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991.
Zhang-Ying Xi Feng-Hua He Rui-Zhen Zeng Ze-Min Zhang Xiao-Hua Ding Wen-Tao Li Gui-Quan Zhang 《Euphytica》2008,160(3):369-377
Backcrossing is a trait introgression method of renewed importance in crops. The evolution of introgressed or substituted
segments through backcross generations has been analyzed theoretically using simulations. In this study, the content of donor
genomes, including donor segment number (DSN), donor segment length (DSL), and donor genome size (DGS), were directly analyzed
in six crosses over three successive backcrosses using a set of single sequence repeat (SSR) markers covering the entire rice
genome. The results of this analysis demonstrated that the average DSN in each genome was 8.39 in BC2F1, 4.13 in BC3F1, and 2.41 in BC4F1, decreasing nearly by half with each backcrossing. The average DSL was 33.43 cM (centiMorgans) in BC2F1, 29.04 cM in BC3F1, and 25.07 cM in BC4F1, display a progressive decrease slightly greater than 10% in each additional backcross generation. Meanwhile the average
DGS was 280.51 cM in BC2F1, 119.97 cM in BC3F1, and 60.53 cM in BC4F1, decreasing 57.2% from BC2F1 to BC3F1 and 50.4% from BC3F1 to BC4F1. This revealed that the reduction in DGS was approximately 50% with each backcrossing. These results provide a guide for
introgression or substitution of target chromosome segments from donors into recipients in backcross programs.
Zhang-Ying Xi and Feng-Hua He contributed equally to this work. 相似文献
992.
Kayode A. Sanni I. Fawole R. G. Guei D. K. Ojo Eklou A. Somado D. Daniel Tia S. Ayoni Ogunbayo I. Sanchez 《Euphytica》2008,160(3):389-400
The knowledge of agro-morphological diversity and the distribution pattern of variation among conserved accessions could be an invaluable aid in germplasm management and crop improvement strategies. In this study, the geographical pattern of morphological variation of 880 landrace rice (Oryza sativa (L.)) accessions in Côte d’Ivoire was evaluated for 13 agro-morphological characters. Shannon –weaver diversity index indicated an overall mean of 0.47 ± 0.07 in the collection, with the greatest diversity from derived Savanna and north-west (H′ = 0.52 and 0.50) while the west-central had the lowest diversity (H′ = 0.41). Canonical discriminant analysis showed that traits such as panicle length, grain size (weight and length), tillering ability, number of days to heading and maturity were the main discriminatory characteristics. Result of the phenotypic frequency shows that, the landraces from the north and north-western zones were mostly tall, early heading and maturity, compared to those from the west and west-central which were mainly dwarf to medium height, late heading and maturing. This differential distribution of landraces with height, heading and maturity period reflected the distribution pattern of different Oryza sativa landraces in Côte d’Ivoire, which could be useful in germplasm management and breeding programs. 相似文献
993.
Luc Baudouin Patricia Lebrun Angélique Berger Wayne Myrie Basil Been Michel Dollet 《Euphytica》2008,161(3):353-360
We applied Bayesian population assignment methods to assess the trueness to type of four populations of the coconut cultivar
Panama Tall (PNT) located in Jamaica and found that two of them presented a high percentage of off-types, while genetic contamination
was low in the two others. The PNT is the pollen parent of the MAYPAN hybrid, which used to be planted in Jamaica to control
an epidemic disease: Lethal Yellowing. The main source of contamination was the susceptible Jamaica Tall, thus increasing
the susceptibility in the resulting MAYPAN progeny. The incidence of genetic contamination seems however to be insufficient
to be the only cause of the latest outbreak of the disease. Neither the MAYPAN nor its parents can be said resistant in the
present context of Jamaica. 相似文献
994.
David Pink Liz Bailey Sandy McClement Paul Hand Evy Mathas Vicky Buchanan-Wollaston Dave Astley Graham King Graham Teakle 《Euphytica》2008,164(2):509-514
Double haploid (DH) plants of Brassica spp. can be produced via anther culture or culture of microspores. This paper reviews the uses of double haploids in crop
improvement research in vegetable brassicas (B. oleracea). Applications of DH lines are described for breeding; construction of linkage maps; genetic analysis of quantitative traits
and capturing genetic variation. The advantages and disadvantages of DH lines are discussed 相似文献
995.
