轮回选择对玉米沈综（C0、FC2）群体的产量组成性状的遗传改良效果研究

对玉米（Zea mays L.）沈综基础群体和TC2实施了化回选择遗传改良，第一轮以半姊妹选择方案完成，获得了沈综（330）C1群体，而后对它进行两轮全姊妹轮回选择改良，选择性状主要以籽粒产量为主，兼顾抗病性和部分植株性状，然后将得到的FC2、FC3群体和C0、CK置于同一环境种植，根据调查和考种结果对各群体产量性状进行分析。结果表明；群体产量获得了7.5%的遗传增益。穗行数、行粒数、百粒重和单穗粒重得到明显的改良。群体中优良个体频率增加，与产量相关性状的变异系数下降。相关分析和通径分析表明；不同群体的农艺性状与单株产量的相关程度有差异，九体产量的提高是由于农艺性状获得到了改善和性状之间的关系得到了协调发展的结果。     

两种轮回选择方法对沈缩C0群体的产量及植株性状的遗传改良效果的研究

应用两种轮回选择方法对玉米（Zea mays L.)基础群体C0及SC1实施轮回选择，根据调查和考种结果，对各种体的产量及植株性状进行比较分析，结果表明：在选择强度为30％的条件下，FC2群体比基础群体提高了25．93％，FC3群体比基础群体提高了35．38％，单株粒重，穗重，穗粗，穗行数，行粒数和百粒重分别获得了12．57，13．06，1．23，6．77，1．54和2＝71的遗传增益，这些性状基本上是朝着对产量有利的方向发展，而今后的选择必须注意穗长，行粒数和植株性状的选择。     

半姊妹与全姊妹轮回选择对玉米沈综（旅）C_1群体改良效果的研究

应用半姊妹轮回选择和全姊妹轮回选择两种方案对玉米沈综（旅）Ｃ_１群体进行改良，根据调查、考种结果对各群体产量及性状进行分析。结果表明，两种方案对群体的改良是有效的，半姊妹、全姊妹改良群体分别比沈综Ｃ_０群体产量提高２８．７％和２３．７％，达到极显著（０．０１）和显著（０．０５）差异水平，ＨＣ_２、ＦＣ_２两群体间产量差异没达到统计上的显著水平，半姊妹改良方案较全姊妹改良方案的实际遗传增益大，二者分别是１１．７２％和７．３７％，其预期遗传增益分别为３．４２％和４．２７％。相关、通径分析表明，不同群体的农艺性状与单株产量的相关程度有差异，其贡献大小也不尽相同，两种轮回选择方法，尤其是半姊妹轮回选择导致群体的遗传变异更趋狭窄。     

沈综玉米群体植株性状改良效果研究

经3轮不同方法的轮回选择,使沈综C0玉米群体产量获得了平均每轮8.67%的遗传增益。3种改良方法均能不同程度的提高植株性状,以全姊妹选择最显著。S1选择或半姊妹选择有增加茎粗的作用,全姊妹选择有使植株向高发展的趋势。经1轮S1选择和半姊妹选择后,大多数植株性状与单株产量的相关系数及植株性状的变异系数增加;经1轮全姊妹选择后,绝大多数植株性状与单株产量的相关系数和植株性状的变异系数有所下降。穗上第1叶叶面积对单株产量的直接通径系数在3轮群体中均为第1位,并逐轮增加,偏回归系数除在HC2绿叶数显著外,3个群体均为株高和茎粗显著。雄穗分枝数在HC2有所减少,与产量的相关性也相应加强。叶面积、茎粗和株型是沈综群体今后需要同时改良的主要植株性状。     

两种轮回选择方法对玉米群体改良效果的研究

本试验以籽实产量主要目标，对沈综（长穗）Ｃ１群进行了半姊妹家系和全姊妹家系轮回选择。通过对诸群体的产量比较试验，分析和比较两种轮回选择方法对产量和其它性状的改良效果。试验结果表明，两种轮回选择的效果是显著的，选择后的全姊妹群体（ＦＣ２）小区平均产量比Ｃ０群体增产１６．７９％，达１％显著水平，半姊妹群体（ＨＣ２）比Ｃ０群体增产１３．５９％，达５％显著水平。产量实际遗传增益，ＦＣ２，ＨＣ２分别为１０．     

两种轮回选择方法对沈综C0群体的产量及植株性状的遗传改良效果的研究

应用两种轮回选择方法对玉米(ZeamaysL.)基础群体C0及SC1实施轮回选择.根据调查和考种结果,对各群体的产量及植株性状进行比较分析.结果表明,在选择强度为30%的条件下,FC2群体比基础群体提高了25.93%,FC3群体比基础群体提高了35.38%.单株粒重、穗重、穗粗、穗行数、行粒数和百粒重分别获得了12.57、13.06、1.23、6.77、1.54和2.71的遗传增益,这些性状基本上是朝着对产量有利的方向发展,而今后的选择必须注意穗长、行粒数和植株性状的选择.     

