Library

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Efficiency of Recurrent Selection Methods to Improve the Line Value of a Population (1993)
    Oxford, UK : Blackwell Publishing Ltd
    Plant breeding 111 (1993), S. 0 
    Details
    ISSN: 1439-0523
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Five breedings methods have been studied for their efficiency in improving the line value of a population, i.e. the value of all lines that can be derived from the population. These methods are: half-sib family recurrent selection (HSF-RS), full-sib family recurrent selection (FSF-RS), half-sib progeny recurrent selection (HSP-RS), recurrent selection (S1-RS) and the single-doubled-haploid descent recurrent selection (SDH-RS). All breeding methods are compared on the basis of the genetic advance per unit of time, with the constraint of the same effective size after the first cycle of selection. Two modalities of SDH-RS are considered for an annual plant without an off-season generation: one with a cycle in four years (SDH1-RS) and the other with a cycle in five years (SDH2-RS). For all methods the possibility of one off-season generation for intercrossing is considered. Fields of efficiency of the best methods are determined considering five main parameters, the heritability, the importance of additive variance, the correlation QL between the additive effect for line value and the additive effect for the per se value, the length of the cycle for SDH-RS and the selection intensities. SDH-RS is the best method when the heritability is low, with a low proportion of additive variance and with a relatively low correlation QL between additive effects for per se and line values. Without off-season generation, S1-RS is the best method among the remaining realistic situations; with one off-season generation for intercrossing it is FSF-RS. The use of an off-season generation reduces the domain of efficiency of SDH-RS while an increase in the selection intensity increases this domain. With a selection intensity for SDH-RS equal to that for S1-RS, SDH-RS is the best in a large range of realistic situations except for SDH2 with one offseason generation and medium to high correlation QL.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1439-0523.1993.tb00604.x
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Three-Way and Four-Way Recurrent Selection in Plant Breeding (1991)
    Oxford, UK : Blackwell Publishing Ltd
    Plant breeding 107 (1991), S. 0 
    Details
    ISSN: 1439-0523
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Three or four-way recurrent selection is proposed for the development of three or four-way crosses. In term of genetic effects, it could be justified if there are interactions between more than three genes, whether alleles or not, if autopolyploids are also considered. For autotetraploids, in particular with tetragenic interaction, four-way recurrent selection could be more effective than reciprocal recurrent selection (two-way selection). According to the types of progenies used to develop the tests, different selection procedures are considered, the two extremes being called method 1 and method 3. With method 1 (selection for three or four-way general combining ability) a plant from a population is used to produce three-way or four-way progenies with the other populations used as testers. With method 3 (selection for three or four-way specific combining ability) three-way or four-way crosses are developed with one plant from each population. To study the genetic advance, the theory is developed to consider either diploidy or autotetraploidy. It is shown that method 3 will allow a greater genetic advance than method 1 for low heritability and low selection intensity. The way towards hybrid development with three and four-way pedigree selection is discussed: again selection can be for general or specific three or four-way combining ability. It is emphasized that an advantage of recurrent selection for three or four-way specific combining ability is that it allows direct varietal development with pedigree selection on three or four-way specific combining ability. Some other practical aspects are also considered.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1439-0523.1991.tb00549.x
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Prediction of the Line Value of a Genotype from a Top Cross with a Single Cross Hybrid (1989)
    Oxford, UK : Blackwell Publishing Ltd
    Plant breeding 103 (1989), S. 0 
    Details
    ISSN: 1439-0523
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: With the assumption of biallelism it is shown that differences in line values of genotypes from a random mating population can be predicted by the differences of values in top cross progenies with a heterozygous tester. This prediction is also valid in the case of multiallelism with a constant degree of dominance for each pair of alleles and if the tester is heterozygous for the more “distant” alleles. With an arbitrary tester, the efficiency of the prediction is affected by the proportion of the loci which are heterozygous for the more distant alleles. However, with the assumptions considered on multiallelism, with partial to complete dominance, the correlation between line value and combining ability with the tester is expected to be high for a large range of the repartition ot the loci. A two tester top cross design using highly complementary lines, could also be used.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1439-0523.1989.tb00384.x
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Effects of competition on means, variances and covariances in quantitative genetics with an application to general combining ability selection (1976)
