应用遣传距离预测爆裂玉米杂种优势

根据80个爆裂玉米自交系数量性状的表现估算了它们之间的遗传距离及它们之间随机组配的67个杂交组合F_1代小区产量、爆粒率和膨胀倍数的杂种优势。相关和回归分析表明,F_1代产量的成分照优势与其双亲之间的遗传距离呈显著的二次曲线关系,而F_1代品质特性爆粒率和膨胀倍数的对照优势与其双亲之间的遗传距离无确定性关系。因此,可以根据亲本间数量性状的综合遗传差异——遗传距离预测爆裂玉米杂种一代产量优势。     

两种类型蓖麻杂交种杂种优势的分析

为进一步了解蓖麻表型性状杂种优势表现特点及与亲本相应性状的关系.选用两种基因类型有明显差异的中高秆和矮杆蓖麻杂交组合的亲本CS-R6(♀)、CS-R181(♂)和CS-R63(♀)、CS-R268(♂)和它们的杂交种CS-R6.181F_1、CS-R6.181F_2、CS-R63.268F_1为研究材料.通过田间试验,测定了地上部干物质积累及在营养体和生殖体中分配速率和成熟期13个表型性状的杂种优势表现.结果表明:两种类型杂交组合的生育特点及杂种优势表现上有明显差别,CS-R6.181F_1属于生殖型为主、体质型为辅的杂种优势类型;而CS-R63.268F_1属于生殖型的杂种优势类型;中高秆杂交种CS-R6.181F_1收获期13个地上部主要性状杂种优势均表现为超高亲优势;而矮秆杂交种CS-R63.268F_1只是在籽粒产量、皮壳率和粗脂肪含量等7个性状表现为超高亲优势,百粒重等3个性状表现为超中亲优势,而营养体3个性状均表现超低亲优势,CS-R63.268F_1综合了母、父本突出的优良特性,生育期趋向父本,是适合密植和机械化栽培的杂交种;蓖麻杂种优势从杂种F_2开始出现衰退,不再适合在生产中应用.     

陆地棉芽黄品系和常规品种间杂种优势利用研究

以５个芽黄品系和６个常规品种进行不完全双列杂交，测定３０个组合在主要农艺性状上的杂种优势和配合力。试验结果表明，陆地棉芽黄品系和常规品种杂交，Ｆ１具有明显的杂种优势。比较各性状竞争优势的相对大小可知，子、皮棉产量的优势最大，分别达１０．５７％和１０．７８％，果枝数、果节数、铃数和早熟性次之，纤维品质性状的优势较小。其中１０个组合Ｆ１皮棉产量的竞争优势率超过１５％杂种棉审定的增产阈值，尤以（ｎｖ３２×苏棉３号）、（ｖ１６ｖ１７×鲁棉１１号）这两个组合最突出。不同组合杂种一代间的性状变异主要受基因型控制，１６个性状同时具有显著或极显著的亲本一般配合力和组合特殊配合力差异，芽黄品系和常规品种间杂种优势的利用潜力较大。     

几个抗条锈病小麦品种杂交组合的杂种优势研究

利用来自不同生态环境的5个抗条锈病品种,组配了10个小麦杂交组合,对杂种一代的不同性状进行了杂种优势以及和双亲平均值的相关性作了分析.结果表明,杂种一代的多数性状都具有不同程度的杂种优势,产量性状显著相关.     

7个粳稻SSR和SRAP分子标记遗传距离比较及其与产量性状杂种优势的关系

本研究选用产量性状有显著差异的7个粳稻品种,按照Griffing双列杂交方法Ⅳ配制21个杂交组合,用SSR和SRAP分子标记分析亲本遗传距离及其与粳稻产量性状杂种优势问的关系,并比较分析两种分子标记在估算遗传距离时的差别.结果表明,每对SSR引物产生1～11条多态性带,平均3.8条,而每对SRAP引物组合产生1～15条多态性带,平均5.2条.SRAP引物所扩增的条带数和多态性何点数分别是SSR引物的3.3倍和1.3倍.两种分子标记对遗传相似系数较小的品种进行聚类分析时可获得一致的结果,但对遗传相似系数较大的品种进行聚类分析时所得结果并不一致;粳稻产量性状杂种优势的表现大小因件状和杂交组合不同而异;F_1杂种产量性状的表现与亲本自身的性状特点和互补关系密切,用SSR和SRAP分子标记遗传距离难以预测粳稻杂种后代的产量表现和杂种优势强弱.     

