首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到19条相似文献,搜索用时 140 毫秒
1.
干旱胁迫对杨树光合生理指标的影响   总被引:29,自引:1,他引:28  
采用PEG模拟干旱胁迫的方法,利用气体交换法和叶绿素荧光技术,研究了干旱胁迫下小青杨(Populus pseudo-simonii)的光合生理变化.结果表明,干旱胁迫初期,小青杨的净光合速率(Pn)、蒸腾速率(Tr)、气孔导度(gs)和胞间CO2浓度(Ci)值均随干旱胁迫增强而下降,杨树Pn的下降主要是由于gs下降引起的;干旱胁迫后期,Ci值逐渐升高,非气孔限制成为光合作用的主要限制因子.干旱胁迫后期,PSⅡ原初光能转化效率(Fv/Fm)和PSⅡ潜在活性(Fv/Fo)明显下降,光抑制增强,光合电子传递受阻.POD酶的活性在胁迫初期升高,后期降低,说明干旱胁迫初期对保护系统酶活性升高有诱导作用,随着胁迫时间的延长,Fv/Fm和Fv/Fo降低,活性氧清除酶活性下降,活性氧代谢的平衡被打破,导致光合器官的伤害.由此表明,干旱胁迫后期Pn的降低与PSⅡ荧光参数及POD酶活性下降有关.  相似文献   

2.
杨梅光合作用的低温光抑制   总被引:14,自引:0,他引:14  
利用便携式调制叶绿素荧光仪和光合作用测定系统研究了短期低温光照对杨梅幼树光合作用的影响。结果表明,低温光照处理后,杨梅叶片的Pn(净光合速率)、Gs(气孔导度)、Fv/Fm(最大的光系统Ⅱ光化学效率)、qP(光化学猝灭系数)和①PSⅡ(光系统Ⅱ的量子产量)下降,Ci/Ca(细胞间隙CO2浓度/环境CO2浓度)、Fo(初始荧光)、qN(非光化学猝灭系数)和(Fi—Fo)/(Fp—Fo)(失活的PSⅡ反应中心数量)上升。此外在同一水平低温下,中等强光(350μmol m^-2s^-1)加剧了PSⅡ反应中心的失活或破坏并且需要更长时间来恢复。这些结果说明低温和有光照条件下引起的杨梅光合作用下降是由于光合机构活性下降所致,即主要是PSⅡ反应中心的失活或破坏:我们推测QA^-(还原态质体醌A)和非还原QB(质体醌B)数量的积累可能是导致PSⅡ反应中心失活或破坏的原因,在低温光抑制过程中非辐射能量耗散对保护光合机构起着重要作用。  相似文献   

3.
水分胁迫下大丽花光合及叶绿素荧光的日变化特性   总被引:2,自引:0,他引:2  
以大丽花品种‘粉西施’为试验材料,采用盆栽方法,研究了不同土壤含水量处理对‘粉西施’叶片光合及荧光特性日变化的影响。结果表明:随着水分胁迫程度的加深,大丽花叶片的Pn、Tr和Gs日平均值均降低,Ci日平均值在轻度和中度胁迫下降低,在重度胁迫下升高;在轻度和中度水分胁迫下大丽花Pn降低的主要原因是气孔限制,而重度水分胁迫下是非气孔因素;Pn在水分胁迫下的日变化曲线由单峰型变成双峰型,出现"午休"现象,且Tr和Gs在水分胁迫下的日变化曲线和Pn一致,但Ci日变化较平稳,与Pn相反。随着水分胁迫程度的加深,大丽花叶片的初始荧光(F0)日平均值升高,日变化曲线呈倒"V"型,PSⅡ反应中心可能破坏或可逆失活;Fm、Fv/Fm和ΦPSⅡ日平均值均降低,日变化曲线呈"V"型。水分胁迫使大丽花光抑制程度加深,抑制了PSⅡ的光化学活性,致使用于光化学反应的光能及实际光化学效率降低。研究结果发现,大丽花品种‘粉西施’在不同水分胁迫下都产生了光合作用的光抑制而使净光合速率降低;光合机构可适应轻度和中度水分胁迫而发生可逆失活,没有受到不可恢复的伤害,而重度水分胁迫降低了叶片的光合机构活性,加剧了光抑制程度,严重限制了光合作用;适宜大丽花生长的土壤含水量应为田间最大持水量的30%以上。  相似文献   

