含有不同温带种质比例的玉米半外来群体选系的杂种优势研究

利用适当的温带种质对外引种质进行改良,可进一步丰富温带玉米遗传基础。以来自CI-MMYT的Pob101群体和我国主要种质的代表系为试验材料,研究不同温带种质比例的Pob101×掖478半外来群体选系与旅大红骨群和Lancaster群的杂种优势,为这些半外来群体的进一步改良和利用提供依据。结果表明,理论上含有75%温带血缘的Pob101×掖478半外来群体选系与旅大红骨群和Lancaster群的杂种优势均值均大于含有25%温带血缘的掖478×Pob101半外来群体选系与旅大红骨群和Lancaster群的杂种优势均值,在高产育种中有较大的利用潜力。     

杂种优势分析

 【研究目的】对8个热带、亚热带玉米群体Pob45、Pob46、Pob501、Pob502、Pool33、Pool34、Pob25、Suwan1进行配合力及杂种优势分析。【方法】试验以自交系昌7-2、郑22、掖478、齐319、Mo17为测验种,采用NCⅡ遗传设计。【结果】Pob25和Pob502的产量一般配合力（GCA）较高,综合产量的一般配合力（GCA）、特殊配合力（SCA）和配合力总效应。【结论】得出塘四平头（昌7-2）×Pob501,塘四平头（昌7-2）×Pob25,Reid（掖478）×Pob25,塘四平头（昌7-2）×Suwan1,旅大红骨（郑22）×Pob502为5大杂优模式。     

我国部分玉米自交系遗传关系和遗传结构解析

玉米自交系遗传关系和遗传结构的解析,对自交系类群划分和杂交组配具有重要的指导意义。本文选用玉米基因组的112个SSR标记对我国97个玉米自交系进行遗传关系和遗传结构分析,并评价了遗传距离聚类和模型聚类方法在玉米自交系遗传关系研究中的应用价值。结果表明,模型聚类方法更适于玉米自交系的遗传关系研究。解析自交系的遗传基础发现,各类群中均有大量自交系含有其他类群的遗传成分。根据模型聚类结果,97个自交系被划分为PB、Reid、塘四平头和旅大红骨4个类群。Reid群与旅大红骨群的遗传关系最近,与塘四平头群遗传关系最远。为了实现杂种优势模式的简化,4个类群可被简化为3大种质类群[A(旅大红骨群与Reid群)、B(PB群)、C(塘四平头群)],或2大种质类群[A(旅大红骨群、Reid群、PB群)、B(塘四平头群)]。研究结果为自交系的改良和利用及杂种优势模式确定提供了理论基础。     

CIMMYT和我国玉米种质群体的配合力及杂种优势分析

采用NCⅡ遗传交配设计,以丹340、Mo17、掖478和黄早四为测验种,通过2年1点田间试验,分析27个国内外玉米群体（14个CIMMYT热带、亚热带群体和13个国内群体）的主要性状配合力和产量杂种优势,并划分杂种优势群。结果表明,大多数CIMMYT群体的产量和产量性状配合力及杂种优势明显优于国内玉米群体,以Suwan l、Pob43、Pob21     

8个热带、亚热带玉米群体的配合力和 杂种优势分析

【研究目的】对8个热带、亚热带玉米群体Pob45、Pob46、Pob501、Pob502、Pool33、Pool34、Pob25、Suwan1进行配合力及杂种优势分析。【方法】试验以自交系昌7-2、郑22、掖478、齐319、Mo17为测验种,采用NCⅡ遗传设计。【结果】Pob25和Pob502的产量一般配合力（GCA）较高,综合产量的一般配合力（GCA）、特殊配合力（SCA）和配合力总效应。【结论】得出塘四平头（昌7-2）×Pob501,塘四平头（昌7-2）×Pob25,Reid（掖478）×Pob25,塘四平头（昌7-2）×Suwan1,旅大红骨（郑22）×Pob502为5大杂优模式。     