烤烟杂种优势及其相关性分析

研究了7个烤烟杂交组合F1代的农艺性状、经济性状及TMV抗性的杂种优势,分析了各性状与亲本间的相关性.结果表明,烤烟杂种优势以单位面积产量最为突出,7个组合的单位面积产量均超过中亲值,优势幅度在6.6%～50.40%之间,有6个组合超过了大值亲本,优势幅度在8.34%～43.78%之间.各性状都有表现超中亲或超高亲的组合,不同性状表现杂优组合比例不同,TMV抗性的高亲优势最强,占71.42%.亲本对杂种一代各性状有不同程度的影响,F1各组合的有效叶数、茎围、单位面积产量、产值几个性状与大值亲本、小值亲本、中亲值、双亲之差无显著相关;自然株高与亲本相关性较大,上等烟比例、TMV抗性优势大小与双亲之差为负相关.     

标记型柱头外露种质系与陆地棉亲本间杂种优势与配合力分析

采用ＮＣⅡ遗传交配设计,对５份标记型柱头外露种质系和３份陆地棉亲本交配后,杂种Ｆ１的１１个性状的杂种优势和配合力进行了分析。结果表明,主要产量性状霜前皮棉产量,超高优势的幅度为－２８．８８％～１３．１７％,平均为－３．０６％,６个组合具正向的杂种优势;中亲优势的幅度为１８．１４％～８０．１２％,平均为５３．０８％,１５个组合均具有正向的中亲优势;竞争优势的幅度为－１５．３２％～４６．４３％,平均为１１．２７％,１０个组合具有正向的竞争优势。其它产量性状中单株铃数的杂种优势最为明显。纤维品质性状,２．５％跨长和比强度的优势明显,麦克隆值的负向优势明显。高亲值、中亲值和低亲值与Ｆ１平均值的相关关系表明,多数产量性状Ｆ１代平均值与高亲值相关性密切,因此在组合筛选时应注意对常规亲本的选择。配合力上,ＧＣＡ效应显著的性状,中棉所１９和石３２１分别在产量、品质性状方面表现较优,９６－１、９６－６７、９６－３３等３份标记型柱头外露种质系表现较优;ＳＣＡ效应显著的８个性状中,Ａ１Ｂ２８个性状的ＳＣＡ效应值均为正,Ａ２Ｂ２和Ａ４Ｂ１均有７个性状的ＳＣＡ效应为正。文中对标记型柱头外露种质及亲本选配等问题进行了讨论。     

红麻品种间杂交杂种一代优势及其与亲本的关系

采用ＮＣⅡ（Ｎｏｒｔｈ Ｃａｒｏｌｉｎａ）交配设计,对４２个品种间杂交杂种一代组合和１３个亲本品种进行比较试验,研究品种间杂交杂种一代优势及其与亲本的关系。结果表明：红麻品种间杂交杂种优势明显,大多数性状杂种优势达极显著水平,其中以杂种一代单株纤维产量优势最明显,影响杂种一代单株产出能力的性状从大到小依次是单株鲜茎（含叶,下同）重,基部茎粗,基部皮厚,株高。同一性状两亲本对不同性状的影响有差异,Ｆ     

与紧凑型小麦品种"莱州3279"正反交F1杂种优势比较

以莱州 32 79为中心亲本 ,与冀东地区 5个基因型不同的冬小麦品种配置正反交组合 ,并对 10个正反交 F1 的产量性状、叶绿素含量及旗叶与茎秆间的夹角进行了对比分析。结果表明 :无论正交还是反交 ,5个产量性状平均中亲杂种优势大小顺序均为 :单株产量 >单株有效穗数 >千粒重 >穗粒数 >每穗结实小穗数。单株产量表现出最强的杂种优势 ,但个别组合优势不明显 ,甚至出现负优势。大部分组合叶绿素含量杂种优势不明显 ,只有 1个组合正反交 F1 叶绿素含量均表现出较强的杂种优势。同一性状的杂种优势某些组合正交高于反交 ,而某些组合反交高于正交。莱州 32 79株型直立紧凑 ,与其他品种配成的正反交 F1 旗叶夹角减小幅度均较大 ,该品种对改良株型有很好的利用价值。杂种优势的表达很复杂 ,不仅与杂种核基因有关 ,核质互作对杂种优势也有很强的影响。     

转基因抗虫棉与陆地棉种质间的杂种优势和配合力分析

采用NCⅡ交配设计,对5份转基因抗虫棉、6份柱头外露种质资源和彩色棉等陆地棉优异亲本组配杂交,分析杂种F1的11个性状的杂种优势和配合力.结果表明,主要产量性状皮棉产量,超高优势的平均值为6.18%,16个组合具正向的杂种优势;中亲优势的平均值为37.41%,24个组合均具有正向的中亲优势;竞争优势的平均值为-15.19%,8个组合出现正向竞争优势.其它产量性状铃重、单株铃数的杂种优势最为明显.纤维品质性状、2.5%跨长、比强度和伸长率的竞争优势明显.高亲值、中亲值和低亲值与F1平均值的相关关系表明,多数性状F1代平均值与中亲值和低亲值相关性密切.经配合力分析,双价321、新棉33 B、HK-1、96-67、惠无3055和01 HN 06表现较显著的GCA效应;SCA效应显著的7个性状中,A 1×B 6、A 2×B 5、A 2×B 3等组合有7个性状的SCA效应为正值.     

