pollinated by sexual deception. The orchids mimic the sex pheromone of receptive female insects, mainly hymenopterans, in order to attract males seeking to copulate. Most Ophrys species have achromatic flowers, but some exhibit a coloured perianth and a bright, conspicuous labellum pattern. We recently showed that the pink perianth of Ophrys heldreichii flowers increases detectability by its pollinator, males of the long-horned bee Eucera berlandi. Here we tested the hypothesis that the bright, complex labellum pattern mimics the female of the pollinator to increase attractiveness toward males. In a dual-choice test we offered E. berlandi males an O. heldreichii flower and a flower from O. dictynnae, which also exhibits a pinkish perianth but no conspicuous labellum pattern. Both flowers were housed in UV-transmitting acrylic glass boxes to exclude olfactory signals. Males significantly preferred O. heldreichii to O. dictynnae flowers. In a second experiment, we replaced the perianth of both flowers with identical artificial perianths made from pink card, so that only the labellum differed between the two flower stimuli. Males then chose between both stimuli at random, suggesting that the presence of a labellum pattern does not affect their choice. Spectral measurements revealed higher colour contrast with the background of the perianth of O. heldreichii compared to O. dictynnae, but no difference in green receptor-specific contrast or brightness. Our results show that male choice is guided by the chromatic contrast of the perianth during the initial flower approach but is not affected by the presence of a labellum pattern. Instead, we hypothesise that the labellum pattern is involved in aversive learning during post-copulatory behaviour and used by the orchid as a strategy to increase outcrossing.     

施氮和供水对混播和单播白羊草叶片叶绿素荧光特性的影响

为明确干旱条件下混播和施氮对白羊草〔Bothriochloa ischaemum(Linn.)Keng〕叶片叶绿素荧光参数的影响,采用盆栽法并设置不同混播比例〔白羊草与柳枝稷(Panicum virgatum Linn.)混播比例分别为8:0、6:2、4:4和2:6〕、施氮水平(即不施氮和1kg干土施01g纯氮)和供水条件(即正常供水和干旱胁迫6d后复水),对白羊草叶片叶绿素荧光参数的变化进行比较分析;在此基础上,采用一般线性模型分析这3个因素及其交互作用对白羊草叶绿素荧光参数的影响效应.结果显示:正常供水条件下,各处理组白羊草的最大光化学效率(Fv/Fm)、实际光化学效率(ΦPSⅡ)、表观光合电子传递速率(ETR)、光化学淬灭系数(qP)和非光化学淬灭系数(NPQ)均无明显变化.干旱及复水条件下,不施氮处理组白羊草的Fv/Fm值在干旱胁迫6 d(即土壤相对含水量最低)时降至最低值,并在复水2 d后恢复至与正常供水条件下相近的水平,而施氮处理组的Fv/Fm值则一直保持与正常供水条件下相近的水平;不论施氮与否,各处理组白羊草的ΦPSⅡ、ETR、qP和NPQ值基本上均表现为在干旱胁迫6 d时达到最高值,并在复水2 d后恢复至正常供水条件下各参数值的90%以上.总体上看,混播白羊草的qP和ETR值均高于单播白羊草,而其NPQ值则低于后者.统计分析结果表明:混播比例、施氮水平和供水条件3个因素间的交互作用对白羊草的ΦPSⅡ、qP和ETR值无显著影响,施氮水平对NPQ值的单独作用、施氮水平和混播比例的交互作用对Fv/Fm值以及施氮水平和供水条件的交互作用对ETR值也无显著影响,但这3个因素的单独作用及两两因素间的交互作用对白羊草其余叶绿素荧光参数均有显著或极显著影响.研究结果表明:一定程度的干旱胁迫有利于提高白羊草叶片PSⅡ反应中心的开放程度、光合电子传递速率和热耗散过剩光能的能力;在干旱胁迫条件下,施氮有助于白羊草叶片维持PSⅡ反应中心的活性和光化学效率;并且,与柳枝稷适度混播可改善白羊草叶片的光合性能,提高其种间竞争适应性.     

