高温胁迫下外源茉莉酸甲酯、钙和水杨酸对蝴蝶兰幼苗耐热性的影响

为了探求外源茉莉酸甲酯、钙和水杨酸对蝴蝶兰耐热性的影响,分别采用最适浓度的3种药液和蒸馏水（对照）喷施蝴蝶兰幼苗叶片,并置于40℃高温胁迫4天,测定了有关生理指标的变化。结果表明：高温胁迫下,与对照处理相比,茉莉酸甲酯、钙处理明显提高了SOD、POD、CAT活性,而水杨酸处理在明显提高了SOD、POD活性的同时,却明显降低了CAT活性;3种处理明显提高了可溶性蛋白质和脯氨酸含量,显著降低了相对电导率和MDA含量。由此认为,茉莉酸甲酯、钙、水杨酸处理能提高蝴蝶兰幼苗的耐热性。根据形态和生理指标的差异性,可得出诱导耐热性强弱的顺序为：茉莉酸甲酯>钙>水杨酸。     

茉莉酸甲酯对烟草抵御棉铃虫的诱导作用

为进一步阐明茉莉酸甲酯（MeJA）诱导植物抗虫的机理,研究了外源MeJA对烟草多酚氧化酶（PPO）、过氧化物酶（POD）、脂氧合酶（LOX）活性及编码氢过氧化物裂解酶（HPL）和蛋白酶抑制剂（PI-I和PI-II）基因表达的诱导作用,并对棉铃虫取食烟草叶片面积及其体重进行了生物学测定。结果表明,用100 μmol/L MeJA处理后,烟草体内PPO、POD和LOX活性显著升高,HPL、PI-I和PI-II表达明显增强,叶片被取食面积减少,棉铃虫体重增加变慢。说明MeJA对诱导烟草抵御棉铃虫有重要作用。     

3种草本植物种子萌发及幼苗初期对镉胁迫的生理响应

通过溶液培养探讨了不同浓度镉胁迫下,韭菜、凤仙花和紫云英种子萌发及幼苗初期叶绿素、丙二醛含量及抗氧化酶活性的变化.结果表明:低镉浓度(≤50 mg/L)促进种子萌发,中高浓度(≥100 mg/L)抑制种子萌发;发芽指数和活力指数均随着镉浓度增加而下降;当镉≥50 mg/L时,根长和芽长均与对照差异显著(p＜0.05),明显阻碍幼苗生长,且根比芽对胁迫敏感;高浓度镉明显阻碍叶绿素的合成;丙二醛含量及抗氧化酶活性均随着胁迫浓度提高呈先升后降的趋势,说明低浓度镉激活植物自身的保护系统发挥作用,高浓度镉抑制其发挥作用.     

外源硅对盐胁迫下黄果厚壳桂幼苗的光合荧光及抗氧化特性的影响

为探讨外源硅对盐胁迫下黄果厚壳硅的缓解作用。以一年生黄果厚壳桂(Cryptocarya concinna)幼苗为材料,在100 mg/L NaCl胁迫下,添加不同浓度(0、0.5、1、2 mmol/L)外源硅对幼苗进行处理,测定和分析不同处理下幼苗叶片的叶绿素含量、光合、叶绿素荧光特性参数和抗氧化酶含量。结果表明,外源硅能不同程度提高Pn、Tr、Gs、Fv/Fm,降低Ci;提高叶绿素a、叶绿素b和类胡萝卜素含量;提高SOD、PPO和APX活性,降低MDA含量。其中PPO在1.0 mmol/L硅处理下效果最佳,其他指标均在 2.0 mmol/L硅处理效果最佳。可见,添加适度浓度硅可以缓解盐胁迫对黄果厚壳桂幼苗的伤害,提高其耐盐能力,该研究为黄果厚壳桂引种栽培提供参考。     

Growth,Physiological Attributes and Antioxidant Enzyme Activities in Soybean Seedlings Treated With or Without Silicon Under UV‐B Radiation Stress

