外源2,4-表油菜素内酯对NaCl胁迫下燕麦幼苗光合特性的影响

为探明外源2,4-表油菜素内酯(EBR)对NaCl胁迫下燕麦光合作用的调控机理,以加燕2号、青引2号燕麦为材料,在100 mmol/L NaCl胁迫下,研究外源EBR对燕麦幼苗光合气体交换参数、荧光动力学参数、光合电子传递速率及PSⅡ光能分配情况的影响。结果表明:NaCl胁迫显著降低了燕麦幼苗的光合色素含量,抑制了PSⅡ反应中心活性,导致燕麦幼苗PSⅡ光化学效率下降,净光合速率(Pn)显著降低。和NaCl胁迫相比较,添加外源EBR后,燕麦幼苗叶片的叶绿素a(Chla)、叶绿素b(Chlb)和类胡萝卜素(Chlx·c)含量显著增加;燕麦幼苗的Pn、蒸腾速率(Tr)、气孔导度(Gs)和水分利用效率(WUE)显著升高,胞间CO_2浓度(Ci)显著降低,最大荧光(Fm)、光化学淬灭系数(qP)、PSⅡ实际光合效率(ФPSⅡ)、PSⅡ潜在活性(Fv/Fo)、PSⅡ原初光能转化效率(Fv/Fm)、天线色素转化效率(Fv′/Fm′)、表观光合电子传递速率(ETR)及PSⅡ光化学反应能(P)显著升高,初始荧光(Fo)、非光化学淬灭系数(NPQ)及反应中心耗散能(E)、天线耗散能(D)显著降低。综上所述,外源EBR能够显著提高NaCl胁迫下燕麦幼苗PSⅡ反应中心的实际光化学效率,有效缓解NaCl胁迫对燕麦幼苗所产生的光抑制和PSⅡ反应中心损伤程度,提高燕麦幼苗的碳同化效率和光合能力,说明外源BRs对盐胁迫下燕麦光合作用起到正向调控作用,能够有效缓解盐胁迫对燕麦幼苗所造成的伤害。     

不同生育时期玉米苞叶叶绿素荧光特性差异分析

以郑单958和农大364两个玉米品种为研究材料,对大田条件下不同生育时期玉米苞叶的叶绿素含量和叶绿素荧光动力学进行了比较分析.结果表明,不同生育时期玉米苞叶叶绿素含量呈先升后降的变化趋势,并在灌浆期达到最高值,且农大364苞叶的叶绿素降低速率要低于郑单958,这样有利于其保持更为持久的光合能力.不同生育时期玉米品种间苞叶叶绿素荧光参数(Fm、Fv、Fv/Fm、Fv/Fo等)的变化规律基本一致,郑单958高于农大364,说明郑单958苞叶反应中心活性较高,具有较高的电子传递速率,并且苞叶叶片开放的PSⅡ反应中心捕获激发能的效率高于后者.     

不同水分条件下小麦旗叶叶绿素a荧光参数与子粒灌浆速率

利用OS－30型叶绿素荧光分析仪研究水分胁迫对小麦旗叶叶绿素a荧光动力学参数的影响。结果表明，水分胁迫下旗叶的T1／2值减少，旗叶光系统Ⅱ（PSⅡ）原初光能转化效率（Fv/Fm)和潜在活性（Fv/Fo)降低，光合作用的潜在活力降低，这些参数下降影响了光合电子的传递和CO2同化的正常进行，表现在可变荧光淬灭速率减慢，可变荧光下降比值减小。同时还讨论了水分胁迫对灌浆速率的影响。     

外源镉胁迫对玉米幼苗光合特性的影响

研究了模拟光条件下,外源Cd胁迫对苗期玉米光合特性的影响。结果表明,Cd胁迫下导致玉米的最大光合速率和叶片蒸腾速率明显降低,光饱和点和表观量子产额有所下降。Cd胁迫下玉米叶片气孔导度减小,低光强时,Cd胁迫对气孔的限制起到较为重要的作用,而在高光强时Cd胁迫导致光合速率较低的原因为非气孔因素,吉甜6的气孔导度受Cd影响更大。Cd胁迫处理使暗适应的玉米叶片的初始荧光Fo升高;2个玉米品种的Fm,Fv,Fv/Fo和Fv/Fm均下降,表明Cd胁迫下PSII的潜在活性和原初光能转换效率减弱;Cd胁迫对吉甜6的光能转换效率和电子传递效率的影响更大。     

干旱胁迫对玉米叶绿素荧光参数及质膜透性的影响

以抗旱性不同的3个玉米品种京单28、郑单958、京科25为试材,研究干旱胁迫下玉米的叶绿素荧光参数及质膜透性的变化.结果表明:干旱胁迫对叶绿素荧光参数的影响非常显著,干旱胁迫会降低玉米PSⅡ的原初光能转化效率(Fv/Fm),使PSⅡ反应中心开放部分比例(qP)降低,用于光合作用电子传递的份额(qP)减少,而以热能的形式耗散,过量的光能不及时耗散会使光合器官受到损伤,导致玉米叶片原生质膜结构伤害,从而引起膜的透性增大,玉米叶片中丙二醛、脯氨酸含量变化.     

