对不同光环境下桢楠幼树叶片主 要叶绿素荧光参数的日变化进行了测定。结果表明:在全光照(Ⅰ型)和90%光照(Ⅱ型)环境下,F0(最小荧光)、Fm(最大荧光)、F'm(光适应下的 最大荧光)、Fv(可变荧光)、Fv/Fm(PSⅡ最大光能转换效率)、Fm/F0(电子传递效率)和Fv/F0(PSⅡ潜在活性),从08:00— 18:00均呈现下降的趋势。而在60%～65%光照(Ⅲ型)和50%～55%光照(Ⅳ型)环境下,则呈现先降后升的单谷型,最小值出现在12:00— 14:00。在全光照(Ⅰ型)和90%光照(Ⅱ型)环境下,NP,Q(非光化学淬灭系数)日变化则呈现上升的趋势;而在60%～65%光照(Ⅲ型)和 50%～55%光照(Ⅳ型)环境下,则呈现先升后降的单峰型,最大值出现在12:00—14:00。在Ⅰ型和Ⅱ型光环境之间,除F0和NP,Q的日均值存 在显著差异(P0.05)外,其他叶绿素荧光参数日均值无显著差异。在Ⅲ型和Ⅳ型光环境之间,各项叶绿素荧光参数日均值均不存在显著差异。但是,Ⅰ型和Ⅱ 型光环境下的F0、Fm、F'm、Fv、Fv/Fm、Fm/F0、Fv/F0日均值都分别极显著(P0.01)低于Ⅲ型和Ⅳ型光环境下的对应值,而Ⅰ型和 Ⅱ型光环境下的NP,Q日均值却极显著(P0.01)高于Ⅲ型和Ⅳ型光环境下的对应值。由此可见,Ⅰ型和Ⅱ型光环境下的桢楠幼树叶片吸收的光能有更大比例 用于热耗散而保护自身的光合机构。

A light control treatment with three light gradients (100%, 66% and 10% of natural light) was conducted to simulate the light conditions of the forest edge, forest gap and understory where seedlings grow. This was achieved by building shade shelters covered by woven black nylon nets. The purpose of this experiment was to study the morphology, photosynthetic characters, biomass accumulation and allocation of Quercus acutissima and Robinia pseudoacacia seedlings in response to diverse gradients of light. The results showed that morphological features of plant height, stem diameter, total leaf area, crown area, leaf area index and total leaf number were seriously inhibited under severe shade conditions, while moderate shade treatment was suitable to growth of seedlings. Effects of light on allometric trajectories of morphology were small in Q. acutissima but more obvious in R. pseudoacacia as the low light depressed the exponents of functions. With a decrease of light, net photosynthetic rate, transpiration rate and stomatal conductance of Q. acutissima were decreased, while the maximum photosynthetic rate of R. pseudoacacia occurred with moderate shade treatment. Light use efficiency in both species increased when the light intensity was restricted. The water use efficiency was the highest under moderate shade treatment, but lowest under severe shade conditions. The trends of biomass accumulation were consistent with those of photosynthetic parameters. Biomass accumulation in each organ was limited by the deficit of light for Q. acutissima, but the best status of biomass accumulation and allocation for R. pseudoacacia was found under moderate shade treatments. Higher leaf area index and lower root to shoot ratio could increase the capacity of light capture. Also, the total content of chlorophyll increased and Chl a/b decreased with decreasing light intensity. The different strategies of growth and light utilization between Q. acutissima and R. pseudoacacia might reveal, to a certain extent, their status in the succession of deciduous broadleaved communities.

通过搭建遮阳棚设置3个光照强度，模拟森林幼苗生长的林缘、林窗和林下光环境，研究麻栎和刺槐幼苗形态结构、光合特性、生物量积累及其分配对不同光照强度的响应。结果表明，极度弱光环境限制了幼苗的株高、基径、总叶面积、冠面积、叶面积指数和总叶数等形态指标的增长，与全光环境相比，适度遮荫有利于幼苗的形态生长，光照对麻栎形态的异速生长曲线影响较小，刺槐较麻栎的曲线变化更明显一些，弱光降低了异速生长指数。随遮荫程度的增加，麻栎的净光合速率、蒸腾速率、气孔导度逐渐降低，刺槐的净光合速率则在适度遮荫下最大，两者的光能利用效率均显著增大，水分利用效率先升后降。随光照强度的减弱，麻栎各器官的生物量积累降低，叶面积比率的增加和根冠比的减少有利于增加光能的捕获，而刺槐的生物量积累和分配则在适度遮荫下达到最优；各叶绿素含量均显著上升，而叶绿素a/b则逐渐下降。麻栎和刺槐显示出不同的生存策略和光利用策略，在一定程度上可以揭示它们在阔叶林群落中不同的演替地位。