4.
麻疯树幼苗对干旱胁迫的响应   总被引:18,自引:0,他引:18  
以不同浓度(5%~25%)的聚乙二醇(PEG-6000)模拟干旱胁迫处理麻疯树三叶期幼苗,研究了不同程度干旱胁迫下麻疯树叶片光合特性及其对干旱的耐受能力.结果表明:在较低浓度PEG(≤15%)处理下,随PEG浓度的增加,麻疯树叶片净光合速率(Pn)、气孔导度(Gs)、胞间CO2浓度(Ci)、PSⅡ实际光化学量子产量(ΦPSⅡ)、光化学猝灭(qP)和表观光合电子传递速率(ETR)下降,PSⅡ原初光能转化效率(Fv/Fm)轻微下降,水分利用效率(WUE)则逐渐升高,非光化学猝灭(NPQ)明显上升,初始荧光(Fo)无显著变化(P>0.05);在高浓度PEG(>15%)处理下,Ci随PEG浓度的增加而显著上升,Pn、Gs和WUE持续下降,Fv/Fm、ΦPSⅡ、qP和ETR下降幅度明显增大,Fo显著上升,而NPQ下降.低浓度PEG处理导致麻疯树叶片Pn下降主要是由气孔因素造成的;在高浓度PEG处理下,Pn的下降则是由非气孔和气孔因素的共同限制作用造成的.当PEG浓度<20%时,虽然出现Pn下降,但光合机构未受损伤.经15 d高浓度PEG处理的植株叶片,在胁迫解除后光合活性能够迅速恢复,且植株可以存活.说明麻疯树对干旱胁迫有较强的耐受能力.  相似文献   

5.
以溶液培养的三角叶滨藜(Atriplex triangularis)和玉米(Zeamays)为材料,测定了等渗的盐分和水分胁迫对2种植物光合作用的短期影响。结果表明:等渗的水分和盐分胁迫均会造成三角叶滨藜和玉米净光合速率(Pn)的降低,而且随着胁迫程度的增强,水分胁迫引起Pn下降的幅度要明显高于等渗的盐分胁迫;在较低渗透胁迫强度下,2种胁迫导致光合速率下降的主要原因是气孔限制;但在环境溶液渗透势为-1.0MPa时,水分胁迫对光合作用的影响逐渐转化成非气孔限制,而盐胁迫仍然是气孔限制起主要作用;由此可见,等渗透势的水分胁迫对2种植物光合系统的影响要明显大于盐分胁迫。  相似文献   

6.
低温弱光胁迫对日光温室栽培杏树光系统功能的影响   总被引:4,自引:0,他引:4  
以温室栽培的金太阳杏为材料,测定了金太阳杏叶片光合速率(Pn)、光系统Ⅱ(PSⅡ)光下实际光化学效率(ΦPSⅡ)、光化学猝灭系数(qP)和开放的PSⅡ反应中心的激发能捕获效率(Fv/Fm), 探讨了低温弱光(7 ℃、200 μmol·m-2·s-1 PFD)对叶片光系统Ⅰ(PSⅠ)和PSⅡ的抑制作用.结果表明:温室栽培的金太阳杏叶光合作用的最适温度在25 ℃左右.光下7 ℃的低温可使叶片净光合速率(Pn)大幅下降,造成激发压(1-qP)增大,进而引起光抑制.低温弱光条件使PSⅠ和PSⅡ功能受到破坏,与单纯低温胁迫(7 ℃,黑暗)处理相比,经低温、弱光(7 ℃, 200 μmol·m-2·s-1PFD)胁迫2 h后,PSⅠ活性下降了28.26%,而PSⅡ最大光化学效率(Fv/Fm)没有发生显著变化,表明低温弱光条件下PSⅠ比PSⅡ 更易发生光抑制.  相似文献   

7.
在盐胁迫下光抑制及其恢复进程对冬小科光合功能的影响   总被引:2,自引:0,他引:2  
研究了盐和强光双重胁迫以及在弱光下恢复对冬小麦(Triticum aestivum L.)光合功能的影响。结果表明,单纯用低浓度盐(200mmol/L NaCl)胁迫时,对反向PSⅡ光合功能的Fv/Fo、Fv/Fm和qP等参数没有什么影响,但巳十分明显地抑制光合碳同化能力,而高盐(400mmol/L NaCl)胁迫损伤PSⅡ功能,从而加剧对碳同化功能的抑制,说明光合作用对不同盐浓度的响应不同。研究结果还表明,盐胁迫能加剧强光对光合功能的损伤,使之受到更加严重的光抑制。在低盐浓度下,光抑制初期形成形成QB-非还原性PSⅡ反应中心,在随后的光抑制进程和弱光下恢复期间,能有效的被用来合成有活性的PSⅡ和修复可逆性失活的PSⅡ反应中心。而高盐和强光双重胁迫使PSⅡ遭受严重破坏,QB-非还原性PSⅡ反应中心只有在光抑制初期可部分地用于修复可逆性失活的PSⅡ,随着光抑制的进程,它们不能用于合成有活性PSⅡ和修复受严重破坏的PSⅡ,结果导致它们的含量在弱光下恢复时继续增加。  相似文献   

