水分胁迫对茶树光合作用的影响

以铁观音茶树品种为材料,测定其干旱胁迫过程中叶片光合作用的和脱落酸含量的变化,结果表明：离体叶片,轻度水分胁迫,气孔导率下降是净光合速率,蒸腾速率下降的主要原因：严重水分胁迫,净光合速度下降是由叶肉细胞光合能力下降引起的。土壤自然干旱过程中,茶树叶片的净光合速率,气孔导度和蒸腾速率随着土壤水势下降而逐渐下降,ＡＢＡ含量逐渐提高;在－３８ｋＰａ开始水分胁迫,临时性萎蔫点在－５０ｋＰａ,永久性萎蔫点在     

水分胁迫对茶树光合作用的影响

以铁观音茶树品种为材料,测定其干旱胁迫过程中叶片光合作用和脱落酸（ＡＢＡ）含量的变化．结果表明：离体叶片,轻度水分胁迫,气孔导度下降是净光合速率、蒸腾速率下降的主要原因;严重水分胁迫,净光合速率下降是由叶肉细胞光合能力下降引起的．土壤自然干旱过程中,茶树叶片的净光合速率、气孔导度和蒸腾速率随着土壤水势下降而逐渐下降,ＡＢＡ含量逐渐提高;在－３８ｋＰａ开始水分胁迫,临时性萎蔫点在－５０ｋＰａ,永久性萎蔫点在－５８ｋＰａ;气孔导度与ＡＢＡ含量呈显著的负相关;复胁迫茶树经过抗旱锻炼后,其抗旱能力明显提高．     

半根及半根交替水分胁迫对苹果幼苗光合作用的影响

 【目的】模拟研究定位灌溉及分根区交替灌溉的‘嘎拉’苹果幼苗光合反应，探讨不同水分条件下叶片光合效率的气孔与非气孔限制作用。【方法】采用18% PEG 6000（w/v）模拟水分胁迫，研究了半根（HRS，模拟定位灌溉）、半根交替（AHRS，模拟分根区交替灌溉）及全根水分胁迫（WRS）下苹果光合参数、光合色素、超氧化物歧化酶（SOD）和丙二醛（MDA）含量的变化，及叶绿素荧光反应特点。【结果】水分胁迫条件下叶片光合速率、气孔导度与细胞间隙CO2浓度显著降低，叶温显著升高。HRS叶片MDA含量和SOD活性及叶绿素荧光反应与对照不存在显著差异；AHRS从交替后第2天起，叶片MDA含量显著高于对照，而Fv/Fo与Fv/Fm则显著低于对照；WRS在胁迫第5或6天后，叶绿素与类胡萝卜素含量、Fv/Fo和Fv/Fm、SOD酶活性显著降低，而MDA含量则显著增加。【结论】不同水分胁迫处理光合速率下降的原因存在差异：HRS主要由气孔限制所引起；AHRS既存在气孔限制，也存在非气孔因素限制；而WRS前期由气孔限制引起，随着胁迫时间延长，非气孔限制起着重要作用。     

水分胁迫对甜菜幼苗光合作用的影响

以HI0466(抗旱性强)和农大甜研4号(对照)为材料,研究了水分胁迫对其幼苗光合作用的影响.结果表明:水分胁迫下2个品种叶片净光合速率(Pn)、气孔导度(Gs)和蒸腾速率(E)均呈下降趋势,但下降幅度不同,HI0466的净光合速率降幅较小而气孔导度和蒸腾速率降幅较大;Ci/Ca比值出现了先下降后上升,表明轻度水分胁迫下叶片Pn下降是气孔限制因素,重度干旱胁迫下Pn降低主要由非气孔因素引起.     