Light is an important factor affecting plant growth and species distribution. In the field, open forest, forest edge, forest gaps and forest understory are typical light environment for species to survive and growth, in which light intensity are different for 10 times and even more. Plant phenotypic plasticity, which allows plants to adapt to different light environments, plays an important role in how plants adapt to changes in lighting, and leaves play an especially important role. Leaves are the main organs plants use for gas exchange with the environment. Leaves have both structural and functional characteristics. Different species show different sensitivities to irradiance. Vitex negundo Linn. var. heterophylla (Franch.) Rehd. is the dominant shrub of the warm temperate zone in China. It is an important native and pioneer species for vegetation restoration of Shandong Province, because of the high soil and water conservation ability. But up to now, studies related to its adaptation to irradiance are lacking. This study provides information related to this shrub and its use in vegetation restoration in Luzhong Mountains of Shandong Province.We measured leaf photosynthetic light response curves, leaf chlorophyll fluorescence, leaf chlorophyll content, leaf nirtogen ( N ) and phosphorus ( P ) content and leaf morphology. We studied the response of V. negundo var. heterophylla to five different light environments in the field: open forest, broad-leaved forest edge broad-leaved forest understory, gaps in needle-leaf forests and needle-leaf forest understory. The results the leaf traits of V. negundo var. heterophylla acclimated well to different habitats. Leaf functional traits were adjusted by leaf structural traits. The species exhibited some shade tolerance based on its ability to modify the characteristics of its leaves. The species improved its light use efficiency and kept growing in low light by increasing its specific leaf area (SLA), its chlorophyll (Chl) content, and the maximal quantum yield of PSII, and by lowering its respiration rate, light saturation point, light compensation point, and Chl a to b ratio. Also, leaf structure, especially SLA, played an important role in the regulation of photosynthesis under high levels of irradiance. Most of the traits were only impacted by the daily total irradiance; however, the variation of SLA and leaf maximal fluorescence in the dark ( F m ) was related to the highest irradiance levels. SLA was sensitive to different light conditions, and responded quickly to changes in lighting. Although light is the most important factor affecting the characteristics of V. negundo var. heterophylla leaves in this study, soil nutrient content also played an important role. Plants with higher nutrient levels had a higher ratio of leaf length to petiole length, revealing an investment tradeoff between resource obtaining and supporting structure.Based on the low leaf N to P ratio, Luzhong Mountains is proved to be short of soil N . Adding N during vegetation restoration activities will assure an adequate supply of N . Also, V. negundo var. heterophylla can be planted in a variety of light environments because of its broad irradiance tolerance.

光照是影响植物生长和分布的重要环境因子。对生长在野外5种不同光环境下(林外、阔叶林林缘、阔叶林林下、针叶林林窗和针叶林林下)的荆条的叶片进行取样研究,通过对光合作用光响应曲线、叶绿素荧光、叶绿素含量、叶片氮磷含量以及叶片形态的测量,来反映荆条对不同光环境的表型可塑性。研究结果表明,荆条叶片对于野外不同的光环境具有很好的适应机制,叶片功能性状受到结构性状的调节。低光下通过高的比叶面积(SLA)、单位质量叶绿素含量、光系统II最大量子产量,低的暗呼吸速率、光饱和点、光补偿点、叶绿素a,b的比值来提高对光能的利用效率,维持生长;高光下则通过与SLA有关的叶片结构的变化对光合作用进行调节。大多数的叶性状只受到日光照总量的影响,SLA的大小与日最高光强有关,可以对不同日变化模式的光照做出迅速的响应,是适应不同光照的敏感指标。尽管光照是不同光环境下影响荆条叶性状的主要环境因子,土壤养分含量同样会对叶性状产生影响,高土壤养分下的高叶长与叶柄长的比值体现了植物对资源获取和支撑结构之间分配的权衡。

