氯化镧对硝酸盐胁迫下黄瓜幼苗光合特性的缓解效应

采用水培方式研究了LaCl₃对140 mmol·L^-1 NO₃-硝酸盐胁迫下黄瓜幼苗光合特性的影响.结果表明: 硝酸盐胁迫显著降低了黄瓜幼苗叶绿素及类胡萝卜素含量,叶片Mg²⁺ ATPase、Ca²⁺ ATPase活性也随之降低;硝酸盐胁迫7 d,黄瓜幼苗叶片光合速率的降低以气孔限制为主,叶片AQY与CE下降,胁迫12 d则以非气孔限制为主.硝酸盐胁迫下,外加LaCl3可以使黄瓜叶片保持较高的Mg²⁺ ATPase、Ca²⁺ ATPase活性及叶绿素和类胡萝卜素含量,尤其是外加低浓度（20 μmol·L^-1）LaCl3显著增加了叶片类胡萝卜素含量;LaCl₃还具有降低气孔关闭、改善叶片气体交换功能,减缓叶片F_v/F_m、Ф_PSII、AQY、CE及q_P的降低幅度等作用,使叶片在盐胁迫下保持较高的光能利用率及CO₂同化能力.20 μmol·L^-1 LaCl₃可以有效缓解硝酸盐对黄瓜幼苗光合作用的影响,而200 μmol·L^-1LaCl₃在胁迫初期对黄瓜幼苗有缓解效果,后期则效果不明显.该结果可为设施土壤的改良提供新的途径.     

外源NO对镉胁迫下番茄活性氧代谢及光合特性的影响

采用水培方法,研究了外源一氧化氮（NO）对镉（Cd）胁迫下番茄幼苗活性氧代谢及光合特性的影响.结果表明：在Cd胁迫下,外施100 μmol·L^-1 硝普钠（SNP）显著增强了番茄超氧化物岐化酶（SOD）、过氧化氢酶（CAT）等抗氧化酶活性,提高了叶片、根系中Ca、Fe等元素含量,提高了叶片叶绿素含量、净光合速率（P_n）、蒸腾速率（T_r）和气孔导度（G_s）,降低了过氧化氢（H₂O₂）、丙二醛（MDA）含量和胞间CO₂浓度（C_i）.但SNP对Cd胁迫下的缓解效应可被牛血红蛋白（Hb,NO的清除剂）消除.在Cd处理液中加入100 μmol·L^-1 NO_x^-（NO的分解产物）或100 μmol·L^-1亚铁氰化钠（SNP的相似物或分解产物）,对Cd胁迫无显著改善.表明外源NO可通过提高活性氧清除能力,维持矿质营养元素平衡,缓解Cd胁迫对番茄幼苗叶片光合机构的破坏,从而维持番茄光合效率.     

外源一氧化氮对硝酸盐胁迫下黄瓜幼苗生长及抗氧化酶活性的影响

采用营养液培养试验,通过添加不同浓度(0.05、0.1、0.2、0. mmol·L^-1)的硝普钠（SNP）作为NO供体,研究外源NO对NO₃-胁迫下黄瓜幼苗生长及叶片抗氧化酶活性的影响.结果表明： 140 mmol·L^-1 NO₃-胁迫下,外加0.1 mmol·L^-1 SNP处理1 d和7 d后,黄瓜幼苗叶片中SOD、CAT和APX活性显著升高;MDA含量显著降低,可溶性蛋白含量增加,说明外加0.1 mmol·L^-1 SNP增强了黄瓜幼苗对活性氧的清除能力,降低了膜脂过氧化程度,幼苗生长势增加,对高浓度NO₃-胁迫的抗性增强;当SNP浓度达0.3 mmol·L^-1处理7 d后,SOD、POD、CAT和APX活性均开始降低,MDA含量增加,黄瓜幼苗受害加重.外加一定浓度(0.1～0.2 mmol·L^-1)的外源NO可缓解NO₃^-胁迫对黄瓜幼苗的影响.     

纯化腐植酸对低氮胁迫下黄瓜幼苗生长及养分吸收的影响

以黄瓜‘新泰密刺’、‘津优1号’为供试品种,研究沙培条件下不同浓度(0、50、100、150、200 mg·L^-1)纯化腐植酸(PHA)浇灌对低氮胁迫(1 mmol·L^-1 NO₃^-)下黄瓜幼苗生长及养分吸收的影响.结果表明: 在较低N供应条件下,沙培浇灌PHA可显著增加黄瓜幼苗的根总长、根表面积及根尖数,增大根体积,促进黄瓜幼苗株高和茎粗生长,增大叶面积;显著提高黄瓜幼苗叶片中脯氨酸及可溶性糖含量;促进N素以及P、K、Ca、Mg、Fe元素的吸收.由参试两黄瓜品种对低氮胁迫下PHA处理响应效果来看,不同品种的某些性状对PHA处理浓度的敏感程度稍有差异,综合结果显示,施用100～150 mg·L^-1PHA可显著促进两品种幼苗生长及养分吸收.     