Silicon (Si) can increase plant defence systems against abiotic and biotic stress, but there is little information on UV‐B radiation stress alleviation by Si for field crops. Using soybean (Glycine max (L.) Mell) seedlings, we determined how Si may mediate UV‐B radiation stress by studying changes in biomass, physiological attributes and antioxidants’ activities. The seedlings were raised with 0, 1.70 and 2.55 mm of Si in the growth chamber under ambient, ambient +2.7 kJ m^?2 day and ambient +5.4 kJ m^?2 day of UV‐B radiation. As expected, plants suffered severe growth limitations under UV‐B radiation, but Si alleviated these limitations through improvements in leaf area (LA) and root‐to‐shoot ratio (R/S). The UV‐B radiation stress reduced the LA by 73.9–94.7%, total dry weight (TDW) by 11.8–36.6% and R/S by 9.2–30.2% but induced the activities of soluble protein by 18.4–21.0%, catalase (CAT) by 22.7–54.2%, superoxide dismutase (SOD) by 31.9–63.1%, and peroxidases (POD) by as much as 162.9–381.6%. Further confirmation of stress alleviations by Si was noted from reductions in these stress signals (antioxidant activities) under UV‐B radiation: CAT decreased significantly by 78.3–79.4%, SOD by 5.3–7.2% and POD by 49.9–61.9% in silicon‐treated UV‐B stressed soybean.     

Alterations in Photochemical and Physiological Activities of Chickpea (Cicer arietinum L.) Cultivars under Drought Stress

In this study, some morphological, physiological and biochemical parameters of two chickpea cultivars, cv. Gökçe and Canıtez, were analysed to understand their tolerance to drought stress. Twenty-day-old plants were subjected to three different regimes of drought stress by withholding water for 3, 5 or 7 days, and then rewatering for 2 days after the initial 7 days of drought stress. Drought treatments only reduced shoot elongation in the Canıtez cultivar. Leaf production and fresh biomass decreased in both cultivars under all drought treatments, however to a greater extent in Canıtez. In both cultivars, malondialdehyde, proline and anthocyanin accumulation increased significantly, whereas relative water content declined under drought stress. The total chlorophyll and carotenoid contents of Gökçe were not affected by drought stress, whereas the chlorophyll content of Canıtez increased greatly at the end of the treatments. Using chlorophyll a fluorescence measurements, we found that extended drought treatment caused photoinhibition of PSII activity in both cultivars. However, this was greater in Canıtez, especially under severe drought stress. Although Canıtez recovered quickly from drought stress and exhibited a good ability to overcome drought stress, via activation of many protection mechanisms such as increasing antioxidant enzymes and proline and anthocyanin accumulation during vegetative stage, our results show that Canıtez is less drought tolerant than Gökçe.     

锌胁迫对国槐幼苗生长及生理特性的影响

为探讨国槐(Sophora japonica)对重金属锌的耐受能力,以水培的3月龄国槐幼苗为试验对象,探讨不同浓度(1、50、200、350、500 μmol/L)锌处理对其生长发育、叶绿素荧光参数、丙二醛含量和抗氧化酶活性的影响.结果 表明,在锌胁迫下,国槐幼苗生长量指标呈现明显的"低促高抑"现象,同时,根系对锌胁迫...     

高温胁迫对蝴蝶兰幼苗叶绿素荧光参数的影响

为了探究高温胁迫对蝴蝶兰幼苗叶片光合机构的影响,将蝴蝶兰幼苗置于38℃处理4天,以25℃为对照,测定了蝴蝶兰幼苗叶绿素荧光参数的变化。结果表明：随着高温胁迫时间的延长,蝴蝶兰叶片叶绿素总含量、最大光化学效率(Fv/Fm)、有效光量子产量(ΦPSⅡ)、表观光合电子传递速率(ETR)、光化学猝灭系数(qP)持续下降,而丙二醛(MDA)含量、初始荧光(Fo)、非光化学猝灭系数(qN)不断上升。与胁迫前相比,胁迫后期的上述指标均存在显著差异。由此表明,高温胁迫下蝴蝶兰幼苗PSⅡ反应中心出现了可逆失活或损伤,使光合原初反应过程受阻,显著降低了原初光能转换效率,从而引起严重的光抑制,极大地减弱了光合电子传递活性,使反应中心积累过剩光能,对光合机构和叶绿素造成光氧化破坏,但蝴蝶兰幼苗能在一定程度上通过热耗散途径来减轻伤害。     

