两种杜鹃花属植物对长期遮阴后全光照环境的生理响应及其光保护机制

植物通过提高光能利用能力和光保护途径以响应环境光强的增加, 但不同植物对环境光强增加的生理响应存在差异, 从而导致植物对光环境的适应性不一致。为探讨植物对光环境变化的生理响应及其适应机制, 该文以遮阴条件下培养1年的2种杜鹃属(Rhododendron)植物比利时杜鹃(R. hybrida)和杜鹃(R. simsii)为材料, 对其由遮阴后转入全光照下培养5天时的叶片叶绿素荧光参数及其快速光曲线变化进行了比较研究, 以期从叶片吸收光能分配和光保护机制的角度探讨这2种植物对光环境变化的适应机制。结果表明: 全光照降低了喜阴植物比利时杜鹃叶片的光化学反应和热耗散能力, 且其吸收光能分配于光化学反应和调节性能量耗散部分的比例减少, 导致光系统II反应中心过量激发能积累, 造成了叶片光抑制甚至光破坏。杜鹃作为耐阴喜光植物对光环境变化具有较强的适应性, 具有较高的光化学反应、热耗散和环式电子传递能力等内在生理特性; 在遮阴和全光照两种光环境下均能维持较高的吸收光能在光化学反应和调节性能量耗散部分的分配比例, 从而保护了光合机构的正常运行, 是其全光照强光未造成叶片光抑制的原因。     

遮阴对高山杜鹃叶片解剖和光合特性的影响

为了解高山杜鹃对光能的需求和适应性,该研究以盆栽3 a生高山杜鹃品种cv. Furnivall's Daughter为材料,探讨了遮阴对高山杜鹃叶片解剖结构和光合特性的影响。结果表明:光照强度对高山杜鹃品种cv. Furnivall's Daughter叶片的气孔密度没有显著影响,其气孔密度范围在299.70~327.22个·mm~(-2)之间,但光照对气孔开度和单个气孔器的面积影响显著,100%全光照和30%全光照处理植株分别具有最小和最大的叶片气孔开度。在处理的光强范围内,随着光强减弱,叶片厚度、栅栏组织厚度、海绵组织厚度以及上、下表皮厚度逐渐降低,有利于提高叶片的光能利用效率。100%全光照处理下,高山杜鹃叶片的光饱和点(LSP)、净光合速率(P_n)、饱和光合速率(P_(max))、气孔导度(Gs)、蒸腾速率(Tr)均较低,遮阴处理有效提高了Pn、P_(max)、G_s、T_r和光能利用效率(LUE),且30%全光照处理植株的叶片光补偿点(LCP)、暗呼吸速率(Rd)最低,而LSP、P_n、P_(max)、G_s、T_r和LUE最高。这表明高山杜鹃在云南昆明地区的最适光照条件是30%左右的全光照,在高山杜鹃的栽培及应用中,应采取适当的遮阴措施以满足其生长的最佳光照条件。     

