陆地棉显性无腺体品系杂种优势及配合力研究

以７个显性无腺体陆地棉品系和４个常规品种（系）为材料，按ＮＣＩ设计，对２８个组合的杂种Ｆ１进行了分析。结果表明。杂种Ｆ１具有明显的优势，２８个组合所研究的１５个性状中全部具有中亲优势，６个性状具有高亲优势，４个性状具有竞争优势；配合力分析的１１个性状中，株高、衣分、纤维长度和麦克隆值主要受基因加性效应控制，而子棉产量、皮棉产量、单株铃数、铃重和子指等性状同时受基因加性和非加性效应作用，显无０７３是丰产的显性无腺体品系，而显无２６０是较好的优良品系，组合显无０７３Ｘ泗棉２号在重要性上表现较好。     

章丘大葱半成株采种单株产量与主要植物学性状的相关分析

章丘大葱采种植株的植物学性状与单株产量存在一定的相关性。通过对油薹初期与开花盛期的半成株采种植株的株高、花茎高、花球高、假茎长、假茎粗、花球横径、叶面积分别进行分析，发现单株采种产量与抽薹初期、开花盛期的叶面积均呈显著直线相关（r=0.582,0,358），花球高在开花盛期与产量呈直线相关（r=0.449），假茎粗则与产量在抽薹初期呈极显著正相关（r=0.557）。     

甘蓝型黄籽油菜产量性状的遗传分析

利用加性－显性－母体的遗传模型，分析了7个不同遗传来源甘蓝型黄籽油菜品系所配制的完全双列杂交资料。结果表明，产量性状主要受加性和显性效应共同控制，环境对产量性状有一定的影响而母体效应影响很小。基因效应分析发现y4单株粒重有极显著的加性效应，y3×y4单株粒重有极显著的显性效应。     

几个小麦品种（系）主要农艺性状配合力与遗传力分析

本文采用不完全双列杂交设计,对15个小麦品种(系)的8个主要农艺性状的配合力与遗传力进行了分析。结果表明,所有的8个性状(单株籽粒产量、单株生物产量、单株穗数、收获指数、株高、抽穗期、穗粒数、千粒重),其广义遗传力都较高,可在早代进行选择;株高与抽穗期的遗传主要受基因加性效应控制;其余性状(产量性状)的遗传除受基因加性效应控制外,非加性效应(显性效应和上位性效应)的影响更大。F1代的表现,同时受到双亲GCA的与SCA的影响。选择单株生物产量与单株穗数GCA较高、性状互补的亲本,才有可能选出单株籽粒产量高的强优势组合。从亲本的表现型不能推断其一般配合力效应的大小。本文同时对各材料的特点进行了分析。     

大麦若干经济性状的遗传特性分析

按Hayman方法对8×8完全双列杂交F_1的6个性状进行基因效应分析与模型检验,株高、穗长、实粒数符合加性-显性模型.株高、实粒数为部分显性,加性方差和显性方差均显著,基因的加性效应比显性效应更重要;穗长为超显性,显性基因效应比加性基因效应更重要.对杂交F_1、F_2进行配合力效应值分析表明,一般配合力方差和特殊配合力方差对所研究性状均重要,多数性状为加性基因效应占主导.亲本85G63、81-18、82-14为最佳配合者,其主要经济性状一般配合力好.杂交F_1各性状均有明显杂种优势,组合间和性状间的优势具有显著差异,以单株籽粒产量优势最强,其余依次为实粒数、穗长、株高、小穗粒数和千粒重.     