美国玉米种质改良系主要农艺性状的配合力及杂种优势分析

试验采用NCⅡ遗传交配设计,以分属于5个杂种优势群的自交系吉853、S122、龙抗11、铁C 8605-2、丹599为测验种,与5个美国玉米种质改良系组配25个杂交组合,分析5个美国玉米种质改良系的主要农艺性状的配合力及杂种优势.结果表明,自交系WY1和WY3单株产量及相关性状一般配合力表现较好,在玉米育种中有较大的利用潜力;组合WY 3×龙抗11、WY5×吉853、WY4×S122是产量及相关性状特殊配合力综合表现优良的前3个组合;WY3×S122、WY1×S122、WY1×丹599、WY4×S122、WY1×吉853是单株产量总配合力和杂种优势表现突出的组合;美国玉米种质改良自交系可与旅大红骨、塘四平头、温带Ⅰ群类群的玉米自交系杂交组配出强优势的玉米杂交种.     

轮回选择对豫综5号玉米群体产量性状配合力的改良效果

玉米群体遗传基础广泛、遗传变异丰富,是培育优良玉米自交系的源泉。玉米群体的改良研究对玉米种质资源创新、优良自交系选育具有重要的指导意义。本研究采用NC II遗传交配设计,以豫综5号5个轮次改良群体为父本,以黄早四、丹340、中综5号、齐319、掖478、Mo17为测验种配制成30个测交组合,通过一年两点的产量性状及其配合力评价试验,研究轮回选择对豫综5号群体的改良效果。结果表明,轮回选择对群体单株产量的改良是有效的,群体与各测验种间的杂交后代产量平均每轮提高3.57%。半姊妹轮回选择和相互半姊妹轮回选择在改良群体产量一般配合力方面, 均得到显著提高,呈逐轮上升的趋势;采用半姊妹轮回选择对豫综5号群体3轮的选择后,C₃群体与C₀相比,一般配合力效应值从–11.63增长到5.57,差异极显著;经1轮相互半姊妹轮回选择后,群体的一般配合力效应值从C₃的5.57增加到C₄的9.75。豫综5号改良群体与黄早四的特殊配合力得到一定的提高,逐轮朝着Reid×唐四平头杂优模式水平提高的方向稳定发展。     

改良Reid类群种质及组配的杂交种在河南省的应用状况

河南省生产上大面积应用的玉米杂交种其亲本的主要来源于瑞德黄马牙、旅大红骨、塘四平头,近年来又从省外引入和选育一批78599等改良种(P群)。重点介绍了改良Reid类群种质的特征特性和应用概况。通过改良Reid类群种质与塘四平头、旅大红骨、P群及其他类群组配的杂交种分析,阐述了改良Reid类群种质的杂交优势模式及该类群种质在河南省玉米育种和杂交种生产中所起的重大作用。     

先锋玉米种质改良系的配合力及杂种优势分析

本研究以分属于5个杂种优势群的自交系B503、B121、B17、B511、B198为测验种,采用不完全双列杂交,与5个先锋玉米种质改良系A101、A203、A302、A306和A425组配25个杂交组合,分析先锋玉米种质改良系的主要农艺性状的配合力及杂种优势。结果表明,改良系A101和A302单株产量及相关性状一般配合力表现较好,在玉米育种方面具有广阔的应用前景;组合A302×B17、AJ425×B503、A306×B121是与产量相关的性状的特殊配合能力综合最优的三种组合;A302×B121、A101×B121、A101×B198、A306×B121、A101×B503是单株产量综合配合力和杂种优势突出的组合。先锋玉米种质改良自交系可与旅大红骨类群、塘四平头、PN78599热带种质玉米自交系杂交组配出强优势玉米杂交种。     