大豆花叶病毒(SMV)株系SC4和SC8的抗性遗传分析

选用我国黄淮和长江流域大豆产区发生频繁的SMV株系SC4和SC8,利用大豆抗病材料和感病材料配制抗感和抗抗杂交组合,研究抗病材料对SC4和SC8株系的遗传方式以及不同大豆材料对SMV抗性基因位点间的等位性关系。结果表明, 接种SC4株系后,由冀LD42、徐豆1号、跃进4号、科丰1号、PI96983、晋大74、汾豆56、大白麻和齐黄22为抗源配制的9个抗感组合的F₁均表现抗病,经卡方测验, F₂抗感分离比例3∶1,F_2:3家系分离比例为1(抗)∶2(分离)∶1(感),表明这些抗源均有1对基因控制对SC4株系的抗性,且抗病表现为显性;5个抗抗组合的F₁均表现抗病,F₂群体分离比例15(抗)∶1(感),表明大白麻与汾豆56、科丰1号和齐黄1号携带抗SC4的基因是不等位的,冀LD42与汾豆56,晋大74与中作229是不等位的。接种SC8株系后,用齐黄1号、中作229、NY58、科丰1号、PI96983、晋大74、汾豆56、大白麻和齐黄22为抗源配制的抗感组合杂交后代分离符合1对基因的分离比例且F₁均表现抗病,说明这些品种对SC8株系的抗性也均由1对显性基因控制。抗抗组合晋大74×汾豆56接种SC8株系后的F₂群体全部表现抗病,F_2:3家系没有抗感分离,表明抗病品种晋大74与汾豆56携带的抗病基因是等位的;齐黄1号×科丰1号、大白麻×汾豆56的F₂群体分离比例15(抗)∶1(感),表明抗病亲本齐黄1号与科丰1号、大白麻与汾豆56携带抗SC8的基因是不等位的,而且独立遗传。     

Heterosis for yield and related characters in pea

Summary To determine the levels of heterosis in F1 hybrids, four current pea (Pisum sativum L.) cultivars from southern Australia were used as female parents and crossed with 18 introduced genotypes. The 22 parents, 72 F1 hybrids and, depending on the environment, either 54 or all 72 F2 families were grown in replicated plots in four environments. Grain yield, total dry matter, harvest index, branches per plant, pods per plant, seeds per pod, hundred seed weight, plant height, onset of flowering and flowering periods were evaluated. For both the F1 and F2 generation, heterosis was determined as the superiority over the mid-parent and also over the better parent. In addition, the superiority over the best commercial cultivar was calculated. Most hybrids were higher yielding than their mid-parent but were less stable in yield across environments. Four F1 hybrids were significantly higher yielding than the best parent, by up to 26%. There were significant correlations between F1 hybrid and mid-parent value for plant height, pods per plant and hundred seed weight but not for yield. Overall, grain yield heterosis was mainly due to more pods per plant in the hybrids. The level of heterosis for yield in a poor yielding environment was higher than that in a high yielding one. Both additive and non-additive gene effects were important in the expression of all studied traits. The average level of heterosis for grain yield and total dry matter in the F2 population was half of that in F1 hybrids. The low level of inbreeding depression from the F1 to the F2 generation suggested that epistatic gene action also contributed to the expression of grain yield. Some F2 populations maintained the high yield levels of the corresponding F1 hybrids.     

An improved breeding strategy for autotetraploid alfalfa (Medicago sativa L.)

