粗柄独尾草不同部位种子特性对不同生境的响应

以新疆准噶尔古尔班通古特沙漠南缘的粗柄独尾草(Eremurus inderiensis)为研究对象,通过划分不同破碎化程度斑块(强、中、弱),并根据植株花序轴高度将其分为长度相等的上部、中部和下部3个部位,研究不同斑块之间植株不同部位粗柄独尾草种子大小以及萌发特性.结果显示:1)随着生境破碎化程度的逐渐加强,各部位的种翅宽没有显著变化,而种子千粒重及种子长和宽均呈减小趋势;2)种子数量在整个植株、植株上部和中部均随着生境破碎的增强显著降低,而植株下部的种子数量在各斑块之间差异不显著;3)生境破碎化弱的植株不同部位种子萌发率均最高,破碎化中的植株上部种子萌发率显著高于破碎化强的,而在植株下部萌发率与之相反.生境破碎化对植物有较大影响,为适应变化生境破碎化和最大程度地繁衍后代,植株不同部位的种子特性会产生相应变化.     

不同繁育机制对异翅独尾草与粗柄独尾草种子活力的影响

本文以沙生短命植物异翅独尾草与粗柄独尾草自交与异交植株的种子为实验材料，测定了种子千粒重，种子萌发时间及种子萌发率等指标，结果显示：自交株种子的萌发时间推迟，萌发率显著降低，但自交株种子的重量却明显地高于异交株。这一方面体现了自交衰退对两种独尾草繁殖能力的影响；另一方面，也反映出两种独尾草的自交繁育机制有助于增加单粒种子的重量，提高了种子发芽及幼苗成活的潜力，这可能是独尾草对自交衰退机制的一种有效补偿，在保证物种的种族繁衍方面具有重要的现实意义。     

入侵杂草对多年生黑麦草种子萌发的化感作用

用外来入侵杂草地上部分及根系不同浓度提取液对多年生黑麦草种子进行室内萌发培养实验,分别测定种子最终萌发率、根长及苗高来研究这些杂草是否对多年生黑麦草萌发及幼苗生长存在化感作用。结果表明:外来入侵杂草有部分对多年生黑麦草种子萌发及幼苗生长存在化感作用。在自然条件下,外来入侵杂草容易形成单一优势种落,对多年生黑麦草草坪具有较大的危害潜力。     

盐分、温度及其互作对甜瓜种子萌发及幼苗生长的影响

研究了不同盐分(0、50、100、150、200 mmol/L)、温度(18、30、42℃)及其二者互作对甜瓜种子萌发和幼苗生长的影响.结果表明,在相同温度下,随着盐浓度的增加,种子发芽率和幼苗生长量(侧根数、茎粗和根长)均有下降的趋势.30℃下,NaCl溶液对种子萌发抑制最小,浓度达到200 mmol/L时,仍有58％的种子萌发,18℃下,对种子萌发抑制作用最大,NaCl溶液浓度为150 mmol/L时,种子萌发被完全抑制;在同一NaCl溶液浓度下,甜瓜幼苗生长量表现为30C＞42℃＞18℃.盐分、温度及其二者互作对甜瓜种子萌发和幼苗生长均有一定的影响.低温比高温与盐分胁迫互作对甜瓜种子萌发和幼苗生长影响明显,甜瓜种子萌发及幼苗生长对盐分的响应依赖于温度的变化,抑制作用表现为:18℃＞42℃＞ 30℃.     

不同种源地乐东拟单性木兰种子的形态特征及萌发特性研究*

为研究乐东拟单性木兰种子的形态特征和种子的发芽率在不同种源间的差异,选取湖南新宁、福建武夷山的乐东拟单性木兰种子作为研究材料,测定果实和种子的纵、横径、千粒重、含水量、果实的出种率等指标,并通过种子发芽试验,分析不同种源地种子的发芽率及幼苗生长情况。结果表明：新宁果实的出种率为19.8%,武夷山果实的出种率为12%;新宁种子纵径9.81 mm,横径7.57 mm,千粒重156.28 g,含水量11.1%;武夷山种子纵径7.04 mm,横径6.61 mm,千粒重111.38 g,含水量8.46%;新宁种子发芽率为87%,武夷山种子发芽率为82%;新宁幼苗株高为9.17 cm、地径为2.31 mm,武夷山幼苗株高为6.23 cm、地径为2.0 mm。方差分析表明,不同种源间种子纵、横径、果实出种率、千粒重、含水量有极显著差异;不同种源间种子的发芽率、幼苗株高、地径生长量有显著差异,发芽率与种子形态特征呈正相关。说明种子的形态特征影响种子的萌发特性,相对较大的种子出种率较高,发芽率较大,幼苗的生长 量也较大。     

铜对黄瓜和萝卜种子萌发和生长的影响

利用Cu2+对黄瓜、萝卜种子进行处理,观察种子的萌发率以及萌发后根芽的生长情况.结果表明:不同浓度的Cu2+对黄瓜、萝卜种子的发芽率、根长、幼苗生长具有不同的作用.低浓度Cu2+促进种子萌发,高浓度Cu2+抑制种子萌发.Cu2+对黄瓜、萝卜根长的影响表现为先促进后抑制,对幼苗芽长的影响不大.Cu2+对黄瓜、萝卜根的影响要显著高于对芽的影响.黄瓜和萝卜种子对Cu2+毒害具有较强的耐性,并且萝卜的耐性要强于黄瓜.     

