小麦旗叶性状与产量因素的相关与回归分析

以59个小麦品种(系)为试材,对旗叶性状与产量及产量因素作了相关与多元回归分析.结果表明,小麦旗叶的长、宽、叶面积、与茎杆的夹角、叶绿素含量与穗粒数、千粒重、穗粒重、产量等性状间的相关系数分别达显著或极显著水平,r=0.4851～0.7481.建立了旗叶性状与产量及产量因素的最优多元回归方程.     

不同年代小麦产量性状与农艺性状的相关性比较

为研究不同年代小麦的主要农艺性状与产量性状之间的相关性,对4个不同年代78个小麦品种的主要性状进行调查分析,得出如下结论:随着年代的推进,小麦株高的降低趋势明显并趋于稳定,旗叶长呈缓慢下降趋势,旗叶宽、旗叶面积先增长后趋于稳定。在各年代中,株高与穗粒数、千粒质量和结实小穗数呈不显著正相关,与不孕小穗数呈不显著负相关。旗叶宽和旗叶面积与穗粒数、千粒质量和结实小穗数呈一定的负相关性,并与不孕小穗数呈一定的正相关性。因此,适当降低株高,增加旗叶宽和旗叶面积,对提高小麦产量有一定的推进作用。穗粒数和不孕小穗数的变异系数均较高,有较大的选择空间。     

小麦茎质系数的基因型差异及与产量性状关系的初步研究

利用11个不同的小麦基因型,对茎质系数的基因型差异及其与产量性状的关系进行了初步研究.结果表明茎质系数在小麦基因型间存在极显著差异,与单茎草重、穗粒数、千粒重、穗粒重呈极显著的正相关,与穗数、经济系数呈极显著的负相关,重穗型品种的茎质系数极显著地高于多穗型品种,但其经济系数、子粒产量/草产量(库源比)极显著地低于多穗型品种,选育中间型品种可以实现高产与抗倒的有机结合.     

小麦旗叶和芒的遗传及其与产量性状的相关性研究

通过对20个小麦品种（系）的研究表明,旗叶、芒对产量形成影响较大。旗叶、芒具有一定的遗传变异度,旗叶性状遗传力中等,芒遗传力较高。旗叶长、旗叶宽、旗叶面积、穗平均芒长均与穗粒重呈显著正相关;旗叶开张角、披垂度与穗粒重呈显著负相关。旗叶长与开张角、披垂度正相关,旗叶宽与开张角、披垂度负相关。育种中可将旗叶宽作为良好的株型性状加以选择。     

2种穗型小麦品种若干性状差异的比较

为了探明胶东地区适宜的小麦品种类型与育种方向,通过11个不同的小麦基因型,采用t测验法对2种穗型小麦品种的若干性状差异进行了研究。结果表明:大穗型品种的单茎草重、茎质系数、穗粒数、千粒重、穗粒重比多穗型品种高0.958 g、0.011 g/cm、5.354粒、5.460 g、0.504 g,均达到极显著水平;多穗型品种的单位面积穗数、经济系数和群体产量比大穗型品种高289.847万/hm2、0.027、859 kg/hm2,均达到极显著水平。在胶东地区生态条件下,应以分蘖力中等、茎秆粗壮、成穗率高、产量三因素协调的多穗型品种为主攻方向。     

源—库变化对小麦籽粒性状和干物质积累的影响

以不同历史时期的小麦品种为材料,研究了源—库变化对小麦籽粒性状和干物质积累的影响表明:穗粒重、千粒重、最大籽粒体积、皱缩指数、单茎生物量和草重有明显的品种间差异.剪叶减源,使穗粒重、最大籽粒体积、千粒重和生物量下降。剪除部分小穗减库,使剩余籽粒的最大体积和千粒重明显增加。新老品种的开花期单茎生物量相同,对减少库的反应基本一致。近期品种开花后单茎干物质积累较多,对源的减少较敏感.要在现有品种基础上提高产量潜力,不但要增加库,而且要增加源     

小麦三雌蕊近等基因系的主要农艺性状分析

为充分利用小麦三雌蕊品系的优良性状,全面分析小麦三雌蕊基因pis1对其农艺性状的遗传效应,本研究对小麦三雌蕊近等基因系CSTP,CM28TP,MY29TP和NM9TP及其相应的轮回亲本的主要农艺性状进行了分析。结果表明,各近等基因系与其轮回亲本在株高、茎粗、旗叶长、旗叶宽、有效穗数、穗长以及小穗数等7个农艺性状上差异不显著,除CSTP外,其它3个近等基因系的穗粒数明显高于其轮回亲本。但千粒重和小区产量均低于轮回亲本。相关性分析表明,小区产量与千粒重呈极显著正相关。而小区产量和千粒重都与穗粒数呈不显著的正相关,即仅提高穗粒数不能有效的提高产量。因而要利用小麦TP品系进行育种研究,其首要目标是提高千粒重。聚类分析表明,近等基因系与相应的轮回亲本聚在一起,这说明构建的近等基因系是成功的。     

