Analysis on Combining Ability and Genetic Parameters of Main Agronomic Characters of 22 Maize Inbred Lines

The general combining ability（GCA）, special combining ability（SCA） and genetic parameter of ten characters of 22 maize inbred lines including plant height and ear height were analyzed using 10×12 through incomplete diallel cross（NC Ⅱ）.The results showed that：（1） Among the 22 maize inbred lines, the yield GCAs of11 HN 097, 11 HN 099, 11 HN 105 and 11 HN 110 were high, which were elite inbred lines to collocate hybridized combinations with strong heterosis. The yield of11 HN110 × 11 HN097, 11 HN110 × 11 HN105, 11 HN112 × 11 HN 097 and 11 HN 106 × 11 HN 104 were in the first four place. The yielding abilities, adaptabilities and yielding stabilities of the four combinations can be further identified by experiment. The heredities of the ten characters were mainly controlled by additive gene effect whereas the influence of non-addictive gene effect was small. The narrow heritabilities of plant height, ear height, ear rows, ear length, kernels per row,100-grain weight and seed-producing percentage were more than 50%. The variances were mainly caused by heredity and early-generation selection should be conducted. The narrow heritabilities of ear diameter, bare tip length and yield was low, which should not be selected in early-generation.

Study of Yield Combining Ability and Genetic Relationship Among Exotic Tropical,Subtropical Maize(Zea mays L.) Inbreds and Temperate Maize Inbreds in China

Information on the genetic relationship between tropical maize (Zea mays L), germplasm and temperate maize germplasm is of great value to maize breeding. The objective of this study was to determine the combining ability and genetic relationship of 25 inbreds extracted from five tropical maize populations and a land race, with four temperate maize inbreds (Huangzaosi, Mol7, B73 and Dan 340). The 25 tropical inbreds were crossed with the four temperate inbreds and evaluated. Lines from Suwanl and POP28 had high general combining ability (GCA) for grain yield. The lines from POP32 (ETO) had the highest special combining ability (SCA) with B73; the average SCA value of the 5 lines was 879 kg/ha. The lines from Suwanl had the second-highest SCA (584 kg/ha) with Huangzaosi. The lines from Suwanl had the greatest relative heterosis (20%) with B73, followed by the lines from POP32 (ETO) with B73 (19%). Five heterotic patterns have been identified from this study: Suwanl × Reid, ETO × Reid, POP28× Reid, POP28× Ludahong-gu, and Suwan1× Lancaster.

Combining Ability and Correlation of Ear Characteristics of Twenty Maize Inbred Lines

The combining ability and correlation of eight ear characteristics in 99 maize hybrids generated by crossing nine female parents with 11 male parents were analyzed by incomplete diallel cross （NC II ） design. The results showed that the line F6 had the highest general combining ability （GCA） for yield, followed by F7, M3, M4 and M8. All of the five lines have great potential in maize breeding. The cross combination M3xF10 had the highest specific combining ability （SCA） for yield, showing strong heterosis. Heritability analysis of ear characteristics showed that GCA variance was higher than SCA variance in ear diameter, number of rows per ear and seed rate, and they were mainly controlled by the additive gene effect, indicating that that the selections for these traits are effective at early generations. The other three traits had lower SCA, for which the selections should be carried out at late generations. The correlation analysis revealed that ear length, number of grains per row, ear diameter, number of rows per ear, 100-seed weight and seed rate had extremely significant positive correlations with grain yield per plant. Among them, number of grains per row had the most significant effect on yield per plant. Barren tip length had a significant negative correlation with grain yield per plant. Therefore, we concluded that the combinations with more grains per row and shorter barren tip should be selected to achieve high yield of maize.

Combining Ability Analysis of Panicle Traits in Six CIMMYT Maize Inbred Lines

In this study, six CIMMYT maize inbred lines and five representative do- mestic maize inbred lines were used as parental lines. By using incomplete diallel cross design, 30 hybrid combinations were developed to analyze the general com- bining ability （GCA）, specific combining ability （SCA） and total combining ability （TCA） of seven panicle traits in six CIMMYT maize inbred lines. The results showed that CIMBL98 and GEMS13 were excellent inbred lines with good compre- hensive performance; CIMBL98 × 340 and GEMS13×Chang 7-2 were superior combinations.

