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玉米的杂种优势群和杂种优势模式 总被引:39,自引:3,他引:36
划分玉米育种材料的杂种优势群和构建杂种优势模式表明,杂交育种技术向理论思维方式的靠近,反映出指导思想与观念的飞跃。尽管至今还不了解杂种优势的形成原因,但杂种优势群的划分具有重要的指导意义,使自交系选育、尤其是二环系的选育技术,群体合成与改良技术和杂交种选配技术及育种研究管理技术等在一定程度上摆脱盲目性。数量遗传学方法与分子生物学技术的结合,将促进对杂种优势群的划分研究,同时也推动了相关学科的研究进展。 相似文献
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利用热带种质资源构建温带玉米杂群和杂种优势模式的商榷 总被引:3,自引:0,他引:3
概括分析了热带玉米种质的遗传组成,地理起源,配合力效应以及热带地区或国家主要应用的种质类群和杂种优势模式,结合我国主要利用的杂种优势群和杂种优势模式,就如何充分利用热带种质,拓宽我国玉米育种的种质基础,构建我国新型杂种优势群和杂种优势模式等进行了讨论。 相似文献
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杂种优势群的划分对于拓宽亲本间遗传基础、提高育种效率,培育突破性新品种具有重要的指导作用。本研究利用全基因组重测序技术对55份春播早熟区40余年生产中主推杂交种亲本系进行全基因组扫描,分析其群体结构,估算遗传距离,划分杂种优势群,分析主推杂交种的杂种优势模式。结果表明,利用全基因组5×测序,过滤到1,304,623个高质量SNP标记用于群体结构分析和杂种优势类群划分。55份高粱亲本系平均遗传距离为0.704,变幅0.627~0.927。多态信息含量(polymorphism information content, PIC)平均为0.2935,变幅为0.1~0.5。群体结构和主成分分析将55份亲本系划分为4个杂种优势群:都拉群(Durra, D群)、卡佛尔/都拉群(Kafir/Durra, KD群)、俄罗斯/卡佛尔群(Russia/Kafir,RK群)、中国高粱群(Kaoliang,K群)。25个主推杂交种中76%的杂交种杂种优势模式为Kafir/Durra×Kaoliang模式,主推高粱杂交种的不育系主要来源于引自国外的Kafir和Durra群,恢复系多来源于我国自产的Kaolian... 相似文献
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作物杂种优势遗传基础研究进展 总被引:13,自引:1,他引:12
杂种优势是生物界的一种普遍现象,可以大幅度提高作物产量和改良作物品质,具有巨大的商用价值。杂种优势遗传基础的研究一直是近百年来遗传和育种学家研究的热点和难点问题。笔者综述了杂种优势遗传基础的两个经典假说-显性假说和超显性假说的基本观点、不足之处。同时概括了利用分子生物学手段解释杂种优势遗传基础的一些新的学术见解,如:上位性效应与杂种优势、基因网络系统与杂种优势、遗传平衡与杂种优势、活性基因效应与杂种优势、遗传差异与杂种优势、QTL效应与杂种优势、基因表达调控与杂种优势,并列举了部分学说的分子证据。以期使人们能够了解杂种优势遗传基础的发展历程和最新研究动态。 相似文献
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在目前许多作物常规杂交育种处于“爬坡”的形势下,利用植物杂种优势,是改良作物最有潜力的育种途径。在这方面已取得举世瞩目的成就。从本世纪20年代第一个玉米杂交种开始,相继实现了近40个食用作物的杂种优势利用。长期以来,育种家在设想种种杂种优势固定的方法,但至今只有少数作物在个 相似文献
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Summary Optimum mutation rates for practical purpose were discussed based on the theoretically derived formulae, and mutagen doses giving the optimum mutation rates were estimated from the experiments reported hitherto. It was suggested that in cereal crops such as rice and barley, considerably low mutation rates as with the mutagen doses lower than 5 kR of or X rays and 2%·h of EMS are appropriate for obtaining directly applicable mutants. High mutation rates seem to be limited to the production of some rare breeding stocks. 相似文献
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Summary In unreplicated field trials a correction for soil heterogeneity is easily achieved by gridding, i.e. by expressing the observations as deviations from a local average. This paper investigates the problem of determining the optimum size of such a neighbourhood to be used in a moving average. The optimum grid size depends on two parameters, i.e. the coarseness of the spatial variation of the trial field and the ratio of genotypic vs. non-genotypic variance. In general these parameters are not known to the breeder. We introduce a method for estimating these parameters from the data. From these estimates the optimum grid size can be obtained using tables presented in this paper.The method has been evaluated by applying it to a series of simulated data. It turned out that the agreement between estimated and true optimum grid size was satisfactory in these simulations.Some theoretical aspects of the results are discussed. 相似文献
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Senescence can influence: (1) leaf area duration, (2) area of transpiringtissue and (3) translocation of nutrients – mainly nitrogen to grain.Therefore, selection for optimum senescence pattern might be efficient forimproving performance of wheat in a given environment. This study wasconducted to investigate the feasibility of a seedling test for estimatinggenotypic differences in senescence rate of wheat. We studied the responseof several wheat genotypes to dark exposure of seedlings, by measuring therate of chlorophyll loss in the first leaf. The rate of chlorophyll loss variedsignificantly among genotypes, the highest rate being more than double ofthe lowest. Linear regression accounted for most of the chlorophyll contentvariation during dark treatment in all cultivars. Significant correlation wasfound between the rate of chlorophyll loss following exposure to darknessand chlorophyll loss during aging in an environment relatively free ofdiseases and stresses. A good correlation was also found between theresponse of several genotypes to dark exposure and chlorophyll loss ofseedlings following starvation. We conclude that a seedling test for darkinduced senescence might allow an easy characterization of senescencepattern, allowing increased genetic progress in its optimization. 相似文献
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In order to procure the optimum quality of control for full-controlled wireless mesh network, the primary influencing factor network time delay is analyzed. In order to get the optimum quality of control,the minimum network time delay should be acquired,and the algorithm of branch and bound is given to solve this problem. According to the numerical simulation, the quality of control for the whole network system with decreasing the delay time can be optimized by adjusting the number of nodes, the average transmission hop counts, and the probability of successful channel access and transmission for random nodes. 相似文献
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Considerable variability in the yield response of temperate dairy pastures to the strategic use of nitrogen (N) fertiliser has been observed previously. Some of this variation could potentially be attributed to environmental effects on the available N (soil mineral N plus fertiliser N) concentration required to optimise pasture growth. Five nitrogen application rate response field experiments were undertaken in an attempt to elucidate the environmental influence on pasture mineral N requirements. A significant response to N fertiliser application rate was detected in four out of the five experiments. The absence of a significant response in one experiment can be attributed to limited water availability. Across the experiments where a significant response to N fertiliser rate was detected the available N that was required to achieve 90% of maximum yield ranged between 60 and 81 kg N/ha. It is concluded that when water availability, soil temperatures and air temperatures are conducive to pasture growth an available N level of between 60 and 81 kg N/ha should be targeted when N fertiliser is used strategically to optimise pasture growth. Soil N testing results should be interpreted in light of the prevailing climatic and edaphic conditions if they are to be used to guide N fertiliser rate decisions within intensively managed temperate pastures. 相似文献
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无架豇豆种子高产栽培技术方案研究 总被引:1,自引:0,他引:1
采用二次回归正交旋转设计方法,经过计算机计算,建立了播期、密度和矮壮素施用量等3项栽培技术与美国无架豇豆产量的数学模型并通过模拟寻优,筛选出每公顷产量2140~2650kg的综合技术优化组合方案。 相似文献