摘　要： 限制酸性土壤作物生长的最重要、最普遍的因子是Al^3＋的毒害和P的缺乏。本文用溶液培养 试验研究两种不同生态型的二色胡枝子在高Al低P胁迫下的矿质营养元素积累情况。试验表明，江西胡枝子比河北胡枝子更耐低P低pH的生长环境，但两者间耐 Al性无显著差异；100μm／LAl处理显著地抑制了两种胡枝子对Ca的吸收，降低了根系Mg的积累量，对植株的K、P、Fe、Zn、Cu含量没有显著 影响：低P处理没有显著降低两种胡枝子对Ca、K、Fe、Zn、Cu和江西胡枝子对Mg的吸收，但是低P处理显著降低了河北胡枝子对Mg的吸收和转运。二 色胡枝子植株吸收的Al主要积累在根部，地上部分Al含量仅是根系的1％左右。

试验采用不同浓度的 Na2CO3、NaHCO3及盐碱混合(n(Na2CO3)∶n(NaHCO3)=1∶1)溶液对胡枝子幼苗进行胁迫处理,比较分析盐碱胁迫对胡枝子幼苗 的生长及其叶片质膜透性、游离脯氨酸及可溶性糖的影响,初步探讨胡枝子的抗盐碱能力。结果显示:在3种盐碱胁迫下,胡枝子叶片电导率、脯氨酸质量分数、可 溶性糖质量分数均随胁迫强度的增加、时间的延长而增加。低、中浓度胁迫对植株造成的伤害相对较弱,高浓度胁迫下胡枝子表现出较严重的盐害症状,生理指标的 分析结果与实际生长状态基本一致。到胁迫后期第55天时,Na2CO3浓度为150 mmol.L-1、NaHCO3浓度为150 mmol.L-1、Na2CO3和NaHCO3的混合溶液浓度为150 mmol.L-1处理下电导率分别达到对照的2.24、1.84、1.72倍,脯氨酸质量分数分别为对照的7.32、5.76、5.37倍,可溶性糖质量 分数较对照分别增加了67.37%、56.65%、52.50%。脯氨酸、可溶性糖的增加都可以看作是植物适应盐渍环境及增加自身抗盐能力的表现,说明胡 枝子对碳酸盐具有一定的适应能力。3种胁迫对胡枝子的伤害程度不同,Na2CO3造成的伤害最大,NaHCO3次之,混合盐碱对胡枝子造成的伤害程度最 弱。

采用312-D最优饱和设计,在辽西北典型的半干旱沙地地区开展了水肥耦合试验,研究了不同水肥处理对章古台地区1年生胡枝子幼苗生物量的影响,建立了胡枝子生物量的水肥回归数学模型.结果表明:不同水肥耦合对胡枝子生物量有显著影响,生物量最高值(43.47 g)出现在高水中氮次低磷组合,即土壤含水率17.52%,施氮量266.822kg·hm-2,施磷量190.187 kg·hm-2.单因素对生物量的影响是水大于氮.氮、磷耦合对生物量有促进的正效应,水、磷之间具有替代作用,对生物量有负效应,水、氮耦合对生物量具有正交互作用.边际效应中,胡枝子生物量随着水分的增加而增加,随着氮、磷的增加而减少.

自然条件下，对5种胡枝子属植物光合作用日进程和光响应进行了观 测，结果表明5种胡枝子净光合速率的日变化在夏季表现为双峰曲线，有光合”午休”现象。牛枝子、达乌里胡枝子、阴山胡枝子、截叶胡枝子和尖叶胡枝子日平均 光合速率分别为3．75μmol CO2·m^-2·s^-1、3．55μmol CO2·m^-2·s^-1、3．37μmol CO2·m^-2·s^-1、4．45μmol CO2·m^-2·s^-1、3．78μmol CO2·m^-2·s^-1；光补偿点分别为38．23μmol CO2·m^-2·s^-1、43．24μmol CO2·m^-2·s^-1、13．75μmol CO2·m^-2·s^-1、36．11μmol CO2·m^-2·s^-1和45．46μmol CO2·m^-2·s^-1；光饱和点分别为：1225μmol CO2·m^-2·s^-1、1262．6μmol CO2·m^-2·s^-1、1287．5μmol CO2·m^-2·s^-1、1462．5μmol CO2·m^-2·s^-1和1312．5μmol CO2·m^-2·s^-1显示了阳生植物特性。表观量子效率分别为0．034、0．037、0．32、0．036和0．033，可看出5种胡枝子叶片光 能转化效率低，其对光的响应敏感性较差。因此，这5种胡枝子对光环境适应能力强，适合在较大范围栽植。