小麦重要产量性状的主基因+多基因混合遗传分析

以单株产量等为代表的重要性状是选育小麦高产良种的主攻目标性状,分析小麦重要产量性状的数量遗传特性,为深入研究其遗传机制提供依据。本研究选用品冬34为母本(P_1)和BARRAN为父本(P_2)配置杂交组合,在2年4个环境下应用主基因+多基因混合遗传模型方法对该组合单世代(P_1、P_2、RIL_(7:8)、RIL_(8:9))单株产量、千粒重、株高、穗下节间长、旗叶上节间长和分蘖数进行遗传及相关分析。结果表明,除千粒重和分蘖数外,其余性状间均显著或极显著相关,穗下节间长与旗叶上节间长平均相关系数达0.91 (P≤0.001)。最优遗传模型对于单株产量是4对加性上位性主基因+多基因遗传模型,其主基因加性效应值分别为3.78、2.89、–6.18和0.15,多基因遗传率为86.23%;对于千粒重是2对互补作用主基因+加性效应多基因混合遗传模型,多基因加性效应值是22.37,主基因遗传率为66.96%,多基因遗传率为28.25%;对于株高是2对累积作用主基因+加性作用多基因混合遗传模型,控制株高的第1对主基因加性效应值是5.15,加性×加性上位性互作效应值为–9.66,多基因加性效应值为–9.31,主基因遗传率为58.57%,多基因遗传率为39.71%;对于穗下节间长和旗叶上节间长均是加性-上位性多基因遗传模型,其主基因遗传率分别为97.65%和99.14%;对于分蘖数是加性-上位性多基因混合遗传模型,主基因遗传率为78.89%,多基因遗传率为19.87%。这些性状在多个环境下主要受主基因+多基因混合遗传控制。在选育优良品系的过程中,要兼顾适应生态环境条件的重要表现,进一步为筛选与目标性状紧密连锁标记及推进分子标记辅助选择提供理论依据。     

蚕豆主要数量性状的配合力和遗传力分析

以性状差异明显的4个青海蚕豆为母本，与具有互补性状的4个外来种质进行不完全双列杂交，配制16个组合。分析了株高、始荚高、有效枝、单株荚数、单株粒数、荚粒数、百粒重和单株产量等8个主要性状的配合力及遗传力。结果表明：（1）加性效应和非加性效应对蚕豆杂交后代性状都有重要作用，且这些性状的基因加性效应均对杂种后代的性状起主导作用，尤其是有效枝、单株荚数、单株粒数和单株产量完全受基因加性效应控制；（2）应根据一般配合力和特殊配合力的大小和育种目标的要求选择合适的亲本和较优的杂交组合；（3）8个主要性状的广义遗传力由大到小的顺序是：百粒重〉株高〉荚粒数〉有效枝〉单株荚数〉始荚高〉单株粒数〉单株产量；狭义遗传力由大到小的顺序为：百粒重〉株高〉有效枝〉荚粒数〉单株荚数〉始荚高〉单株粒数〉单株产量。在改良品种粒重时，可进行早代选择，而其他性状的遗传力中等偏低，易受环境因素影响，应连续多代选择。     

红麻产量和纤维品质性状的遗传效应与杂种优势分析

红麻产量与品质性状的各项遗传效应、关联性及其杂种优势表现是杂种优势利用的基础，采用加性-显性遗传模型，分析了7个杂交红麻亲本和21个F1 代组合的12个产量与品质性状的研究结果表明，（1）株高、鲜皮厚、单株干皮重、千粒重、纤维支数同时受到加性和显性效应的控制;而茎粗、单株干茎重、皮骨比、出麻率、单株纤维重、精     

小麦几个数量性状不同生长时期的基因效应分析

依据Ｌｏｇｉｓｔｉｃ生长拟合曲线，把小麦株高，单株叶数和千粒粒重等性状建成划分为个生长时期。采用世代平均值分析法，对不同生长时期净增量进行了基因效应分析，结果表明，各性状不同生长时期基因作用的方向和程度具有明显差异，遗传模型也有所不同，并且各个时期的基因效应相互独立。上位性效应对于株高和单株叶数的遗传具有重要作用，而粒重的遗传基本符合加性－生三参模型。     

特用玉米主要性状的配合力及相关分析

以 PST等 7个特用玉米自交系为亲本 ,按 griffing( )配成 2 1个杂交组合 ,分析单株粒重等 10个性状的一般配合力和特殊配合力 ,主要农艺性状和产量之间的关系。结果表明 :行粒数主要受加性基因控制 ,其余大部分性状的加性和非加性基因效应同时存在。在一般配合力效应上 ,同一性状不同亲本的效应值不同 ,各性状值的效应最高出现于不同亲本。在单株产量上 ,一般配合力效应值大小为 PHT>PYT>PHBT;特殊配合力效应较大的组合有 :PYT× PHT>PYT× PHBT>PHT× PHBT等 ,这些具有较高 SCA和 TCA的组合一般都符合本地种质与热带种质、本地种质与温带种质和热带种质与温带种质的杂交组配模式。相关分析表明 ,行粒数与产量关系最为密切 ,其次为株高、穗长。对于这些性状而言 ,一般配合力高的亲本容易产生特殊配合力高的组合 ,但也不排除一般配合力都不高的双亲获得较高的特殊配合力的可能性 ,根据配合力互补原理 ,可望从 7个亲本间选配出高产优质的组合。     

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.     