两种化感物质对茄子幼苗光合作用及叶绿素荧光参数的影响

采用基质栽培,研究不同浓度的2,6-二叔丁基苯酚及邻苯二甲酸二甲酯对茄子幼苗光合作用及叶绿素荧光参数的影响.结果表明,两种化感物质使茄子叶片叶绿素含量、光合速率（P_n）、气孔导度（G_s）下降,细胞间隙CO₂浓度（C_i）先降低后升高;使茄子叶片的初始荧光(F_o)增加,PSⅡ最大光化学效率(F_v/F_m)、光系统Ⅱ光合电子传递量子效率(Ф_PSⅡ)、光化学猝灭系数(q_P)、天线转化效率(F_v^' /F_m^′)降低.2,6-二叔丁基苯酚使茄子叶片非光化学猝灭系数(q_N)先升高后降低,邻苯二甲酸二甲酯使q_N低于对照,对茄子叶片光合机构造成了伤害.     

Tolerance of gametophytes of Acrostichum aureum (L.) to salinity and water stress

Tolerance of gametophytes of Acrostichum aureum to NaCl and dehydration was investigated under controlled conditions following the changes in chlorophyll fluorescence parameters (Fv/Fm, qP, qN). Salt tolerance was increased by growing gametophytes in low concentrations of NaCl. However, such treatment could not increase the tolerance of gametophytes to dehydration. Under water stress, a decrease in photochemical quenching (qP) was accompanied by an increase in non-photochemical quenching (qN). Under salt stress, qP also decreased, but qN did not change significantly in salt-hardened gametophytes. This revised version was published online in June 2006 with corrections to the Cover Date.     

外源甜菜碱对干旱／盐胁迫下的小麦幼苗生长和光合功能的改善

本文用甜菜碱溶液浸种,研究了外源甜碱对干旱／盐胁迫下的小麦幼苗的生长状况和叶片光合转能的影响,结果表明,外源甜菜碱能使干旱／盐胁迫下的小麦幼苗地上部和根部的干重和含水量增加,使叶片叶绿素a荧光诱导动力学参数Fv/Vo,Fv/Fm和qP增高,qN降低,说明外源甜菜碱有利于植物对光能的捕获和转换,明显促进植物生长,降低干旱／盐胁迫对植物的抑制作用。     

低温胁迫下不同甘蔗品种(系)光合特性的变化及其与耐寒性的关系

以广西农科院甘蔗研究所自育的7个新材料和2个生产上的主栽品种为研究对象,在甘蔗苗期进行低温胁迫处理,研究了各品种(系)甘蔗形态特征的冷害指数、叶绿素含量及光合特性相关指标的变化及其光合特性相关指标与甘蔗抗寒性间的相关性。结果表明:随着低温胁迫处理时间的延长,冷害指数不断增大,但变化的大小与快慢因品种(系)不同表现不一样。各甘蔗品种(系)叶片叶绿素含量均随时间延长而降低。叶片净光合速率、气孔导度在低温处理与常温处理间具有显著差异。低温胁迫处理显著降低了各甘蔗品种(系)最大光化学效率(Fv/Fm)、PSⅡ实际光能转化效率ΦPSⅡ、光适应下PSⅡ反应中心的最大光能转化效率Fv′/Fm′、光化学猝灭系数qP、电子传递速率ETR,而显著提高了初始荧光Fo、稳态荧光Fs、非光化学猝灭系数qNP。相关性分析表明整个测定时期各指标间相关显著,Fv/Fm、Fv′/Fm′、ΦPSⅡ与冷害指数I之间的相关系数在0.800以上,Fv/Fm、Fv′/Fm′、ΦPSⅡ可以作为甘蔗品种(系)抗寒性鉴定的重要参考指标。