Genetic interpretations of the effects of bulk breeding on four populations of beans (Phaseolus vulgaris L.)

Summary The effects of bulk breeding on yield and its components in two high-yeilding and two low-yielding bean populations when grown at crop densities are interpreted in terms of gene action and selection. There was considerable additive variation in the crosses, dominance effects were variable but tended to be negative. The results were compared with results obtained at low density by another worker with the same populations, and this showed that interpretations of gene action in hybrid vigour depend on the test environment used. The interpretations were also compared with plant breeding interpretations made on the same material (Hamblin, 1977), and it was found that a single pattern of response to natural selection, in plant breeding terms, may be explained by more than one genetic interpretation and, conversely, a single genetic interpretation may result in different patterns of response in plant breeding terms. The value of composite crosses in plant breeding are discussed and it is concluded that there is a greater chance of producing improved lines from a large number of simple crosses than from a smaller number of composite crosses.     

草坪坪床对土壤的要求

通过对土壤理化性质及其生物组成的分析 ,对草坪坪床土壤提出了要求 ,并且提出了改良措施     

Evaluation of the efficiency of alternative two-tier nucleus breeding systems designed to improve meat sheep in Kenya

A deterministic approach was used to genetically and economically evaluate the efficiency of five two‐tier nucleus breeding systems for meat sheep in Kenya. The nucleus breeding systems differed in terms of whether the system was closed or open, in the type of animals that were involved in the movement of genetic superiority and in the number of selection pathways in each system. These systems were compared under four alternative breeding objectives based on monetary genetic gain and profit per ewe. The first objective simulated a situation where the flock size cannot be increased due to non‐feed related constraints (FLOCK). The second specifically assumed that the flock size is restricted due to limited amount of feed resources (FEED). The third and fourth objectives assumed that sheep performed only tangible roles (TR) and both tangible and intangible roles (IR) in the production system respectively. Monetary genetic gains were highest for all objectives in an open nucleus system with a certain proportion of commercial‐born ewes being introduced in the nucleus while at the same time utilizing young rams from the nucleus to breed sires and dams for the nucleus and commercial sector (ONyre). Utilizing young rams in a closed nucleus system for the dissemination of superior genes resulted in higher annual monetary genetic gain than utilization of old rams. Profit per ewe was significantly higher for FLOCK and IR in ONyre. In a closed system that allowed for downward movement of dams from the nucleus to the commercial sector to breed sires and dams, profit per ewe was highest for FEED and TR. The success of a nucleus breeding system should also focus on the profitability and logistics of establishing it. The implication of these results on the choice of two‐tier nucleus breeding systems for the improvement of meat sheep is discussed.     

基于选择信号分析揭示猪终端父本群体间性状趋同的关键基因

【目的】试验旨在揭示终端父本皮特兰猪与杜洛克猪在人工选择作用下重要经济性状呈现出表型趋同的基因组变化特征。【方法】利用376头皮特兰猪、451头杜洛克猪品系Ⅰ、841头杜洛克猪品系Ⅱ和497头杜洛克猪品系Ⅲ群体的50K SNP芯片数据,以100 kb窗口、50 kb步长计算综合单倍型评分(iHS)和等位基因频率差(△AF),分别取前5%作为猪群体内、群体间的基因组选择信号候选区域;利用bedtools分别对iHS、△AF按照左右200 kb进行合并,每2个群体间合并后的iHS、△AF统计量的重叠区域定义为性状趋同区域,并挖掘该区域与猪重要经济性状相关的平行选择信号。【结果】iHS结果显示,在皮特兰猪和杜洛克猪4个群体内共检测到5 112个选择信号候选区域,总长约487.51 Mb。基于△AF方法,于皮特兰猪和杜洛克猪每2个群体间共检测到9 579个选择信号显著区域,总长约913.50 Mb。基于合并后的iHS和△AF,共检测到52个性状趋同区域,总长约4.67 Mb,注释到88个与猪的繁殖、胴体和肉质等性状相关的平行选择候选基因。【结论】皮特兰猪和杜洛克猪群体间存在性状趋同的基因组选择区域有52个,平行选择信号主要涉及猪的繁殖、胴体及肉质等重要经济性状,这与瘦肉型猪种相同的育种方向相关,这些关键基因的发现可为后续商业猪品种遗传改良提供参考。     