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.     

Mechanisms and diversity of resistance to sorghum shoot fly,Atherigona soccata

Sorghum shoot fly, Atherigona soccata, is one of the important pests of postrainy season sorghums. Of the 90 sorghum genotypes evaluated for resistance to this pest, RHRB 12, ICSV 713, 25026, 93046 and 25027, IS 33844‐5, Giddi Maldandi and RVRT 3 exhibited resistance in postrainy season, while ICSB 463, Phule Anuradha, RHRB 19, Parbhani Moti, ICSV 705, PS 35805, IS 5480, 5622, 17726, 18368 and 34722, RVRT 1, ICSR 93031 and Dagidi Solapur showed resistance in rainy season, suggesting season‐specific expression of resistance to A. soccata. ICSB 461, ICSB 463, Phule Yasodha, M 35‐1, ICSV 700, 711, 25010, 25019 and 93089, IS 18662, Phule Vasudha, IS 18551 and 33844‐5 and Barsizoot had fewer deadhearts than plants with eggs across seasons, suggesting antibiosis as one of the resistance mechanism. Five genotypes exhibited resistance with high grain yield across seasons. Correlation, path and stepwise regression analyses indicated that leaf glossiness, seedling vigour, trichome density, oviposition and leaf sheath pigmentation were associated with the expression of resistance/susceptibility to shoot fly, and these can be used as marker traits to select and develop shoot fly‐resistant sorghums.     

Reaction of tritordeum to Fusarium culmorum and Septoria nodorum

Summary Hordeum chilense is a wild barley extensively used in wide crosses in the Triticeae. It could be a valuable source of resistance to Fusarium culmorum and Septoria nodorum. Some H. chilense x Triticum spp. amphiploids, named tritordeums, were more resistant than the parental wheat line to these diseases, others were not. Average contents of ergosterol and deoxynivalenol (DON) suggested that resistance to colonization by Fusarium was the highest for Hordeum chilense, followed by tritordeum and wheat in decreasing order. In particular, the H. chilense genotypes H7 and H17 enhanced the wheat resistance to F. culmorum in its tritordeum offsprings. Resistance to S. nodorum in tritordeum was not associated with tall plant height. There is sufficient genetic variation for resistance to F. culmorum and S. nodorum among tritordeum to allow the breeding of lines combining short straw and resistance to both diseases.     

Disease resistance in protected crops and mushrooms

Summary Cultivars of tomatoes, cucumbers, lettuce and peppers have been bred for resistance to one or more pathogens. Some tomato and cucumber cultivars have resistance to a wide range of diseases. Resistance has been transient in many cases and a succession of cultivars with new genes or new combinations of resistance genes has been necessary to maintain control. There has been a number of notable exceptions and these have included durable resistance to such pathogens asFulvia fulva and tomato mosaic virus. With lettuce the resistance situation is complicated by the occurrence of fungicide resistant pathotypes. There are no strains ofAgaricus bisporus purposely bred for disease resistance.In protected flower crops only resistance to Fusarium wilt in carnations has been purposely bred but differences in disease resistance are apparent in cultivars of many ornamental crops. This is particularly so in chrysanthemums where there are cultivars with resistance to many of the major pathogens. Similar situations occur with other flower crops and pot plants. Cultivars of some species have not been systematically investigated for resistance.The need for genetic resistance will increase with the further reduction, in the limits on pesticide use and an increasing public awareness and importance of pesticide pollution.ADAS is an executive agency of the Ministry of Agiculture, Fisheries and Food and the Welsh Office.     

Relation between wheat-rye crossability and seed set of common wheat after pollination with other species in the Hordeae

Summary Cultivars of common wheat (Triticum aestivum L. em. Thell.) of high wheat-rye (Secale cereale L.) crossability set more seed with pollen of other related species than did wheats of low wheat-rye crossability. This was found to be true for pollen parents from the genera Triticum, Aegilops, Secale, Agropyron and Elymus.     

