不同CO2浓度下渗透胁迫对小麦膜伤害的影响

研究了常规CO₂(350μl·L^-1)和CO₂倍增(700μl·L^-1)环境中生长的春小麦幼苗,渗透胁迫时叶片中活性氧含量的变化和质膜透性的变化.结果表明,生长在CO₂倍增环境中的春小麦幼苗,渗透胁迫时O₂^·-及H₂O₂的增长幅度均小于常规CO₂浓度下生长的春小麦幼苗.质膜透性的增长幅度也是前者小于后者.据此认为,CO₂浓度倍增可以减轻渗透胁迫对质膜的氧化伤害,提高植物的抗旱力.     

C02倍增对渗透胁迫下小麦叶片抗氧化酶类及细胞程序性死亡的影响

经渗透胁迫后 ,CO2 倍增条件下小麦叶片的SOD、POX和CAT的活性均显著高于对照 ,上升或稳定时期较长 ;在渗透胁迫后期MDA含量和电解质泄露率增加较慢 ,显著低于对照 ;H2 O2 含量一直高于对照但进行PEG胁迫后增长较慢。CO2 倍增条件下 ,小麦细胞出现DNA梯的时间较晚而且持续的时间较长 ,DNA梯出现时抗氧化酶和H2 O2 处于相对稳定状态。结果表明在渗透胁迫下CO2 倍增使小麦的抗氧化能力增强从而减轻了对细胞膜和DNA的损伤 ,并且干旱条件下小麦的细胞程序性死亡可能是由于细胞内氧化过强所致     

不同土壤水分条件下CO2浓度对禾谷缢管蚜种群的影响

利用开顶式熏气室研究了不同土壤水分条件下不同CO2浓度对禾谷缢管蚜种群的影响,以期对未来大气CO2浓度升高条件下不同降雨地区的小麦－蚜虫关系发展趋势做出蚜虫关系发展趋势做出初步预测,结果表明,随CO2浓度从350ul.L^-1上升至550ul.L^-1时,60％土壤水分下的种群增长最快;当CO2浓度从550ul.L^-1上升到700ul.L^-1时,60％和40％土亍水分下的种群增长相近,且高于80％土壤水分下的增长,据此可以认为,随大气CO2浓度升高,禾谷缢管蚜种群会持续增长,从目前至下世纪中叶的时间内可能是蚜种群增长最快的阶段,特别在干旱,半干旱地区禾谷缢管蚜种群增长幅度较大,小麦受受较重。     

外源一氧化氮对渗透胁迫下小麦幼苗叶片膜脂过氧化的缓解作用

采用15%的聚乙二醇-6000(PEG-6000)对扬麦158三叶一心期的幼苗根部进行轻度渗透胁迫处理,并通过添加不同浓度的一氧化氮(nitric oxide,NO)供体硝普钠(sodium nitropussidi,SNP)和相应的对照(BO-3/NO-2),研究外源NO处理对渗透胁迫下小麦幼苗叶片膜脂过氧化作用的影响.结果发现,0.1 nnol/L的SNP能降低渗透胁迫造成的小麦幼苗叶片脂氧合酶(lipoxygenase,LOX)活性的提高,降低超氧阴离子(O-2)的产生速率和质膜相对透性的增加以及丙二醛(MDA)和H2O2的累积;0.1 mmol/L的SNP还能够诱导超氧化物歧化酶(superoxide dismutase,SOD)活性,加速脯氨酸(Pro)的累积,而0.5mmo1/L的SNP和0.1mmo1/L的NO3/NO2(对照)处理的效果则不明显.上述结果表明低浓度NO对渗透胁迫造成的膜脂过氧化有明显的缓解效应.     

The effects of La(III) on the peroxidation of membrane lipids in wheat seedling leaves under osmotic stress

The physiological effects of the rare earth ion La³⁺ on the peroxidation of membrane lipids in wheat (Triticum aestivum L.) seedling leaves under osmotic stress were determined. With the passage of time under osmotic stress, the inhibition ability of lanthanum ions to the relative membrane permeability and concentration of malondialdehyde, Superoxide radicals, and hydrogen peroxide caused by osmotic stress increased substantially, but no changes were noted in ferrous and relative water content. It indicated that lanthanum ions could not retain the water content because of osmotic stress. However, La³⁺ appears to decrease the production of OH by reducing the content of O₂ and H₂O₂ of Haber-Weiss and Fenton reactions, which efficiently alleviated peroxidation of membrane lipids under osmotic stress and, to some degree, protected the membrane from injury of free radicals. Thus, La³⁺ increased the tolerance ability of plant to osmotic stress, which could assure the function of membrane normal temporally after stressed.     