光强因子对少花桂幼苗形态和生理指标及精油含量的影响

光是影响植物生长的重要因子之一。它不仅能够影响植物的光合作用,同时,光还以环境信号的形式作用于植物,通过光敏色素等作用途径调节植物生长、发育和形态建成,使植物更好地适应外界环境。除此之外,光还可以影响植物的初生代谢过程和次生代谢。因此提高植物体内重要次生代谢产物,光的因素不可忽视。少花桂(Cinnamomum pauciflorum)是樟科樟属多年生常绿小乔木,其体内含有精油,鲜叶含油量可达3．5％,比黄樟树根含油量高出1倍左右,精油中黄樟油素纯度高达95％以上。以少花桂为材料,采用人工模拟不同生境的光照条件,探讨光强因子对少花桂生长及精油含量的影响,以求对其生产提供理论指导。通过窗纱遮荫实现对其生境光的控制,研究了光强因子对少花桂幼苗形态结构、水分状况、光合指标、生物量、香桂油含量和纯度的影响。结果表明：随生境相对光照强度的减弱,叶片厚度、叶片上表皮厚度、下表皮厚度、栅栏组织、海绵组织厚度、根冠比等都呈现降低的趋势;而平均单叶面积却呈现出增加的趋势;株叶面积在61．5％的全光照下有所增加,而在33．8％和15．4％全光照条件下大幅度减小;遮荫条件下生长的少花桂幼苗根系相对不发达,根冠比小;生境的光照强度会影响植株的水分蒸腾,从而影响含水量。在同样光照下,全光照条件下生长的少花桂幼苗保水能力最强,其次是61．5％全光照,最差的是15．4％全光照。少花桂幼苗的光饱和点、光补偿点随生境中的光强减弱而降低。过度遮荫条件下生长的少花桂幼苗CO2补偿点明显高于自然条件下生长的少花桂幼苗;随生境中的光强度的减弱其光呼吸速率升高,单位叶面积的叶绿素含量增加．Chla／Chlb值减小。遮荫处理后,不同光照条件下生长的少花桂幼苗的质量增加存在显著差异。遮荫过程中61．5％、33．8％和15．4％全光照条件下生长的少花桂幼苗叶片鲜质量的增长速率分别为全光照的1．6倍、1．2倍和0．77倍。香桂油含量以61．5％和33．8％全光照为多,均比全光照高出5％左右,而15．4％全光照叶片含油量又较全光照少5％左右。香桂油中黄樟油素纯度,以33．8％、15．4％全光照生境下的少花桂幼苗叶片为高。少花桂幼苗轻微遮荫(61．5％全光照)栽培．能获得较高的枝叶产量和香桂油产率．重度遮荫(33．8％、15．4％全光照)能获得纯度较高的黄樟油素。     

光照条件对高山杜鹃光合生理特性的影响

以高山杜鹃‘Furnivall’s Daughter’3年生植株为材料,采用遮阳网遮荫方法设置100%(L1)、53%(L2)、30%(L3)、17%(L4)全光照,研究不同光照对其光合特性及其相关生理特性的影响,探讨高山杜鹃对不同光强的响应及适应机制。结果表明:(1)与全光照条件相比,遮阴处理可有效提高光饱和点(LSP),降低光补偿点(LCP)和呼吸速率(Rd),从而具有较高的净光合速率(Pn);其中L3处理植株的LCP、Rd最低,而且其LSP和饱和光合速率(Pmax)最高,表明L3光照条件是其最适宜的生长光强。(2)随着光照强度的降低,叶片的叶绿素a呈轻微下降趋势,而叶绿素b、单位面积叶氮含量(LNCa)、光合氮利用效率(PNUE)则呈显著增加趋势,且光照强度对叶绿素b的影响较叶绿素a敏感,从而导致总叶绿素含量显著增加,而叶绿素a/b比值下降。(3)可塑性分析结果表明,高山杜鹃‘Furnivall’s Daughter’主要通过Pmax、LSP、LCP、Rd、PNUE和叶绿素含量的改变来适应光环境的变化,而比叶重(LMA)、LNCa、丙二醛(MDA)、超氧化物歧化酶(SOD)在其适应光环境的过程中作用较小。     