水分胁迫对玉米叶片光合作用的影响

试验在盆栽人工控制水分的条件下,选用耐旱性不同的玉米杂交种沈单10、掖单13号和丹玉13号为试验材料,比较了不同水分胁迫强度对不同耐旱性玉米杂交种叶片光合作用的影响。结果表明,水分胁迫下玉米叶片光合速率随胁迫增强而下降,而在重度胁迫下光合速率显著下降。     

柑桔对水分胁迫的光合驯化(英文)

在柑桔苗水培液中加入PEG-4000(聚乙二醇,分子量4000)造成根际水分胁迫.处理后,植株水势急剧下降,光合、蒸腾受到严重抑制,气孔导度和叶肉导度也相应下降.随着胁迫的持续,受胁迫最严重的植株3天后全株落叶,其它处理叶水势(ψ_1)仍保持较低值,叶片相对含水量(LWC)回升,光合(Pn)和叶肉导度(Gm)也有所回升,而蒸腾(Tr)和气孔导度(Gs)回升迟于Pn和Gm,且都没有回升到处理前的水平.据此认为柑桔具有对水分胁迫的光合驯化现象.经三轮干旱处理的柑桔叶片光合下降的ψ_1阈值为-2.70MPa,而对照为-1.65MPa,这一结果也支持柑桔具有光合驯化现象的结论.经干旱驯化的柑桔叶片总体初始渗透势(π_O)和初始质壁分离时的总体渗透势(π_P)都下降,叶片脯氨酸含量提高,揭示了柑桔对水分胁迫的光合驯化是通过渗透调节完成的.根际水分胁迫解除后,植株Pn和Tr有恢复过头现象.     

水分胁迫对辣椒光合作用及相关生理特性的影响

 【目的】研究水分胁迫对辣椒光合作用及相关生理特性的影响, 揭示水分胁迫与辣椒光合作用及生理指标之间的关系,为辣椒栽培管理,抗性筛选提供理论参考。【方法】采用盆栽的方式,分别在正常供水和水分胁迫条件下,研究辣椒生长形态及相关生理指标,光合参数,叶绿素荧光参数,叶片气孔特征及叶绿体超微结构的变化。【结果】水分胁迫显著抑制了辣椒的生长,植株总的干物质含量下降,并且干物质含量向根的分配比例增加,向茎叶的分配比例减少。叶片水势（Ψ）、叶片相对含水量（RWC）、叶绿素（Chl.）及类胡萝卜素（Car.）的含量显著下降,叶片中丙二醛（MDA）含量,游离脯氨酸（Pro）的含量,超氧化物歧化酶（SOD）,过氧化物酶（POD）的活性均有所提高。叶片净光合速率（Pn）、气孔导度（Gs）、蒸腾速率（Tr）、胞间CO2浓度（Ci）、PSⅡ光化学量子效率（ΦPSⅡ）、光化学猝灭系数（qP）及光合电子传递速率（ETR）均下降,非光化学猝灭系数（NPQ）和水分利用效率（WUE）提高。水分胁迫后叶片气孔密度、气孔长度、气孔宽度均有所下降,大部分气孔关闭深陷。叶绿体变圆,基粒片层和基质片层弯曲排列紊乱,淀粉粒减少或消失。【结论】水分胁迫下辣椒光合速率的下降主要是由气孔限制引起的。光合参数、叶绿素荧光参数、叶片气孔特征以及叶绿体超微结构的变化与品种的抗性密切相关。     

水分胁迫对草莓光合作用的影响

研究了水分胁迫下草莓光合性能的变化及光合速率与气孔导度之间的相互关系．结果表明,水分胁迫降低了草毒的光合速率和叶片水势,使叶绿素含量减少．轻度胁迫时（处理前期）气孔导度的限制是导致光合率降低的主要原因,重度胁迫时（处理后期）叶肉光合能力的下降是引起光合速率降低的主要原因．     

土壤干旱下云锦杜鹃光合作用的限制形式*

 以盆栽五年生云锦杜鹃为材料,研究了土壤干旱胁迫下光合作用的限制形式。结果表明：轻度干旱胁迫下光合速率的下降主要由气孔限制引起,中度和重度胁迫下主要由非气孔限制引起,此时表观量子效率、最大光化学效率和羧化效率明显降低。云锦杜鹃光合日进程中出现了明显的光合“午休”。“午休”主要由非气孔限制引起,表观量子效率和光化学效率下降表明光抑制是午间非气孔限制形成和发展的深层原因。干旱胁迫加重了午间光合作用的光抑制。     

Responsibility of non-stomatal limitations for the reduction of photosynthesis—response of photosynthesis and antioxidant enzyme characteristics in alfalfa (Medicago sativa L.) seedlings to water stress and rehydration

