遮荫对8种红树植物幼苗叶片叶绿素荧光参数的影响

为探讨红树植物光适应的生理生态机制,通过遮荫控制试验对无瓣海桑(Sonneratia apetala)、秋茄(Kandelia candel)、木榄(Bruguiera gymnorrhiza)、桐花树(Aegiceras corniculatum)、老鼠簕(Acanthus ilicifolius)、卤蕨(Acrostichum aureum)、银叶树(Heritiera littoralis)、黄槿(Hibiscus tiliaceus)等8种红树植物的1 a生幼苗在不同生长光强(自然光强的100%、45%、30%、10%)下的叶绿素荧光参数进行了研究。结果表明,8种红树植物在遮荫后光系统II最大光化学效率(Fv/Fm)和光系统II实际光化学效率(ΦPSII)总体呈上升趋势,而电子传递速率(ETR)则显著下降。无瓣海桑、秋茄、桐花树、银叶树和黄槿在全光照下表现出比其他3种植物更高的Fv/Fm,同时桐花树和银叶树的ΦPSII和ETR也显著高于木榄、老鼠簕和卤蕨。因此,无瓣海桑、秋茄、桐花树、银叶树和黄槿在高光辐射下具有更高的光能利用率,同时桐花树和银叶树能更好地利用高光并耗散过剩光能...     

几种红树植物幼苗中可溶性糖的含量

用Ｓｏｍｏｇｙｉ法测定了红海榄、木榄和秋茄３种红树植物幼苗的根、茎、叶和胚轴中可溶性糖的含量。同时．进行了加样回收率试验,回收率平均为１００．４８％,变异系数为２．１４％     

不同生长光强下8种红树植物幼苗叶片的光响应特征

为探讨红树植物光适应的生理生态策略,对6种真红树植物[无瓣海桑(Sonneratia apetala)、秋茄(Kandelia candel)、木榄(Bruguiera gymnorrhiza)、桐花树(Aegiceras corniculatum)、老鼠簕(Acanthus ilicifolius)、卤蕨(Acrostichum aureum)]和2种半红树植物[银叶树(Heritiera littoralis)、黄槿(Hibiscus tiliaceus)]的1 a生幼苗在不同生长光强(自然光强的100%、45%、30%、10%)下的光合光响应特征进行了研究。结果表明,不同生长光强对红树植物光响应特征的影响因物种而异,遮荫显著提高了秋茄和木榄的最大净光合速率(Pmax),而对其他红树植物的Pmax没有显著影响;秋茄在45%光强下具有较高的Pmax,木榄的Pmax则在45%和30%光强下显著高于其他2个处理。随着生长光强的下降,秋茄幼苗叶片的光饱和点显著上升,木榄、老鼠簕和卤蕨的光补偿点呈下降趋势,木榄和卤蕨的表观量子效率升高的同时暗呼吸速率下降。木榄、老鼠簕和卤蕨具有较强的耐荫性,...     

光照强度对8种红树植物幼苗生长和生物量分配的影响

选取无瓣海桑(Sonneratia apetala Buch-Ham.)、卤蕨(Acrostichum aureum Linn.)、桐花树(Aegiceras corniculatum Blanco.)、老鼠簕(Acanthus ilicifolius Linn.)、木榄(Bruguiera gymnorrhiza Lam.)、秋茄(Kandelia candel Druce.)、银叶树(Heritiera littoralis Ait.)和黄槿(Hibiscus tiliaceus L.)为研究对象,通过遮荫控制实验,研究这8种红树植物幼苗在不同光照强度(自然光强的100%、45%、30%、10%)下的生长和生物量分配特征。结果表明:(1)遮荫对无瓣海桑幼苗相对生长速率、生物量积累、基径的增长和叶片数的增长均有显著的抑制作用;(2)桐花和老鼠簕在遮荫处理下生长状况较好,遮荫对桐花生长的影响不显著,对老鼠簕幼苗的生长则有一定的促进作用;(3)当光照强度降低时,无瓣海桑、秋茄、老鼠簕、桐花树的幼苗都对地上部分投入了更多的生物量,其中秋茄、老鼠簕和桐花树通过提高叶生物量来获取更大的光能捕获能力。研究结果表明,从对光照的生长适应角度来看,桐花、老鼠簕和卤蕨适宜种植在郁闭度较高的林下;秋茄适宜在郁闭度较低的林下种植;真红树无瓣海桑和木榄以及半红树黄槿和银叶树则不适合在林下种植。     

