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1.
T. D. Johnston 《Euphytica》1965,14(1):119-123
The production of hybrid seed on a commercial scale is discussed. It is suggested that the special problems connected therewith are not great and that the hybrid seed need not be appreciably more expensive than seed produced in the normal way.A system for selecting desirable double-cross hybrids is suggested as a working pattern for a practical breeding programme based on this approach. 相似文献
2.
Caitlin Harris Madison Hall Ruby Arrowfield Rowan Herridge Colin Eady Richard Macknight Lynette Brownfield 《Plant Breeding》2023,142(4):518-526
Perennial ryegrass is an important turf and forage grass in temperate regions worldwide. Limited genetic gains have been made with current breeding strategies compared with other grass crops, such as rice and maize, which benefit from Filial 1 (F1) hybrid breeding. One of the largest constraints on hybrid breeding in ryegrass is self-incompatibility preventing inbreeding, as homozygous parental lines are required to develop hybrids with maximal hybrid vigour. Obligate outcrossing in ryegrass has resulted in cultivars with high levels of heterozygosity, lacking trait uniformity across the population. A naturally occurring self-fertile (SF) locus that overcomes the self-incompatibility system has been identified in a European perennial ryegrass population. This study crossed the SF locus into an elite cultivar, producing a self-compatible population that was inbred for several generations. Genotyping-by-sequencing (GBS) was used to assess the population structure and degree of inbreeding in the self-compatible population. Phenotypic analysis indicated that increased homozygosity did not necessarily affect growth and performance. This study concludes that self-compatible ryegrass is a promising tool for hybrid breeding and agronomic improvement of perennial ryegrass. 相似文献
3.
Increased Yield and Revenue with a Seedling Transplanting System for Hybrid Seed Production in Bt Cotton 总被引：5，自引：0，他引：5
H. Z. Dong W. J. Li W. Tang Z. H. Li D. M. Zhang 《Journal of Agronomy and Crop Science》2005,191(2):116-124
Rapid adoption of Bacillus thuringiensis (Bt) transgenic hybrid cotton (Gossypium hirsutum L.) in China is greatly attributed to high-quality hybrid seed produced in northern Shandong cotton production area; however, seed yield has reached a plateau in this area in recent years. Shifting the growing season earlier in the year by planting earlier in a greenhouse-like hut and transplanting the raised seedlings to the open fields later may allow the crop to produce more seeds. Four-year consecutive experiments conducted in Huimin County (northern Shandong, China) showed that early-season chilling stress on seedlings was avoided in such a hut, and that the blooming period was extended by about 1 week longer and the peak blooming occurred 5 days earlier in the year in the transplanting system than in the normal planting system. The number of early-season blooms and the number of bolls retained per unit area in transplanting system were significantly higher than those in normal planting system, but there were no significant differences in boll size and lint percentage between the two planting systems. Seed yield and quality parameters were significantly improved in the transplanting system through the increased number of bolls per square metre and earlier blooming respectively. As a result of improvement in seed yield and quality, the net revenue for seed producers with the transplanting system was increased by 20.8 and 22.5 % in 2002 and 2003, respectively, compared with the corresponding net revenue in the normal planting system. Seedling transplanting is a potent way to enhance hybrid seed production in Bt transgenic cotton. 相似文献
4.
为适应公园城市建设对风景园林专业人才的需要,有必要对现有风景园林专业课程体系进行改革。以徐州工程学院风景园林专业现有课程体系为例,对比其他高校风景园林专业课程体系,以气候顶级群落结合人文资源特点构建作为公园城市景观建设的目标,分析现有课程体系构成,并以公园城市建设目标为依据,改革现有风景园林专业课程体系。提出了通识必修课程、学科基础课、专业必修课、专业选修课、实践教育等课程区块的改革建议。建议增加应用气象学、森林生态学、风景园林遗产保护与管理、环境心理学、民俗学、人文地理学等有利于构建气候顶级群落和体现人文特点的相关课程,进一步完善适应公园城市建设的风景园林专业课程体系。 相似文献
5.