Water stress by polyethylene glycol (PEG)-6000 solution (ψ _s = 0.2 MPa, stress time: 48 h, rehydration time: 48 h) was performed in leaves of two alfalfa cultivar (Long-Dong and Algonquin) seedlings. Gas exchange parameters, chlorophyll fluorescence parameters, activity of antioxidant enzyme and photosynthetic pigment concentrations were measured to investigate the available photosynthetic and antioxidant enzyme response to variable water conditions as well as stomatal and non-stomatal limitations to photosynthesis. The results showed that non-stomatal limitations were responsible for the reduction of photosynthesis during water stress. At the beginning of water stress (12 h), water was lost and then the stomata closed rapidly, which resulted in a decrease of transpiration, net photosynthesis and CO₂ diffusion. Therefore, when intercellular CO₂ concentration and carboxylation efficiency decrease, water use efficiency and value of stomatal limitation would increase. However, the decline of net photosynthetic rate was faster than transpiration rate. At the same time, the maximal photochemical efficiency, potential activity of PSII reaction center and photochemical quenching of chlorophyll fluorescence declined significantly, the activity of antioxidant enzyme increased rapidly and the photosynthetic pigment concentrations changed slightly. The results also indicated that, at the initial period of stress, neither oxidative stress nor membrane lipid peroxidation was induced, nor were photosynthetic structures damaged, but photosynthetic functions were partly inhibited. Therefore, the stomatal limitation and non-stomatal limitations had the same responsibility for the reduction of photosynthesis. At the mid-late stage of water stress, net photosynthetic rate, stomatal conductance, maximal photochemical efficiency, potential activity of PSII reaction center and photochemical quenching of chlorophyll fluorescence decreased linearly with the decline of the relative water content. And the relative electron transport rate, the effective quantum yield of PSII photochemistry and photosynthetic pigment concentrations declined continually. The activity of antioxidant enzymes maintained at a higher level but malondialdehyde accumulated gradually with prolonging of water stress. Simultaneously, the non-photochemical quenching of chlorophyll fluorescence increased obviously after water stress for 24 h. The remarkable decline of light saturated point of photosynthetic electron transport, that is, the initial point of photo-inhibition, was observed in advance. Therefore, non-stomatal limitations dominated the changes of a series of physiological and biochemical reactions during mid-late period of water stress. After 48 h rehydration, all the parameters except intercellular CO₂ concentration in Long-Dong recovered obviously but incompletely, which resulted from severe oxidative injury and photo-inhibition induced by water stress even though photo-protection was triggered during water stress in alfalfa leaves. Alfalfa seedlings were sensitive to water stress and there were certain differences between cultivars.     

Beneficial effects of silicon on photosynthesis of tomato seedlings under water stress

Silicon can improve drought tolerance of plants,but the mechanism still remains unclear.Previous studies have mainly concentrated on silicon-accumulating plants,whereas less work has been conducted in silicon-excluding plants,such as tomato(Solanum lycopersicum L.).In this study,we investigated the effects of exogenous silicon(2.5 mmol L~(–1))on the chlorophyll fluorescence and expression of photosynthesis-related genes in tomato seedlings(Zhongza 9)under water stress induced by 10%(w/v)polyethylene glycol(PEG-6000).The results showed that under water stress,the growth of shoot and root was inhibited,and the chlorophyll and carotenoid concentrations were decreased,while silicon addition improved the plant growth and increased the concentrations of chlorophyll and carotenoid.Under water sterss,chlorophyll fluorescence parameters such as PSII maximum photochemical efficiency(F_v/F_m),effective quantum efficiency,actual photochemical quantum efficiency(Ф_(PSII)),photosynthetic electron transport rate(ETR),and photochemical quenching coefficient(q_P)were decreased;while these changes were reversed in the presence of added silicon.The expressions of some photosynthesis-related genes including PetE,PetF,PsbP,PsbQ,PsbW,and Psb28 were down-regulated under water stress,and exogenous Si could partially up-regulate their expressions.These results suggest that silicon plays a role in the alleviation of water stress by modulating some photosynthesis-related genes and regulating the photochemical process,and thus promoting photosynthesis.     