越冬期遮阴条件下3个不同秋眠型紫花苜蓿品种叶片解剖结构与其光生态适应性

在我国南北气候过渡地区, 采用遮阴试验和石蜡切片法, 研究越冬期不同光强对3个不同秋眠型紫花苜蓿(Medicago sativa)品种(‘维多利亚’、 ‘巨人201’和‘游客’)叶片解剖结构的影响。结果表明: 随着光强减弱, 各紫花苜蓿品种表皮结构中上、下表皮角质层厚度, 气孔密度和气孔开度明显下降; 上、下表皮厚度呈上升趋势。随着遮阴强度增加, 叶肉组织中海绵组织细胞宽度显著上升, 栅栏组织厚度、栅栏组织细胞层数、栅栏组织厚度/海绵组织厚度显著下降; 品种间海绵组织厚度和栅栏组织细胞宽度变化趋势不一致。叶片结构整体特征中叶片厚度、叶肉厚度、中脉厚度、组织结构紧密度随光强减弱而显著下降, 组织结构疏松度明显上升, 叶脉突起度变化不明显。品种间各叶片解剖性状变幅及可塑性指数具有明显的差异, 表明其对弱光适应方式不同。Pearson相关分析表明, 各紫花苜蓿品种叶片气孔密度、栅栏组织厚度、叶肉厚度、叶片厚度及栅栏组织厚度/海绵组织厚度与光强呈显著正相关, 可能是紫花苜蓿叶片解剖结构光强敏感特征参数, 其中, ‘维多利亚’叶片敏感特征参数与光强相关程度较低, 与光强相关的性状较少。综合各项分析结果, 初步确定越冬期紫花苜蓿耐阴性与其秋眠性相关, 半秋眠型品种‘维多利亚’ >秋眠型品种‘巨人201’≥非秋眠型品种‘游客’。     

两种绣线菊耐弱光能力的光合适应性

研究彩色叶花灌木金山绣线菊(Spiraea bunmalba‘Goldmound’)、金焰绣线菊(Spiraea bunmalba‘Goldflame’)对弱光胁迫的光合适应能力,分析其弱光处理及恢复过程中光合特性的变化,探讨其对弱光环境的光合生理适应性变化,为绣线菊在城市园林不同光照环境中得到科学应用提供参考.2种绣线菊具明显光合日变化规律,光强为自然光照60％-65％、40％-45％时光合速率日变化为双峰型曲线,第1峰值高于第2峰值,有明显光合“午休”现象,光强为自然光照20％-25％时光合速率日变化为单峰型曲线,无明显光合“午休”现象;2种绣线菊最大净光合速率、光补偿点、光饱和点、最大表观量子效率和暗呼吸速率随处理光强减弱而减小;叶绿素(a+b)、类胡萝卜素含量随处理光强减弱而增加,叶绿素a/b值随处理光强减弱而降低;随处理光强减弱2种绣线菊叶片变薄,上、下表皮细胞变小,栅栏组织、海绵组织厚度变薄,海绵组织细胞间隙变大,2者比值减小;2种绣线菊弱光胁迫均产生低分子量(45.0-66.2 kDa)特异表达蛋白,推测为弱光胁迫诱导蛋白.2种绣线菊经60％-65％、40％-45％弱光处理后具一定恢复能力,光强仅为自然光照20％-25％处理时其恢复能力较弱.栅栏组织与海绵组织厚度比值、叶绿素a/b值和最大净光合速率是评价2种绣线菊耐弱光能力的重要指标,叶绿素a/b值与耐弱光能力显著负相关,栅栏组织与海绵组织厚度比值、最大净光合速率与耐弱光能力显著正相关,2种绣线菊耐弱光能力按隶属函数值排序为金焰绣线菊＞金山绣线菊.     

人工针叶林林下11种植物叶片解剖特征对不同生境的适应性

人工林内两种主要生境（林窗和林内）的光照条件存在着显著差异,而这种差异也是影响人工林林下植物叶片形态和结构的重要环境因子。对川西米亚罗林区60a人工云杉林2种不同生境（林窗和林内）的11种植物比叶重、叶片解剖结构及气孔特征等进行了比较研究,结果显示：林窗生境中11种供试植物比叶重（LMA）均显著大于林内生境;多数阔叶物种叶片厚度（LT）、栅栏组织厚度（PT）、栅栏组织厚度／海绵组织厚度（PT／ST）、栅栏细胞层数在林窗生境中更大或更多,但叶表皮细胞厚度（UET、LET）、海绵组织厚度（ST）在两种生境中无显著差异;林窗生境中生长的各物种栅栏细胞均为长形且长度大于林内生长的相同物种;不同物种气孔密度（SD）对两种生境有一致的响应趋势,但显著程度有异,除三褶脉紫菀外10种植物的气孔长径（SL）受两种生境影响不大,这与气孔特性受多种环境因素制约,且各种因素对气孔作用效应和作用方面不同有关。结合各物种喜光特性综合分析后认为同一群落的林下植物对光生境具有一定程度的趋同适应性;从可塑性方面分析发现叶片光合组织的可塑性大于非光合组织,且各物种叶片平均可塑性与喜光特性基本吻合。     