在大兴安岭加格达奇地区,选择 处于不同退化阶段的蒙古栎林、灌丛、灌草丛和草丛,进行土壤和植物叶片C、N、P浓度及其化学计量比分析。结果表明,土壤全N、全P浓度随植被退化逐渐下 降,而土壤全C浓度在灌丛达到最高。随着植被退化,各退化阶段植物群落的叶片C、N、P浓度逐渐降低,而N/P比值则逐渐增加。蒙古栎林、灌丛、灌草丛和 草丛植物群落的叶片N/P比值分别为:7.35、8.04、9.36和13.61,均小于14。各退化阶段9个共有物种的叶片N/P比值,在蒙古栎林和灌 丛群落中均小于14;在灌草丛群落中小于14的共有物种8个,在14～16之间的共有物种1个;在草丛群落中小于14的共有物种7个,大于16的共有物种 2个。根据以往对N/P临界值的确定,可以认为该区各退化阶段的植物生长主要受N素的限制。

以桑树(Morus alba L.)为研究材料,在相同Na+浓度下,研究了中性盐(NaCl)和碱性盐(Na2CO3)胁迫下桑树幼苗生长和光合特性的响应特性。结果表明,100 mmol/L NaCl对桑树幼苗的生长和光合影响较小,桑树幼苗可以通过增加根冠比和叶片非光化学淬灭(NPQ)来适应盐胁迫。但是,50 mmol/L Na+浓度下,Na2CO3胁迫对桑树幼苗植株的生长和根系生长的抑制效果明显大于NaCl的。同时,Na2CO3胁迫降低了桑树幼苗叶片的叶绿素含量和 桑树幼苗叶片对光能的利用能力,光饱和时的最大光合速率(Pmax)降低,并且桑树幼苗叶片吸收的光能不能完全用于电子传递,而NPQ等光合热耗散能力受 抑制,导致过剩光能的大量积累。因此,在相同Na+浓度下,碱性盐(Na2CO3)胁迫对桑树幼苗的伤害比中性盐(NaCl)胁迫的严重,Na2CO3胁 迫不但抑制了桑树幼苗根系的生长,而且降低了叶片的光合热耗散能力。

以紫丁香(Syringa oblata Lindl.)为试验材料,研究了叶片展开过程中花色素苷含量变化对叶绿素含量、叶绿素荧光特性和光合激发能分配的影响。结果表明:紫丁香叶片从幼叶伸出 到叶片成熟的各生育阶段,花色素苷含量降低,而叶绿素含量增加,二者之间呈明显的负相关,叶片对光能的捕获和利用能力也随着花色素苷的降低而增强,但是, 从叶片伸出到叶片展开,叶片最大光化学效率(F v/F m)没有明显变化。在紫丁香叶片伸出到扩展的进程中,花色素苷含量降低,PSⅡ反应中心吸收的光能分配到失活PSⅡ反应中心的热耗散量子产额(ФNF)下 降,以及依赖于叶黄素循环的量子产额(ФNPQ)下降。说明叶片叶龄越小,花色素苷含量越多,依赖于类囊体膜两侧质子梯度和叶黄素循环耗散的能量比例明显 高于成熟叶片,而且PSⅡ反应中心吸收光能分配到无活性反应中心的比例较大,这种光能的分配机制明显降低了幼叶中有活性PSⅡ反应中心的压力,因此,花色 素苷可防止幼叶光合机制受到过剩光能的破坏。