真红树和半红树植物叶片性状的比较研究

红树植物是一类生长在热带、亚热带海岸潮间带的乔木、灌木或草本植物,根据其分布特征可分为真红树植物植物和半红树植物。为了探究两者对海岸潮间带高盐、高光和缺氧等环境的生态适应策略的异同,该文选取5种真红树植物植物[卤蕨(Acrostichum aureum)、木榄(Bruguiera gymnorrhiza)、老鼠簕(Acanthus ilicifolius)、桐花树(Aegiceras corniculatum)、秋茄(Kandelia candel)]和4种半红树植物[银叶树(Heritiera littoralis)、水黄皮(Pongamia pinnata)、黄槿(Hibiscus tiliaceus)、杨叶肖槿(Thespesia populnea)]为研究对象,对叶片解剖和功能性状进行了对比研究。结果表明:(1)9种红树植物叶片的共同特征表现为均具有角质层、叶肉具有栅栏组织和海绵组织分化、气孔下陷等。(2)不同之处在于真红树植物植物叶片有蜡质层和内皮层、无表皮毛、气孔仅分布在下表皮,而半红树植物的叶片则较少有蜡质层,部分有表皮毛,无内皮层,气孔在上下表皮分布不完全一致。(3)真红树植物植物的气孔密度和比叶面积显著小于半红树植物(P<0.05),而叶片厚度、含水量、比叶重和鲜干重比则显著大于半红树植物(P<0.05)。以上结果说明真红树植物植物的叶片性状使其在维持盐度平衡及贮水保水能力方面强于半红树植物,从而能更好地适应海岸潮间带高盐环境。     

薇甘菊可溶性蛋白和抗氧化酶活性对田野菟丝子不同寄生密度的响应

为探求利用寄生植物田野菟丝予对入侵杂草薇甘菊进行生物控制的有效措施,研究了薇甘菊对0、1、2、4和8棵田野菟丝子幼苗寄生在可溶性蛋白和一些抗氧化酶活性方面的响应.寄生后30 d,1棵田野菟丝子/株薇甘菊（以下简称棵/株）以上的寄生密度导致薇甘菊可溶性蛋白含量显著降低.和对照相比,在寄生密度为1棵/株时,超氧物歧化酶(S...     

铅对红树植物木榄幼苗几种生理特性的影响

试验材料为木榄[Bruguiera gymnorrhiza(L.) Lam],其成熟胚采自广西英罗港。胚种植在沙基中,于室内室温下培养。胚长出第3对叶时,选取重量和高度大体一致的幼苗种植于一个不漏水的塑料桶内,每桶2株,桶中装有2kg河沙。铅     

三种红树植物叶片的比较解剖学研究

研究了采自福建九龙江口的3种红树植物,秋茄(Kandeliacandel)、木榄(Bruguieragymnorrhiza)和红海榄(Rhizophorastylosa)的叶片结构并探讨了其生态学意义。结果表明,这3种红树植物叶片都具有适应海生环境的结构,较厚的角质层,表皮之内有内皮层,内皮层属贮水组织;气孔都分布在下表皮,下陷,并有大的孔下室;中脉有发达的维管束,其导管粗大。从叶片的横切面来看,秋茄叶片具有对称的结构,为等面叶;木榄和红海榄的叶片结构不对称,为异面叶。3种植物叶内都含有较丰富的单宁,以秋茄最高,红海榄次之,木榄最少。这些结构差异可为物种鉴定提供依据。     