四种热带雨林树种光合和形态解剖特征对不同生长光强的适应

研究了西双版纳热带雨林2种喜光树种中平树(Macaranga denticulata)、倒樱木(Pnravallaris macrophylla)和2种耐荫树种云南肉豆蔻(Myristica yunnanensis)、金丝李(Garcinia paucinervis)幼苗叶片光合和形态解剖特征对3种不同生长光强(5％、25%和50％相对光强)的适应。研究结果表明,与强光下相比,弱光下生长的4种植物最大净光合速率、光饱和点、光补偿点、暗呼吸速率、叶绿素a／b、叶片和栅栏组织厚度、气孔密度和比叶重都降低,而海绵组织／栅栏组织和叶绿素含量升高。在相同光强下,与2种耐荫树种相比,2种喜光树种有较大的最大净光合速率、暗呼吸速率、气孔密度和较低的叶绿素含量。在不同光强下,4种植物均表现出了对光适应有利的生理和形态解剖可塑性,而喜光树种比耐荫树种有较大的生理和形态可塑性,表明喜光树种具有比耐荫树种对强光有更强的适应能力。4种植物的生理指标的可塑性均大于叶片解剖结构的可塑性。     

毛白杜鹃(Rhododendron mucronatum) 适生光强的生理生化研究

研究了毛白杜鹃最适生境的相对光强和其在不同相对光强生境中抗性变化的规律。结果表明：当生境的相对光强处于65％以上时,毛白杜鹃叶子内过氧化物酶和过氧化氢酶活性达到较低值,而还原型Vc,单宁酸,多酚类的含量达到了较高值。同时,在相对光强为65％以上的生境中,毛白杜鹃类不仅生长发育健壮,抗逆性强,而且,开花指数和观赏价值达到了较高值。因此,推断毛白杜鹃类适生生境的相对光强为65％以上。而且过氧化物酶和过氧化氢酶活性及还原型Vc、单宁酸、多酚类的含量可以作为衡量植物是否处于适生生境的指标。     

遮阴对绣球光合特性和叶绿素荧光参数的影响北大核心CSCD

为了从光合作用机制及叶片吸收光能分配的角度解释绣球(Hydrangea macrophylla)对不同光环境的适应机制,探讨绣球对光环境变化的生理响应和适应性,该文以盆栽的绣球品种‘无尽夏新娘’为材料,设置遮阴(遮光率为50%、75%)两种处理,并以全光照为对照,经过60天的处理,测定其光合-光响应曲线、气体交换参数、叶绿素荧光参数。结果表明:遮阴60天后,绣球的暗呼吸速率、光补偿点和光饱和点均有所下降,而表观量子效率(AQY)上升,说明绣球能够通过这些途径提高对弱光的利用能力并降低呼吸消耗,以维持植株正常生长,从而表现出了极强的适应能力;在50%的遮阴处理下,绣球叶片的净光合速率、胞间CO2浓度、蒸腾速率和水分利用效率均与其全光照和75%遮阴处理下差异显著;遮阴导致光系统II(PSII)最大光化学效率(Fv/Fm)增加,3种光照处理下呈显著差异,全光照下Fv/Fm低于50%遮阴处理,初始荧光水平高于50%遮阴处理,推断此条件下的绣球叶片发生了光抑制;而随着光照的减弱,非光化学淬灭系数在降低,说明遮阴降低了绣球叶片PSII天线色素吸收光能以热的形式耗散的比例,绣球叶片吸收的能量约70%用于热耗散,约20%用于非光化学反应,仅有4%的能量用于光化学反应,说明绣球处于饱和光环境下时,主要通过提高叶片吸收光能向热耗散等PSII调节性能量耗散途径的分配,削弱反应中心过量激发能的积累。     