玉米叶片光合生理与抗旱性关系研究

在水分胁迫条件下,对玉米叶片净光舍速率、叶绿素含量及叶绿素荧光参数的变化进行了研究.结果表明:玉米叶片净光合速率(Pn)、叶绿素a(Chl a)、叶绿素b(Chl b)、总叶绿素含量(Chl)、叶绿素a/b比值(Chl a/b)、最大荧光(Fm)和PsⅡ光化学效率(Fv/Fm)比对照均有所下降,基础荧光(Fo)增加;Pn和Ctd a/b比值占对照百分率与品种抗旱性呈极显著正相关(r=0.8807**,P<0.01;r=0.8804**,P<0.01),Fo占对照百分率与品种抗旱性则呈显著负相关(r=-0.764 0*,P<0.05),Fm和Fv/Fm占对照百分率与品种抗旱性则呈显著正相关(r=0.711 6*,P<0.05;r=0.772 3*,P<0.05).因此,净光合速率、叶绿素a/b比值、Fo、Fin和Fv/,m可以用来评定不同玉米品种的抗旱性.     

DCPTA对低温胁迫下玉米幼苗叶片叶绿素含量及其荧光特性的影响

以郑单958为盆栽试验材料,设置3个昼夜温度梯度(18℃/9℃、16℃/7℃、14℃/5℃),研究喷施不同浓度DCPTA对玉米幼苗叶片的叶绿素含量以及叶绿素荧光特性的调控机制。结果表明,低温胁迫下喷施DCPTA玉米幼苗的叶绿素含量比对照(清水处理)高23.62%~144.55%;玉米叶片Fo(初始荧光)比对照低4.55%~39.53%,Fv/Fo(PSⅡ潜在活性)、Fv/Fm(PSⅡ最大光化学效率)、qN(非光化学猝灭系数)分别比对照高出30.26%~112.39%、7.47%~32.96%、5.98%~57.52%;浓度为50mg/L的DCPTA喷施玉米幼苗叶片后,对低温胁迫下玉米叶片光合系统的保护效果最好,这有利于提高玉米幼苗叶片的抗冷性。     

高温胁迫下不同杜鹃品种PSII活性变化及其耐热性比较

为了解杜鹃光合机构对高温的响应机制与筛选耐热品种,以7 个杜鹃品种‘胭脂蜜’、‘吐蕊玫瑰’、‘小青莲’、‘夏锦袍’、‘锦袍’、‘艳春’与‘紫鹤’为材料,研究了3 种高温(30℃/28℃、35℃/30℃、38℃/35℃)胁迫下,供试杜鹃品种的外观形态与叶绿素荧光参数Fo（初始荧光）、Fv/Fo（PSII 潜在活性）、Fv/Fm（最大光化学效率）、Fv’/Fm’（PSII 反应中心激发能捕获效率）与NPQ（非光化学猝灭系数）的变化。结果表明：供试杜鹃品种随着胁迫时间增加Fo 上升,Fv/Fo、Fv/Fm与Fv’/Fm’下降,变化幅度与胁迫强度及时间成正比;NPQ表现为前期下降后期升高,耐热性强的杜鹃品种叶绿素荧光参数变化幅度小而耐热性差的品种变化幅度大,与外观表现一致。隶属函数综合分析表明,‘胭脂蜜’、‘吐蕊玫瑰’、‘小青莲’耐热性较强,可部分替代常规品种‘紫鹤’应用于城市绿化。     