Tef is a staple cereal of Ethiopia in high demand by consumers. In order to cope up with this high consumer demand, productivity
per unit of land must increase through the development and use of high-yielding varieties. To this effect, the National Tef
Research Project has long been striving towards the development of high yielding varieties through direct selection from germplasm
and concentrating favourable alleles through hybridization and selection, despite the tedious crossing technique. The objective
of this study was to assess the degree of genetic variation in F2 populations of tef as a basis for improving grain yield. F2 populations from 12 crosses and their parents were grown at the Debre Zeit Agricultural Research Center, Ethiopia, and assessment
was made on eight traits on individual plant basis. Eleven of the 12 crosses showed substantial genetic variation for grain
yield and its components, indicating the potential for improvement through selection. Moreover, grain yield, plant weight
and yield related traits showed moderate to high heritability values (17–80%). In all the crosses, tiller number, panicle
weight, yield per panicle and panicle length showed significant (P ≤ 0.05) and positive association with grain yield. Considering the degree of genetic variation and heritability values, emphasis
should be given to selected crosses in an effort to developing high-yielding tef varieties. 相似文献
996.
Kateřina Pánková Zbyněk Milec James Simmonds Michelle Leverington-Waite Lesley Fish John W. Snape 《Euphytica》2008,164(3):779-787
The single chromosome substitution lines of chromosome 3B of the Czech alternative wheat variety Česká Přesívka (CP 3B) into
two spring varieties Zlatka and Sandra, revealed clear differences in flowering time compared to the recipient varieties.
To map this gene(s), recombinant substitution lines for chromosome 3B were produced from crosses of the substitution lines
with their recipient parents and genetic maps developed using SSR markers. Two populations were mapped, Sandra//Sandra 3B/Sandra
(CP 3B) and Zlatka//Zlatka/Zlatka (CP 3B). Combining the genotype data with phenotype data on flowering time in five independent
experiments under natural long day or controlled short day conditions revealed a single flowering time QTL. This gene had
an additive effect of 1–6 days, depending on environment and genetic background, and was mapped in both populations to a position
in the region of marker Xbarc164 near the centromere on the long arm of 3B. Comparisons of the genetic maps with other 3B maps developed by the authors indicated
that the QTL may be homologous to a QTL segregating in UK germplasm. 相似文献
997.
茶叶加工过程中的物理特性变化规律 总被引:1,自引:0,他引:1
为了探讨茶叶加工过程中物理参数的变化规律,以春季茶叶为试验材料,分别采用103°恒重法、量筒法、仪器法、注入法和斜面法,研究探讨鲜叶、萎凋叶、杀青叶、揉捻叶、作形茶及成品茶的含水率、容重、孔隙率和休止角,以及茶叶与不同茶机材料静摩擦角的变化规律。研究结果表明,绿茶在加工过程中含水率从73.7%一直下降到4.2%,作形过程中含水率下降最显著,揉捻过程中含水率下降最少;绿茶加工过程中成品茶容重最大,鲜叶容重最小,各加工阶段茶叶的容重变化范围为74.5~210.3kg/m3;鲜叶的孔隙率最大,揉捻叶的孔隙率最小,茶叶在制品的孔隙率在0.696~0.732之间变化;在整个茶叶加工过程中,休止角都在50°~60°之间变化;茶叶在铝板上的静摩擦角最大,浸胶帆布带上的次之,而在铜板、镀锌钢、不锈钢和普通钢板上则相差不大,在所有茶机材料上,作形之后茶叶的静摩擦角最小。 相似文献
998.
大米称誉为五谷之首,是我国的主要粮食作物。大米产地鉴别方法的研究对于保护广大消费者和生产厂家的利益、推动我国大米出口业的发展等都具有重要意义。为此,选取了19个响水大米样品和10个非响水大米样品,使用等离子体原子发射光谱的方法测定了样品中P,B,Zn,Fe,Cu,Mn,Na,K,Mg和Ca等10种微量元素的含量,并利用样品中的微量元素含量数据,使用K-Means聚类法和Hierarchical聚类法对大米样品进行了聚类分析。结果表明,K-Means和Hierarchical聚类法对于样品有聚类趋势。研究结果能够为大米生产厂商与质检部门鉴别大米产地提供参考和借鉴。 相似文献
999.
滴灌灌水器流道堵塞及防治研究进展 总被引:1,自引:0,他引:1
滴灌的堵塞问题一直是困扰滴灌技术应用与发展的限制性因素,为了探索解决或者预防该问题的技术途径,从堵塞的成因、机理以及预防措施等方面进行了论述,提出了预防灌水器堵塞的基本措施,包括改进灌水器流道结构、强化水质处理以及严格过程管理。在此基础上,对今后的重点研究方向提出了若干建议。 相似文献
1000.