8.
高温胁迫对切花菊‘神马’光合作用与叶绿素荧光的影响   总被引:12,自引:1,他引:11  
以切花菊品种‘神马’为试材,在40 ℃/35 ℃(昼/夜)与33 ℃/28 ℃高温下分别胁迫11 d,然后转入23 ℃/18 ℃恢复5 d,研究不同高温强度及恢复对菊花光合作用的影响.结果表明:33 ℃/28 ℃下净光合速率(Pn)逐渐降低,气孔导度(Gs)5 d后明显降低,两参数均可在23 ℃/18 ℃下恢复到对照的80%以上;40 ℃/35 ℃高温下Pn与Gs大幅度持续降低,胁迫前期,胞间CO2浓度(Ci)上升,Pn的降低主要由非气孔因素导致;9 d后Ci与Pn同时降低,气孔限制成为Pn 降低的主要因素.高温使菊花叶片的PSⅡ潜在活性(Fv/Fo)、最大光化效率(Fv/Fm)、实际光化效率(ΦPSⅡ)与天线转换效率 (Fv′/Fm′)降低,天线热耗散(D)增加,表明高温胁迫下菊花通过降低光能的捕获与通过PSⅡ的电子传递效率来保护反应中心免受伤害.33 ℃/28 ℃下光化学猝灭系数(qP)呈先下降后上升趋势,推测此温度下受体端电子传递首先受到抑制;40 ℃/35 ℃下qP持续增加,表明放氧复合体(OEC)可能是菊花光合系统中极端高温伤害的原初位点.  相似文献   

9.
以岩溶特有药用植物地枫皮为材料,研究土壤水分胁迫及复水条件下,其叶片光合参数、叶绿素荧光参数及光合色素含量的变化特性,进而探讨其对水分胁迫的生理生态适应性。结果表明:停止供水10 d,水分胁迫地枫皮叶片的P_n(净光合速率)、C_i(胞间CO_2浓度)、G_s(气孔导度)和L_s(气孔限制值)均下降,气孔限制是P_n降低的主要原因;停止供水15 d,水分胁迫地枫皮叶片的P_n日变化呈逐渐下降趋势,上午9:30以后全天的P_n值均接近零,非气孔限制成为P_n下降的主要因素;而对照地枫皮叶片的P_n日变化呈"双峰型",中午P_n下降的主要原因依然是气孔限制。水分胁迫下,地枫皮叶片叶绿素含量降低和Chl_(a/b)升高,减少了叶片对光能的捕获,减轻了光合机构遭受光氧化的破坏,而Car/Chl_(a+b)升高增强了光保护能力。水分胁迫下,地枫皮叶片的初始荧光(F_o)显著增大,最大荧光(F_m)、光系统Ⅱ(PSⅡ)潜在活性(F_v/F_o)和最大光化学效率(F_v/F_m)均显著降低,表明水分胁迫对地枫皮叶片的PSⅡ反应中心和电子传递造成了一定的破坏,从而使其PSⅡ的潜在活性和最大光化学效率降低。复水5 d后,地枫皮的上述生理生态参数均能恢复到对照水平,表明其复水后的生理修复能力很强。  相似文献   

10.
不同光照强度下三角叶滨藜光合作用对盐激胁迫的响应   总被引:2,自引:1,他引:1  
以溶液培养的三角叶滨藜植株为材料研究了不同光照条件下其叶片光合作用对盐(NaCl)激胁迫的即刻反应及变化规律.结果表明,三角叶滨藜光合作用对盐激胁迫的响应有8 min左右的滞后期.在光照强度为100umol·m-2·-1和100 mmol·L-1浓度NaCl共同作用下,三角叶滨藜叶片净光合速率略有上升;但随NaCl浓度和光照强度进一步增加,其净光合速率呈下降趋势,且光照越强,盐胁迫导致的净光合速率下降幅度越大.同时,弱光下或强光低浓度NaCl胁迫下,盐激胁迫导致的净光合速率下降主要是气孔限制引起的;而强光下,高浓度的NaCl胁迫导致的净光合速率下降在盐激胁迫处理的前30-40 min主要由气孔限制引起.40 min后则主要由非气孔限制引起.可见,不同光照强度和NaCl浓度胁迫下三角叶滨藜叶片光合作用响应规律不同,引起净光合速率下降机制各异.  相似文献   

