滇青冈地上部挥发物对小麦化感作用测定

为揭示滇青冈化感物质的释放途径,研究了滇中地区滇青冈地上部挥发物对小麦种子及其幼苗的化感作用。结果表明:滇青冈茎叶的质量和其在空气中放置的时间对小麦种子萌发率,幼苗叶片中叶绿素含量及其幼苗生长的部分指标(根长、苗高、根数目、幼苗鲜重和干重)都具有抑制作用。随着滇青冈茎和叶在空气中放置时间的延长,其挥发物对小麦种子萌发和幼苗叶片中叶绿素含量及其幼苗生长的抑制效应不断减弱,而滇青冈茎叶质量的增加,其挥发物对小麦种子萌发和幼苗叶片中叶绿素含量及其幼苗生长的抑制效应未呈现出规律性的变化。     

高湿对破除休眠农田狗尾草种子萌发及幼苗胚芽鞘生长的影响

以破除休眠的狗尾草种子为材料,研究7个老化时间、相对湿度(20％、30％、50％、60％、80％)人工胁迫处理对种子萌发及幼苗胚芽鞘生长的影响.结果表明,在80％湿度条件,胁迫7、9、11、13d的种子萌发率逐渐降至0,表明增加胁迫时间抑制种子萌发.在80％湿度下胁迫4种时间的狗尾草种子萌发率变异系数、死亡率和休眠逐渐增高,胚根和胚芽鞘的长度均低于对照,表明种子出苗整齐程度和诱导进入次生休眠受高湿条件的影响,80％湿度为种子萌发力衰退的临界湿度环境.     

赤皮青冈种子质量与萌发特性研究

为了缩短种子发芽时间,提高种子发芽率,研究其内果皮、种皮、硫脲以及不同浓度的赤霉素对种子萌发的影响,以赤皮青冈种子为材料,测定种子的质量指标,掌握该种子的基本特性。结果表明：（1）赤皮青冈种子呈现卵状圆柱形,坚果,内果皮光滑,颜色为褐色或亮棕色。整个种子无胚乳结构,去掉种皮后是一个团状胚的结构。种子长(1.82±0.35) cm,种子宽(1.35±0.08) cm,种脐宽(0.76±0.36) cm,壳斗宽(1.61±0.18) cm,壳斗内径(1.60±0.09) cm,壳斗高(0.698±0.102) cm,百粒重为(150.1±40.95) g,鲜种子含水率在40%左右,未经贮藏种子发芽率为44.2%,发芽时间达68天。（2）同时,去掉内果皮和种皮,种子萌发所需时间最短,发芽率达66.5%;4%硫脲液浸泡处理,种子的露白和萌发时间也较短,发芽率为56.5%;200 mg/kg、600 mg/kg浓度的GA3 2组处理,种子的发芽率分别为34.0%、45.8%,说明600 mg/kg的浓度处理效果较佳。     

滇真冈种子萌发的生态生物学研究

由于种皮的抑制作用，滇青冈种子有休眠现象，新鲜种子萌发率极低，变温有利于克服种皮障碍，提高萌发率。砂藏可解除休眠，不同种子解除休眠的时间长短不一，种子种群有较宽广的可萌发时限。滇青冈林地上种子在落到地面后的9个月内，由于虫害和鼠害全部损失萌发能力，没有种子萌发转化成幼苗。滇青冈种子直播造林，应在10月采种，杀虫处理砂藏至次年雨季前播种。     

滇龙胆草种子萌发及育苗研究

在野生状态下滇龙胆草种子萌发和幼苗生长较为缓慢,为了探索加快种子萌发和幼苗生长的方法,对滇龙胆草种子采取了不同播种基质、不同播种深度、不同播种基质含水量及不同育苗方式播种育苗.结果表明:滇龙胆草种子萌发及幼苗生长适宜的播种基质应有较好的透气、透水性,适宜的播种深度不超过1.5 cm,播种适宜的土壤含水量为40％～50％;为提高种子出苗率且缩短出苗时间,生产上可考虑使用漂塑料薄膜覆盖育苗及播种前对种子进行催芽处理.     