    Springer
    Theoretical and applied genetics 47 (1976), S. 189-195 
    Details
    ISSN: 1432-2242
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary General expressions are established for means, variances and covariances, taking into account the effect of interactions between individuals. For simplicity, only groups of size two are considered so that interactions are restricted to pairs of individuals; genetic effects are reduced to additivity and to additive × additive interaction between the direct effect of an allele and the associate effect of another. The effect of family structure is studied, and some consequences of interest to plant breeding are discussed by an application to general combining ability selection. From a population genetic point of view, this approach reveals a new application of coefficients of kinship.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00278377
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Selection among synthetics (1974)
    Springer
    Theoretical and applied genetics 44 (1974), S. 24-30 
    Details
    ISSN: 1432-2242
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The effect of the number of parents and their level of inbreeding on the mean and the variance of synthetic varieties was studied for diploids and autotetraploids. The number of parents and their level of inbreeding act in opposing ways. Maximum mean requires a high number of parents and no inbreeding. Maximum variance requires a small number of highly inbred and unrelated parents. When the number of parents increases (k ≥ 2) the coefficients of the components of variance decrease, and the decrease is more rapid for variances associated with increasing order of interactions between genes. The coefficients of components of variance increase as the level of inbreeding of the parents increases and the increase is greater for components associated with increasing order of interactions between genes. Consequently, according to the values of inbreeding depression and the components of genetic variance and heritability, an optimum genetic base may exist, i.e., an ideal combination of the number of parents and the level of their inbreeding. With no inbreeding, selection among synthetics uses mainly additive variance. By increasing the level of inbreeding of the parents, the effects of dominance and of additive X additive variances on genetic advance when selecting among synthetics increase. One cycle of selection among synthetics appears more efficient than individual selection within populations. The problem of population improvement before selecting among synthetics is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00277704
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Relationship between heterosis and heterozygosity at marker loci: a theoretical computation (1991)
    Springer
    Theoretical and applied genetics 81 (1991), S. 571-575 
    Details
    ISSN: 1432-2242
    Keywords: Heterosis ; Heterozygosity ; Markers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary In this paper we have studied the linear correlation between a genetic distance index between two parent lines (based on marker loci information) and the heterosis observed in the F1 hybrid from the two lines, for a quantitative character (determined by several loci, or QTL). Theoretical computations of the correlation coefficient (ϱ) between the distance index and the heterosis were made, assuming the biallelic model (defined by Fisher). When the alleles at both marker loci and QTL are equally distributed among the whole population of considered lines, the coefficient ϱ is a function of the squares of linkage disequilibria between alleles at marker loci and alleles at QTL. The QTL that are not marked by marker loci and marker loci that do not mark any QTL play symmetrical roles and can decrease ϱ greatly. We conclude that the prediction of F1 hybrid heterosis based on marker loci would be more efficient if these markers were selected for their relationship to the alleles implicated in the heterotic traits considered.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00226720
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    A general approach for the study of a population of testcross progenies and consequences for recurrent selection (1991)
    Springer
    Theoretical and applied genetics 81 (1991), S. 493-503 
    Details
    ISSN: 1432-2242
    Keywords: Combining ability ; Additive x additive epistasis ; Combined selection ; Tester
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A model to study genetic effects at the level of a population of testcross progenies is presented. As there is no dominance for the testcross value, with the restriction of epistasis to pairs of loci, only additive x additive epistasis can contribute to the variance among progenies. To estimate the variance among progenies due to epistasis, it is necessary to have the population structured in families of full sibs, half sibs or S1, with only a few plants per family tested in combination with the tester. Using a two-way mating design to produce the families, it is possible to estimate the variance due to additive x additive epistasis. The consequence of the presence of epistasis is studied at the level of recurrent selection for combining ability with the tester. It seems that epistasis itself does not change the efficiency of the breeding methods considered. However, when the population from intercrossing is structured in families, it could be efficient to use a combined selection when the heritability is very low. In this case it would be efficient to produce full-sib families (by single-pair matings) at the level of intercrossing. The best procedure is to produce such families at the same time as crossing with the tester. In comparison to the classical scheme of selection for combining ability with a tester, such a modification increases the efficiency of selection 41.1% if an off-season generation can be used.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00219439