真红树和半红树植物叶片氯含量及叶性状的比较

 依据红树植物在潮间带的分布,将其分为真红树植物和半红树植物两大类。但对一些过渡地带种类的归属问题一直存在争议。该研究选取国内大部分红树植物,比较其成熟叶片中的Cl含量、肉质化程度、比叶面积（SLA）、单位重量叶氮含量（N_mass）和单位面积叶氮含量（N_area）,并对争议树种重新进行界定。结果表明：1）真红树植物叶片中Cl含量和肉质化程度远高于半红树植物;2）真红树植物具有低SLA和高N_area的特点,除水芫花(Pemphis acidula)外半红树植物具有高SLA和低N_area的特点。3）争议的7种红树植物中,银叶树（Heritiera littoralis）、海漆（Excoecaria agallocha）、卤蕨（Acrostichum aureum ）和尖叶卤蕨（Acrostichum speciosum）归为半红树植物更合适;老鼠（Acanthus ilicifolius）和小花老鼠（Acanthus ebrecteatus）归为真红树植物。木果楝（Xylocarpus granatum）有待进一步研究。     

香果树(Emmenopterys henryi)幼苗生长特性和叶绿素荧光对不同光强的响应

研究了室内人工气候箱中相对高、中和低（（5000&#177;230）lx、（2200&#177;110）lx和（1000&#177;80）lx）光强下香果树幼苗的生长特性及荧光参数的动态变化,结果表明,中光强下的幼苗生长迅速,株高和生物量一直维持最高水平;高光强下的幼苗,生长极其缓慢,株高和生物量均处于最低水平;低光强下的幼苗比叶面积最大;而根冠比则以高光强下的为最高;叶绿素（a＋b）含量在低光强下最高,中光下次之,强光下最小。前期,低光强下幼苗叶片的叶绿素a/b值较大,随着幼苗的生长呈下降的趋势,120d后与其他处理相比达到最小。荧光参数的结果显示,高光强下,香果树幼苗的电子传递速率（ETR）、光化学猝灭系数（qP）和非光化学猝灭系数（qNP）均处于最低水平,而测定初始荧光（Fo）和最大荧光（Fm）却处于最高水平,在低和中光强下则刚好相反。由此可见,高光强对香果树幼苗生长极其不利,而低和中光强下生长较好。建议在室内培育香果树幼苗时,适当减弱光强,保证其正常生长。     

镉诱导萝卜幼苗活性氧产生、脂质过氧化和抗氧化酶活性的变化

通过水培试验,研究Cd2+胁迫对萝卜幼苗活性氧的产生、脂质过氧化和抗氧化酶活性的影响。超氧 阴离子(O 2)的产生速率和丙二醛(MDA)的含量与对照相比有不同程度的增加,表明Cd2+胁迫能导致萝卜体 内的氧化胁迫;超氧化物歧化酶(SOD)的活性,随着Cd2+浓度提高,首先明显上升,然后逐渐下降,甚至低于 对照,叶片过氧化氢酶(CAT)的活性明显增加,根系CAT活性则减少,根系以及较高浓度Cd2+处理后期叶片 谷胱甘肽还原酶(GR)的活性均显著增加。推测:胁迫初期可能主要由SOD和CAT发挥抗氧化作用;后期由 于抗坏血酸—谷胱甘肽(AsA GsH)循环途径的激活,以及还原型谷胱甘肽(GSH)和植物络合素(Phytochela tins,PCs)的合成,可能在清除活性氧或者直接鏊合Cd2+中起作用。     

Cross-talk between calcium and reactive oxygen species originated from NADPH oxidase in abscisic acid-induced antioxidant defence in leaves of maize seedlings