外源调环酸钙对盐碱胁迫下大豆幼苗生长及生理特性的影响

为明确外源调环酸钙(Pro-Ca)缓解大豆幼苗盐碱胁迫的机理,以大豆‘合丰50’为试验材料,研究在110 mmol·L^-1复合盐碱胁迫下,叶面喷施100 mg·L^-1 Pro-Ca对大豆幼苗生长、光合特性、抗氧化代谢、AsA-GSH循环以及渗透调节的影响。结果表明：盐碱胁迫显著抑制大豆幼苗生长,降低了净光合速率(P_n)、叶绿素、可溶性蛋白、可溶性糖、蔗糖和淀粉含量;增加了过氧化氢酶(CAT)活性以及脯氨酸、活性氧(ROS)、丙二醛(MDA)和电解质渗漏率积累;与盐碱处理相比,喷施Pro-Ca能够改善大豆幼苗地上部和根系生长,提高叶绿素a、叶绿素b、类胡萝卜素和总叶绿素含量,维持较高的P_n,促进蔗糖、果糖和淀粉的积累;显著上调叶片6种抗氧化酶(SOD、POD、CAT、GR、MDHAR和DHAR)活性、2种非酶抗氧化剂(AsA和GSH)水平和脯氨酸含量;而电解质渗漏率、O₂^-·产生速率以及MDA和H₂O₂含量显著降低...     

苯丙烯酸对黄瓜幼苗生理特性的影响

采用基质栽培模拟实验,研究了不同浓度苯丙烯酸对黄瓜幼苗生理特性的影响.结果表明,苯丙烯酸对黄瓜幼苗的光合色素、光合速率、蒸腾速率和根系活力产生了抑制作用.当处理浓度为25μmol·L^-1时,对类胡萝卜素产生抑制作用,对叶绿素a、叶绿素b为促进作用;当浓度为50μmol·L^-1时,对光合速率、蒸腾速率和根系活力均产生显著的抑制作用(P<0.05),并随着处理浓度的增加抑制作用增强;当浓度为150μmol·L^-1时,对叶绿素a、叶绿素b产生显著抑制作用(P<0.05);随着处理浓度的增加,对黄瓜上述生理特性的抑制作用增强.低浓度苯丙烯酸(25～50μmol·L^-1)对幼苗根系活力的抑制强度不大,可在处理后期得到恢复;高浓度(100～150μmol·L^-1)处理则表现出显著的抑制作用,随着处理时间延长,抑制作用增强(P<0.05).     

高温胁迫下三唑酮对黄瓜幼苗某些生理性质的影响

研究了三唑酮浸种对黄瓜幼苗抗热性的影响。结果表明,高温胁迫下黄瓜幼苗子叶叶绿素a、b及可溶性蛋白质含量下降,Chla／b比值、游离脯氩酸和可溶性糖含量增加。20mg／L三唑酮浸种抑制了黄瓜幼苗子叶的叶绿素a、b和可溶性蛋白质含量的下降及可溶性糖含量的增加,但脯氨酸含量降低,Chla／b比值上升。恢复温度后子叶的叶绿素a、b及可溶性蛋白、脯氨酸和可溶性糖含量与胁迫后相比均有不同程度的下降,但三唑酮处理下降的幅度低于对照。综上结果,三唑酮增强了黄瓜幼苗的耐热性。     

硅对低温胁迫下黄瓜幼苗生长的影响

采用砂基培养的方法,研究硅对低温胁迫下黄瓜幼苗生长的影响.结果表明加硅处理能使低温胁迫下的黄瓜幼苗超氧化物歧化酶(SOD)、过氧化物酶(POD)活性显著升高:丙二醛(MDA)含量和超氧阴离子自由基(O₂^-)产生速率显著下降,叶片质膜透性降低;硅提高了低温胁迫下黄瓜幼苗的可溶性蛋白质和叶绿素含量、叶绿素a/b比值及植株生物量.因此,硅可以减弱低温胁迫对黄瓜幼苗的伤害.     