11.
Xia QP  Gao HB  Li JR 《应用生态学报》2011,22(4):999-1006
By the method of hydroponic culture, this paper studied the effects of exogenous gamma-aminobutyric acid (GABA) on the photosynthetic pigment contents, photosynthesis, and chlorophyll fluorescence parameters of muskmelon seedlings under hypoxia stress. Hypoxia stress induced a significant decrease of photosynthetic pigment contents, resulting in the decrease of photosynthesis. Applying GABA could significantly increase the photosynthetic pigment contents, net photosynthetic rate (P(n)), stomatal conductance (G(s)), intercellular CO2 concentration (C(i)), carboxylation efficiency (CE), maximal photochemical efficiency of PS II (F(v)/F(m)), photochemical quenching (q(P)), apparent photosynthetic electron transfer rate (ETR), and quantum yield of PS II electron transport (phi(PS II)), and decrease the stomatal limitation value (L(s)), minimal fluorescence (F(o)), and non-photochemical quenching (NPQ) under both hypoxic and normal conditions. The alleviation effect of GABA on photosynthetic characteristics was more obvious under hypoxia stress. However, simultaneously applying GABA and VGB could significantly decrease the alleviation effect of GABA under hypoxia stress.  相似文献   

12.
紫细菌是研究细菌光合作用的重要生物.介绍了紫细菌光合机构捕光色素蛋白复合体Ⅰ(light-harvestingⅠ)、捕光色素蛋白复合体Ⅱ(1ight-harvesting Ⅱ)和光化学反应中心(reaction center)的结构,并探讨了其光合作用基因的转录调控机制,重点阐述了PpsR/AppA系统对紫细菌光合作用基因的转录调控.  相似文献   

13.
紫细菌是研究细菌光合作用的重要生物。介绍了紫细菌光合机构捕光色素蛋白复合体Ⅰ(light-harvesting I)、捕光色素蛋白复合体Ⅱ(light-harvesting II)和光化学反应中心(reaction center)的结构, 并探讨了其光合作用基因的转录调控机制, 重点阐述了PpsR/AppA系统对紫细菌光合作用基因的转录调控。  相似文献   

14.
Photoprotection mechanisms of rice plants were studied when its seedlings were subjected to the combined stress of water and high light. The imposition of water stress, induced by PEG 6000 which was applied to roots, resulted in substantial inhibition of stomatal conductance and net photosynthesis under all irradiance treatments. Under high light stress, the rapid decline of photosynthesis with the development of water stress was accompanied by decreases in the maximum velocity of RuBP carboxylation by Rubisco (V(cmax)), the capacity for ribulose-1,5-bisphosphate regeneration (J(max)), Rubisco and stromal FBPase activities, and the quantum efficiency of photosystem II, in the absence of any stomatal limitation of CO(2) supply. Water stress significantly reduced the energy flux via linear electron transport (J(PSII)), but increased light-dependent and DeltapH- and xanthophyll-mediated thermal dissipation (J(NPQ)). It is concluded that the drought-induced inhibition of photosynthesis under different irradiances in the rice was due to both diffusive and metabolic limitations. Metabolic limitation of photosynthesis may be related to the adverse effects of some metabolic processes and the oxidative damage to the chloroplast. Meanwhile, an enhanced thermal dissipation is an important process to minimize the adverse effects of drought and high irradiance when CO(2) assimilation is suppressed.  相似文献   

15.
The effects of drought on the photosynthetic characteristics of three Mediterranean plants (olive, Olea europea L.; rosemary, Rosmarinus officinalis L.; lavender, Lavandula stoechas L.) exposed to elevated UV-B irradiation in a glasshouse were investigated over a period of weeks. Drought conditions were imposed on 2-year-old plants by withholding water. During the onset of water stress, analyses of the response of net carbon assimilation of leaves to their intercellular CO2 concentration were used to examine the potential limitations imposed by stomata, carboxylation velocity and capacity for regeneration of ribulose 1,5-bisphosphate on photosynthesis. Measurements of chlorophyll fluorescence were used to determine changes in the efficiency of light utilization for electron transport, the occurrence of photoinhibition of photosystem II photochemistry and the possibility of stomatal patchiness across leaves. The first stages of water stress produced decreases in the light-saturated rate of CO2 assimilation which were accompanied by decreases in the maximum carboxylation velocity and the capacity for regeneration of ribulose 1,5-bisphosphate in the absence of any significant photodamage to photosystem II. Leaves of rosemary and lavender were more sensitive than those of olive during the first stages of the drought treatment and also exhibited increases in stomatal limitation. With increasing water stress, significant decreases in the maximum quantum efficiency of photosystem II photochemistry occurred in lavender and rosemary, and stomatal limitation was increased in olive. No indication of any heterogeneity of photosynthesis was found in any leaves. Drought treatment significantly decreased leaf area in all species, an important factor in drought-induced decreases in photosynthetic productivity. Exposure of plants to elevated UV-B radiation (0.47 W m(-2)) prior to and during the drought treatment had no significant effects on the growth or photosynthetic activities of the plants. Consequently, it is predicted that increasing UV-B due to future stratospheric ozone depletion is unlikely to have any significant impact on the photosynthetic productivity of olive, lavender and rosemary in the field.  相似文献   