Photosynthetic responses to light in seedlings of selected Amazonian and Australian rainforest tree species

Summary Seedlings of the Caesalpinoids Hymenaea courbaril, H. parvifolia and Copaifera venezuelana, emergent trees of Amazonian rainforest canopies, and of the Araucarian conifers Agathis microstachya and A. robusta, important elements in tropical Australian rainforests, were grown at 6% (shade) and 100% full sunlight (sun) in glasshouses. All species produced more leaves in full sunlight than in shade and leaves of sun plants contained more nitrogen and less chlorophyll per unit leaf area, and had a higher specific leaf weight than leaves of shade plants. The photosynthetic response curves as a function of photon flux density for leaves of shade-grown seedlings showed lower compensation points, higher quantum yields and lower respiration rates per unit leaf area than those of sun-grown seedlings. However, except for A. robusta, photosynthetic acclimation between sun and shade was not observed; the light saturated rates of assimilation were not significantly different. Intercellular CO₂ partial pressure was similar in leaves of sun and shade-grown plants, and assimilation was limited more by intrinsic mesophyll factors than by stomata. Comparison of assimilation as a function of intercellular CO₂ partial pressure in sun- and shade-grown Agathis spp. showed a higher initial slope in leaves of sun plants, which was correlated with higher leaf nitrogen content. Assimilation was reduced at high transpiration rates and substantial photoinhibition was observed when seedlings were transferred from shade to sun. However, after transfer, newly formed leaves in A. robusta showed the same light responses as leaves of sun-grown seedlings. These observations on the limited potential for acclimation to high light in leaves of seedlings of rainforest trees are discussed in relation to regeneration following formation of gaps in the canopy.     

Adaptations of the Photosynthetic Mechanism of Sugar Maple (Acer saccharum) Seedlings Grown in Various Light Intensities

Sugar maple (Acer saccharum Marsh.) seedlings were grown in a nursery for three years in 13, 25, 45 and 100 per cent of full daylight. During the third year of growth, the rates of their apparent photosynthesis and respiration were measured periodically with an infra-red gas analyzer at various light intensities and normal CO₂ concentration. In addition, the rates of apparent photosynthesis of a single attached leaf of the same seedlings were measured at saturating light intensity, hut varying CO₂ concentrations. An increase in the light intensity in which seedlings were grown had no effect on their height or mean leaf area, hut resulted in thicker leaves, an increase in the total leaf area per seedling due to an increase in the number of leaves, an increase in the dry weight especially of roots and a decrease in the chlorophyll content of leaves. Throughout the growing season seedlings grown in full daylight, as compared with those grown in lower light intensities, had the lowest rates of apparent photosynthesis measured at standard conditions (21,600 lux light intensity and 300 ul/l of CO₂), when this was expressed per unit leaf area, hut the highest rates on a per seedling basis. Thus dry matter production attained at the end of the growing season correlated positively with the photosynthetic rate per seedling, but not per unit leaf area. The rates of apparent photosynthesis of seedlings grown at lower light intensities were more responsive to changes in light intensity or CO₂ concentration than those of seedlings grown in full daylight intensity.     

热带雨林蒲桃属3个树种的幼苗光合作用对生长光强的适应

 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。     

成熟期光强对烤烟理化特性和致香成分含量的影响

2004、2005年在四川凉山烟科所通过盆栽试验,在烤烟成熟期营造不同的光照强度,研究了成熟期光强不同对烤烟品质的影响。结果表明:成熟期随着光照强度的降低,叶片厚度降低,栅栏组织/海绵组织的比值降低,烤后烟叶单叶重、厚度、叶质重降低,叶片含梗率增加,总糖和还原糖含量降低,总氮和烟碱含量升高,钾和氯含量增加,叶黄素、β-胡萝卜素和类胡萝卜素总量增加,中性致香成分含量呈增加趋势,增加到一定程度开始降低。     