外源表油菜素内酯对NaHCO3胁迫下黄瓜幼苗生长及氧化还原平衡的影响

以‘津研四号’黄瓜为试材,以30 mmol·L^-1 NaHCO₃模拟盐碱环境,采用水培法研究了0.2 μmol·L^-1外源2,4表油菜素内酯(2,4-epibrassinolide,EBR)对盐碱胁迫下黄瓜幼苗生长和活性氧代谢的影响.结果表明: NaHCO₃胁迫显著诱导了叶片及根系中O₂^-·的产生和H₂O₂的积累,导致丙二醛含量和电解质渗透率提高.NaHCO₃胁迫下,超氧化物歧化酶、过氧化物酶、过氧化氢酶、抗坏血酸过氧化物酶、脱氢抗坏血酸还原酶、单脱氢抗坏血酸还原酶、谷胱甘肽还原酶活性及还原型抗坏血酸、还原型谷胱甘肽含量随胁迫时间延长呈现先升后降的趋势.外源EBR显著提高了NaHCO₃胁迫下黄瓜叶片和根系中抗氧化酶活性、抗氧化物质的含量以及AsA/DHA(双脱氢抗坏血酸)和GSH/GSSG(氧化型谷胱甘肽)比值,维持了植株内的氧化还原平衡,降低了活性氧积累水平,缓解了膜脂过氧化,从而提高了黄瓜幼苗的盐碱耐受性.     

外源茉莉酸处理地下部对玉米化学防御反应影响的时间和浓度效应

在“高油115”玉米幼苗地下部施用4种不同浓度（10、50、100、200 μmol·L^-1）的茉莉酸3～48 h后,采用生化成分分析和基因表达分析方法,检测了处理部位（根系）和非处理部位（叶片）中防御物质及防御相关基因的表达,以探讨茉莉酸诱导玉米地下部对化学防御反应影响的时间和浓度效应.结果表明：茉莉酸处理玉米地下部对处理部位（根系）和非处理部位（叶片）化学防御反应的影响均与茉莉酸作用的时间和浓度相关.茉莉酸处理玉米地下部后,在3～12 h内就能直接诱导处理部位（根系）Bx9、PAL、PR-2a、MPI和FPS基因的表达,使得根中的丁布含量增加而总酚含量下降,其中100 μmol·L^-1茉莉酸处理浓度产生的诱导作用最强,其次是50 μmol·L^-1,再次是10 μmol·L^-1;后期诱导作用则逐渐减弱.另外,茉莉酸处理玉米地下部还能间接影响到非处理部位（叶片）的化学防御反应,50 μmol·L^-1茉莉酸在处理后3 h就能系统诱导叶片中Bx9和FPS基因的表达,使叶片的丁布含量增加;在6～24 h内则使叶片Bx9、PAL、PR-1、MPI和TPS基因表达量增加,丁布和总酚含量降低.可见,对于大部分检测指标来说,茉莉酸处理玉米地下部对地上部的间接诱导作用不如对地下部的直接诱导作用强,根系启动防御反应的时间较叶片早,同时,随着处理浓度的增加,茉莉酸对根系和叶片防御反应的诱导作用有增强趋势.     

三唑酮浸种后黄瓜幼苗的生理生化变化

黄瓜以一定浓度的三唑酮浸种后,幼苗的根长,株高受到明显抑制,但增大了根重、根冠比、子叶游离氨基酸含量及子叶呼吸速率,同时降低了子叶可溶性糖含量,30d苗龄第1、2片真叶中叶绿素、蛋白质含量、POD、CAT活力增有不同程度的提高,因此表现出一定的壮苗作用。其中50μmol/L对壮苗是最佳的,但高浓度对幼苗生长不利。     

The Effect of Exogenous ABA on the Resistance to the Chilling Stress in Cucumber Seedlings

In the cucumber seedlings pretreated with ABA under light and dark or additional photosynthetic inhibitor (DCMU) before chilling, the effect and the regulative role of ABA on the chilling resistance of cucumber seedlings were investigated. After the excised cotyledonary discs were floated on 10-6 mol/l ABA solution for 24 h and the seedlings were sprayed by 10-4 mol/1 ABA in light, it has been found that ABA has an effect of the protection against low temperature injury in cucumber seedlings. The results showed that the leakage of electrolytes in cucumber cotyledory discs was decreased. The content of glutathione and the accumulation of MDA content in cotyledon of cucumber seedlings were decreased, and decline of the photosynthesis of the leaves or the quenching of chlorophyll fluorescence were slowed, thus the rate of survival in cucumber seedlings was raised. The effect of these regulation was able to be limited by dark or DCMU.     