The Polima cytoplasmic male sterility (CMS) system has been successfully used in three/two-line hybrid production in rapeseed
(Brassica napus L.). However, the sterility of the Polima (pol) CMS lines is sensitive to temperature fluctuations. Also, traces of pollen
can cause self-pollination within the CMS lines, which results in reduced levels of F1 hybrid seed purity and leads to a significant yield loss. Self-incompatibility (SI) is another important approach for hybrid
seed production in rapeseed. Despite having a wide range of restorers and being easily selected in a breeding program, SI
system has some drawbacks. In this study, SI genes from a self-incompatible line of Brassica napus were transferred to a pol CMS line and S372A, a novel line of combined cytoplasmic male sterility with self-incompatibility
was bred. Due to the SI genes, this line produced very few seeds when it was selfed at low temperature and no seeds at high
temperature. This suggested that the line with CMS + SI had combined the advantages and overcome the disadvantages of both
the pol CMS and SI systems. Furthermore, our results showed that most of the maintainers and all the restorers of the pol
CMS system were also maintainers and restorers of the CMS + SI line, respectively. This indicates that the CMS + SI system
can be easily used to establish three-line hybrids of rapeseed, and we believe this novel system could be extended to other
species of Brassica. 相似文献
6.
分子标记技术在杂交小麦研究中的应用 总被引：2，自引：0，他引：2
杂交小麦的研究相对于水稻、玉米等作物来说仍处于初级阶段，生物技术的出现对杂交小麦的研究起了很大的推动作用，尤其是分子标记技术的迅速发展，更是为杂交小麦的研究提供了巨大的潜力。分子标记技术依靠提供准确、稳定可靠的DNA水平的遗传标记，在杂交小麦育种研究中已用于构建遗传图谱、标定和定位恢复基因和育性相关基因、探寻杂种优势的机理和细胞质雄性不育(CMS)机理及分子标记辅助选育等方面，为杂交小麦的研究提供了理论基础。本文针对小麦杂种优势利用研究的现状，综述了分子标记技术在各方面的应用进展，提出了目前存在的问题，并讨论了分子标记技术在杂交小麦研究中的应用前景。 相似文献
7.
2006-2007年广西杂交稻区试回顾及发展商榷 总被引：3，自引：0，他引：3
回顾了广西杂交水稻区试历程,通过对2006、2007年广西杂交稻区试结果进行具体分析,肯定成绩,发现问题,并提出对今后发展方向的建议。2年来的区试结果表明,广西杂交水稻区试的参试组合类型配套齐全丰富,在选育组合数量,产量水平及稻米品质方面取得较大进步。但是存在着一些影响育种突破的重要问题。首先,参试组合很难在抗病虫上有所突破。其次,参试组合的综合性状有待进一步提高。今后,杂交水稻育种应扩大遗传基础,加大籼粳稻种质的遗传利用,加强野生稻优异种质的利用,把抗性育种放到主要议事日程,进一步促进杂交水稻综合性状的改良与协调,向超高产稻方向发展。 相似文献
8.
Summary S1 to S5 inbred lines, derived from a maize population bred for its overall resistance to three tropical viruses, were screened for resistance to maize streak virus (MSV) by artificial plant infection using viruliferous leafhoppers. Symptoms were rated and intra-line frequency distributions studied for all pedigree inbred lines. Mortality due to MSV was very low among these inbreds. Symptoms appeared later, developed slower and were less severe than in the susceptible control hybrid. Results of a study of 500 S1 and 93 S2 lines suggested that resistance is under genetic control via a system involving loci with major genes (with dominance for resistance) controlling high to complete resistance, associated with a genetic system involving loci with minor genes controlling partial resistance. Lines expressing complete resistance to MSV were developed from 5 cycles of inbreeding and selection. The relevance of such complete and partial resistance is discussed.Abbreviations MRPS
Mean Rating for Plants exhibiting Symptoms 相似文献
9.
The intense coupled and nonlinear behaviors were observed on the tall long span tower line systems which were under the icing and wind loads in heavy icing areas. A set of stiffness equations of insulator, conductor and boundary conditions was deduced. Taking the ±800 kV UHV DC transmission line from Xiangjiaba to Shanghai as an example, the simplified numerical model of transmission tower, conductor, insulator and constraint was developed. The long span transmission tower line system models under seven loads conditions were analyzed by static nonlinear methods. It was found that the P Δ effect of tower components was small when the covered ice was uniformly distributed. The unbalanced wire loads on the tower would lead to twist effect when the covered ice was uneven distributed. The axial forces, moments at restraint nodes and the longest cantilever member were greatly affected by the P Δ effect, under which the unfavorable effect on the structure should be considered. 相似文献
10.
