玉米人工合成群体配合力效应及遗传潜势研究

选用6个自交系为测验种, 采用NCII遗传交配设计, 对以我国西南地区优良玉米地方种质巫溪14, 兰花早和北美, 热、 亚热带种质为主体的人工合成群体LBM、 WBM、 LLS、 WLS和两个美国优良群体BSSSR、 BS16等6个群体的配合力效应及遗传潜势进行了系统评估。 两年两地(武汉、 安阳)的研究结果表明： LBM、 WBM、 WLS群体的单株     

不同世代玉米自交系配合力规律及杂种优势表现研究

研究不同世代玉米自交系配合力变化规律及杂种优势表现,确定最佳配合力测定时期,可以为玉米早代选择和缩短育种进程提供理论参考。将2个群体早中晚3个不同世代18个选系（每个世代3个选系）和4个测验种（每个群体2个测验种）,按NCII试验设计组配36个杂交组合,对各世代抽丝期、株高、收获时籽粒含水量及产量配合力变化规律和杂种优势表现进行研究。结果表明：随着世代的增加,不同世代配合力间变幅逐渐减小,趋于稳定,S1～S3世代是自交系严重分离,S3～S5自交系从分离走向稳定,S3是配合力测定的最佳时期,应该结合自交系自身表现进行选系,进一步增加选系的准确性。S3与S5世代间超标优势呈极显著正相关,说明在育种过程中可以通过S3世代组合的杂种优势预测S5世代组合的杂种优势。     

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。     

5个玉米人工合成群体选系的配合力分析

选用8个自交系为测验种,采用不完全双列杂交设计,对5个玉米人工合成群体新选的15个自交系的配合力、杂种优势以及主要性状遗传参数进行了分析。结果表明,单株产量GCA表现突出,且构成产量因子性状GCA表现也较好的新选自交系有GP2-1,GP5-2和GP5-5;SCA值高、杂种优势强的组合是48-2×GP3-3和ES40×GP1-2;在穗长、秃尖长、穗粗等12个性状中,亲本的基因加性效应对F1性状形成起主导作用,而穗重和单株产量的遗传变异主要来自于基因非加性效应。因此,对于高产组合的选配,至少要选择1个GCA高的材料作亲本,并在此基础上兼顾SCA的选择,而利用群体自交选系则应根据性状遗传特性决定其选择时期和选择强度。     

5个玉米人工合成群体主要性状育种潜势分析

对5个玉米人工合成群体主要性状表现、杂种优势以及配合力进行了研究。结果表明，群体内个体间均存在较丰富的遗传变异，群体间主要性状及其配合力差异更为明显，其中群体GP-5和GP-3植株穗位高低适中，主要产量性状及其GCA表现较好，优良个体出现频率较高，比对照高产的组合出现次数较多，具有较大改良利用潜势；群体GP-4虽主要产量性状均值偏低，GCA正向效应值偏小，但植株较矮，穗位较低，比对照高产的组合出现次数较多，通过GCA改良和SCA选择有一定利用前景；群体GP-1和GP-2植株穗位偏高，主要产量性状的GCA均为负值，育种潜力不大。     

利用南斯拉夫玉米自交系改良478的效果初报

本研究通过对14个（478×外引系）后代选系与国内属于不同优势类群的8个骨干自交系杂交组配的56个测交组合的配合力和杂种优势研究结果表明：利用南斯拉夫自交系9804、9805、9806改良478是可行和有效的,在14个（478×外引系）优良后代选系中,有3个选系的GCA为显著和极显著正值,具有较高的直接组配利用价值。在56个测交种中,有13个单株产量显著或极显著高于CK 3.85%~33.28%。     

运轮1号玉米群体轮回选择改良效果

种质资源遗传基础狭窄是制约玉米育种的重要因素,而群体轮回选择是拓宽玉米资源遗传多样性的重要方法。以具有中国reid 血缘的8 个自交系组成的群体和美国坚秆种质群体BSSS 杂交后经过一轮混合授粉形成运轮1 号玉米群体。3 轮混合选择后,以昌7-2 为测验种分析了运轮1号群体的产量性状的配合力。结果表明,群体内单株间产量配合力差异显著,遗传变异较丰富。从138 个测交种中筛选出20 个较优良的对应自交单株作为新一轮轮回选择的亲本。预计新一轮合成群体产量配合力将提高11.6%,灌浆脱水速率较对照优越,其他农艺性状也得到相应改良。     

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.     