Photosynthetic pigments content, <Emphasis Type="Italic">δ</Emphasis>-aminolevulinic acid dehydratase and acid phosphatase activities and mineral nutrients concentration in cadmium-exposed <Emphasis Type="Italic">Cucumis sativus</Emphasis> L.

In this study, the effects of cadmium chloride (CdCl₂) on plant growth, histology of roots, photosynthetic pigments content, δ-aminolevulinic acid dehydratase (ALA-D; E.C. 4.2.1.24) and acid phosphatase activities (AP; E.C. 3.1.3.2), soluble phosphorus (Pi) measurement and mineral nutrients content in cucumber seedlings (Cucumis sativus L.) were investigated. Cucumber seedlings were grown in vitro in an agar-solidified substrate containing four CdCl₂ treatments (0, 100, 400, and 1000 μM) for ten days. Cd was readily absorbed by seedlings and its content was greater in the roots than in the shoot. Cd reduced shoot and root length, and fresh and dry biomass of seedlings. Inhibition of root cell elongation in Cd-treated seedlings was observed by the increase of the mean radial size of cells belonging to three zones of the root tip. The highest level of Cd reduced in a similar manner chlorophyll a, chlorophyll b and total chlorophyll contents. Increasing concentrations of Cd resulted in a linear decrease in carotenoids levels of cotyledons. Interestingly, the ALA-D activity in cotyledons was inhibited only at the highest level of Cd. Root and shoot AP activities were, respectively, activated and inhibited at all CdCl₂ concentrations. Root Pi concentration was increased in all Cd treatments and it was not altered in the shoot tissues. Moreover, in general, the nutrient contents were increased in the root and decreased in the shoot. Therefore, we suggest that Cd affects negatively growth, photosynthetic pigments, ALA-D and AP activities and partition of mineral nutrients in cucumber seedlings.     

复合外源物质对玉米幼苗抗寒性的影响

该研究采用不同浓度的水杨酸(SA)、脱落酸(ABA)、磷酸二氢钾(KH2PO4)以及抗坏血酸(VC)进行正交组合获得不同浓度组合的复合外源物质,同时以蒸馏水处理作为对照,将其喷施于玉米幼苗后进行低温胁迫处理,在胁迫结束后使幼苗恢复生长,并测定叶片相关生长指标及生理生化指标的变化。结果表明:(1)与对照组相比,9种复合外源物质处理均可显著提高玉米幼苗的相对生长速率、干物质积累速率及脯氨酸含量,降低相对电导率,总体上提高了玉米幼苗的素质。(2)在4℃低温胁迫下,9种复合外源物质处理下幼苗相对生长速率、干物质积累速率、根系活力、脯氨酸含量、可溶性蛋白含量及可溶性糖含量,均显著高于对照,并减缓了丙二醛的积累和相应的膜脂过氧化,降低了相对电导率,提高了玉米幼苗的耐冷性。低温胁迫条件下,水杨酸、脱落酸、磷酸二氢钾和抗坏血酸四种物质组成的复合物可以提高玉米幼苗的耐冷性,其中以SA0.14 g·L~(-1)+ABA 0.015 g·L~(-1)+KH_2PO_4 3.0 g·L~(-1)+V_C 3.0 g·L~(-1)的复合物效果最好。该研究结果为新型复合抗寒剂的应用推广提供了技术支持。     

Improved Tolerance of Teak (Tectona grandis L.f.) Seedlings to Low-Temperature Stress by the Combined Effect of Arbuscular Mycorrhiza and Paclobutrazol

Low-temperature damage is a common problem for tropical and subtropical plants during their early-growth stage. In this study, an experiment with a L₁₈ (2¹?×?3⁷) mixed orthogonal array in a greenhouse was conducted to determine whether arbuscular mycorrhizal fungi (AMF) inoculation and paclobutrazol (PBZ) application through foliar spray would enhance the chilling tolerance of teak seedlings. One-month-old seedlings of clones 8301, 7544, and 7552 from a Myanmar provenance propagated by tissue culture techniques were inoculated with Glomus versiforme and cultivated for 6?months. The foliar surface of both mycorrhizal and nonmycorrhizal treated plants was sprayed with PBZ at concentrations of 0, 50, and 100?mg?l^?1 once a week for 3?weeks prior to exposure to low temperatures of 6, 3, and 0°C for 12?h in an artificial climate chamber, followed by 12?h of recovery at 20°C room temperature. AMF colonization significantly promoted height and RCD growth and dry biomass accumulation of shoot and root. Under low-temperature stress, AM symbiosis increased leaf chlorophyll content by 22.8%, soluble protein content by 19.6%, superoxide dismutase (SOD) activity by 10.6%, and peroxidase (POX) activity by 9.5%, whereas malondialdehyde content was decreased by 14.1%. Both AMF colonization and the foliar spray PBZ at 50 and 100?mg?l^?1 were capable of alleviating the damage caused by low-temperature stress on teak seedlings by increasing the photosynthetic pigments, accumulation of osmotic adjustment compounds, and antioxidant enzyme (SOD and POX) activity, and by decreasing membrane lipid peroxidation. AMF colonization and foliar spraying of PBZ at 50?mg?l^?1 produced a positive interaction and appears to be a good way to enhance chilling tolerance of teak seedlings experiencing stress at 6, 3 and 0°C for 12?h.     