It is very important for rapeseed hybrid production to develop and utilize a novel cytoplasmic male sterility (CMS) system concerning the possible risk because of a narrow cytoplasm background. Here the anatomy of anther development in the CMS system, named NCa , was observed using light microscope and transmission electron microscope, and the restriction fragment length polymorphism (RFLP) analyses of mitochondrial DNA of NCa sterile line were also performed in comparison with the other rapeseed sterile lines, such as pol , nap , ogura , and tour . The anther abortion of this CMS line occurred at the later uninucleate microspore stage, and the anatomic aborting characteristics were obviously different from all the other rapeseed CMS lines reported before. The RFLP analyses revealed that five probe/enzyme combinations could distinguish the five CMS lines. The results of anatomic observations and mitochondrial DNA polymorphism indicated that the NCa CMS system is a novel one which differs from the pol , nap , ogura , and tour systems. 相似文献
11.
Cytoplasmic-nuclear male-sterility is an important biological tool, which has been used by plant breeders to increase yields
in cross-pollinated cereals and vegetables by commercial exploitation of the phenomenon of hybrid vigor. In legumes, no such
example exists due to the absence of an economic way of mass pollen transfer from male to female parent. Pigeonpea [Cajanus cajan (L.) Millsp.], however, is a different legume where a moderate level of insect-aided natural out-crossing (25–70%) exists
and it can be used to produce commercial hybrid cultivars, if an efficient and stable cytoplasmic-nuclear male-sterility (CMS)
system is available. This paper reports the development of a stable CMS system (ICP 2039A), derived from an inter-specific
hybrid of Cajanus cajanifolius, a wild relative of pigeonpea, with a cultivar ICP 11501. Using this genetic material, designated as the A4 cytoplasm, a number of fertility restorers and maintainers have been developed. The best short-duration experimental pigeonpea
hybrid ICPH 2470 produced 3205 kg ha−1 grain yield in 125 days, exhibiting 77.5% advantage over the control cultivar UPAS 120. At present, all the important biological
systems necessary for a successful commercial hybrid breeding program are available in pigeonpea and the package of this technology
has been adopted by private seed sector in India for the production and marketing of hybrid varieties. 相似文献
12.
Competition among construction companies becomes drastic while market economy is gradually established in China.It is a problem of concern that how to rationally evaluate the competitive ability of construction companies in order to plan the competitive strategy for companies.The multi index system and comprehensive index are proposed in this paper and Analytic Hierarch Process(AHP) is applied to calculate the weights of multi index.The evaluation model of competitive performance of construction companies is presented based on AHP.An example for the evaluation model is given.The results demonstrate that the model can be used to efficiently evaluate the competitive performance of construction companies.The competitive strategy can be suggested through analyzing some factors influencing the competitive performance of construction companies. 相似文献
13.
14.
水稻无花粉型雄性不育基因的遗传关系剖析及定位 总被引：1，自引：0，他引：1
本文以同时携带脚基因（无花粉型雄性不育）和wx（糯性）基因的wxB^ms系及cms、ms和wx基因的wxA^ms为材料,观察ms、cms及wx的遗传关系并对ms基因进行染色体定位。研究结果如下：遗传分析表明,无花粉型雄性不育受一对隐性核基因控制;糯性基因wx与ms表现独立遗传,非糯性突变导致ms后代育性异常分离,故只要去除保持系中带有ms突变基因的植株,便可实现不育系cms-龙特浦wxA的保纯繁殖;本试验中出现的cms-龙特浦wxA^ms／龙特浦wxB的F1代育性恢复现象解释为：ms基因上位cms,ms的雄性遗传表达早于cms,cms雄性不育的发育表达因滞后而被掩盖;采用SSR分子标记技术,将ms基因定位在第1条染色体上的SSR标记RM579和RM23,为克隆该基因进行雄性不育机理研究奠定基础。 相似文献
15.