EMS处理对尾叶紫薇种子萌发的影响及半致死剂量的研究

以尾叶紫薇的成熟种子为研究材料,比较和分析EMS不同浓度和处理时间对尾叶紫薇种子萌发及幼苗生长的影响.结果表明,EMS处理能够抑制尾叶紫薇的种子萌发和幼苗生长,浓度越高、处理时间越长,抑制作用越明显,4％浓度处理8 h和12 h后全部致死.2％浓度处理4 h的相对致死率为48.18％,接近半致死浓度.利用matlab建...     

粗柄独尾草种子萌发特性的研究

粗柄独尾草(Eremurus.inderiensis(M.Bieb)Regel)为典型的沙生类短命植物,在我国仅分布于新疆北疆地区沙漠.其种子需要较长时间的低温层积处理才能萌发,且冷冻处理(-18℃)的层积效果好于冷藏(0～4℃)处理的层积效果.萌发的最佳温度为10℃,最适合的培养基质为沙培,其在光照和黑暗的萌发条件下发芽率略有差别,光照条件下略好于黑暗条件.     

紫茎泽兰叶片对两种土著辣椒的化感效应

测定紫茎泽兰(Eupatorium adenophorum)地上部水提液对两种辣椒种子萌发、幼苗生长及一些生理的影响.结果表明,低浓度对独山种子发芽速率、萌发率没有影响,高浓度延迟种子发芽,降低种子发芽速率影响最终萌发率,高浓度抑制幼苗的生长;低浓度对福泉辣椒种子提高发芽速率最终提高萌发率,低浓度时幼苗根和苗生长增加,高浓度抑制根长和苗高的生长,有明显的化感作用特征.两种辣椒幼苗丙二醛含量随着处理浓度的升高而升高,叶绿素a/b值随着处理浓度的升高而降低.     

不同枫香种群种子萌发特性分析

为探寻枫香(Liquidambar formosana)种子适宜的萌发温度和耐盐种群,了解种子在不同温度和盐胁迫处理下的萌发特性,采用单因素方差分析,相关分析等方法,通过不同温度和盐浓度处理,研究6个枫香种群种子的发芽率、发芽势、发芽指数和正常幼苗率变化。结果表明:1)枫香北方种群种子的发芽率高于南方,发芽率与种子千粒重没有相关性,受种群所在的气候因子影响较大。2)随着温度的降低,枫香种子的萌发率显著的下降,高温环境可适当促进枫香种子萌发。3)随着盐浓度增加,枫香种群种子的萌发率、萌发指数、和正常幼苗率均下降,盐浓度过高,种子失活不再萌发。盐胁迫对枫香幼苗根部的破坏严重,随着NaCl浓度增加,枫香幼苗须根减少、主根逐渐坏死。4)宁强种群种子对低温和盐胁迫具有较强的耐受性,低温和盐胁迫在不同程度上延长种子的发芽时间。     

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.     

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...     

Pollen and pollination experiments. III. The viability of apple and pear pollen as affected by irradiation and storage

Summary Apple and pear pollen was irradiated with doses of 0, 50, 100, 250 and 500 krad (gamma rays) and stored at 4°C and 0–10% r.h. From the in-vitro germination percentages an average LD 50 dose of about 220 krad was estimated. For both irradiated and untreated pollen a close and corresponding lineair relationship existed between germination percentage and pollen tube growth.Irradiated pollen was much more sensitive to dry storage conditions than untreated pollen, resulting in less germination and more bursting. Apparently, irradiation caused the pollen cell membrane to lose its flexibility faster than normal. Rehydration of dry-stored, irradiated pollen in water-saturated air restored germination percentages up to their initial levels. The importance of this procedure in germination trials is stressed.     

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...     

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.     

Optimization of Extraction Technology and Determination of Content of Total Phenols of Leaves in Acanthopanax giraldii Harms

[Objectives] To determine the optimum extraction technology for total phenols of leaves in Acanthopanax giraldii Harms.[Methods]The single factor test and ortho...     