矮秆CHA杂种小麦优势分析

本文对９个矮秆ＣＨＡ杂种小麦产量及相关因素的优势表现进行了分析。产量最高优势为６．１％，穗粒数普遍表现明显超标优势，亩穗数表现负优势，千粒重优势很不一致。穗长增加，结实小穗数增多，穗粒重有很强的优势，表现出大穗，多花多实特性，主茎旗叶，倒二叶面积增大，光合能力强，收获指数高，库源关系比较协调。     

抗条锈矮秆大穗型小麦茎叶穗遗传及各性状相关研究

以4个矮秆大穗型小麦材料为母本，6个高产小麦为父本，采用不完全双列杂交设计，对小麦15个茎叶穗农艺性状进行遗传分析。结果表明：15个农艺性状的表现都是由加性和非加性基因共同决定的。15个性状遗传力均较高，除旗叶宽、旗叶面积和单株粒重三性状外，其余性状主要由加性基因决定。除叶宽和结实小穗两性状外，其余各性状的GCV均较大，表明对其选择和改良的潜力较大。各茎叶穗农艺性状一般配合力间存在不同程度的依存关系。指出小麦高产育种应注意协调好提高结实小穗、穗长、每穗粒数与提高穗下节长和穗颈节长以及穗长与单株穗数问的关系。     

矮杆基因对春小麦植株生长发育的影响及对子粒产量的间接作用

利用以春小麦品种ＡｐｒｉｌＢｅａｒｄｅｄ为背景的含有不同矮秆基因Ｒｈｔ１、Ｒｈｔ２、Ｒｈｔ３、Ｒｈｔ１＋Ｒｈｔ２和Ｒｈｔ２＋Ｒｈｔ３的５个近等基因系,研究了不同矮秆基因对小麦生长发育的作用。结果表明：Ｒｈｔ１半矮秆基因显著缩短了小麦植株生长发育进程,促进了地上部干物质积累,加大了旗叶面积和倒二叶面积,提高了单株成穗率,减少了无效分蘖;Ｒｈｔ２半矮秆基因显著增大了倒二叶面积,提高了单株成穗率和穗长,减少了无效分蘖;Ｒｈｔ３矮秆基因显著加大了旗叶面积,但对地上部干物质的积累、单株成穗和穗长均有显著的负向作用;Ｒｈｔ１＋Ｒｈｔ２基因结合没有突出的优势存在：Ｒｈｔ２和Ｒｈｔ３基因结合对有利于提高小麦产量性状的作用均为负向最大;上述３种矮秆基因及其不同的结合形式均有显著的使茎秆矮化的作用。因此认为Ｒｈｔ１半矮秆基因在小麦育种中利用价值较大,Ｒｈｔ３矮秆基因利用价值则较小。     

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.     

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.     

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.     

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.     

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).     

Production and characterization of intergeneric diploid cybrids derived from symmetric fusion between Microcitrus papuana Swingle and sour orange (Citrus aurantium)

Plants were regenerated from intergeneric somatic hybridization between embryogenic protoplasts of Microcitrus papuana Swingle and leaf-derived protoplasts of sour orange (Citrus aurantium L.) via electrofusion. The regenerated plants were morphologically similar to the leaf parent in growth vigor, leaf and branch structure. FCM analysis showed that they were diploids. Simple-sequence-repeat (SSR) and cleaved-amplified-polymorphic-sequence(CAPS) were employed for hybridity characterization. SSR banding patterns of the regenerated plants were identical to the leaf parent, sour orange, indicating that they possessed nuclear component derived from sour orange. DNA amplification with chloroplast and mitochondrial universal primers, followed by restriction endonuclease digestion, revealed polymorphism between the fusion parents. Therefore, this method was used to determine the cytoplasmic compositions of the regenerated plants. Banding patterns for all the polymorphic primer/enzyme combinations of the regenerated plants were similar to those of the embryogenic parent, M. papuana, suggesting that only the cytoplasmic components derived from the embryogenic parent were present in the regenerated plants. FCM, SSR and CAPS demonstrated that intergeneric diploid cybrids have been successfully obtained by symmetric fusion. Related results concerning nuclear and cytoplasmic composition of previous diploid somatic hybrids and potential mechanism for regeneration of such kind of plants are discussed herein. This revised version was published online in July 2006 with corrections to the Cover Date.