铝胁迫对西瓜幼苗光合及叶绿素荧光特性的影响

为了探明铝胁迫对西瓜光合特性的影响。以西瓜品种早蜜王(ZM)、早春红玉(HY)为材料,研究不同浓度铝(0,250,500,1 000,1 500μmol/L)处理下西瓜幼苗生长指标、叶绿素含量、光合特性及叶绿素荧光参数的变化。随铝浓度升高,铝处理对两西瓜品种幼苗根长及生物量的影响基本都表现为"先促后抑",且对ZM的抑制作用较HY更明显。对光合作用的影响主要有以下3个方面:铝处理下HY叶绿素含量均高于对照,ZM叶绿素含量仅在低浓度(250μmol/L)铝处理下高于对照;HY叶绿素a/b随铝浓度升高呈下降趋势;Al3+≤500μmol/L的铝处理下,ZM气孔导度、胞间CO2浓度、净光合速率、蒸腾速率受影响程度较HY明显,在Al3+≥1 000μmol/L处理下,HY、ZM的4个参数均呈降低趋势。在大于250μmol/L的铝处理下,两西瓜品种在铝胁迫下荧光参数变化表现为:初始荧光(Fo)、最大荧光(Fm)、潜在光化学活性(Fv/Fo)、最大光化学效率(Fv/Fm)和实际量子产量Y(Ⅱ)下降,非光化学猝灭(NPQ)上升,光化学猝灭(q P)与PSⅡ电子传递速率(ETR)降低。HY较ZM耐铝在荧光参数变化上表现为:低浓度胁迫(250μmol/L)下,Fo、Fm、Fv/Fo、Fv/Fm更加稳定;电子传递速率受铝处理影响较小,非光化学猝灭(NPQ)在不同浓度铝处理下较为恒定,即能够维持恒定的光保护能力。     

DCPTA对寒地不同基因型玉米叶片光合特性及根系发育的影响

本试验以玉米东农253、先玉335为试验材料,在盆栽条件下,叶面喷施DCPTA,设置浓度为30mg/L,60mg/L,90mg/L,以清水处理作为对照（CK）,喷施处理后分别在3、6、9、12天进行取样分析,以明确DCPTA对寒地不同基因型玉米光合特性以及根系发育的影响。结果表明DCPTA可以显著提高两玉米品种的生物量、叶片的SPAD值、气孔导度、光合速率、蒸腾速率,降低胞间CO2浓度;可显著提高超氧化物歧化酶（SOD）和过氧化物酶（POD）的活性;显著提高了光系统Ⅱ(PSⅡ)反应中初始荧光F0值、最大PSⅡ的光能转换效率Fv/Fm。经DCPTA处理,两品种的根系活力及根的总长、表面积、体积和总须根数相比对照也有所提高。本试验发现60mg/L的DCPTA处理效果好,而在第9天促进作用达到顶峰。两品种之间对比发现,DCPTA对先玉335品种喷施后的促进作用更为明显。     

Biological Activity and Quantification of Suspected Allelochemicals from Alfalfa Plant Parts

Autotoxicity restricts reseeding of alfalfa (Medicago sativa L.) after alfalfa until autotoxic chemical(s) breaks down or is dispersed into external environments. A series of aqueous extracts from leaves, stems, roots and seeds of alfalfa ‘Vernal’ were bioassayed against alfalfa seedlings of the same cultivar to determine their autotoxicity. The highest inhibition was found in the extracts from the leaves. Extracts at 40 g dry tissue l^?1 from alfalfa leaves were 15.4, 17.5 and 28.7 times more toxic to alfalfa root growth than were those from roots, stems and seeds, respectively. A high‐performance liquid chromatography (HPLC) analysis with nine standard compounds showed that the concentrations and compositions of allelopathic compounds depended on the plant parts. In leaf extracts that showed the most inhibitory effect on root growth, the highest amounts of allelochemicals were detected. Among nine phenolic compounds assayed for their phytotoxicity on root growth of alfalfa, coumarin, trans‐cinnamic acid and o‐coumaric acid at 10^?3 m were most inhibitory. The type and amount of causative allelochemicals found in alfalfa plant parts were highly correlated with the results of the bioassay, indicating that the autotoxic effects of alfalfa plant parts significantly differed.     

Changes in Seed Yield and Quality with Maturity in Onion (Allium cepa L., cv. 'Early Cream Gold')

Development of onion (Allium cepa L., cv. ‘Early Cream Gold’) seed under cool climate conditions in Tasmania, Australia occurred over a longer duration than previously reported, but similar patterns of change in yield components were recorded. In contrast to previous studies, umbel moisture content declined from 85 to 67 % over 57 days while seed moisture content decreased from 85 to 31 %. Seed yield continued to increase over the duration of crop development, with increasing seed weight compensating for seed loss resulting from capsule dehiscence in the later stages of maturation. Germination percentage was high and did not vary significantly from 53 to 77 days after full bloom (DAF), but mean germination time declined and uniformity of germination increased significantly over the same time period. The percentage abnormal seedlings declined with later harvest date, resulting in highest seed quality at 77 DAF. The results of this study suggest that the decision to harvest cool climate onion seed crops before capsule dehiscence will result in a loss of potential seed yield and quality.     

