陆地棉枯萎病抗性的双列杂交分析

在发病严重而均匀的田间病圃中，对４个抗病品种和４个感病品种的８个亲本及其２８个Ｆ１（无反交）进行抗枯萎病性鉴定。发现亲本的抗性水平与其配合力效应、显性作用大小是基本一致的，以苏棉３号、中棉所１２和鄂６２—１抗性最高，配合力最好，显性作用最大，是较好的抗病亲本。Ｈａｙｍａｎ—Ｊｉｎｋｓ法分析表明，抗病性为部分显性，以加性效应占优势，显性效应较小，无上位性。广义和狭义遗传力均很高，分别为Ｏ．９１和０．８３，至少有一组显性抗病基因控制棉花枯萎病抗性的遗传。     

大白菜芜菁花叶病毒病抗性遗传分析

为了明确不同感病亲本对大白菜芜菁花叶病毒病抗性遗传规律的影响,以大白菜抗TuMV的国家级抗源材料8407和高抗TuMV的高代自交系材料73为亲本之一,分别与2个感病材料冠291和06-247构建F1杂交组合,并制备F2群体。采用摩擦接种法对上述亲本及其F1、F2群体接种TuMV-C4,采用生物学观察的方法,根据病情分级和归类标准对大白菜TuMV抗性进行鉴定。结果表明,以8407为抗病亲本,当感病亲本为冠291时,表现为由1对显性基因控制;当感病亲本为06-247时,表现为由1对隐性基因控制。以73为抗病亲本,当感病亲本为06-247时,TuMV抗性由1对隐性基因控制;同一个抗病亲本,当感病亲本为冠291时,又表现为由两对隐性基因控制。因此,大白菜TuMV的抗性遗传规律十分复杂,同一个抗病材料,当感病亲本不同时,所配制的组合间TuMV抗性表现不同。     

大豆花叶病引起的大豆顶端坏死症

２个抗病亲本和２个感病亲本配制４个杂交组合和４个回交组合。调查其Ｆ１、Ｆ２和ＢＣＦ１群体接种东北大豆花叶病毒二号株系后，顶端坏死株的形成和分离比例。Ｆ１表现两种类型：无症株和坏死株，Ｆ２表现三种类型：无症株、有症株（花叶、皱缩等）和坏死株。其分离比例或为３抗：１感，或为７抗；９感，χ＾２测验符合一对显性基因控制或者两对隐性互补基因控制。     

超甜玉米种子活力研究

以13个种子活力表现差异显著的超甜玉米自交系为研究对象，采用Griffing不完全双列杂交法，分析了其配合力和遗传特性。结果表明，亲本的GCA值均达到极显著水平，说明其均可将自身种子活力遗传特性高效率地传给子代和F1代杂交组合。超甜玉米种子活力的广义遗传力和狭义遗传力分别为99.48%和58.79%，亲本的遗传能力较高，在种子活力遗传效应中，固定遗传的加性效应显著，是可以早代选择的性状。     

小麦品种A552抗白粉病遗传规律研究

用高抗白粉病品种Ａ５５２与遗传背景不同的３个感病品种杂交,用４个小麦白粉病菌生理小种１５、３１１、３１５、３７３分别对亲本、Ｆ１和Ｆ２进行室内接种鉴定,结果Ｆ２分别呈９７、３１、５５９、１３、７９和１３３分离,从而可认为Ａ５５２抗性基础复杂,在不同遗传背景下能将１～３对不等的抗性基因遗传给后代有效控制其抗性表现,是不可多得的抗源材料。     

谷子（粟）对粒黑穗病的抗性及遗传分析

谷子不同品种对粒黑穗病的抗性差异很大，其中有７９．５％的品种属感病或高度感高类型。谷子抗粒黑穗病的遗传背景十分复杂，遗传方式为多基因控制的数量遗传，遗传力为３７．６６％，超亲遗传比较明显，双亲发病株率平均值和差值与Ｆ２高抗株率呈极显著的负相关，ｒ＝０．８４４６和ｒ＝０．８６３８，正确选配杂交组合对抗病育种的成败至关重要。     

我国几个陆地棉品种枯萎病抗性的遗传分析

根据Hayman(1958)方法对4个抗病品种和4个感病品种共8个亲本及其8个半双列杂交组合的F_2代的平均病级进行双列杂交分析,结果表明.棉花对枯萎病的抗性存在加性和显性效应,无上位性,以加性效应为主;抗性呈不完全显性,受一对基因控制,广义、狭义遗传力都高达90％以上。16个抗×感组合的F_2代抗、感植株出现3:1比例分离,亦证实抗性受一对基因控制。抗、感病品种一般配合力差异达极显著水平,抗×感组合特殊配合力普遍低于感×感,抗×抗组合.因而抗病育种以配制抗×感类型组合为佳。     

小麦品质性状沉降值在F1代杂种优势及配合力表现

测定研究了１４个品系和用其做的１５个杂交组合沉降值的杂种优势。证明：小麦品质性状沉降值在杂交Ｆ１代具有明显的杂种优势。１５个组合Ｆ１代的沉降值平均为６３．７ｍｌ，较其１４个亲本沉降值平均５５．５７ｍｌ高８．１３ｍｌ，杂种优势率为１７．７４％表现极显著。不同品系的沉降值配合力有差异，选择性沉降值配合力高的品种做亲本，可以选出沉降值特殊配合力高的优质组合，杂交小麦利用品质优势是可行的。     

食葵菌核病抗性及抗性配合力

旨在了解现有食葵亲本材料的菌核病抗性及抗性配合力,以及用这些亲本材料配制杂交组合后F1的抗病表现,从而为亲本的合理选配提供依据。试验采用6个食葵细胞质雄性不育系为母本、6个恢复系为父本,配制36个杂交组合。翌年,种植12个亲本及36个F1,于盛花期接种核盘菌,通过比较亲本间、亲本与F1、F1间的田间发病率、病情指数及相对潜伏期差异,分析了食葵的菌核病抗性及抗性配合力。结果表明:供试的绝大多数亲本材料对菌核病不具备抗性,仅有少部分表现中等抗性,没有发现高抗材料;供试的绝大多数材料从亲本到F1抗病能力明显提高,具体表现为发病率下降,病斑面积缩小,发病时间推迟,并且F1中出现高抗材料,表现出明显的抗病优势;不同亲本间的抗性配合力差异较大,亲本本身的抗性表现与抗性配合力之间没有必然联系。亲本本身抗病较强、抗性配合力又较高的材料是最理想的亲本材料。     

番茄晚疫病抗性遗传研究

通过对4份亲本材料完全双列杂交后代进行方差分析、配合力分析,对番茄晚疫病抗性遗传规律进行了研究,结果表明:一般配合力和特殊配合力均达到极显著水平,但一般配合力较大,其二者比值为(GCA/SCA)18.7,说明番茄对晚疫病的抗性以加性效应为主;利用Haym an双列杂交法,对各亲本和杂交组合后代间的方差(Vr)、协方差(W r)进行回归分析,抗性符合"加性-显性"模型,遗传效应中存在加性效应和显性效应,广义遗传力为96.8%,狭义遗传力85.6%,进一步说明了在番茄抗晚疫病的遗传中以加性效应为主。     

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.     

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.     

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...     

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.     

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.