In order to explore the effects of different water treatments and plant densities on growth, photosynthetic pigments and chlorophyll fluorescence of Cynodon dactylon, 4 water treatments and 4 planting densities including 16 treatments were applied. The water treatments included normal water supply (CK), light floodinglight drought alternating (FD), light flooding (LF) and flooding (FL) and planting densities included 1 plant per pot (CK), 2 plants per pot (low density), 4 plants per pot (medium density), and 12 plants per pot (high density). The results showed that water treatments, plant densities and their interaction significantly affected (P

以盆栽当年生狗牙根(Cynodon dactylon)扦插苗为试验材料，通过模拟水库库区河岸带不同土壤水分及不同种植密度对狗牙根生长、光合色素及荧光特性的影响进行探究。试验设置4个土壤水分处理组：水分对照组(CK)、水淹与干旱交替组(FD)、土壤水分饱和组(LF)和全淹组(FL)，4种种植密度：对照（1株·盆-1）、低密度（2株·盆-1）、中密度（4株·盆-1）及高密度（12株·盆-1）。结果表明，1）水分、种植密度及二者的交互作用均显著影响狗牙根叶面积指数、单株总生物量及主茎长(P 0.05）；二者交互作用显著影响狗牙根光化学猝灭系数(qP)（P

对6个不结球白菜品种的光合作用特性进行了研究.结果表明,在800μmol·m-2·s-1的光强下,不结球白菜的净光合速率以‘正大抗热青3号’最高,达16.37μmol CO2·m-2·s-1,其光合作用表观量子效率、羧化效率和水分利用效率也最高,分别为0.044 2、0.085 4 mol·m-2·s-1和6.20μmol CO2·mmol-1 H2O;暗呼吸速率以‘绿星’最低,为2.24μmol CO2·m-2·s-1;Pn-PFD响应曲线显示,在光强300μmol·m-2·s-1以下,各品种的净光合速率差异较小,在光强为300～1 000μmol·m-2·s-1区段时,净光合速率随着光照强度增加而迅速增加.‘正大抗热青3号’光饱和点最高,达1 910.3μmol·m-2·s-1,其光饱和点的净光合速率也最高,达20.2μmol CO2·m-2·s-1;不结球白菜不同品种净光合速率日变化进程相似,不论数值高低均呈双峰曲线型,有明显的"午休"现象.

基于指数改进模型估算了亚热带常绿阔叶林优势树种米槠(castanopsiscarlesii)、丝栗栲(castanopsisfargesii)和木荷(schimasuperba)生长旺盛期(春、夏、秋季)的光合参数特性。结果表明:米槠、丝栗栲、木荷光饱和点春季最小,分别为1241.25、1245.93、1366.49μmol/(m2？s);最大净光合速率夏季均最大,分别为3.78、5.39、7.20μmol/(m2？s)。木荷春季的光饱和点、光补偿点、最大净光合速率、暗呼吸速率均大于米槠和丝栗栲。在夏季和秋季,木荷和丝栗栲光饱和点均大于米槠;木荷最大净光合速率均大于米槠和丝栗栲,且在秋季其最大净光合速率仍大于米槠。综合比较得出:木荷具有较强的光合能力和光环境适应能力,其次是丝栗栲,米槠较差。

The effects of calcium chloride on photosynthesis characteristic and chlorophyll fluorescence characteristic of flue-curing tobacco seedlings under chilling and high light acclimation were studied, and the seedlings of flue-curing tobacco variety Longjiang 911 was grown as material. The results showed that the net photosynthetic rates(Pn), stomatal condu ctance(Gs), maximal photochemical efficiency of PSⅡ(Fv/Fm) and actual photochemical efficiency of PSⅡ(ФPSⅡ) significantly decreased under the chilling and high light acclimation compared with non-acclimation seedlings, suggesting that the stress resistance was strengthened while photosynthetic capacity reduced. Pn, Fv/Fm and ФPSⅡof flue-curing tobacco seedlings increased to various degrees at the later stage of acclimation, which implied that the flue-curing tobacco seedlings leaves protected against damage of photosynthetic apparatus by suffering photo-inhibition under temperature and light intensity conducted in the experiment. The carbon dioxide compensation point(CCP) significantly decreased, while Pn, Gs, Fv/Fm,ФPSⅡ, apparent quantum yield(AQY), photosynthetic rate saturated light (Pmax), light compensation points (LCP), light saturation point(LSP), carbolyation efficiency (CE) and photosynthetic rate at saturated carbon dioxide(Jmax) of flue-curing tobacco seedlings leaves were significantly higher than that of acclimation seedlings after spraying calcium chloride. It is concluded that calcium chloride could alleviate damage of the photosynthetic apparatus of tobacco seedlings leaves under chilling and high light acclimation.