Effects of light and temperature on leaf anatomy and photosynthesis in Fragaria vesca

Summary Fragaria vesca, the woodland strawberry, was grown under a series of controlled environments including variations in light intensity, average temperatures, and temperature amplitude around a constant mean. Observations on CO₂ exchange capacities, leaf anatomy, and cell ultrastructure were made for each treatment to determine relationships between these variables. With increasing light intensity, leaf thickness, leaf density, and mesophyll cell surface area and volume per leaf surface area increased. Net photosynthesis (NPS) per leaf weight decreased with increasing light pretreatment while NPS per area increased from low to medium intensity, then decreased at the highest intensity. Depression of photosynthesis at the highest light pretreatment may have been due to massive starch accumulation in the chloroplasts associated with the sodium vapor lamps used. Correlation of all anatomical variables was highly significant with dark respiration and NPS per dry weight but insignificant for NPS per leaf area. In the variable temperature treatments, photosynthetic acclimation occurred with a shift in optimum temperature for NPS in the direction of prevailing growth temperature. Absolute rates were highest at moderate pretreatment temperatures and were reduced by extreme growth temperatures. Thick leaves with low density mesophyll became thinner and more dense with increasing growth temperature corresponding to an increase in maximum net photosynthetic rates. Leaves became thicker and more dense at the highest temperatures, but with an increase in cell damage and indications of changes in metabolic pathways. Highest correlations for gas exchange rates were with specific leaf weight (weight per area). Correlation with other anatomical variables were scattered or insignificant. It was concluded that adaptation to a range of environmental conditions cannot be consistently attributed to changes in mesophyll cell volume or surface area.     

光强对烟草幼苗形态和生理指标的影响

通过白纱布遮荫模拟不同光生境条件(透光率分别为100%、68.2%、35.4%和16.7%),研究了光强因子对烟草幼苗形态和生理指标的影响.结果表明:随相对光强的减弱,幼苗高度增加,茎粗、干鲜比、叶片厚度和单位叶面积质量均呈降低趋势,幼苗干物质积累减少,但其对叶数的影响不大.弱光条件下,叶片自由水、叶绿素、总氮和蛋白质含量增加,束缚水含量降低,叶绿素a/b值减小,转化酶活性降低;烟草幼苗根系相对不发达,根冠比和根生物量减小,根系活力降低.表明弱光条件不利于培育烟草壮苗,生产中应尽可能改善苗床的光照条件.     

The Effects of Increased Illumination and Shading on the Low-Light-Induced Decline in Photosynthesis in Cotton Leaves

An experiment was carried out to study whether low-light-induced damage to the photosynthetic system in leaves of cotton (Gossypium hirsutum cv. Deltapine) which are below the compensation point in the canopy can be arrested and reversed by increased illumination. In addition it was intended to find out whether the photosynthetic system in leaves of shade plants show a greater resistance to low-light-induced damage than leaves of plants from more exposed habitats. The plants were grown at high density, and increased illumination to the shade leaves in the canopy was achieved by thinning the stand. Thinning was carried out at two stages and its effects on the decline in the photosynthetic capacity of the 4th leaf were followed. An early thinning was carried out shortly after the 4th leaf dropped below the compensation point and a late thinning 2 weeks later. Comparison was also made between the low-light-induced damage to the photosynthetic capacity of the 4th leaf in plants grown under two light regimes during the progressive increase in self-shading of the 4th leaf within the canopy. It was observed that both types of thinning arrested the low-light-induced damage to the photosynthetic system in shade leaves. The decline in photosynthetic capacity of the 4th leaf was stopped after both early and late thinning. The dry weight of the shoot system in the early and late thinned plants was not significantly different. It was double that of the control plants. The plants thinned early did not have higher shoot weight than the late thinned plants since there was a rapid shedding of flowers and fruits after early thinning. The 4th leaf in the early thinned plants showed a 30% increase in chlorophyll content and dry weight per unit leaf area. It is suggested that shedding of flowers and fruits, and increases in chlorophyll and dry weight per unit leaf area in the early thinned plants were caused by a change in the hormonal balance of the plants. The photosynthetic system in leaves of shade plants showed a greater resistance to damage by low light intensity than the photosynthetic system in leaves of plants grown at higher light intensities.     