The signal interactions between calcium (Ca2+) and reactive oxygen species (ROS) originated from plasma membrane NADPH oxidase in abscisic acid (ABA)-induced antioxidant defence were investigated in leaves of maize (Zea mays L.) seedlings. Treatment with ABA led to significant increases in the activity of plasma membrane NADPH oxidase, the production of leaf O2-, and the activities of several antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX) and glutathione reductase (GR). However, such increases were blocked by the pretreatment with Ca2+ chelator EGTA or Ca2+ channel blockers La3+ and verapamil, and NADPH oxidase inhibitors such as diphenylene iodonium (DPI), imidazole and pyridine. Treatment with Ca2+ also significantly induced the increases in NADPH oxidase activity, O2- production and the activities of antioxidant enzymes, and the increases were arrested by pretreatment with the NADPH oxidase inhibitors. Treatment with oxidative stress induced by paraquat, which generates O2-, led to the induction of antioxidant defence enzymes, and the up-regulation was suppressed by the pretreatment of Ca2+ chelator and Ca2+ channel blockers. Our data suggest that a cross-talk between Ca2+ and ROS originated from plasma membrane-bound NADPH oxidase is involved in the ABA signal transduction pathway leading to the induction of antioxidant enzyme activity, and Ca2+ functions upstream as well as downstream of ROS production in the signal transduction event in plants.     

The effects of dopamine on antioxidant enzymes activities and reactive oxygen species levels in soybean roots

In the current work, we investigated the effects of dopamine, an neurotransmitter found in several plant species on antioxidant enzyme activities and ROS in soybean (Glycine max L. Merrill) roots. The effects of dopamine on SOD, CAT and POD activities, as well as H₂O₂, O₂^•−, melanin contents and lipid peroxidation were evaluated. Three-day-old seedlings were cultivated in half-strength Hoagland nutrient solution (pH 6.0), without or with 0.1 to 1.0 mM dopamine, in a growth chamber (25°C, 12 h photoperiod, irradiance of 280 μmol m⁻² s⁻¹) for 24 h. Significant increases in melanin content were observed. The levels of ROS and lipid peroxidation decreased at all concentrations of dopamine tested. The SOD activity increased significantly under the action of dopamine, while CT activity was inhibited and POD activity was unaffected. The results suggest a close relationship between a possible antioxidant activity of dopamine and melanin and activation of SOD, reducing the levels of ROS and damage on membranes of soybean roots.     

Nitric oxide levels and antioxidant enzyme activities in jaundices of premature infants

Free radicals are effective in the genesis of several diseases in the neonatal period. This study aimed to show the relationship between serum bilirubin levels and plasma nitric oxide and the activity of enzymes in the erythrocyte such as superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and catalase (CAT) in premature infants. In the study, 20 premature infants with newborn jaundice were included and the control group was formed by 15 premature infants without jaundice. Venous blood samples were taken from all neonates in the study and control groups on the first day of hospitalization. Plasma nitric oxide levels and activities of SOD, GSH-Px and CAT enzymes in the erythrocytes were investigated in these samples. Plasma nitric oxide and serum bilirubin levels were found to be significantly higher in the study group (47.4 +/- 7.25 micromol l(-1), 18.41 +/- 3.28 mg dl(-1), respectively) than those in the control group (33.46 +/- 6.43 micromol l(-1), 4.35 +/- 0.60 mg dl(-1), respectively; p < 0.001). In addition, erythrocyte SOD, GSH-Px and CAT enzyme activities (724 +/- 78.61, 673 +/- 90.5, 63 +/- 12.8 U g(-1) Hb, respectively) were found to be significantly lower in the study group than those in the control group (1208 +/- 129.04, 1097.6 +/- 75.8, 99.06 +/- 12.4 U g(-1) Hb, respectively, p < 0.001). It was concluded that in the aetiology of hyperbilirubinemia, neonatal erythrocytes and nitric oxide reactions are affected differently and that erythrocyte haemolysis caused as a result of these effects may play a role in the aetiopathogenesis of unconjugated hyperbilirubinemia. Haemolysis may also be seen because of the inadequacy of the protection by erythrocytes against the cytotoxic effects of free radicals resulting from the lack of antioxidant enzymes in these cells.     