以烤烟品种龙江911为材料,研究了喷施CaCl 2 对烤烟幼苗低温高光锻炼过程中光合和叶绿素荧光特性的影响。结果表明:低温高光锻炼过程中,烤烟幼苗的净光合速率(Pn)、气孔导度(Gs)、最大光化学效率(Fv/Fm)和实际光化学效率(ФPSⅡ)均明显低于未锻炼幼苗,说明低温高光锻炼虽然能够增强烤烟幼苗的抗逆性,但却降低了其光合能力。锻炼后期烤烟幼苗的Pn、Gs、Fv/Fm和ФPSⅡ有所恢复,说明在锻炼期间烤烟幼苗叶片发生了光抑制,但这种温度和光强的锻炼并没有对烤烟幼苗光合机构产生破坏。喷施CaCl 2 后,烤烟幼苗叶片的Pn、Fv/Fm、ФPSⅡ、表观量子效率(AQY)、光饱合时的净光合速率(Pmax)、光补偿点(LCP)、光饱合点(LSP)、羧化效率(CE)以及CO 2 饱合时的净光合速率(Jmax)均明显高于低温高光锻炼幼苗,并且喷施CaCl 2 可以显著降低CO 2 补偿点(CCP),说明在烤烟幼苗低温高光锻炼过程中,喷施CaCl 2 可以减轻锻炼期间因锻炼本身引起烤烟幼苗光合作用的下调。

Light is one of the most important factors that affect the regeneration and succession of tropical rain forests. Tropical trees with different successional status have different acclimation capacities to different growth light environments. In the present study, gas exchange and diurnal variation of chlorophyll fluorescence parameters were measured in the seedlings of three tropical rainforest Syzygium species, which are early (S. szemaoense), middle (S. cumini) and late (S. latilimbum) successional species. The seedlings were cultivated under three different light regimes (fully open site, 42% and 14% daylight). Their leaf mass per unit area (LMA) and chlorophyll content were also determined. The early successional species had the highest light- saturated photosynthetic rate (Pmax) and photosynthetic acclimation capacity to the variation of growth light environments, the next was the middle successional species. The late successional species had the lowest Pmax values and its photosynthesis was strongly suppressed when grown in full light. Nevertheless, grown under both the full light and 42% daylight, all the three species did not suffer from irreversible photoinhibition, as indicated by their dawn values of maximal photochemical efficiency of PS Ⅱ (Fv/Fm) larger than 0.8, and their φPSⅡ was able to recover on the same day. Dynamic (reversible) photoinhibition occurred in all species, the degree of which increased with growth light level. Among species, the degrees of dynamic photoinhibition were similar. The non-photochemical fluorescence-quenching rate (NPQ) increased with the growth light level for all species. However, in the fully open site, the NPQ rates in the morning were higher in the late and middle successional species than in the early successional species. This compensated for the lower photosynthetic rates of the former two species, and probably plays a role in preventing photodamage to these species under full light. Leaf dark respiration rate per unit area (Rd) and leaf mass per area (LMA) tended to increase with the growth light level. Under the same light regimes, Rd was higher in early than in middle and late successional species. The LMA values of late successional species were higher than for the other two species. This could be favorable for this shade-tolerant species to prevent herbivory. For all of the three species grown in 14% daylight, area-based Pmax, photosynthetic light saturation point, light compensation point, Rd and LMA were reduced, while chlorophyll content per unit dry weight were increased compared to those in the other two light regimes. This showed their favorable acclimation to low light. Nevertheless, under 14% daylight the seedlings of both the early and middle species died, only the seedlings of the late successional species were still alive. This indicates that this late successional species has high capacity to acclimate to low light.