外源ABA对黄瓜幼苗抗低温胁迫的作用

在光照下对黄瓜(Cucuntis sativus L.)离体子叶圆片和幼苗分别使用10~(-6)mol/l 与10~(-4)mol/l ABA 处理,有防御低温伤害的作用,表现为降低子叶圆片的电解质渗漏,阻抑幼苗子叶的谷胱甘肽含量的下降和膜脂过氧化产物丙二醛(MDA)的累积,减缓叶片的光合作用的下降和叶绿素荧光的猝灭,提高幼苗的存活率。但这种作用可被黑暗和光合抑制剂(DCMU)所限制。     

黄瓜核心种质低温耐受性的田间评价

在自然低温条件下,利用幼苗存活率、冷害指数、叶片数、株高及叶绿素含量5个指标对303份黄瓜核心种质进行了低温耐受性评价,结果表明:5个指标基本符合正态分布的特点,幼苗存活率和冷害指数均有明显向低值和高值区域偏离的趋势。相关分析结果显示冷害指数与幼苗存活率、叶片数、株高及叶绿素含量4个指标呈极显著负相关。通过隶属度函数综合评价群体的低温耐受性,共筛选获得28份耐低温种质,为黄瓜耐低温的品种选育及进一步深入挖掘低温耐受性相关基因奠定了基础。     

Frost resistance and water status of winter rape leaves as affected by differential shoot/root temperature

Twenty day-old winter rape ( Brassica napus L. var. oleifera L. cv. Jantar) seedlings, grown in nutrient solution, were exposed to different shoot/root temperature (i. e. 20/20, 20/3, 3/20 and 3/3°C) for 2 or 4 weeks. Chilling treatments modified markedly the pattern of plant growth as indicated by changes in dry matter accumulation in individual plant parts (leaves, hypocotyls, roots) and decreased leaf specific area. Growth of roots was less sensitive to low temperature than that of shoots. This was reflected by a decrease in shoot/root biomass ratio. Chilling treatments increased freezing resistance, decreased water content and water potential and modified reducing sugar, soluble protein and phospholipid contents in the leaves. A biphasic character of tissue responses to chilling temperature was observed, the most remarkable changes being registered during the first 7 or 14 days of the treatment. Effects of root or shoot exposure to chilling temperature on ice nucleation temperature, LT₅₀, water potential, accumulation of sugars and phospholipids in leaves were additive. All the observations point to the important role of the root system in plant acclimation to cold. Its impact on water status of leaves is emphasized and some mechanisms of root involvement in acclimation processes are proposed.     

低温胁迫对嫁接西瓜耐冷性和活性氧清除系统的影响

研究了西瓜实生苗和以黑籽南瓜、超丰F1为砧木的嫁接苗的耐冷性及活性氧清除系统的差异．结果表明,低温胁迫下,嫁接苗的耐冷性明显高于实生苗,表现为以黑籽南瓜为砧木的嫁接苗的耐冷性>以超丰F1为砧木的嫁接苗>实生苗,此外嫁接苗和实生苗均表现为叶片中叶绿素含量下降,丙二醛(MDA)含量上升,非酶促抗氧化剂抗坏血酸(AsA)、谷胱甘肽(GSH)含量和抗氧化酶超氧化物歧化酶(SOD)、抗坏血酸过氧化物酶(AsA-POD)、脱氢抗坏血酸还原酶(DR)活性下降,说明低温逆境降低了植物体防御活性氧有关的酶促和非酶促保护系统能力,提高了体内自由基浓度,加剧了膜脂过氧化．嫁接苗的活性氧清除能力均高于自根苗,且嫁接苗中耐冷性越强的活性氧清除能力越高,说明西瓜嫁接后耐冷性的提高是与植物体内活性氧清除系统中抗氧化剂含量和抗氧化酶活性提高有关。