A note on the origin of Kalanchoë x vadensis Boom & Zeilinga (Crassulaceae)

Summary K x vadensis is a hybrid of K. blossfeldiana and K. marmorata obtained after doubling the number of chromosomes.     

Location of a high-lysine gene and the DDT-resistance gene on barley chromosome 7

Summary The high-lysine gene in Risø mutant 1508 conditions an increased lysine content in the endosperm via a changed protein composition, a decreased seed size, and several other characters of the seed. The designation lys3a, lys3b, and lys3c, is proposed for the allelic high-lysine genes in three Risø mutants, nos 1508, 18, and 19. Linkage studies with translocations locate the lys3 locus in the centromere region of chromosome 7. A linkage study involving the loci lys3 and ddt (resistance to DDT) together with the marker loci fs (fragile stem), s (short rachilla hairs), and r (smooth awn) show that the order of the five loci on chromosome 7 from the long to the short chromosome arm is r, s, fs, lys3, ddt. The distance from locus r to locus ddt is about 100 centimorgans.     

Simultaneous Determination of Four Phenolic Acids in Radix Salviae Miltiorrhizae Formula Granules by QAMS

[Objectives]This study aimed to establish a QAMS(quantitative analysis of multi-components by single-marker)method for simultaneous determination of four phenol...     

Avoidance of leaf rust fungi in wild relatives of cultivated cereals

Summary Avoidance of rust fungi that was based on poor appressorium induction was previously found in Hordeum chilense. In the present study 95 accessions of Triticeae were screened for avoidance of Puccinia hordei. The percentage of appressorium formation per germinated spore ranged from 6 to 90%. On none of the 41 accessions of Aegilops, Agropyron, Elymus, Secale, Thinopyrum or Triticum studied was the rate of appressorium formation lower than 25%. Lower rates of appressorium formation were, however, found on accessions of wild barley species Hordeum brachyantherum, H. marinum, H. parodii and H. secalinum. Its implications in cereal breeding are discussed.     

Variation in forage grasses as hosts of the root-knot nematode Meloidogyne naasi (Franklin) and selection for resistance in ryegrass

Summary Reactions of 13 grasses to Meloidogyne naasi varied with species; ryegrasses, fescues and their hybrids were generally susceptible and cocksfoot and timothy resistant. Marked variation in host resistance levels occurred between genotypes within cultivars.Selection of single plants, followed by tests on replicate tillers, identified resistant and susceptible genotypes in both Italian and perennial ryegrass cultivars. Resistant plants had few nematode-induced galls and fewer females and eggs than susceptibles. There was more or less continuous variation, with many genotypes intermediate between extremes of resistance and susceptibility. Selected resistant and susceptible genotypes are of use in assessing variation in nematode populations and as controls for breeding and selection programmes.     

Current and future strategies in breeding lentil for resistance to biotic and abiotic stresses

Lentil production is limited by lack of moisture and unfavorable temperatures throughout its distribution. Waterlogging and salinity are only locally important. Progress has been made in breeding for tolerance to drought through selection for an appropriate phenology and increased water use efficiency and in breeding for winter hardiness through selection for cold tolerance.The diseases rust, vascular wilt, and Ascochyta blight, caused by Uromyces viciae-fabae, Fusarium oxysporum f. sp. lentis, and Ascochyta fabae f. sp. lentis, respectively, are the key fungal pathogens of lentil. Cultivars with resistance to rust and Ascochyta blight have been released in several countries and resistant sources to vascular wilt are being exploited. Sources of resistance to several other fungal and viral diseases of regional importance are known. In contrast, although the pea leaf weevil (Sitona spp.) and the parasitic weed broomrape (Orobanche spp.), and to a lesser extent the cyst nematode (Heterodera ciceri), are significant yield reducers of lentil, no sources of resistance to these biotic stresses have been found. Directions for future research in lentil on both biotic and abiotic stresses are discussed.     

Present status and future strategy in breeding faba beans (Vicia Faba L.) for resistance to biotic and abiotic stresses

Progress is being made, mainly by ICARDA but also elsewhere, in breeding for resistance to Botrytis, AScochyta, Uromyces, and Orobanche; and some lines have resistance to more than one pathogen. The strategy is to extend multiple resistance but also to seek new and durable forms of resistance. Internationally coordinated programs are needed to maintain the momentum of this work.Tolerance of abiotic stresses leads to types suited to dry or cold environments rather than broad adaptability, but in this cross-pollinated species, the more hybrid vigor expressed by a cultivar, the more it is likely to tolerate various stresses.     

Water Extraction Process of Chinese Herbal Compound Man Gan Ning

[Objectives]To optimize the water extraction process of Chinese Herbal Compound Man Gan Ning and establish a method for its extraction and content determination...