优质、抗逆甜玉米群体配合力及 遗传潜势分析

为了充分利用新近合成的优质、抗逆甜玉米群体,同时加速育种进程。试验采用不完全双列杂交设计,以2个自育超甜玉米骨干系作测验种,与63个穗行的75个单株杂交,配制组合150个,通过杂交组合鉴定试验、株系的食用品质及抗性等的鉴定评价,对群体配合力及遗传潜势进行了分析,结果发现在75个被测株中,36个株系的单株产量一般配合力为正,而通过对其产量相关性状、商品性及农艺性状一般配合力分析也发现,其GCA表现较好的株系比例接近或超过50%。结合株系自身表现,筛选获得9个苗头株系;同时根据杂交组合鉴定结果,获得8个苗头组合。综合群体内株系的配合力及群体自身表现,初步认为该群体优良基因频率较高,遗传变异较为丰富,具有较大利用潜力。     

遗传潜势分析

 为了充分利用新近合成的优质、抗逆甜玉米群体,同时加速育种进程。试验采用不完全双列杂交设计,以2个自育超甜玉米骨干系作测验种,与63个穗行的75个单株杂交,配制组合150个,通过杂交组合鉴定试验、株系的食用品质及抗性等的鉴定评价,对群体配合力及遗传潜势进行了分析,结果发现在75个被测株中,36个株系的单株产量一般配合力为正,而通过对其产量相关性状、商品性及农艺性状一般配合力分析也发现,其GCA表现较好的株系比例接近或超过50%。结合株系自身表现,筛选获得9个苗头株系;同时根据杂交组合鉴定结果,获得8个苗头组合。综合群体内株系的配合力及群体自身表现,初步认为该群体优良基因频率较高,遗传变异较为丰富,具有较大利用潜力。     

三峡库区玉米地方品种配合力分析

为了明确三峡库区玉米地方品种育种潜势,以三峡库区常用的7个玉米自交系为测验种,采用NCⅡ设计,对三峡库区14个玉米地方品种的配合力以及主要性状遗传参数进行了分析。结果表明,‘文峰白玉米’、‘大寨玉米’、‘太阳河白玉米’在单株产量、穗长、穗粗、穗行数、行粒数、百粒重上具有较高的一般配合力。‘文峰白玉米’、‘大寨玉米’在改善株型、提高产量有更为突出的表现。不同性状SCA效应值变幅差异较大,其中单株产量变幅最大,为-25.48%~30.47%。所有性状中,亲本的基因加性效应均对F1性状形成起主导作用;穗长、穗粗、行数等7个性状广义遗传力和狭义遗传力均较高,可在早代进行选择;秃尖长、单株产量的广义遗传力较高,但狭义遗传力较低,不宜过早进行选择。     

转基因抗虫棉核不育系配合力及杂种优势分析

为了分析转基因抗虫棉不育系的配合力和杂种优势。采用6×6NCⅡ交配设计,分析了6份转基因抗虫核不育系与6份陆地棉亲本杂交后,9个性状杂种F1的超父本优势、竞争优势和配合力。结果表明,籽棉产量超父本优势的平均值为19.44%,22个组合具正向的杂种优势;竞争优势的平均值为-8.36%,16个组合出现正向竞争优势。单株铃数的杂种优势最为明显。父本值与F1平均值的相关关系表明,8个性状F1代平均值与父本值的相关性达到极显著水平。经配合力分析,A1、A4、B1、B5等亲本的GCA较好;SCA效应显著的6个性状中,A1×B6、A3×B3等组合的SCA效应均为正值。     