测定了生长于3种光强下（100％、42％和14％自然光强） 热带雨林演替早期（思茅蒲桃Syzygium latilimbum）、中期（乌墨S.cumini）和后期（阔叶蒲桃S. szemaoense）出现的蒲桃属 （Syzygium）3个树种幼苗叶片气体交换参数和叶绿素荧光参数的日变化、比叶重和叶绿素含量。发现演替早期树种光合能力和光合可塑性最大、中期树种次之，后期树种光合能力最弱且在强光下受到显著抑制。但是，生长在强光下，3个树种均未发生长期光抑制和光破坏。随生长光强增加，3个树种热耗散速率都升高。不过在强光下，中期和后期树种通过热耗散消耗的过剩光能较多，通过叶黄素循环的热耗散可能对于这两个树种在强光下避免光合机构的光破坏起到了重要作用。14％光强下，3个树种最大净光合速率、光合作用的光饱和点、光补偿点、暗呼吸速率、比叶重降低，叶片单位干重叶绿素含量提高，对低光环境有了较好的形态学和生理学适应。但是，在4％光强下思茅蒲桃和乌墨幼苗全部死亡，只有阔叶蒲桃幼苗仍能存活，说明阔叶蒲桃幼苗适应弱光环境的能力高于思茅蒲桃和乌墨，与它们的演替状态一致。

To explore the adaptation mechanisms of Fagopyrum dibotrys to high temperature stress and to evaluate the differences of heat resistance of eight F. dibotrys germplasm resources, it was measured that the characteristics of gas exchange and chlorophyll fluorescence parameters in leaves of eight germplasm resources under the high temperature (35 ℃ and 45 ℃) stress. The results showed that: There were very obvious effects of heat stress on photosynthesis and chlorophyll fluorescence parameters; With the strength of the heat stress, it was significantly decreased that the net photosynthetic rate (Pn), stomatal conductance (Gs), transpiration rate (Tr), water use efficiency (WUE), PSⅡ potential activity(Fv/Fo), PSⅡ maximum photochemical efficiency (Fv/Fm), PSⅡ actual photochemical quantum yield (yield) and PSⅡ photochemical fluorescence quenching (qP) in all of germplasm resources; However, it was increased that the nonphotochemical fluorescence quenching (NPQ) in leave of JQ4, JQ5, JQ7, but decreased as the strength of heat stress was increased, and steadily increased that the non-photochemical fluorescence quenching (NPQ) in leave of JQ1, JQ2, JQ3, JQ6, JQ8. The nine single indexes were changed into two comprehensive indexes by using the principal components analysis. The weight of two comprehensive indexes were 0.816 and 0.184, respectively. According to the results of subordinate function value analysis, the heat resistance capability was in the order of JQ6＞JQ2＞JQ3＞JQ1＞JQ8＞JQ4＞JQ5＞JQ7 in eight F. dibotrys materials. Based on above, the better heat-tolerant F. dibotrys germplasm resourses could regulate the stomatal conductance, decrease the transpiration rate, increase the water use efficiency, and made excited energy dissipated as thermal dissipation to resist high temperature and protect the photosynthetic apparatus.

以8个野生金荞麦（Fagopyrum dibotrys）种质为试材，在室内模拟35和45 ℃高温胁迫，测定了各种质气体交换和叶绿素荧光参数，探讨金荞麦对高温胁迫的光合适应机制，并在利用主成分分析和隶属函数法综合考虑各综合指标权重的基础上，评价种质间耐热性强弱。随着高温胁迫强度的增加，各金荞麦种质的净光合速率（Pn）、气孔导度（Gs）、蒸腾速率（Tr）、水分利用效率（WUE）、PSⅡ的潜在活性（Fv/Fo）、最大光化学效率（Fv/Fm）、实际光量子产量（Yield）和光化学猝灭系数（qP）等参数均逐渐降低；叶片非光化学荧光猝灭系数（NPQ）则先增加后降低（JQ4、JQ5和JQ7）或一直增加（JQ1、JQ2、JQ3、JQ6和JQ8）。利用主成分分析将9个单项指标转换为相互独立的两个综合指标（第一、二主成分），其权重分别为0.816和0.184。隶属函数法综合评价出8个金荞麦种质耐热性顺序分别为JQ6＞JQ2＞JQ3＞JQ1＞JQ8＞JQ4＞JQ5＞JQ7。为抵御高温，耐热性强的金荞麦种质通过调节气孔导度，减小蒸腾速率，提高水分利用率，并将过剩的激发能以热的形式耗散掉，以保护光合机构。