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    Analysis of variance components of testcross progenies in an autotetraploid species and consequences for recurrent selection with a tester (1992)
    Springer
    Theoretical and applied genetics 83 (1992), S. 353-359 
    Details
    ISSN: 1432-2242
    Keywords: Autotetraploidy ; Combining ability ; Tester ; Combined selection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary For autotetraploid species the development of the concept of test value (value in testcross) leads to a simple description of the variance among testcross progenies. When defining directly genetic effects at the level of the value of the progenies, there is no contribution of triand tetragenic interactions. To estimate additive and dominance variances it is only necessary to have the population of progenies structured in half-sib or full-sib families; it is then possible to determine the presence of epistasis using a two-way mating design. When the theory of recurrent selection is applied dominance variance can be neglected for the prediction of genetic advance in one cycle as well for the development of combined selection when progenies are structured in families. The results are similar to those for diploids with two-locus epistasis. The more efficient scheme consists of the development of pair-crossing in off-season generations (for intercrossing) and simultaneous crossing of each plant to the tester. In comparison to the classical scheme, the relative efficiency of such a scheme is 41%. The use of combined selection will further increase this superiority.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00224282
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    Predicting mean and variance of all possible lines and hybrids from designs with partially inbred progenies (1994)
    Springer
    Theoretical and applied genetics 89 (1994), S. 693-697 
    Details
    ISSN: 1432-2242
    Keywords: Two-factor mating design Variance components ; Inbred relatives ; Epistasis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Two-factor mating designs at consecutive Sn and S(n+1) levels (S0 and S1 S1 and S2, or F2 and F3) allow estimation of all components of the variation among homozygous lines and F1 hybrids that can be derived from a given population. They also allow for the prediction of the mean of these lines and single-cross hybrids. Some tests for the presence of epistasis are possible at the levels of means and of variances. Such mating designs can be very useful for predicting the value of the best possible lines or the best possible F1 hybrids when it is difficult to produce, at an experimental level for exploratory purposes, either lines or hybrids.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00223707
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    Combined genetic analysis of partial blast resistance in an upland rice population and recurrent selection for line and hybrid values (1996)
    Springer
    Theoretical and applied genetics 92 (1996), S. 644-653 
    Details
    ISSN: 1432-2242
    Keywords: Key words Quantitative genetics ; Recurrent selection ; Partial resistance ; Magnaporthe grisea ; Oryza sativa L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  The CNA-IRAT 5 upland rice population has been improved for 4 years by recurrent selection for blast resistance in Brazil. In order to predict the efficiency of recurrent selection in different test systems and to compare the relative advantage of hybrids versus pure line breeding, a combined genetic analysis of partial blast resistance in the CNA-IRAT 5 population was undertaken. A three-level hierarchical design in inbreeding and a factorial design were derived from the base population. Partial blast resistance of lines and hybrids was evaluated in the greenhouse and in the field by inoculation with one virulent blast isolate. The means and genetic variances of the hybrids and lines were estimated. Genetic advance by recurrent selection was predicted from estimates of variance components. The inheritance of partial blast resistance was mainly additive but non-additive effects were detected at both levels of means and variances. Mean heterosis ranged from 4%–8% for lesion size and lesion density to 10–12% for leaf and panicle resistance. High dominance or homozygous dominance variances relative to additive variance and negative covariance between additive and homozygous dominance effects were estimated. A low frequency of favourable alleles for partial resistance would explain the observed organisation of genetic variability in the base population. Recurrent selection will efficiently improve partial blast resistance of the CNA-IRAT 5 population. Genetic advance for line or hybrid values was expected to be higher testing doubled haploid lines than S1 lines, or than general combining ability. Two components of partial resistance assessed in the greenhouse, lesion size and lesion density, could be used as indirect selection criteria to improve field resistance. On the whole, hybrid breeding for partial blast resistance appeared to be slightly more advantageous than pure line breeding.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001220050174
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...