含CIMMYT种质的改良系的改良效果研究

摘要：本研究将黑龙江省玉米自交系吉846和K10与CIMMYT种质Pob45、Pob46杂交构建半外来群体并从中选育改良系,再按原杂交种的组配形式或配制成若干改良杂交组合,对其产量和其它性状进行测定并与原杂交种进行比较,研究其产量和产量性状的变化特点与规律,分析改良的效果和进一步改良的方向,为更有效地利用外来种质特别是来自CIMMYT的热带和亚热带多数种质改良黑龙江省现有的种质资源提供参考。结果表明从半外来群体吉846×Pob45中选育的吉846改良系与K10组配的杂交组合的产量有高于同熟期对照龙单13和原组合的,部分杂交组合的株高、穗位有所降低,部分杂交组合的雄穗一级分枝数、全株叶面积、出籽率、百粒重也有较明显的改良。从半外来群体K10×Pob46中选育的K10改良系与吉846组配的杂交组合的产量都低于同熟期对照龙单13和原组合,但个别性状如百粒重、出籽率、行粒数、穗长有一定的改良效果。     

含CIMMYT种质的半外来玉米群体选系对丝黑穗病的抗性研究

本文采用田间人工接种方法研究了部分含CIMMYT玉米种质的半外来群体选系对丝黑穗病的抗性。结果表明在用CIMMYT种质Pob45和Pob46与黑龙江省部分自交系杂交构建的半外来群体的选系中,对丝黑穗病中抗及其以上的选系占一半以上,其中高抗占35.9%。CIMMYT种质的引进总体上有利于提高黑龙江省种质资源对丝黑穗病的抗性。     

玉米矮花叶病毒抗性资源鉴定的研究

利用人工接毒方法对 70份玉米种质资源进行了两年玉米矮花叶病毒B株系的抗性鉴定。依据病情指数 ( % )将抗病程度分为高抗、抗、中抗及感病 4个等级。试验筛选出高抗自交系 4份、高抗单交种 3个、抗病毒自交系 10份、抗病单交种 3个 ;中抗自交系 6份、中抗群体 3个。讨论了这些种质资源在我国抗玉米矮花叶病遗传及育种研究上的应用价值     

Combining ability amongst CIMMYT’s early maturing maize (<Emphasis Type="Italic">Zea mays</Emphasis> L.) germplasm under stress and non-stress conditions and identification of testers

CIMMYT (International Maize and Wheat Research Institute) Zimbabwe’s early maturing maize program, which aims to supply seed to approximately 4 million hectares of maize area in eastern and southern Africa, lacks adequate information on heterotic relationships among early maturing germplasm and has no early maturing testers for hybrid development. Open-pollinated varieties (OPVs) and hybrids are the products targeted for this region. Among the hybrids, three-way and double-cross hybrids are desired. Thus the use of single crosses as testers would be an appropriate choice for such a breeding program as one could potentially identify three-way combinations during the early generation test. A twelve-parent diallel was formed and crosses evaluated to identify heterotic groups and single-cross testers. Crosses were evaluated under four different environments in Zimbabwe, two optimal, one low nitrogen stress and one drought stress. P5 (an early maturing line from heterotic group A) and CML 395 (a late maturing inbred line from heterotic group B) were used as reference parents to establish heterotic groupings of germplasm used in the diallel. The single cross (P7/P8) was identified as a potential group A tester because of: (a) co-classification of inbred lines into heterotic group A, (b) good yields-9.8 t/ha (optimal), 3.4 t/ha (low nitrogen) and 2.1 t/ha (drought); and (c) good GCA effects for grain yield (0.49 t/ha) of line P7 while line P8 contributed to reduced height and anthesis-silking interval.     