Analysis on Breeding Potential of 17 Maize Inbred Lines from Land Races

[Objective] The primary objective of this study was to estimate combining ability and genetic parameters of 17 new inbred lines.[Method] By using 11 commonly used maize inbred lines from Southwest China as testers and incomplete diallel cross design,combining ability and heterosis of 17 new inbred lines bred from the land races in Sichuan Basin and its surrounding areas were analyzed.In addition,the genetic parameters and heterotic groups were also investigated based on combining ability.[Result] P1-1,P1-16 and P1-14 with the better comprehensive characters can be directly used in maize breeding program.The SCA of P1-10×P2-4 was high in most traits.It is more possible to obtain high-yield hybrid combinations by the pattern Sipingtou × Lancaster.GCA variance was bigger than SCA variance in four traits such as rows per ear,grains per row,which were affected by the environments slightly and should be selected at early generations;while SCA variance was bigger than GCA variance in five traits such as 100-grain weight and plant weight,which were significantly influenced by environment and thus should be selected in later generations.[Conclusion] The paper will provide theoretical basis for further improvement of local maize varieties.

Combining Ability Analysis on Yield Traits of Recombinant Inbred Lines in Hybrid Rice

A population of 140 recombinant inbred lines at F8 generation were obtained after seven successive generations of self-pollination using single seed descent（SSD） method from the F2 hybrids of three-line restorers Luhui 8258 with high combining ability and Yanghui 34. Then, the 140 inbred lines obtained above and their parents Luhui 8258 and Yanghui 34 were crossed with three different types of cyto-plasmic male sterile（CMS） lines（Gang 46 A, Ⅱ-32 A and Lu 98A） according to NCⅡ design. The resulting 426 combinations were planted at Deyang and Suining bases to test the combining ability and inheritance of five yield traits： yield per plant, panicle number per plant, filled grain number per panicle, seed setting rate and 1 000-grain weight. The results showed that the variances of both general and specific combining abilities of the five traits all reached a significant or extremely significant level at the two sites. The broad and narrow heritability of the yield traits（except 1 000-grain weight whose broad and narrow heritability were both over70%） were all below 50% at the two experimental bases, suggesting that the four traits were easily subjected to environment influence. Very significant positive correlation of general combining ability was found between yield per plant and other traits except 1 000-grain weight. The general combining ability variance showed a normal distribution among the recombinant inbred lines at two sites, right in line with inheritance of quantitative traits. So, the genes controlling rice general combining ability can be targeted by QTL mapping.

Conversion of the Statistical Combining Ability into a Genetic Concept

Since the combining ability was proposed in 1942, efforts to uncover the genetic basis underlying this phenomenon have been ongoing for nearly 70 yr, with little success. Some breeding strategies based on evaluation of combining ability have been produced, and are still extensively used in hybrid breeding. In this review, the genetic basis underlying these breeding strategies is discussed, and a potential genetic control of general combining ability （GCA） is postulated. We suggested that GCA and the yields of inbred lines might be genetically controlled by different sets of loci on the maize genome that are transmitted into offspring. Different inbred lines might possess different favorable alleles for GCA. In hybrids, loci involved in multiple pathways, which are directly or indirectly associated with yield performance, might be regulated by GCA loci. In addition, a case of GCA mapping using a set of testcross progeny from introgression lines is provided.

Results of Selection Studies of Alfalfa Based on Inbred Lines

The collection of alfalfa in the context of ecology-geographical groups was studied, consisting of 1,078 samples, including 985 samples of the cultivated species--M, sativa L. and M. varia Mart., and 93 samples for other wild species. Highly productive samples are allocated in the three-year cycle of using the grass stand in the haymaking regime. Individual genotypes of isolated samples are used for selection of inbred lines required for the formation of synthetic varieties. Inbred lines were created by forced self-pollination on genotypes with signs of self-fertility. Methodical experiments established the efficiency of bringing inbred lines to generations J2 and J3. In this case, the overall combinational ability reaches a potential value, and further incubation outside of J2 and J3 does not significantly affect its value. With the selection of the best inbred lines in J2 and J3, the lucerne varieties： Kokorai, Osimtal and Kokbalausa, which are protected by patents and author＇s certificates, have been created in accordance with the general combination ability and their inclusion in the structure of synthetic varieties.