The effects of D1 protein turnover and xanthophylls cycle on photosystem Ⅱ functions of Morus alba leaves under NaCl stress were studied by using their inhibitors. The results showed that there were sound mechanisms of photoprotection in M. alba leaves and PSⅡ reaction center remained high activity under 100 mmol·L -1 NaCl stress. PSⅡfunctions in SM or DTT treated leaves were damaged under NaCl stress. More severe damage occurred in SM treated leaves than that in DTT treated ones, which indicated D1 protein turnover and xanthophylls cycle played an important role in protecting PSⅡ functions in leaves of M. alba under NaCl stress, and D1 protein turnover might play more important role than xanthophylls cycle. DTT treatment limited protection ability of the xanthophlly cycle in leaves of M. alba under NaCl stress, but was able to reduce the damage of the excessive excitation energy to PSⅡ reaction center by increasing dissipation of ineffective fluorescence and heat. SM not only damaged the xanthophylls cycle but also fluorescence and heat dissipation functions, leading to (1- q P )/ NPQ large accumulation and PSⅡ reaction center deactivation. SM not only suppressed the D1 protein turnover, but also aggravated the Q B reduction degree, which reduced the electronic transfer and the capacity of PQ. The decrease of PQ capacity ievitably depressed the thylakoid membrane functions establishing protons gradient (△pH) and limited the xanthophylls cycle that is dependent on △pH. In summary, inhibition of D1 protein turnover damaged xanthophylls cycle, which could interpret the reason why D1 protein turnover played more important role than xanthophylls cycle in protecting PS Ⅱ functions in leaves of M. alba under NaCl stress.

采用抑制剂法研究盐胁迫下D1蛋白周转和叶黄素循环对桑树叶片PSⅡ功能的影响。结果表明: 桑树叶片在100 mmol·L -1 NaCl胁迫下保持较高的PSⅡ反应中心的活性,具有完善的光破坏防御机制。通过硫酸链霉素(SM)抑制D1蛋白的周转和二硫苏糖醇(DTT)抑制叶黄素循环,损伤盐胁迫下桑树叶片的PSⅡ反应中心,加剧盐胁迫对桑树叶片PSⅡ反应中心的伤害,说明D1蛋白周转和叶黄素循环在保护盐胁迫下桑树叶片PSⅡ功能中发挥重要的作用,并且D1蛋白周转的保护作用大于叶黄素循环。DTT抑制盐胁迫下桑树叶片的叶黄素循环,却将PSⅡ反应中心吸收的光能大部分以无效的荧光和热能形式耗散,减缓过剩激发能对PSⅡ反应中心的伤害程度。SM处理可抑制D1蛋白周转,减弱盐胁迫下桑树叶片以叶黄素循环为主的耗散非辐射能量的能力,降低过剩激发能的热耗散程度,导致叶片中的过剩光能(1- q P )/NPQ成倍积累,造成PSⅡ反应中心大量失活。因此,SM不但可抑制D1蛋白的周转,还可增强Q B 的还原程度,降低电子传递链上的电子传递,PQ库容量降低,减弱依赖PQ在类囊体膜两侧建立质子梯度(△pH)的能力,从而限制依赖于△pH的叶黄素循环。因此,盐胁迫下抑制D1蛋白的周转不但降低吸收光能后用于电子传递的比例,而且会破坏叶黄素循环耗散过剩的光能,这也是D1蛋白周转对PSⅡ的保护作用大于叶黄素循环的原因之一。

缺铁叶片的光合速率大幅度下降.这种降低可能不是色素含量降低的结果;而且缺铁对PSII复合物的活性影响很小;较高的PQ还原程度显示缺铁叶片PSII 受体侧电子传递受阻,这可能是导致光合速率下降的主要因素.强光下缺铁叶片的天线转化效率比正常叶片低,用于光化学反应的激发能很少.缺铁导致大豆叶片激发能耗散增加.通过抑制剂处理和叶黄素组分的分析,可以认为在耗散过剩激发能的过程中,缺铁叶片充分启动了叶黄素循环.