5种贵州特有山茶的种子繁殖试验研究

对贵州特有的5种野生山茶植物种子繁殖试验进行了研究.采回的种子分别采用蛭石贮藏和湿润砂藏150 d,蛭石和湿润砂贮藏种子的完好保存率分别是64.0%和86.1%.小黄花茶(Camellia luteoflora)、狭叶瘤果茶(C.neriifotia)、美丽红山茶(C.delicata)、长柱红山茶(C.longistylla)和四球茶(C.tetrecocea)的种子繁殖出苗率分别为30.5%、53.0%、70.0%、70.O%和83.5%,其出苗率与萌芽率的比值分别是51.7%、83.8%、89.7%、87.5%和90.2%.种子萌发与温度和空气湿度有关,但种间无明显差异,成熟种子在5～22℃,≥60%相对湿度的暗光或无光条件下30d均开始发芽,其种子萌发的最适宜气温为(17±1)℃,最适宜的相对温度为80±5%.适时采种和有效控制种子萌发与出苗的温湿度,解决好种子出苗整齐,培育壮苗的关键技术,在物种保育和生产应用上有着重要意义.     

山血丹种子萌发特性的初步研究

研究了山血丹果实和种子形态及不同温度、播种基质、GA3和ABA、种子的脱水、室温贮藏对种子萌发的影响.结果表明:种子百粒鲜重为6.34～6.95 g,含水量为51.87％ ～ 52.97％.新鲜种子在15、20、25、30℃条件下均能萌发,温度在25℃和30℃时,萌发率达到92％.在播种深度为3 cm的黄土、蛭石、棕糠、珍珠岩4种基质中,黄土的出苗率最高,其次为棕糠和珍珠岩,而蛭石则几乎不出苗.30～ 90 mg/L的GA3和10～ 60 mg/L ABA对室温贮藏60d的成熟种子的萌发无显著影响.种子经硅胶脱水1 ～3d后,含水量由52％降至18％,其发芽率、发芽指数均有不同程度的降低,常温储藏3、5、12个月后,发芽率显著降低,表明它是一种顽拗性种子.     

昆仑雪菊种子萌发特性研究

以昆仑雪菊种子为材料,测定种子在不同温度、相对湿度、光照、激素等处理下的发芽率、发芽势等.结果表明:昆仑雪菊种子最适萌发温度为15～25℃;最适萌发相对湿度为65％～75％;适当激素处理可提高昆仑雪菊种子发芽势,光照对种子萌发率影响无显著差异.     

花木蓝种子生物学特性及不同处理对其种子萌发的影响

花木蓝是一种优良的观赏植物,为了解花木蓝种子性状特征和萌发特性,研究种子形态特点及其不同的贮藏条件、温度、光照、盐度、干旱程度、酸碱度等因子对其种子萌发的影响。结果表明,不同采集地点的果实和种子性状存在一定差异,采于哈尔滨师范大学的种子性状较优良,其长度、宽度和千粒重分别为4.87 mm、3.63 mm、36.03 g。冷冻贮藏8年的种子各项发芽指标与当年采收种子差异不显著,常温贮藏5年的种子活力显著降低。光照对花木蓝种子发芽率影响不显著;其种子的萌发温幅较宽,最适萌发温度为25℃,发芽率为84%。低浓度的干旱胁迫和盐胁迫处理下花木蓝种子均可萌发,且对其幼苗生长有一定促进作用。花木蓝种子和幼苗酸碱耐受范围较广,与种子相比其幼苗耐碱性胁迫的能力更强。研究表明,花木蓝种子属于光不敏感种子,冷冻贮藏可明显延长种子寿命,种子和幼苗具有较宽的环境适生范围,并且具备一定的耐盐、耐酸碱和抗旱能力。     

无瓣海桑种子特征及不同贮藏环境下萌发特性的研究

种子的萌发除了与自身的生理结构、萌发时外界条件有关外,不同的贮藏条件和时间处理对种子萌发也有影响.本实验以无瓣海桑种子为研究对象,通过无瓣海桑种子的基本特征及不同贮藏环境(常温、常温干燥、-4℃、-70℃分别对应Ⅰ、Ⅱ、Ⅲ、Ⅳ)和时间(15,30,45,60,90 d)下其种子萌发特性的分析发现:径级对无瓣海桑的果重和种子的粒数均有显著影响;低温处理可显著缩短种子的萌发时间,同时有助于保持无瓣海桑的种子活性;无瓣海桑种子的活力会随着贮藏时间的增加而下降,因此不适宜长期贮藏,但短期贮藏时低温干燥贮藏可较好地保持其种子活力.     

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.     

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.     

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.     

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...