Alfalfa cultivar development will be enhanced by breeding strategies whichutilize the full potential of autotetraploid population genetic structures. Thisstudy evaluates the effectiveness of an allelic selection scheme, which wasdeveloped to overcome limitations of inbreeding depression and to exploitgeneral and specific combining ability effects in autotetraploid populations.Allelic selection entails the minimization of non-additive genetic effects byselecting among full-sib families (F1) which are at uniform levels ofheterozygosity. Such F1 lines are developed by crossing individuals fromtwo unrelated random mating populations. Selected F1 lines wereintercrossed to form an improved population. Eight random matingpopulations of alfalfa were developed to study the effectiveness of allelicselection. Selection for increased dry matter yield resulted in alfalfapopulations with 38 percent greater yield than the parent populations. Twocycles of intercrossing, among selected F1 lines, did not dissipate the gainfrom selection. This result has important implications for synthetic cultivardevelopment in which a major limitation is the decline in productivity withadvancing generations of seed increase. A positively correlated response toselection for dry matter yield was observed for plant height and stemdiameter. The results of this research indicate that continued testing of theallelic selection scheme is warranted and could have a significant impact onthe breeding of autotetraploid alfalfa, particularly for synthetic cultivardevelopment.     

Early Generation Selection for Grain Yield in Narrow-Leaf Lupin (Lupinus angustifolius L.)

Experiments were conducted with early segregating generations of a selected narrow-leaf lupin cross to determine the effectiveness of selection for yield based on alternative criteria. F2 plants were selected on the basis of seed yield and several other yield-related characters to generate separate F3 populations. Randomly selected plants from each population were grown over the summer (off-season) in a glasshouse to generate F4 populations. Analyses of relationships between F2 plant measurements and F3 progeny mean yields revealed significant correlations only for those characters with the highest heritabilities - flowering time, 100 seed weight and harvest index. However, selection for the earliest flowering F2 plants followed by selection within this group of plants with the highest number of pod bearing branches would result in the greatest increase in F3 mean yield. The F2-derived F4 populations with the highest seed yields were those obtained by selection for total plant dry weight, number of pod bearing branches and number of pods per plant. Improvement in commercial crop yield should therefore be obtained through selection in early generations for those characters contributing to the greatest number of pods per unit area. A scheme involving selection for early flowering and high number of pod bearing branches in the F2 combined with replicated yield tests in the F4 is proposed.     

QTL Mapping for Yield and Fiber Quality Traits in Double-Cross Population of Chromosome Segment Introgression Lines from Gossypium hirsutum×Gossypium barbadense

[Objective] The aim of this study was to map quantitative traits loci (QTLs) for yield and fiber quality traits in chromosome segment introgression lines (CSILs) from Gossypium hirsutum×Gossypium barbadense. [Method] Four CSILs, MBI 7115, MBI 7412, MBI 7153 and MBI 7346, which were obtained by advanced backcrossing and continuous inbreeding from upland cotton variety CCRI 45 and sea-island cotton variety Hai 1, were used to construct double-cross segregating populations F1 and F1:2 through the following crosses: [(MBI 7115×MBI 7412)×(MBI 7153×MBI 7346)]. Simple sequence repeat (SSR) molecular markers were used to evaluate the genotyes of parents. The F1 and F1:2 populations were used to map QTLs for yield and fiber quality-related traits. [Result] The recovery rates of the recurrent parent CCRI 45 in the four CSILs were all above 97%. Forty-one QTLs, which were distributed across 11 chromosomes, were detected using the two segregating populations. There were 30 QTLs controlling fiber quality with phenotypic variations ranging from 1.11% to 11.80% and 11 QTLs controlling yield-related traits with 1.09%–13.57% phenotypic variations. [Conclusion] Five QTLs for fiber quality were consistently detected in two populations and they were all newly discovered QTLs. This study provides an important theoretical basis for fine mapping of these QTLs and molecular marker-assisted breeding for excellent fiber quality.     

Early generation testing for yield and physiological components in groundnut (Arachis hypogaea L.)

Selection of superior crosses of groundnut (Arachis hypogaea L.) in early generations would increase the probability of identifying superior lines. The objective of this study was to determine the potential of selecting for physiological traits identified in a yield model [crop growth rate (C), reproductive duration (DR) and partitioning (p)] in segregating populations. Forty populations and nine parental lines were evaluated in replicated trials in 1992 (F2, 1993 (F3) and 1994 (F4) at three locations in Niger. Physiological traits were estimated from final yield and biomass as well as data on flowering and maturity. Regressions from two different parent-offspring generations (F2: F3 and F3: F4) were calculated. The results were compared to determine if early generation performance accurately predicts the performance of cross bulks in later generations. Differences were observed among populations and parents for all traits. Effects of locations were significant for C, p and DR in F2 and F3 but nonsignificant for yield and C in F4. Regression coefficients from F3: F2 were 0.10 ± 0.08 for C, 0.45 ± 0.17 for p, 0.10 ± 0.03 for DR and 0.16 ± 0.03 for pod yield. Based on F3: F4 regression, the coefficients were 0.12 ± 0.23 for C, 0.46 ± 0.17 for p and 0.57 ± 0.17 for yield. Parent-offspring correlations were in most cases similar to the regression values. It was concluded that selection for yield and model components in early generation bulks may inneffective. This revised version was published online in July 2006 with corrections to the Cover Date.     