光照强度对广西地不容光合特性和生长的影响

以盆栽当年生广西地不容为材料,研究不同光照强度(100%、50%、30%和15%自然光强)对其光合特性和生长的影响。结果表明:随着光照强度的降低,广西地不容最大净光合速率(P_(max))、光饱和点(LSP)、光补偿点(LCP)先减小,而后稍有增大;表观量子效率(AQY)在30%和50%光强下显著高于100%和15%光强处理;叶片叶绿素总量(Chl)、叶绿素a(Chla)、叶绿素b(Chlb)、类胡萝卜素(Car)含量随光强的减弱而增大,Car/Chl随光强的减弱而减小,Chla/Chlb比值在各处理间无显著差异;单叶面积随生长光强的减弱而增大,比叶重(LMA)则随着生长光强的减弱而减小;30%光强下广西地不容块根生物量最高,光照过强和过弱都不利于其生物量的积累。广西地不容对光强的适应范围较广,但光照过强或过荫均对生长造成不良影响,光合速率降低,生长减缓,块根生物量积累下降,30%光强是其当年生苗生长的最佳光强。     

四种热带雨林树种幼苗比叶重,光合特性和暗呼吸对生长光环境的适应

雾凉季研究了西双版纳热带雨林4种植物幼苗对生长光环境的适应,其中两个树种幼苗喜光（团花和滇南插柚紫）,两个树种幼苗耐荫（滇南红厚壳和玉蕊）发现弱光环境中生长的4种植物比叶重、光合能力、光饱和点、光补偿点暗呼吸速度、叶绿素a/b比较低,叶绿素含量较高。玉蕊和滇南红厚壳幼苗的光合能力和呼吸速度 于团花树和滇南插柚紫。团花树和滇南插机紫的比叶重和光合作用的可塑性大于玉蕊和滇南红厚壳。高光强下生长的团花树和滇南插机紫增加叶氮分配给羧化酶的比较。减少分配给叶绿素的比例。滇南红厚壳和玉蕊适应弱光环境的能力略强于团花树和滇南插机紫,但适应强光的能力较差。研究结果支持树种的生理生态特性决定了其演替状况和生境选择的假说,单位干重叶的光合能力和呼吸速率并未表现出利于光适应的可塑性,表明4种植物生理适应能力较差,形态学上的适应在4种热带雨林树种幼苗光适应方面起到了重要的作用,叶氮分配也是它们光适应的策略之一。     

Photosynthetic acclimation of plants to growth irradiance: the relative importance of specific leaf area and nitrogen partitioning in maximizing carbon gain

Changes in specific leaf area (SLA, projected leaf area per unit leaf dry mass) and nitrogen partitioning between proteins within leaves occur during the acclimation of plants to their growth irradiance. In this paper, the relative importance of both of these changes in maximizing carbon gain is quantified. Photosynthesis, SLA and nitrogen partitioning within leaves was determined from 10 dicotyledonous C₃ species grown in photon irradiances of 200 and 1000 µmol m^?2 s^?1. Photosynthetic rate per unit leaf area measured under the growth irradiance was, on average, three times higher for high‐light‐grown plants than for those grown under low light, and two times higher when measured near light saturation. However, light‐saturated photosynthetic rate per unit leaf dry mass was unaltered by growth irradiance because low‐light plants had double the SLA. Nitrogen concentrations per unit leaf mass were constant between the two light treatments, but plants grown in low light partitioned a larger fraction of leaf nitrogen into light harvesting. Leaf absorptance was curvilinearly related to chlorophyll content and independent of SLA. Daily photosynthesis per unit leaf dry mass under low‐light conditions was much more responsive to changes in SLA than to nitrogen partitioning. Under high light, sensitivity to nitrogen partitioning increased, but changes in SLA were still more important.