Cytoplasmic male sterility,resistance to gall mite and mildew,and season of leafing out in black currants

Summary Cytoplasmic male sterility (cms) is described in the F₁ hybrids Ribes × carrierei (R. glutinosum albidum × R. nigrum) and R. sanguineum × R. nigrum. In backcrosses to R. nigrum, progenies with R. glutinosum cytoplasm were either all male sterile, or segregated for full male fertility (F) and complete (S) and partial (I) male sterility. Ratios of F:I+S suggested that two linked genes controlled cms, F plants being dominant for one (Rf ₁) and recessive for the other (Rf ₂).Segregation for cms in relation to three linded genes, Ce (resistance to the gall mite, Cecidophyopsis ribes), Sph ₃(resistance to American gooseberry mildew, Sphaerotheca mors-uvae) and Lf ₁(one of two dominant additive genes controlling early season leafing out) indicated that Rf ₁and Rf ₂were in this linkage group. The gene order and approximate crossover values appeared to be: % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXafv3ySLgzGmvETj2BSbqef0uAJj3BZ9Mz0bYu% H52CGmvzYLMzaerbd9wDYLwzYbItLDharqqr1ngBPrgifHhDYfgasa% acOqpw0xe9v8qqaqFD0xXdHaVhbbf9v8qqaqFr0xc9pk0xbba9q8Wq% Ffea0-yr0RYxir-Jbba9q8aq0-yq-He9q8qqQ8frFve9Fve9Ff0dme% aabaqaciGacaGaamqadaabaeaafaaakeaacaWGdbGaamyzamaamaaa% baGaaiiiaiaacccacaGGWaGaaiOlaiaacgdacaGG0aGaaiiiaiaacc% caaaGaaiiiaiaacccacaGGGaGaamOuaiaadAgaliaaigdakmaamaaa% baGaaiiiaiaacccacaGGGaGaaiiiaiaaccdacaGGUaGaaiOmaiaacs% dacaGGGaGaaiiiaiaacccacaGGGaGaaiiiaaaacaWGsbGaamOzaSGa% aGOmaOWaaWaaaeaacaGGGaGaaiiiaiaacccacaGGGaGaaiiiaiaacc% cacaGGGaGaaiiiaiaacccaaaGaamitaiaadAgaliaaigdakmaamaaa% baGaaiiiaiaacccacaGGGaGaaiiiaiaacccacaGGGaGaaiiiaiaacc% cacaGGGaGaaiiiaiaacccacaGGGaaaaiaadofacaWGWbGaamiAaSGa% aG4maaaa!6E4D!\[Ce\underline { 0.14 } Rf1\underline { 0.24 } Rf2\underline { } Lf1\underline { } Sph3\]. Crossover values of 0.36 for Ce-Lf ₁, and 0.15 for Lf ₁-Sph ₃were estimated from the relative mean differences in season of leafing out between seedlings dominant and recessive for Ce and Sph ₃.It is suggested that competitive disadvantage of lf ₁-carrying gametes and/or zygotes at low temperatures may be implicated in the almost invariable deficit of plants dominant for the closely linked mildew resistance allele Sph ₃. Poor performance of lf ₁- (and possibly lf ₂-) carrying gametes and young zygotes during periods of low temperature at flowering might also account for the liability of some late season cultivars and selections to premature fruit drop (running off).     

Screening techniques and sources of resistance to parasitic angiosperms

Parasitic angiosperms cause great losses in many important crops under different climatic conditions and soil types. The most widespread and important parasitic angiosperms belong to the genera Orobanche, Striga, and Cuscuta. The most important economical hosts belong to the Poaceae, Asteraceae, Solanaceae, Cucurbitaceae, and Fabaceae. Although some resistant cultivars have been identified in several crops, great gaps exist in our knowledge of the parasites and the genetic basis of the resistance, as well as the availability of in vitro screening techniques. Screening techniques are based on reactions of the host root or foliage. In vitro or greenhouse screening methods based on the reaction of root and/or foliar tissues are usually superior to field screenings and can be used with many species. To utilize them in plant breeding, it is necessary to demonstrate a strong correlation between in vitro and field data. The correlation should be calculated for every environment in which selection is practiced. Using biochemical analysis as a screening technique has had limited success. The reason seems to be the complex host-parasite interactions which lead to germination, rhizotropism, infection, and growth of the parasite. Germination results from chemicals produced by the host. Resistance is only available in a small group of crops. Resistance has been found in cultivated, primitive and wild forms, depending on the specific host-parasite system. An additional problem is the existence of pathotypes in the parasites. Inheritance of host resistance is usually polygenic and its transfer is slow and tedious. Molecular techniques have yet to be used to locate resistance to parasitic angiosperms. While intensifying the search for genes that control resistance to specific parasitic angiosperms, the best strategy to screen for resistance is to improve the already existing in vitro or greenhouse screening techniques.