生长环境光强对两种热带雨林树种幼苗光合作用的影响

以西双版纳热带雨林中演替后期种绒毛番龙眼和先锋树种山黄麻为材料 ,于雾凉季测定了不同光强下生长的 2种树苗叶片最大净光合速率 (Pmax)、叶绿素荧光参数以及光合色素含量和比叶重 (L MA) ,探讨了不同生态习性热带雨林树种幼苗对光强的适应及光保护机制。发现在一定光强范围内随生长环境光强的增加 ,2种树苗 L MA、荧光的非化学猝灭 (N PQ)、类胡萝卜素(Car)含量、Car与叶绿素 (Chl)之比升高 ,光饱和点和光补偿点也有随生长环境光强的增大而升高的趋势 ,Chl含量降低 ,2种树苗均能通过形态和生理特性的变化适应不同的光强环境。相同的生长光强下 ,绒毛番龙眼光抑制明显比山黄麻重 ,山黄麻适应强光的能力强。随生长环境光强的增加 ,山黄麻 N PQ增加不显著 ,热耗散较少 ,相同光强下其 Pmax显著高于绒毛番龙眼。绒毛番龙眼则相反 ,其热耗散随生长环境光强的升高显著增多 ,但 Pmax差异不显著。表明先锋种山黄麻主要通过提高 Pmax利用光能防止光合机构光破坏 ,而演替后期种绒毛番龙眼却较大程度通过增强非光化学猝灭来耗散过量光能。上午人为降低光强度对先锋种山黄麻影响不大 ,但可以明显缓解绒毛番龙眼的光抑制 ,表明上午一定程度的遮光 (如有雾 )可减缓绒毛番龙眼光抑制     

Polyphenols, tannins and antioxidant activities of eight true mangrove plant species in South China

Background and aims

(i) compare the concentrations of total polyphenols (TP) and condensed tannins (CT), and CT profiles in different organs of mature trees and seedlings of eight true mangrove species in Hong Kong; (ii) examine the antioxidant activities of CT and (iii) relate the non-enzymatic antioxidative defence system with the vertical zonation pattern of mangrove species.

Methods

Mature trees and seedlings of eight species were collected from a Hong Kong mangrove swamp to determine TP and CT concentrations and the antioxidant activities of CT.

Results

According to TP concentrations, the true mangrove species could be broadly classified into three groups, (i) Lumnitzera racemosa and Aegiceras corniculatum > (ii) Heritiera littoralis, Excoecaria agallocha, Bruguiera gymnorrhiza and Kandelia obovata > (iii) Acanthus ilicifolius and Avicennia marina. The last two are pioneer species in the most foreshore location. They also had significantly lower antioxidant activities, CT concentrations and different CT profiles than the other six species in mid- and low-tides.

Conclusions

Classification of the eight true mangrove species into three groups based on polyphenols was similar to their vertical zonation from land to sea. The relationships between these antioxidants and zonation should be further verified by transplantation studies.     

光强对喜树幼苗叶片次生代谢产物喜树碱的影响

喜树碱是我国特有树种——喜树中所含的重要次生代谢产物 ,在人工控制条件下观察了光强对喜树幼苗叶片喜树碱含量的影响。喜树幼苗叶片的喜树碱含量随着遮荫程度的增加 (光照强度降低 )而增加 ,但严重遮荫的 (光强为全光照的 2 0 % )在处理后期 (75 d)喜树碱含量降低。叶片的喜树碱产量 (喜树碱含量与叶片生物量乘积 )在处理初期 (30 d)随光强减弱而缓慢地略有增加 ,处理后期 (45 d以后 )随光强的减弱而有明显增加 ,但光强低于全光照的 6 0 %以后喜树碱产量迅速下降。喜树碱的增加可能是喜树幼苗通过次生代谢过程对不良环境 (遮荫 )的一种适应性反应