Identification of Potential F₁Hybrids in Maize Responsive to Water Deficient Condition

The assessment of heterotic F1 combinations is a basic requisite for hybrid seed development. A set of 30 F1 hybrids along with their parental inbred lines were evaluated under both normal and water deficit conditions for various physiological and agronomic traits. Highly significant mean squares due to general combining ability, specific combining ability and reciprocal effect were observed for all traits under both water regimes. Components of variation exhibited greater estimates for GCA variance (б2g) than SCA variance (б2s) for majority of the traits under both normal and stress conditions depicting the predominant role of additive genetic component. Inbred lines NCIL-20-20, D-157 and OH-8 were found to be the best general combiner on the basis of performance regarding grain yield per plant under water deficit condition. The F1 combinations namely, NCIL-20-20 × D-109, NCIL-20-20 × OH-8 and D-157 × NCIL-20-20 were out-performers based on yield and yield attributes under water deficit conditions. On the basis of our results, we recommend these hybrids for further exploitation to assess their potential for commercial cultivation under water deficit condition.

玉米自交系配合力分析及育种潜力评价

以最新选育的20个玉米自交系为被测系,以5个分别来自Suwan、Reid和非Reid三个杂种优势类群的自交系为测验种,采用NC-Ⅱ遗传交配设计,共配制100个杂交组合,在云南省宣威市、嵩明县2个不同生态条件下进行田间鉴定,分析研究新选自交系的配合力。结果表明,YML12、YML11、YML20、YML05、YML07为综合性状配合力比较优良的自交系,较易组配出优良杂交组合,具有较高的育种利用潜力。杂交组合YML05×T1、YML12×T1、YML07×T1具有较高的产量对照优势,可进一步研究其丰产性、稳产性和适应性。采用单倍体诱导育种选系时先自交1~2代再诱导,可淘汰一些不利基因,有利于获得更多的优良DH系,但不同育种材料间差异较大。

20份玉米自交系主要性状配合力及杂种优势分析

为筛选优良玉米自交系和杂交组合,用20个玉米自交系按照12×8 NCII遗传交配设计配制96个组合,对单株产量等11个主要性状的配合力、遗传力和杂种优势进行分析。结果表明,自交系B4、A2、A5、B7、A3和B2的单株产量一般配合力效应值较高,组合A11×B2的单株产量特殊配合力效应值最高,有8个杂交组合的单株产量对照优势超过15%,分别为A9×B4、A11×B2、A2×B6、A3×B7、A10×B4、A5×B7、A2×B4、A6×B1,可进一步鉴定;遗传力分析表明,株高、雄穗主轴长、穗位高、雄穗分枝数、籽粒含水量、穗粗、穗行数、秃尖长8个性状的广义遗传力和狭义遗传力均较高,可在早代选择。穗长、行粒数、单株产量3个性状的广义遗传力较高,但狭义遗传力较低,适合在晚代选择;组合F 1的表型值与亲本的一般配合力和组合的特殊配合力均呈极显著正相关,配合力贡献率因性状而异;组合的单株产量杂种优势与亲本的一般配合力、组合的特殊配合力均呈极显著正相关,且组合的特殊配合力对杂种优势的贡献更大;亲本一般配合力与组合特殊配合力之间几乎没有相关性。

10份甜糯双隐性玉米自交系的农艺及品质性状配合力分析

为筛选适宜东北地区推广种植的甜糯玉米新品种,以10份甜糯双隐性玉米自交系为母本(P1),3份糯玉米自交系为父本(P2),采用不完全双列杂交NCⅡ设计,配置玉米杂交组合并对10个农艺及品质性状进行配合力分析,具体为株高、穗位高、穗长、穗粗、穗行数、穗粒质量、行粒数、百粒质量、皮渣率和支链淀粉含量。结果表明:一般配合力方面,JT124在穗长、行粒数、百粒质量、皮渣率和支链淀粉含量等方面表现最好,较好的自交系有JT120、JT111、JT113。特殊配合力方面,组合JT124×JN55、JT124×JN88、JT120×JN55表现较好。JT124、JT120、JT111和JT113可直接利用,其余自交系需经改良后再进一步利用。株高、穗行数、行粒数和百粒质量等性状应在早代进行选择,而穗位高、穗粗、皮渣率和支链淀粉含量等性状应在晚代进行选择,该选育特点更有利于育种家科学设定育种目标并选择合适的亲本自交系。