Genetic constitution and diversity in four narrow endemic redwoods from the family Cupressaceae

The genetic constitution and diversity of four relictual redwoods are discussed in this review. These include monotypic genera of the family Cupressaceae: coast redwood (Sequoia sempervirens), giant sequoia (Sequoiadendron giganteum), dawn redwood (Metasequoia glyptostroboides), and alerce (Fitzroya cupressoides). All four species are narrow endemics, share a number of common phenotypic traits, including red wood, and are threatened species. Fossil history suggests that the ancestors of redwoods probably originated during the Cretaceous and Tertiary periods and flourished thereafter for millions of years. Towards the end of the Tertiary period began their decline and struggle for existence that continued during the subsequent geologic upheavals and climate changes, until the survival of the present-day redwoods in the current restricted locations in the world (USA, China, and South America). Although two species, Sequoiadendron and Metasequoia, are diploids (2n = 22), and the other two are polyploids: Fitzroya a tetraploid (2n = 4x = 44), and Sequoia a hexaploid (2n = 6x = 66); they all share the same basic chromosome number x = 11. The genome size in the hexaploid Sequoia is one of the largest (31,500 MB) in the conifers, while the genome sizes of diploid Metasequoia and Sequoiadendron are about one-third (~10,000 MB) of Sequoia. Genetic diversity in the redwoods is lower than most other gymnosperms, except in Sequoia, which seems to rank near the upper quarter of the coniferous forest trees. Genomic research is sparse in the redwoods, and should be pursued for a better understanding of their genome structure, function, and adaptive genetic diversity.     

Distribution,ecology and reproductive biology of wild tomatoes and related nightshades from the Atacama Desert region of northern Chile

Over the past 20 years, several expeditions were made to northern Chile to collect populations of wild tomatoes (Solanum chilense, S. peruvianum) and allied nightshades (S. lycopersicoides, S. sitiens), and obtain information about their geographic distribution, ecology and reproductive biology. Restricted mainly to drainages of the Andean and the coastal cordillera, populations are geographically fragmented. The two nightshade species are rare and threatened by human activities. Adaptation to extreme aridity and soil salinity are evident in S. chilense and S. sitiens (the latter exhibits several xerophytic traits not seen in the tomatoes) and to low temperatures in S. lycopersicoides and S. chilense. All tested accessions are self-incompatible, with the exception of one S. peruvianum population collected at the southern limit of its distribution. Several distinguishing reproductive traits—anther color, attachment, and dehiscence, pollen size, and flower scent—suggest S. sitiens and S. lycopersicoides attract different pollinators than S. chilense and S. peruvianum. The four Solanum spp. native or endemic to Chile provide a variety of novel traits which, through hybridization and introgression with cultivated tomato, could facilitate development of improved varieties, as well as research on a variety of basic topics, including plant-pollinator interactions, abiotic stress responses, and evolution of reproductive barriers.     

The induction in vitro of adventitious shoots in Rosa

Summary Adventitious shoots were formed on excised leaves, roots and callus of Rosa persica x xanthina and on excised leaves of R. laevigata and R. wichuraiana on culture media that included BAP and NAA as growth regulators. Shoots formed freely on freshly cultured callus of R. persica x xanthina but their production declined in successive cultures and ceased after twelve weeks. Transplantation to soil was improved by rooting plantlets in cellulose plugs in vitro and transferring plantlets to soil while still in the plugs.     

The exploration of genetic resources of Portuguese cabbage and kale for resistance to several Brassica diseases

Summary Twenty three accessions of nine Portuguese cabbage and kale land races from different geographic origins were tested at the seedling stage for resistance to several important brassica diseases. Resistance to downy mildew (Peronospora parasitica), expressed as necrosis of the cotyledon mesophyll, was found in all the accessions. Type A resistance to cabbage yellows (Fusarium oxysporum f. sp. conglutinans race 1) was present in most of the landraces. Resistance to clubroot (Plasmodiophora brassicae race 6) was found in one accession of the Portuguese tree kale. High resistance to blackleg (Leptosphaeria maculans) and white rust (Albuco candida) was not detected, although several accessions showed 20 to 30% of plants with intermediate expression of resistance. All Portuguese cole accessions were susceptible to blackrot (Xanthomonas campestris pv. campestris).