4个谷子不育系主要农艺性状的配合力分析

为测定4个谷子不育系的育种应用潜力,将4个不育系与5个恢复系按NCII不完全双列杂交方式配组,对其杂种F₁的7个主要农艺性状进行配合力分析,结果表明：所有组合的7个主要农艺性状存在显著差异。配合力分析,新选育不育系Y1A、Y2A一般配合力都一般,Y1A有利于选配大穗杂交谷子,Y2A则有利于选配矮秆、子粒饱满的杂交谷子;当地常用的2个不育系张1A、晋1A中,晋1A的一般配合力明显好于张1A,说明晋1A更适合于谷子中晚熟种植区。4个不育系所组配的20个组合中杂种优势不明显,7个主要农艺性状中,晋1A所组配的组合综合性状几乎都最优,组合晋1A×沧239产量最高;Y1A、Y2A和张1A所配组合综合性状高低各不相同。产量前3的组合分别为晋1A×沧239、Y2A×衡优17和张1A×朝阳谷子。分析表明,要想有强优势组合,不仅需要有较高的一般配合力亲本,亲本间还要有较高的特殊配合力。     

Combining ability and correlations for yield components in early generations of potato breeding

A partial diallel set of crosses was made between 14 potato cultivars chosen for their fertility, from those included in a potato breeding programme at the NEIKER – Basque Institute for Agricultural Research. The progeny were grown in completely randomized trials from 1997 to 1999. Performance for yield, tuber number and average tuber weight was analysed in seedling and two clonal generations. Variance estimates due to both general combining ability (GCA) and specific combining ability (SCA) were significant in all generations for all traits under study. However, SCA was more important than GCA in almost all cases. Correlation coefficients among characters, generations, GCA and SCA effects were examined. For tuber yield no relation was obtained between generations; however, average tuber weight and yield were positively associated in all generations. The results indicate that appropriate selection criteria depend strongly on the particular cross. The implication for a breeding strategy are discussed.     

玉米和紫苜蓿配合力的稳定性分析

分析了玉米和紫苜蓿的五个双列杂交试验,结果表明,在采用稳定材料进行两种配合力的研究中,除个别性状外.其余各性状均表现GCA(一般配合力)×环境互作大于SCA(特殊配合力)×环境互作而SCA的SSs/(SSs+SSsc)×100比值小于GCA的SSg/(ssg+SSgc)×100,说明在不同环境中GCA较SCA稳定.但两种配合力与环境互作同相应主效的比值表现出SCA大于GCA的趋势.放在不同环境中应着重测定GCA,而在特定环境中则不能忽视SCA的测定.GCA与环境的工作主要是不同环境中方差值的变化所致,其本质则是生态因素对性状影响的差异.     

食用向日葵产量与籽粒主要性状配合力及遗传分析

选用4份分枝型恢复系和6份雄性不育系材料作亲本,按照不完全双列杂交（NCII）设计配制24份向日葵杂交组合,对组合的小区产量、单株产量、单盘实粒数、百粒重、籽仁率、籽粒长度和籽粒宽度7个性状的亲本配合力、遗传参数及竞争优势进行分析。结果表明,24份组合的7个性状存在真实性的遗传差异。在亲本不育系一般配合力（GCA）选择的基础上,应注意组合特殊配合力（SCA）的选择,GCA效应值高的亲本育种潜力较大,组配出优势组合的概率大;籽粒长度和籽粒宽度的狭义遗传力较低,分别为7.91%和14.89%,不宜进行早代选择;GCA较高的不育系为亲本A和亲本D,其中亲本A在各性状上均为正向GCA效应值,且在供试不育系中,其GCA效应值最大,其次为亲本D;组合1×A小区产量的SCA效应值及竞争优势最高,为本试验中的最优组合,其他籽粒性状与对照相比也均有提升。     

Genetic variation among cocoa (Theobroma cacao L.) families for resistance to cocoa swollen shoot virus disease in relation to total phenolic content