CIMMYT玉米自交系青贮品质的主要性状配合力分析

本研究以从CIMMYT引进的高蛋白玉米自交系为试验材料(10份待测系和4份测验种),采用NCⅡ设计的方法产生40个杂交组合,并测定与分析5个青贮品质性状(生物产量、干物质、粗蛋白、淀粉、中性洗涤纤维)及其配合力。结果表明:(1)5个青贮品质性状在地点和杂交组合间的差异均达极显著水平,试验基因型间存在显著遗传差异;(2)生物产量的一般配合力GCA效应值最高的自交系是C3,其次是C6,C1最低;(3)生物产量的特殊配合力SCA效应值为正值的有C6T4、C1T2、C8T2、C10T1、C5T4和C7T1等24个组合,其中效应最高的是C6T4,其次是C1T2和C8T2;(4)在所有杂交组合中,C3T1的平均生物产量最高,C3T2和C6T4次之,这3个组合可作为潜势组合进一步试验。青贮玉米育种中自交系配合力测定与分析时除考虑生物产量性状外,还需同时考虑干物质、粗蛋白、淀粉含量等其他性状,使育成品种的实际生产利用效率更高。

25个玉米自交系配合力分析

以优良的自交系配成杂交种作为基础材料,并导入热带或温带材料进行选择多次二环系选育,用优良自交系配成杂交组合,从中自交选出新系,按Griffing(1956)方法4组配25×25完全双列杂交得到300个杂交组合,于2016年春进行一年3点的试验,分别在贵州省贵阳市三县区进行随机区组试验。结果表明,25个自交系一般配合力(GCA)为正值的有13个自交系,最高为QET(40.19),其余自交系(GCA)为负值,其中107 C 171(-39.05)为最低,组合特殊配合力(SCA)LSJ 107×DK 171(171.99)最高,组合LSJ 106×LSJ 107(-286.14)最低。组合LSJ 107×DK 171产量最高,为660.82 kg/667 m^(2),组合LSJ 106×LSJ 107产量最低,为212.7 kg/667 m^(2)。从中筛选出的自交系配制的杂交组合黔单26、黔单27已审定。

根据产量特殊配合力分析玉米自交系杂种优势群

采用NCII设计 ,以Mo17、B73、黄早四、丹 340、K12、K2 2为测验种 ,12个自交系为被测系 ,通过两年、两点完全区组试验设计 ,分析了 18个玉米自交系的配合力和杂种优势群。结果表明 ,18个自交系可分为 5群 ,即兰卡斯特 (Mo17和P138)、瑞得 (B73、8112、铁 792 2和掖 10 7)、四平头 (黄早四、K12和 5 15 )、旅大红骨 (丹 340、E2 8、自 330、S37和 8 93)和PA群 (K2 2、CA15 6、掖 4 78和沈 5 0 0 3)。在 72个杂交组合中 ,K12× 8 93、B73×S37、B73× 8 93、K2 2×S37、Mo17× 8 93、Mo17×S37、丹 340×铁 792 2、丹 340×P138、丹 340×S37为 9个强优势组合。K12、S37、8 93和丹340的产量一般配合力高 ,参与组配的强优势组合较多。因此 ,这 4个自交系及其衍生系在我国玉米育种和生产中会有较大的应用潜力。