16.
采用人为控制土壤含水量的方法对欧李进行轻度和重度干旱的处理,测定叶片的气体交换和叶绿素荧光参数的日变化。结果表明,干旱胁迫下欧李叶片净光合速率、蒸腾速率、水分利用效率、气孔导度、PSII最大光化学效率、光化学量子效率显著下降,但胞间CO2浓度、非光化学猝灭系数以及叶黄素循脱环氧化状态(Z+0.5A)/(V+A+Z)和Z含量升高。两干旱处理植株的影响程度存在差异。这表明在长时间干旱条件下,欧李叶片光合作用的降低受到气孔与非气孔因素的双重影响,叶黄素循环的启动增加了胁迫条件下的热耗散能力以保护光合机构免受干旱胁迫的进一步伤害。  相似文献   

17.
In plants, drought stress coupled with high levels of illumination causes not only dehydration of tissues, but also oxidative damage resulting from excess absorbed light energy. In this study, we analyzed the regulation of electron transport under drought/high-light stress conditions in wild watermelon, a xerophyte that shows strong resistance to this type of stress. Under drought/high-light conditions that completely suppressed CO(2) fixation, the linear electron flow was diminished between photosystem (PS) II and PS I, there was no photoinhibitory damage to PS II and PS I and no decrease in the abundance of the two PSs. Proteome analyses revealed changes in the abundance of protein spots representing the Rieske-type iron-sulfur protein (ISP) and I and K subunits of NAD(P)H dehydrogenase in response to drought stress. Two-dimensional electrophoresis and immunoblot analyses revealed new ISP protein spots with more acidic isoelectric points in plants under drought stress. Our findings suggest that the modified ISPs depress the linear electron transport activity under stress conditions to protect PS I from photoinhibition. The qualitative changes in photosynthetic proteins may switch the photosynthetic electron transport from normal photosynthesis mode to stress-tolerance mode.  相似文献   

18.
To understand the mechanisms of salt tolerance in a halophyte, sea aster ( Aster tripolium L.), we studied the changes of water relation and the factors of photosynthetic limitation under water stress and 300 mM NaCl stress. The contents of Na(+) and Cl(-) were highest in NaCl-stressed leaves. Leaf osmotic potentials ( Psi(s)) were decreased by both stress treatments, whereas leaf turgor pressure ( Psi(t)) was maintained under NaCl stress. Decrease in Psi(s) without any loss of Psi(t) accounted for osmotic adjustment using Na(+) and Cl(-) accumulated under NaCl stress. Stress treatments affected photosynthesis, and stomatal limitation was higher under water stress than under NaCl stress. Additionally, maximum CO(2) fixation rate and O(2) evolution rate decreased only under water stress, indicating irreversible damage to photosynthetic systems, mainly by dehydration. Water stress severely affected the water relation and photosynthetic capacity. On the other hand, turgid leaves under NaCl stress have dehydration tolerance due to maintenance of Psi(t) and photosynthetic activity. These results show that sea aster might not suffer from tissue dehydration in highly salinized environments. We conclude that the adaptation of sea aster to salinity may be accomplished by osmotic adjustment using accumulated Na(+) and Cl(-), and that this plant has typical halophyte characteristics, but not drought tolerance.  相似文献   

19.
Velikova  V.  Tsonev  T.  Edreva  A.  Gürel  A.  Hakerlerler  H. 《Photosynthetica》2002,40(3):449-452
Strong inhibition of rates of CO2 assimilation and transpiration, stomatal conductance, and water use efficiency as well as photosystem 2 (PS2) photochemical activity were related to the severity of reddening. The inhibition of photosynthesis in red cotton leaves was due to both decreased photochemical activity and stomatal limitation. Lowered photosynthetic capacity could be one of the main factors of reduced yield in reddening cotton.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号