Genetic characterization of 218 elite CIMMYT maize inbred lines using RFLP markers

Characterization of genetic diversity among maize inbred lines can facilitate organization of germplasm and improve efficiency of breeding programs. A set of 218 phenotypically diverse inbred maize lines developed at CIMMYT for hybrid production was characterized using 32 RFLP markers to: (1) analyze the genetic diversity present; (2) define potential heterotic groups based on clusters formed with marker data; and (3) identify the most representative testers for each potential heterotic group. Lines were clustered using five different genetic distance measurements to find consensus non-hierarchical clusters. Dendrograms were produced to study hierarchical classification within smaller groups of lines. A very high average allelic diversity was seen in this germplasm. Lines did not cluster based on phenotype, environmental adaptation, grain color or type, maturity, or heterotic response (as determined based on hybrid performance with testers), but lines related by pedigree usually did cluster together. Previously defined testers from opposite heterotic groups were not genetically differentiated, and did not represent well their heterotic group. Discrete clusters were difficult to find; thus, potential heterotic groups will be difficult to suggest using RFLP markers alone. However, suggestions on how to use molecular markers and cross performance information to refine heterotic groups and select representative testers are presented.     

导入热带种质的温带玉米自交系的利用潜力

用5个热带及亚热带玉米自交系和5个导入热带种质并经连续回交改良的温带玉米自交系, 采用Griffing双列杂交方法III杂交, 共配制90个杂交组合。2008年、2009年以大面积推广杂交种云瑞6号为对照, 对供试自交系进行配合力、杂种优势及利用潜力研究。结果表明, 导入热带种质并经连续回交改良的温带玉米自交系YML598、YML58的多数性状一般配合力效应为极显著正值, 在杂交育种中具有较大的利用潜力;单株产量配合力效应值与诸多产量影响因素的配合力效应值密切相关, 雌雄间隔期、秃尖与单株产量呈负相关, 而其他性状与单株产量呈正相关;产量对照优势H≥10%的组合大多为热带、亚热带种质×改良温带种质, 单株产量特殊配合力效应为极显著正值的组合均为热带、亚热带种质×改良温带种质, 说明热带、亚热带玉米种质与经热带种质改良后的温带玉米种质之间仍具有较强的杂种优势, 且导入热带种质的温带系与热带、亚热带供体系的杂种优势仍然存在, 其所属的杂种优势群并未改变。以热带、亚热带玉米种质为供体, 采用连续回交的方法改良温带玉米自交系是利用热带、亚热带玉米种质的有效方法。     

Heterosis and combining ability of seven maize germplasm populations

Understanding the combining ability and heterosis of available germplasm is a prerequisite for successful maize improvement and breeding. The objectives of this study were to analyze the combining ability and heterosis of seven representative maize germplasm populations, and further, to evaluate their potential utility in germplasm improvement. A total of 21 crosses were made among these seven populations in a complete diallel without reciprocals. The parental populations and 21 crosses were evaluated for days to silking (DS), ear height (EH), and grain yield (GY) in the Northeast and Yellow and Huai River maize growing areas in China in 2012. Csyn5, Csyn7, Cpop.11, and Cpop.12 had desirable general combining ability (GCA) effects for DS and EH in both the Northeast China mega-environment (NCM) and the Yellow and Huai River Regions of China mega-environment (YHCM). Cpop.11 possessed a favorable GCA effect for GY in the NCM, as did Csyn5, Cpop.17, and Cpop.18 in the YHCM. Csyn6 and Csyn7 exhibited tremendous yield-enhancing potential in both mega-environments. Additionally, six combinations including Csyn7 × Csyn6, Csyn5 × Csyn6, Cpop.11 × Cpop.18, Cpop.12 × Cpop.17, Csyn7 × Cpop.17, and Csyn5 × Csyn7 exhibited better specific combining ability effects for GY, yield performance, and mid-parent heterosis in the appropriate mega-environment. These results indicated that the seven populations would be very useful for the improvement of related agronomic traits, and the six candidate combinations possessed great potential for further improvement and utilization.     