外来热带、亚热带玉米自交系与温带玉米自交系产量配合力分析及其遗传关系的研究

以 4个分别代表我国北方温带玉米四大优势群的自交系 (黄早四、Mo17,B73和丹 340 )为测验种 ,采用NCⅡ设计 ,对来自 5个热带、亚热带玉米群体、地理族的 2 5个自交系进行产量配合力及杂种优势分析 ,根据配合力和杂种优势的表现 ,研究这些外来热带、亚热带玉米自交系与 4个测验种之间的遗传关系。研究结果表明 ,来自群体Suwan1、POP2 8的自交系的产量一般配合力 (GCA)效应值较高 ,5个自交系的平均产量GCA效应值分别为10 10 .6 4和 2 6 6 .5 7;来自群体POP32 (ETO)的自交系与B73及来自群体Suwan1的自交系与黄早四之间的平均产量特殊配合力 (SCA)效应值最高 ,分别为 879.2 9和 5 83.81;来自群体Suwan1的自交系与B73之间组合的杂种优势最大 ,平均产量对照优势值为 2 0 .36 % ,其次为来自群体POP32 (ETO)的自交系与B73的平均产量对照优势值(19.38% )。由此 ,Suwan1×瑞得、ETO×瑞得、POP2 8×瑞得、POP2 8×旅大红骨和Suwan1×兰卡斯特为

玉米主要抗旱性状的配合力及遗传参数分析 Ⅱ.植株性状

按Griffing双列杂交(Ⅳ)方法,分析了8个玉米自交系的株高、穗位高、叶片数、雄穗分枝数、茎粗和单株叶面积等与抗旱性相关的植株性状在雨养地和水分胁迫下的GCA、SCA及遗传变量。结果表明:6个植株性状主要受加性基因效应控制,非加性基因效应作用较小。6221、6270、5003、8902表现较好,有一定的利用价值。6221×8902、6221×5003、8902×330等10个组合表现出了较合理的抗旱植株性状。

玉米主要抗旱性状的配合力及遗传参数分析 Ⅰ.产量性状

按Griffing双列杂交(Ⅳ)方法,分析了8个玉米自交系的穗长、秃尖长、穗粗、穗行数、行粒数、单穗重、单株产量和百粒重等与抗旱性相关的性状在雨养地和水分胁迫下的GCA、SCA及遗传变量。结果表明:穗长、单穗重、穗行数、行粒数和单穗产量以加性基因效应为主,穗粗、百粒重以非加性基因效应为主。6221、6620、5003及330能产生抗旱高产且产量性状良好的杂交组合,是有利用价值的亲本。6221×8902、6221×5003、6221×6270、6620×8902、6620×6270、6620×330、金599×8902和Mo17×330等组合可在干旱、半干旱地区示范种植。产量性状在不同水分环境下的遗传特点存在一致性,对其遗传改进和产量潜力的选择宜在无胁迫条件下进行。

10个玉米自交系穗部性状的配合力分析

采用5×5不完全双列杂交设计,对10个玉米自交系的单株产量等7个性状的一般配合力和特殊配合力进行了分析。结果表明:交51、7922、丹340、自330有较高的一般配合力,黄早四×7922、自330×木4、Mo17×5331、丹340×095、32×7922、自330×交51和丹340×交51有较高的特殊配合力。在所有杂交组合中,丹340×交51的产量最高,丹340×095、自330×交51的产量次之,这3个组合可作为潜势组合进一步试验。在选择性状时,玉米穗长、穗粗、穗行数和单株产量宜早代选择,行粒数、出籽率、百粒重宜晚代选择。

几个玉米骨干自交系主要性状的配合力分析

8个骨干自交系按griffing双列杂交 4设计 ,配成 2 8个单交组合。采用完全随机区组设计进行试验 ,分析了生育期、株高、穗位高、穗长、穗粗、穗行数、行粒数、出籽率、千粒重、单株粒重、小区产量等 1 1个农艺性状的一般配合力 (GCA)、特殊配合力 (SCA)和遗传变量。结果表明 ,除生育期的SCA外 ,其余各性状的GCA和SCA都有显著或极显著差异。自交系 81 1 2、(素1×吉 840 ) 2 2 2 2 、云 1_7、M丹 1 5 1 2的多数性状GCA较好 ,SCA表现较好的有 81 1 2×M丹 1 5 2 2、云 1_7×M丹 1 5 2 2、云 1_7×M丹 1 5 1 2、云 1 4 3×M丹 1 5 1 2等组合。表现好的组合符合温带种质×热导系。