Evaluation of parent selection methods for yield improvement of cowpea (Vigna unguiculata (L.) Walp.)

Summary The mean aim of this study was to identify an effective method of predicting cross-potential in respect of yield improvement of the cowpea (Vigna unguiculata (L.) Walp.) through hybridization and subsequent selection.Three prediction tests based on data collected from experiments with ten cowpea lines and the F1 and F2 generations of all possible crosses between these lines were evaluated. The three prediction tests were based on: i Yields of prospective parents. ii. General combining abilities estimated from F1 and parental data iii. Frequencies of superior plants in F2 populationsEach of the three procedures was used to identify the crosses with the lowest or highest yield potential, i.e. those crosses most likely to produce the greatest number of lines with yields higher or lower than those of either parent. Crosses selected on the basis of these criteria were evaluated in the following growing season on the basis of biometrical analysis of F2 and backcross populations and the performance of the respective F3 and F4 generations.Six different crosses were selected from the 45 tested on the basis of the three prediction tests. Analyses of F2 and backeross populations from each cross provided estimates of [d] the difference in parental means and 1/2D the additive genetic component which, in turn, were used to predict the frequency of transgressive inbred lines obtained by single-seed descent from the F2. Both crosses selected on the basis of F2 data were expected to produce a much higher frequency of transgressive lines than those selected on the basis of parental yields. The high potential cross selected on the basis of general combining ability was expected to produce a higher frequency of transgressive lines than the corresponding low yield potential cross. Replicated trails of F3 bulks of the selected crosses showed that high yield potential crosses were significantly higher yielding than low yield potential crosses for all prediction criteria. In a trial with 22F4 lines of each of the two crosses selected on the basis of parental yields and frequency of high yielding F2 plants, the high yield potential cross in each case had a greater mean and variance for seed yield than the corresponding low yield potential cross.It was concluded that parental yields provide a sound basis for an initial screening of prospective parents. This screening should identify a high yielding line which can be crossed with a number of contrasting lines to produce F2 populations for the final screening phase.     

棉花多亲本杂交F_2群体产量性状的效应分析

本文对棉花聚合杂交体系中９个不同亲人配制的８个单交、１０个４交、１１个８交的Ｆ＿２代群体的产量及产量组合性状进行综合分析。结果表明，随着率交亲本数的增加，聚合程度逐步提高，使产量及主要产量组分的遗传增益不断上升，并达到了显著或极显著水平的增加，其中尤以８交群体的聚合增效最为突出。说明多亲本聚合杂交在棉花丰产、优质、抗病和早熟目标的育种中，对产量性状的提高具有显著效果。     

转Bt基因杂交棉主要性状优势率分布研究

分析了 73个转 Bt基因抗虫杂交组合 F1主要性状的杂种优势及优势率分布 ,认为 :1杂种一代的霜前皮棉产量、株高、铃重、衣分、霜前花率等性状具有明显的正向优势。 2 5 6%的组合霜前皮棉产量竞争优势 ( CH% )集中在 1 0 .1 %～ 35 %之间 ;子棉总产则以 0 .1～ 2 0 %居多 ;铃重、衣分、子指、霜前花率的 CH%主要分布在 0 .1 %～ 1 5 %之间 ;生育期、2 .5 %跨长为负优势 ,多在 - 5 %～ - 0 .1 %之间。 3与 F1相比 ,除子指、2 .5 %跨长外 ,F2主要性状杂种优势均不同程度下降 ,以子棉总产、霜前皮棉产量、霜前花率、单株铃数降幅较大 ;生育期变化较小 ;铃重、衣分、子指虽比 F1有所下降 ,但仍呈现较强的正向优势     

高州普通野生稻雄性不育胞质对杂种一代单株产量的影响

为了明确新发现的雄性不育细胞质对杂种一代产量的影响,为它的开发利用提供依据。用3种同核异质雄性不育系及其保持系与4个恢复系配制16个杂交稻组合进行了两年三季裂区试验,在相同核背景下比较雄性不育细胞质对杂种一代单株产量的影响。结果表明：高州普通野生稻雄性不育细胞质对杂种一代单株产量表现出不同程度的负效应,但均未达显著水平;高野所配组合的平均单株产量低于华南晚籼雄性不育胞质夜公、但高于野败,说明它是一个值得进一步研究利用的新型雄性不育细胞质。