家禽重要性状的基因组学研究与应用现状

近一个世纪的传统选育使家禽的各项生产性能接近表型选育极限,基因组学领域的发展成为突破这一瓶颈的新途径。自2004年第一个鸡的基因组草图发布以来,鸡、鸭、鹅等家禽的基因组参考序列在近年相继发布,且质量逐步提升。基于家禽高质量的基因组参考序列,研究学者进一步对家禽的重要性状展开了系列研究,这些研究加速了我们对家禽重要性状的认识和理解,并为在家禽基因组选择育种中应用筛选出有效的分子标记。本文就家禽的基因组参考序列研究、重要性状的基因组学研究及其应用进行综述。     

植物育种的物理学方法

介绍了草原生态恢复中选育优良牧草种子的一些物理学方法,包括电场、磁场、物理辐射、激光、离子束和交变应力等在植物的生物学效应、诱变育种和转基因技术中的应用.     

近红外光谱技术在牧草育种研究中的应用前景

近红外光谱技术(NIRS)是一种快速、高效、无损的现代检测技术,已经在许多领域广泛应用.简要介绍了NIRS的基本原理、特点以及应用于牧草育种研究的意义,阐述了NIRS在牧草营养品质改良、次生代谢产物分析、病虫害抗性分析、抗逆能力评价等牧草育种方面的应用现状和前景.     

屡配不孕母牛发情开始后八天内血清促黄体素（LH）含量的变化

本实验采用放射免疫测定技术(RIA)分析了9头屡配不孕母牛和6头正常母牛于发情开始后8天内的血清促黄体素(LH)的含量变化。测定结果表明:屡配不孕母牛的LH排卵峰值低于正常母牛,其峰值分别为2.71±1.00ng/ml和4.70±1.71ng/ml,差异显著(P<0.025)。为了初步验证LH峰值与屡配不孕之间的关系,对20头屡配不孕母牛在发情开始至配种前肌肉注射外源性LH180IU,其配种后60天的受胎率为70％(14/20),而未用LH处理的11头屡配不孕母牛的受胎率为18％(2/11),两者差异极显著(P<0.01)。上述实验结果提示:体内LH排卵峰值降低可能是导致乳牛屡配不孕的重要原因之一。     

石塘镇牛品改工作现状及整改措施

据笔者在石塘镇水产畜牧兽医站工作十余年,本文对石塘镇牛品改工作存在的问题及整改措施进行了分析,只有剖析与解决了制约牛品改工作发展的不利因素,才能促进石塘镇牛品改工作的顺利发展,提高广大养殖户的经济收入。     

大花萱草‘金娃娃’的花器结构和繁育系统观察

通过观察,运用杂交指数、花粉/胚珠、花粉及柱头活力、坐果率等指标对大花萱草‘金娃娃’(Hemerocallis hybridus cv.‘Stella de oro’)的花部特征、开花动态及授粉特性等进行研究。在人工栽培条件下,金娃娃萱草5-9月开花,花苔分3～4次抽生,首次开花群体花期32 d,单苔花期9～16 d,单花花期1 d。雄蕊短于花柱,花药与柱头相差2.71 cm,在花朵开放的整个过程中雌、雄蕊的相对位置始终不变。开花前1 d的花粉活力最强,开花前1 d和开花当天的柱头具有较强的可授性。杂交指数为4,花粉/胚珠值为1 164,结合坐果率,可以判断其繁育系统属于兼性异交,部分自交亲和,需要传粉者。特殊的花部结构、缺少传粉者和花期短可能是金娃娃萱草结实率较低的原因。