豫综5号玉米群体产量性状轮回选择改良效果分析

以半姊妹和相互半姊妹轮回选择改良的豫综5号5个轮次群体为材料,通过2点产量比较试验,对豫综5号群体产量及穗部性状的改良效果进行了比较研究.结果表明,随着改良轮次的增加,豫综5号群体的单株产量逐轮提高,平均每轮提高6.36%,其中,半姊妹轮回选择改良的3轮群体平均每轮提高6.30%,相互半姊妹轮回选择的改良群体提高5.51%,群体产量的变异系数从15.4%下降到12.8%,基本符合选择预期效果,群体内仍有较丰富的变异,说明2种选择方法对群体单株产量的改良是有效的.对改良群体穗部性状的比较发现,穗长和行粒数分别提高5.27%和9.96%.说明穗长和行粒数的改良效果明显,它们的提高是群体单株产量提高的主要因素.本研究还对相互轮回选择的方法和豫综5号群体改良利用等问题进行了探讨.     

Genetic Diversity of Maize Populations Developed by Two Kinds of Recurrent Selection Methods Investigated with SSR Markers

Two cycles of biparental mass selection （MS） and one cycle of half-sib-S3 family combining selection （HS-S3） for yield were carried out in 2 synthetic maize populations P4C0 and P5C0 synchronously. The genetic diversity of 8 maize populations, including both the basic populations and their developed populations, were evaluated by 30 SSR primers. On the 30 SSR loci, a total of 184 alleles had been detected in these populations. At each locus, the number of alleles varied from 2 to 14, with an average of 6.13. The number and ratio of polymorphic loci in both the basic populations were higher than those of their developed populations, respectively. There was nearly no difference after MS but decreased after HS-S3 in both the basic populations in the mean gene heterozygosity. The mean genetic distance changed slightly after MS but decreased in a bigger degree after HS-S3 in both the basic populations. Analyses on the distribution of genetic distances showed that the ranges of the genetic distance were wider after MS and most of the genetic distances in populations developed by HS-S3 were smaller than those in both the basic populations. The number of genotypes increased after MS but decreased after HS-S3 in both the basic populations. The genetic diversity of intra-population was much more than genetic diversity of inter-population in both the basic populations. All these indexes demonstrated that the genetic diversity of populations after MS was similar to their basic populations, and the genetic diversity was maintained during MS, whereas the genetic diversity of populations decreased after HS-S3. This result indicated that heterogeneity between some of the individuals in the developed populations increased after MS, whereas the populations become more homozygotic after HS-S3.     

Comparisons of Three Recurrent Selection Methods in the Improvement of Maize Populations

The maize population Csyn 4 was improved for three cycles with three recurrent selection methods MS1, MS1-HS, and MHSRRS in northern China. A total of 40 NC Ⅱ testcrosses were made by four testers with Csyn 4 and 10 improved populations, which were evaluated in four environments in the cropping season of 2005. Analysis of variance indicated a significant progress （P〈 0.05） in yield and other chief agronomic traits in the improved populations and testcrosses, demonstrating that the three recurrent selection methods were effective for increasing grain yield of testcrosses and improvement of general combining ability in maize population. The average grain yield increase of population Csyn 4 in MS1, MS1-HS, and MHSRRS recurrent selections was 266.7 kg ha^-1 （5.3%）, 288.0 kg ha^-1 （5.7%）, and 231.3 kg ha^-1 （4.6%） per cycle, while the grain yield of S 1 progeny of population for Csyn 4 was increased by 420.0 kg ha^-1 （10.9%）, 376.0 kg ha^-1 （9.8%）, and 414.7 kg ha^-1 （10.8%） per cycle in MS1, MS1-HS, and MHSRRS recurrent selections, respectively. Linear responses （b） in the MS1, MS1-HS, and MHSRRS recurrent selections were the same as the realized responses of the selection （G） for grain yield increase of Csyn 4 and S1 progeny of the populations. The grain yield of testcrosses increased by 3.3-5.2% on average per cycle. The value of heterosis did not display any differences amongst the different cycles of selections. The GCA for yield component traits of population Csyn 4 was improved significantly by means of three selection methods, whereas the GCA for plant height, ear height, days to silking, and days to pollen did not show significant increase in the recurrent selections. GCA for the number of tassel branches were decreased in the selections, while GCA for the number of plant leaves were increased, but the difference was not significant.     

Genetic Diversity of Recurrent Selection Populations with Ms2 Gene Assessed by Gliadins in Common Wheat （Triticum aestivum L.）