干旱胁迫对大豆气孔特征和光合参数的影响

利用盆栽法对大豆进行了不同梯度的水分处理,以研究不同水分胁迫条件对大豆气孔特征和光合特征的影响。试验结果表明：随着水分胁迫强度的增加,大豆叶片的气孔长度、宽度、周长、面积均呈减小趋势,气孔密度呈增加趋势。轻度水分胁迫条件下,大豆叶片的净光合速率（Pn）日均值较高,而在充分灌水条件下,大豆叶片的最大光量子效率值（Fv/Fm）较高,不同水分胁迫处理之间叶绿素含量没有显著差异。不同水分胁迫下大豆的净光合速率与气孔导度间均存在极显著相关关系,而气孔导度与单一气孔特征之间无显著相关关系,表明气孔传导力是大豆光合能力的主要限制因素之一,但同时也存在非气孔限制因素。实验中大豆生长的最适宜土壤相对含水量是60%～65%,此时的光合速率下降是由气孔限制引起。当土壤相对含水量低于60%时,光合作用的非气孔限制因素开始出现。当土壤相对含水量在35%～40%时,非气孔限制逐渐成为大豆叶片光合能力下降主导因子,并可能导致光合器官受到损伤。     

不同类型核桃的光合和蒸腾性能对土壤水分胁迫响应的研究

研究了6个核桃品种当年生实生苗主要光合和蒸腾性能指标对土壤水分胁迫的响应。土壤干旱胁迫,其生理过程均受到显著影响,但各项生理指标对水分亏缺的敏感性不同;随着水分胁迫加剧,净光合速率、蒸腾速率、气孔导度均表现为下降的趋势,而水分利用率、叶温与气温差迅速提高;不同品种的光合和蒸腾性能指标对水分胁迫的响应不同。品种间响应值的变化,表明其抗旱性的差别。将6个品种的响应值,用隶属函数或反隶属函数法统计、比较,得出皮山1号、野核桃的耐旱能力最强;皮山2号、魁核桃次之;南1号、美国黑核桃的抗旱能力最差。     

水分胁迫下外源甜菜碱对桃叶片光合作用的影响

笔者研究了水分胁迫下叶面喷施甜菜碱对桃叶片光合作用的影响。结果表明,水分胁迫前期光合速率下降与气孔因素有关,后期光合速率下降与非气孔因素有关。对桃叶片喷施一定浓度的外源甜菜碱可以提高胁迫前期的净光合速率;这可能与甜菜碱处理提高SOD的活性,保持较低的超氧阴离子自由基生成速率和MDA含量,减轻干旱对树体伤害有关。     

水分胁迫对小麦旗叶光合特性的影响

利用OS－30型叶绿素荧光分析仪研究了水分胁迫对小麦旗叶叶绿素a荧光动力学参数的影响，结果表明，水分胁迫下旗叶的初始荧光产量到最大荧光产量所需的一半值（T1／2）减少，旗叶光系统Ⅰ（PSⅡ）原初光能转化效率（Fv/Fm）和潜在活性（Fv/Fo）降低，光合作用的潜在活力降低，影响了光合电子的传递和CO2同化的正常进行，表现在可变荧光淬灭速率（△Fv/Fo）减慢，可变荧光下降比值（Ffd=△Fv/Ft）减小，进而影响冬小麦旗叶的光合速率，同时还讨论了水分胁迫对灌浆速率的影响。     

低温胁迫对处于不同水分状态柑桔光合作用的影响

研究了低温胁迫对处于不同水分条件下柑桔光合作用的影响规律.结果表明,低温胁迫对柑桔光合作用的影响与土壤水分状态关系密切.对于正常供水的植株,低温能明显降低Pn和Gs.Ci/Ca的比值升高表明低温主要抑制了叶内细胞的光合能力;而适宜的根部温度能够提高受低温影响叶片的Pn和Gs,但从酶的大幅度增加可知,这是以散失大量水分为代价的.而对于受水分胁迫的植株,一方面低温对Pn的抑制作用不明显.即水分胁迫使柑桔对低温胁迫变得不敏感;另一方面,与仅受低温影响的植株相比,提高根温反而使Pn下降幅度更大,但Gs和酶却增加,从而进一步加剧了水分胁迫状况.