Phenolic compounds have been suggested as one of the defence mechanisms to cocoa swollen shoot virus disease (CSSVD), but not well studied. Correlation and genetic variation of total phenolic content (TPC) and CSSVD resistance among 53 cocoa families were investigated. Three‐month‐old seedlings of 15 families obtained from an incomplete 6 × 3 NCII mating design, of 24 families from a 3 × 8 NCII mating design and of 14 other families were evaluated for CSSVD and TPC. Plants were inoculated with viruliferous mealybugs carrying the New Juaben CSSV strain (1A) in a gauze house facility. A single seedling randomization within blocks procedure was followed, using the gauze house units as blocks. There were six blocks with five seedlings of each family randomized within each block. Disease severity scores on leaf flushes at the first, second, third and seventh flushes after inoculation were recorded. The TPC before and 3 months after inoculation was also determined. Family effects were highly significant (P ≤ 0.01) for CSSVD severity scores and TPC. Narrow‐ and broad‐sense heritability estimates were low for CSSVD severity but moderate to high for TPC evaluations. Correlations between severity scores and TPC were weak (r = ?0.22 to 0.40) suggesting that the TPC may be of little value in selecting CSSVD resistance varieties in cocoa. Additive effect in terms of significant GCA was important for CSSVD severity scores whereas both additive and non‐additive effects were important for TPC values when the 3 × 8 and 6 × 3 NCII mating designs were analysed. Only clones GU 239/H, GU 290/H and GU 225/V had favourable GCA effects for CSSVD symptom expression indicating their potential for developing progeny with high levels of resistance to CSSVD infection.     

A diallel crossing approach aimed on selection for ripening time and yield in breeding of new strawberry (Fragaria × ananassa Duch.) cultivars

The extension of the ripening season in open field production is of high economic interest for strawberry growers. Therefore, targeted breeding for extreme early or late ripening cultivars with high yield potential is of particular interest. Thirteen strawberry cultivars were crossed in a reciprocal way without selfing, and the 144 resulting F₁ populations were evaluated in a field trial over a period of two consecutive years. The data were analysed using a mixed‐model approach adapted for diallel crossing designs using SAS 9.3. The variability in the crossing approach is mainly based on the general combining ability (GCA) of the cultivars (additive effects). Specific and reciprocal combining abilities (non‐additive effects) appear less important. The highest GCAs for the trait Marketable Yield were found for the cultivars ‘Polka’ and ‘Yamaska’. The trait Earliness is bilateral with significantly low GCAs for early ripening in ‘Clery’ and ‘Daroyal’ and significantly high GCAs for late ripening in ‘Yamaska’ and ‘Florence’. Crosses with these cultivars are likely to deliver populations with both high yield and an extended ripening period.     

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 combining ability of glucoraphanin level and other horticultural traits of broccoli

Broccoli (Brassica oleracea L., Italica Group) is a source of glucosinolates and their respective isothiocyanate metabolites that are believed to have chemoprotective properties in humans. Glucoraphanin (4-methylsulfinyl-butyl glucosinolate) is a predominant glucosinolate of broccoli. Its cognate isothiocyanate, sulforaphane, has proven a potent inducer of phase II detoxification enzymes that protect cells against carcinogens and toxic electrophiles. Little is known about the genetic combining ability for glucosinolate levels or the types of genetic variation (i.e., additive vs. dominance) that influence those levels in broccoli. In this study, a diallel mating design was employed in two field experiments to estimate combining abilities for glucoraphanin content. The diallel population was developed by crossing nine doubled-haploid (inbred) parents in all possible combinations (36), excluding the reciprocals. Horticultural traits of all entries were assessed on a plot basis. In fall 2001, glucoraphanin concentration of broccoli heads ranged from 0.83 to 6.00 μmol/gdw, and in spring 2002, ranged from 0.26 to 7.82 μmol/gdw. In both years, significant general combining ability was observed for glucoraphanin concentration and total head content, days from transplant to harvest, head weight, and stem diameter. Conversely, no significant specific combining ability was observed for any trait in either year. Results indicate that a given inbred will combine with others to make hybrids with relatively predictable levels of head glucoraphanin as well as, other important horticultural traits. This should allow identification of inbreds that typically contribute high glucoraphanin levels when hybridized with others.Mention of trade names or commercial products in this publication is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the U.S. Department of Agriculture.