水分胁迫对棉花幼苗水分利用和光合特性的影响

以转基因棉花品种农大棉8号和鲁棉研28号为材料进行盆栽试验,设置正常处理(CK)、轻度胁迫(LS)、中度胁迫(MS)、重度胁迫(SS)和极度胁迫(ES)5个水分处理。结果表明:随着水分胁迫程度的加重,棉花幼苗的生长受到明显的抑制,2个品种的叶片相对含水率、叶水势、净光合速率(Pn)、光能利用率(LUE)、PSⅡ最大光化学效率(Fv/Fm)、PSⅡ光化学量子效率(φPSⅡ)、光化学猝灭系数(qP)呈下降趋势;气孔限制值(Ls)、水分利用率(WUE)和非光化学猝灭系数(NPQ)呈上升趋势。两品种的Pn和NPQ的MS、SS和ES与CK相比差异显著,不同测定时期各胁迫处理的平均Pn比CK分别下降了11.5%、18.1%、32.1%和38.1%;平均NPQ比CK上升了24.1%、50.9%、79.4%和145.1%。表明棉花幼苗期持续轻度水分胁迫对叶片光合能力无显著影响,但高于中度的持续水分胁迫会造成叶片光合能力下降和光抑制加重。     

干旱和盐胁迫对棉苗光合抑制效应的比较

以无盐正常供水为对照,研究了等渗条件下干旱和NaCl处理对棉苗光合速率(Pn)、叶绿素荧光参数、过氧化物酶(POD)活性和丙二醛(MAD)与游离脯氨酸(Pro)含量的影响.干旱和盐胁迫都显著降低叶片的Pn、蒸腾速率(Tr)、气孔导度(Gs)、气孔限制值(Ls)和叶绿素与类胡罗卜素含量.干旱或盐胁迫引起初始荧光(F0)上升,最大荧光(Fm)、PSⅡ原初光能转化效率(Fv/Fm)和PSⅡ潜在活性(Fv/F0)显著下降,PSⅡ实际光化学量子产量(φPSⅡ)略有降低,而POD活性、MDA和Pro含量显著提高.棉苗在不同胁迫后的叶绿素含量、POD活性、MDA和Pro累积等方面存在量上的差异,说明等渗条件下干旱和盐胁迫对光合的抑制效应与机理存在诸多相似性,也有特异性.     

谷胱甘肽对盐胁迫大麦叶片活性氧清除系统的保护作用

盐胁迫下大麦叶片K+含量下降, Na+含量上升, K+/Na+比下降, 叶绿素(chl)含量下降, 叶片内源谷胱甘肽(GSH)含量与K+/Na+比、 叶绿素含量呈极显著的正相关。 外源GSH处理可明显提高活性氧清除系统中超氧物歧化酶(SOD)、 过氧化氢酶(CAT)、 谷胱甘肽还原酶(GR)、 过氧化物酶(POD)活性以及抗氧化剂GSH、 类胡萝卜素(Car)、 维     

谷胱甘肽对盐胁迫大麦叶片活性氧清除系统的保护作用

盐胁迫下大麦叶片K+含量下降, Na+含量上升, K+/Na+比下降, 叶绿素(chl)含量下降, 叶片内源谷胱甘肽(GSH)含量与K+/Na+比、 叶绿素含量呈极显著的正相关。 外源GSH处理可明显提高活性氧清除系统中超氧物歧化酶(SOD)、 过氧化氢酶(CAT)、 谷胱甘肽还原酶(GR)、 过氧化物酶(POD)活性以及抗氧化剂GSH、 类胡萝卜素(Car)、 维     