Breeding potential of maize germplasm populations to improve yield and predominant heterotic pattern in Northeast China

Increasing the frequency of favorable alleles in elite germplasm is necessary for germplasm improvement and innovation in maize (Zea mays L.) breeding programs. Jidan27 (Si287 × Si144), an elite commercial single cross hybrid that represents the predominant heterotic pattern Chinese Sipingtou × Stiff Stalk Synthetic, has been widely cultivated in the Northeast China Corn Belt. However, the use of the hybrid Jidan27 has been hampered gradually due to its low yield potential, lack of resistance to lodging, and considerable incidence of head smut disease. Previous studies have evaluated yield potential of exotic populations, but few have considered using these germplasms as donors with favorable alleles to overcome these deficiencies in the hybrid Jidan27. In the present study, 12 exotic populations from CIMMYT and the U.S. and three semi-exotic populations were investigated as sources of favorable alleles to increase yield and lodging resistance, and reducing head smut susceptibility of the hybrid Jidan27. The performance of a set of 30 inbred × populations crosses, the hybrid Jidan27, and the two parental inbred lines Si287 and Si144 was evaluated in three locations for 2 years. Two populations, BS10(FR)C10 and Pop43, were identified as the best donors of favorable alleles lacking in the hybrid for improving the target traits. Further, BS13(S)C7 and Cpop.16 were also found to be better choices for improving grain yield and head smut resistance of the hybrid. These results suggest that the elite exotic germplasms evaluated here could provide useful genetic variability to improve other Chinese Sipingtou × Stiff Stalk Synthetic crosses related to Si287 × Si144 that are widely grown in Northeast China.     

Heterotic relationships among European maize inbreds

European flint maize (Zea mays L.)cannot be considered an uniform group of germplasm based on its origin and area of adaptation. However, maize breeders have not taken full advantage of the variability within the European flint germplasm. The objective of this work was to study the heterotic relationships among European maize inbreds from different origins. Nine European flint inbreds were crossed in a diallel that was evaluated in three environments in northwestern Spain. The variability within the European flint germplasm and the agronomic value of some inbreds could be utilized for maize breeding programs as an alternative to the systematic introduction of U.S. dent germplasm that is narrowing the germplasm base of breeding programs even in places where it is poorly adapted. Some European flint inbreds may also be valuable sources of earliness (F7 and EP42), resistance to root lodging (EA1070), and yield (EP42).These results suggest that, within the European flint germplasm, there could be some heterotic patterns, such as ‘north-central Europe × southern Europe’, which could provide an alternative to the heterotic pattern ‘European flint × U.S. dent’. This revised version was published online in August 2006 with corrections to the Cover Date.     

Phenotypic assessment of genetic gain from selection for improved drought tolerance in semi-tropical maize populations

Most maize production across the globe is rain-fed, and production is set to be negatively impacted as duration and occurrence of droughts increases due to climate change. Development of water-deficit tolerant maize germplasm has been a major focus for most breeding programmes. Here, we sought to assess the genetic gain for grain yield in two maize populations developed for drought tolerance at CIMMYT by evaluating their cycle progeny through hybrid performance. Inbreds derived from different cycles of the Drought Tolerant Population (DTP) and La Posta Sequia (LPS) were mated to a tester (CML550), and resulting hybrids were evaluated under managed water-deficit stress and well-watered conditions. The difference in yield between water-deficit and well-watered treatments was 27% and 36% for the DTP and LPS, respectively. Genetic gain for grain yield across cycles for the two populations was confirmed in the study. Genetic gain was observed for both treatments indicating that selection for water-deficit stress tolerance simultaneously improves grain yield in well-watered conditions. The DTP population had a genetic gain of 0.07 t ha⁻¹ cycle⁻¹, while the LPS had 0.16 t ha⁻¹ cycle⁻¹ under water-deficit conditions. Significant genetic gain was also observed in the well-watered treatments for both populations. Anthesis to silking interval was significantly reduced under water-deficit stress conditions in both populations. Plant and ear height were reduced in the LPS population in both treatments, while no reductions were observed for the trait in the DTP population. Potential water-deficit stress tolerance donor lines with yields comparable to commercial check varieties were identified.