Ran Li Ren Zhen Jiang Zejia 《保鲜与加工》1988,(6)
An optimal active power adjustment model is deve in this paper for hybrid AC/DC systems after outage contingencies. The objective of the model is to minimize the rejection of load when some elements are out of service, with adjustment strategy approaching practical system operation. A large number of outage contingencies are simulated when the Monte-Carlo Method is emyloyed to evaluate the system reliability, requiring fast calculation of each simulation. The model and computer method proposed in this paper satisfy such a requirment because of the application of concentric relaxation, recursive branch constraint treatment in linear programming and a direct method for B-1 matrix modification. This paper is concerned with the simplified steady state conditions of the system based on DC load-flow, which implies the reliability indices calculated are the measures about static loss of load. The results for a 14-bus hybrid AC/DC system are given. 相似文献
16.
17.
为了建立遗传群体构建的分子标记检测体系,利用SSR分子标记技术构建了从DNA提取、引物多态性筛选、亲本和子代植株的PCR扩增、扩增产物的电泳检测等4 步检测体系,实验中仅用1 对位于大麦7H染色体上的引物HvWaxy4 就对7 个F1子代植株进行了鉴定,通过鉴定判断出其中3 个植株为F1子代,4 个单株为自花授粉产生的子代。表明SSR标记技术在验证遗传群体构建过程中F1杂交植株真伪的可行性,该方法适用于自花授粉作物的遗传群体构建过程中F1植株的真伪检测。 相似文献
18.
Membrane Bioreactor (MBR) is a new technology in wastewater treatment, using membrane to enhance biological-chemical reaction. It has many advantages such as high efficiency and low sludge production rate. By analyzing the factor influencing MBR, a new submerged hybrid dynamic membrane bioreactor(HDMBR) is suggested and the characteristics of the new HDMBR from different viewpoints are expounded. It shows that this technology is a process of high efficiency and low consumption. 相似文献
19.
杂种劣势是存在于自然种群之间的一种合子后生殖障碍,水稻杂种劣势的研究有利于探讨种间、亚种间和亚种内杂交不亲和原因,对建立新的杂种优势利用模式具有重要的理论及实践意义。本研究旨在通过对三个韩国粳稻劣势亲本"Aranghyangchalbyeo"(CH7)、"Sanghaehyangheolua"(CH8)和"Shinseonchalbyeo"(CH9)及其杂交后代(F1, F2)的生物学特征、特性进行比较,解析水稻粳稻亚种内杂种劣势的遗传模式;同时利用单倍型分析和图位克隆比对,探明CH8和CH9两个劣势亲本中所携带的劣势相关基因序列差异。结果表明,携带劣势基因的亲本自身生长正常,但正反交后F1表现稳定且明显的杂种劣势,F2群体中劣势植株与正常植株呈现9:7的分离,推断该杂种劣势的表型由两个互补的显性基因控制;劣势亲本CH8第1号染色体携带了稀有的劣势基因Hwc1;劣势亲本CH9不携带Hwc1和Hwc2基因,可能携带了其他劣势基因。该结果为揭示杂种劣势的基因多样性及分子遗传机制提供了科学依据。 相似文献
20.
杂交棉标杂A1和石杂2号超高产冠层特性及其与群体光合生产的关系 总被引：14，自引：0，他引：14
在田间自然条件下, 以标杂A1、石杂2号为材料, 研究了超高产(3 500 kg hm-2以上)杂交棉冠层的叶面积配置、叶倾角和光分布等冠层特性的变化及与群体光合生产的关系。结果表明, 超高产条件下杂交棉叶面积指数高且持续期长, 群体叶面积配置与光分布较均匀, 花铃期冠层中部有较好的透光性, 吐絮期底部漏光损失较小, 整个冠层仍保持较高的光吸收率。超高产杂交棉不仅群体光合速率峰值高, 而且高值持续时间长, 生育后期非叶器官仍维持较高的光合能力, 特别是茎的光合贡献率为常规高产棉花的1.6~4.9倍, 这是杂交棉在生育后期能保证群体光合优势的一个重要原因。超高产杂交棉的棉铃干物质空间分布与叶分布、光分布和冠层光合分布的比例吻合程度较高, 保证了光能的有效利用, 促进同化物及时向棉铃转运, 有利于挖掘杂交棉品种的增产潜力。 相似文献