氟节胺抑制枇杷嫁接成苗砧木萌蘖相关机理初探

为寻找更长效、无害的化学控蘖剂以减轻田间管理劳动强度,以枇杷(Eriobotrya japonica)嫁接成苗为材料,喷施有效成分浓度为0.050%,0.071%和0.125%的氟节胺,于不同时期取样观察控蘖效果,并尝试探究相关机理。结果表明,氟节胺减少了叶片单位面积光能的吸收量、抑制了光化学转换,但叶片的热耗散量并无明显变化。进一步测定植株氧化还原状态发现,氟节胺能够快速促进细胞内超氧阴离子(O₂^.-)积累并延缓或抑制H₂O₂的转化,从而诱发氧化胁迫。由此可见,氟节胺可能通过抑制叶片光化学转换和热耗散来破坏新生萌蘖的光合性能,进而抑制其萌发生长,而成熟叶片则通过提升自身抗氧化系统活性耐受氟节胺造成的轻度胁迫。在本试验中,各浓度的氟节胺对控制砧木萌蘖有不同程度的效果,其中浓度为0.125%的氟节胺控蘖效果相对最佳,且基本不会对砧木和嫁接成苗造成持续伤害,其作为化学控蘖剂有一定的应用潜力。     

铝胁迫对烟草叶片光能利用、光保护系统及活性氧代谢的影响

为了揭示烟草叶片光能利用和光保护系统在铝诱导的活性氧代谢中的作用机理,以2个不同耐铝性的烟草品种云烟100(耐铝)和云烟105(敏感)为材料,采用水培法研究了不同铝浓度(0,50,100,200μmol/L)对烟草植株生长、叶片活性氧含量、光合特性、叶绿素荧光参数、光呼吸、超氧化物歧化酶(SOD)和抗坏血酸过氧化物酶(APX)活性的影响。结果表明,铝浓度的升高显著降低了烟草叶片叶绿素含量、净光合速率(Pn)、最大光化学效率(Fv/Fm)、PSⅡ光合电子传递量子效率(ΦPSⅡ)和光化学猝灭系数(q P),提高了反应中心PSⅡ过剩激发能,从而导致叶片O_2-·和H2O_2含量升高,植株生物量下降,其中对云烟105影响大于云烟100。随铝处理浓度的升高,烟草叶片非光化学猝灭系数(NPQ)、光呼吸速率、SOD和APX活性呈先升后降的趋势。与敏感品种云烟105相比,耐铝品种云烟100在不同铝浓度胁迫下表现出更高的ΦPSⅡ、q P、NPQ、光呼吸速率以及SOD和APX活性,说明低浓度铝胁迫下烟草叶片可通过提高光化学反应能力、热耗散、光呼吸以及抗氧化酶活性等途径来降低反应中心PSⅡ过剩激发能,防止或清除活性氧的积累,从而增强其对铝的耐性。     

Changes in Water Status,Membrane Stability and Antioxidant Capacity of Wheat Seedlings Carrying Different Rht‐B1 Dwarfing Alleles under Drought Stress

Water deficiency is a major constraint to wheat productivity in drought prone regions. The wheat DELLA‐encoding height‐reducing genes (Rht) are associated with significant increase in grain yield. However, the knowledge of their benefit in dry environments is insufficient. The objective of the study was to examine the effect of induced drought on leaf water content, level of oxidative stress, cell membrane stability, accumulation of osmoprotectants and activity of some antioxidant enzymes in wheat near‐isogenic lines carrying the alleles Rht‐B1b (semidwarfing) and Rht‐B1c (dwarfing) in comparison with the tall control Rht‐B1a. Six‐day‐long water deprivation was imposed at seedling stage. Plants carrying Rht‐B1c and, to a lesser extent, those carrying Rht‐B1b performed better under stress compared with Rht‐B1a in terms of more sustained membrane integrity, enhanced osmoregulation and better antioxidant defence. These differential responses could reflect pleiotropic effects of the Rht‐B1 gene associated with the accumulation of the mutant gene product, that is, altered DELLA proteins, or might be related to allelic variations at neighbouring loci carrying candidate genes for proteins with a major role in plant water regulations and stress adaptation. These findings might be of importance to breeders when introducing Rht‐B1 alleles into wheat cultivars designed to be grown in drought liable regions.