The male-sterile lines with Ms2 gene were highly evaluated in recurrent selection in wheat （Triticum aestivum L.）. Three populations C6 （population after six cycles of selection）, C7 （population after seven cycles of selection）, and C8 （population after eight cycles of selection） were constructed through recurrent selection with 12 parental materials （P）. Acid polyacrymide gel electrophoresis （A-PAGE） analysis was used to identify gliadin patterns and evaluate the genetic diversity in 12 parents and three populations. A total of 63 bands were identified, of which 17 polymorphic bands and 7 unique bands were present in populations and seven polymorphic bands and four unique bands were present in parents. The number of polymorphic and unique bands decreased gradually from C6 to C8, especially for to- and y-gliadins. The genetic distances in C6, C7, and C8 were calculated. The distributions of genetic distance were different in three recurrent selection populations. From C6 to C8, the genetic distance was 0.2687, 0.2652 and 0.1987, respectively. Statistically significant differences were detected between C7 and C8 with the T value of 37.9718. The result of cluster analysis based on genetic similarity matrix of three populations fitted well to those of principle coordinates analysis （PCoA）. Compared with 12 parents, almost all individuals of three populations are new genotypes. Most of the individuals from C6 and C7 could be divided into two groups, while most individuals of C8 were in one cluster. In conclusion, the results indicated that the genetic diversity was decreased severely according to the information revealed by A-PAGE, although some variations could be created in the recurrent selection. It was necessary to introduce diverse germplasm based on the genetic database of recurrent population to maintain and improve the breeding efficiency in the further program.     

对玉米人工合成群体遗传性状改良效果的研究

为对玉米群体改良提供理论依据和实践经验，对其进行限制性选择的株型改良以及确定合理的选择指数是群体改良的一项重要内容，在选择强度，有效群体和环境条件均一致的条件下，对玉米（Zea mayL.)沈综基础群体和（S1）C1群体实施两种方案的轮回选择，得到半同胞家系HC2群体和全同胞家系FC3群体，同时对产量组成性状，植株性状及抗病性进行表型选择，结果表明，在HC2群体中，穗长，穗粗，行粒数，穗行数，百粒重的通径系数总效应分别为：0.579,0.415,0.363,0.311,0.293,在FC3群体中，分别为0.511,0.317,0.578,0.014,0.368。与产量相关农艺性状的变异系数有所下降。群体植株性状获得的遗传增益不尽相同，营养体的生长量有所增加。     

红麻产量和纤维品质性状的遗传变异及其选择指数

采用7(7+1)/2双列杂交遗传设计,估算和分析了11个产量与品质性状的基本遗传参数及其选择指数,揭示了对单株干皮产量进行指数选择,单株鲜茎重、始果位高具有很高的遗传进度和相关选择的相对效率.始果位高不但遗传力高,而且与单株干皮重、纤维支数、纤维强力3个重要目标性状呈高度正相关.因此,增加对单株鲜茎重和始果位高两个性状综合选择的强度,可望使红麻产量与品质性状的改良获得较高的遗传进度.     

Study on Quality Improvement Effect and Separate Character of Soybean Male Sterile （MS1） Recurrent Selection Population

To solve the problem that soybean has narrow genetic base, we constructed a series of male sterile recurrent selection populations, and studied the effects of quality improvement and practical value. An LD-base population, which fits to our ecology type was constructed by 6 years＇ gene enrichment through the introduction of new genes from 23 local varieties and recurrent selection. The LD-base populations were then improved by making crosses with high protein and high oil genotypes. As a result we obtained a high protein sub-population （db） and a high oil sub-population （gy）, For the db sub-population, the protein content is 1.18% higher than the base population, 22.38% of the individuals contain 45% or more of protein, which is 10.99% higher than the base population. For the gy sub-population, oil content is 0.24% higher than the base population. Individuals with oil content of 20% or more are 11.05% higher than the base population. The quantitative characters such as flowering date, mature date, pod habit, and hilum color, etc., all showed wide range of separation, and the segregation ratio approached balance. The c.v. of branch number of ms1 recurrent population （72.8%） is higher than general cross-population （57.3%）, and the c.v. of 100 seed weight of ms1 （18.1%） is higher than general cross population （16.5%）, the coefficient of variation of plant height, pods per plant, and seeds per pod were not significantly different. It was demonstrated in this paper that the quality character of ms 1 male sterile recurrent selection population was improved by adding new genes. And the segregation of other characters widened, making the populations suitable for the objective of soybean breeding. In this paper, we also discussed the breeding method, key technology, and selection effect of soybean ms 1 population.     

糯玉米自交系遗传多样性及其产量、农艺性状与SSR分子标记的关联研究

[目的]研究糯玉米自交系的遗传多样性,确定其亲缘关系远近,为糯玉米的新品种选育提供依据。[方法]以84个糯玉米自交系为试验材料,利用分布在玉米全基因组上的71个SSR标记对供试材料的遗传多样性进行分析,并对其产量及农艺性状与SSR标记进行了关联分析。[结果]150对SSR引物中有71对在糯玉米自交系中能扩增出多态性条带,共检测到342个等位基因,每对引物可检测到2～11个数目不等的等位基因,多态性信息量为0.249～0.876;糯玉米自交系间的遗传距离为0.02～0.32,均值为0.178,4个自交系可划分为8个组别;玉米10个连锁群上71个SSR位点的2 485个组合,都存在一定程度的连锁不平衡;共检测出21个SSR座位与10个产量、农艺性状显著相关。[结论]该试验阐明了所选糯玉米自交系的遗传多样性及相互间的亲缘关系,为有目的的组配糯玉米杂交种及其新品种选育提供了参考。