NaCl胁迫对互花米草细胞膜和光响应曲线特征参数的影响

以大米草的互花米草为材料,研究了不同盐浓度对其细胞膜透性、丙二醛(MDA)含量和光响应曲线的特征参数的变化情况。结果表明:盐浓度低于300mmol·L-1时,互花米草细胞膜透性和MDA含量较对照组无显著差异;其较高的最大光合速率(>30μmol·m-2·s-1),表观量子效率(>0.05mol·mol-1Photons)以及较低的暗呼吸速率(<1.5μmolCO2·m-2·s-1)和光补偿点(<20μmol·m-2·s-1)为其有机物质积累、竞争、建立种群并扩散提供条件。盐浓度高于500mmol·L-1时,互花米草膜透性和MDA含量显著上升,最大光合速率(Amax)及表观量子效率(Q)显著下降,暗呼吸速率(Rday)和光补偿点(LCP)上升。表明细胞膜和光合作用有关酶受到迫害,抑制了其正常生长。盐胁迫下互花米草光合速率降低,但蒸腾速率的显著下降提高了单叶水分利用效率,从而部分缓解了渗透势变化对细胞的迫害,为其生存和生长提供条件。     

Photosynthesis and Carbohydrate Partitioning for the C3 Desert Shrub Encelia farinosa under Current and Doubled CO2 Concentrations

Changes in photosynthesis (A) and carbohydrate partitioning were studied for Encelia farinosa, a common C3 desert shrub in the southwestern United States, after a 3-month exposure to the current or a doubled CO2 concentration (750 [mu]L L-1). A remained unchanged under the current CO2 concentration but decreased during the day under the doubled CO2 concentration, resulting in a 46% enhancement in the early morning, 26% at midday, and 15% in the late afternoon by the elevated CO2. The decrease during the day under the doubled CO2 concentration may represent end-product inhibition, because the sucrose and the starch contents increased during the day proportionally more than under the current CO2 concentration. The 14CO2 activity in sink leaves was maximal 3 h after labeling under the doubled and at 5 h under the current CO2 concentration, indicating faster movement of photosynthate out of source leaves and into sink tissues under the doubled CO2 concentration, which may have been responsible for the sustained enhancement in A under the doubled CO2 concentration.     

盐胁迫下CO2加倍对春小麦一些光合功能的影响

 研究了在盐胁迫下CO2浓度加倍对春小麦(Triticum aestivum)青323光合色素含量和一些光合功能的影响。结果表明,盐胁迫降低春小麦叶片单位鲜重叶绿素(Chl)和类胡萝卜素(Car)的含量、叶绿体对光能的吸收能力,Mg2+对两个光系统(PSⅡ和PSⅠ)之间激发能分配的调节能力,以及荧光猝灭速率(△FV/T)。然而,CO2加倍有提高上述各参数的作用,表明高CO2浓度能减轻盐胁迫对光合功能的不利效应。     

等渗NaCl和KCl胁迫对高粱幼苗生长和气体交换的影响

本文比较研究了等渗ＮａＣｌ和ＫＣｌ胁迫下,高粱幼苗生长及叶片离子含量、质膜相对透性和有关气体交换参数的变化。结果表明,在低浓度ＮａＣｌ和ＫＣｌ胁迫７天时,高粱生长、含水量和质膜相对透性与对照相比没有明显变化,而净光合速率、蒸腾速率和气孔导度已明显下降,叶肉细胞间隙ＣＯ２浓度明显增加。ＮａＣｌ胁迫下叶片Ｎａ＋含量成倍增加,而Ｋ＋和Ｃａ２＋含量无明显变化。ＫＣｌ胁迫时叶片Ｋ＋含量明显增加,Ｃａ２＋含量明显下降,而Ｎａ＋含量没有明显变化。随着ＮａＣｌ或ＫＣｌ浓度的增加,幼苗生长和叶片含水量明显下降,质膜透性和细胞间隙ＣＯ２浓度明显增加,净光合速率、蒸腾速率和气孔导度进一步下降。ＮａＣｌ胁迫下叶片Ｎａ＋含量进一步增加,Ｋ＋和Ｃａ２＋进一步下降,而ＫＣｌ胁迫下叶片Ｋ＋含量进一步增加,Ｎａ＋和Ｃａ２＋含量进一步下降。ＫＣｌ对高粱生长抑制、质膜透性、Ｃａ２＋含量下降及光合气体交换参数的影响均明显大于等渗的ＮａＣｌ。     

CO2和O3浓度倍增及其交互作用对大豆叶绿体超微结构的影响

应用透射电镜观察了模拟大气CO2和O3浓度倍增及其交互作用(开顶箱法)对大豆叶肉细胞叶绿体超微结构的影响。结果表明,CO2浓度倍增促进了大豆叶绿体的发育,内含淀粉粒积累明显增多、体积增大;叶绿体被膜保持完好;叶绿体基粒片层排列整齐,而O3浓度倍增抑制了叶绿体内淀粉粒的累积,并导致叶绿体被膜破碎,片层解体,严重地破坏了叶绿体的结构和功能CO2和O3浓度倍增的交互作用对叶绿体超微结构有不同程度的破坏,但二者浓度呈梯度增加对叶绿体的损害作用要大于二者浓度持续倍增对叶绿体的影响,进一步表明CO2正效应对O3负效应的补偿作用。