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
    Computer simulation of a selection strategy to accommodate genotype environment interactions in a wheat recurrent selection programme (1999)
    Oxford, UK : Blackwell Publishing Ltd
    Plant breeding 118 (1999), S. 0 
    Details
    ISSN: 1439-0523
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Multi-environment trials (METs) are used in plant breeding programmes to evaluate genotypes (lines/families) as a basis for selection on expected performance (yield and/or quality) in a target population of environments (TPE). When a large component of the genotype environment (G × E) interactions results from crossover interactions, samples of environments in METs that deviate from the TPE provide a suboptimal basis for selection of genotypes on performance expected in the TPE. To adjust for the negative effects of these deviations, a selection strategy that weights the data from the MET according to their expected frequency of occurrence in the TPE (i.e. a weighted selection strategy) was investigated. Computer simulation methodology was used to obtain preliminary information on the weighted selection strategy and compare it to the traditional unweighted selection strategy for a range of MET scenarios and G × E interaction models. The evaluation of the weighted selection strategy was conducted in context with the germplasm enhancement programme (GEP) of the Northern Wheat Improvement Programme in Australia. The results indicated that when the environments sampled in the MET matched those expected in the TPE, the unweighted and weighted selection strategies achieved a similar response to selection in the TPE. However, when the environments sampled in the MET did not match the expectations in the TPE and a large component of the G × E interactions resulted from crossover interactions, the weighted selection strategy achieved a greater response to selection in the TPE. The advantage of the weighted strategy increased as the amount of crossover G × E interaction increased or fewer environments were sampled in the METs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1439-0523.1999.118001017.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
    Phenotypic and functional analysis of peripheral blood lymphocytes in oral lichen planus (1992)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of oral pathology & medicine 21 (1992), S. 0 
    Details
    ISSN: 1600-0714
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: To assess cellular immunity in oral lichen planus (OLP), peripheral blood mononuclear cells (PBMC) were obtained from 19 OLP patients and 30 control subjects. The proportions of circulating CD45RA+ and CD29+ lymphocyte subsets were determined. The proliferative activity of PBMC to the non-specific plant mitogens phytohemagglutinin (PHA) and concanavalin A (Con A) was examined together with the spontaneous proliferative response and the response in the autologous mixed lymphocyte reaction (AMLR). In the OLP group, the proportion of CD4+CD45RA+ T lymphocytes was significantly less than control subjects and the proportion of CD4+ CD29+ T lymphocytes was increased significantly. The proliferative response to PHA was similar in OLP and controls subjects. Con A-stimulated PBMC proliferation was decreased significantly in the OLP group. Spontaneous PBMC proliferation in patients with non-reticular lesions was significantly less than control subjects. Despite a mildly depressed response in the AMLR in OLP patients, this result was not statistically significant. Results of the phenotypic analysis of peripheral blood lymphocytes indicate a decreased proportion of naive T cells and an increased proportion of primed memory T cells, although the antigen specificity of these memory cells remains to be determined. Results of the functional assays would seem to reflect this phenotypic shift, and as T cells responding to Con A stimulation and in the AMLR possess suppressor-inducer activity, these results may also suggest an association between OLP and defective innate T cell-mediated suppressor circuits.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1600-0714.1992.tb00972.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
    Multiattribute evaluation of regional cotton variety trials (1990)
    Springer
    Theoretical and applied genetics 79 (1990), S. 225-234 
    Details
    ISSN: 1432-2242
    Keywords: Three way data ; Clustering via mixtures ; Principal component analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The Australian Cotton Cultivar Trials (ACCT) are designed to investigate various cotton [Gossypium hirsutum (L.)] lines in several locations in New South Wales and Queensland each year. If these lines are to be assessed by the simultaneous use of yield and lint quality data, then a multivariate technique applicable to three-way data is desirable. Two such techniques, the mixture maximum likelihood method of clustering and three-mode principal component analysis, are described and used to analyze these data. Applied together, the methods enhance each other's usefulness in interpreting the information on the line response patterns across the locations. The methods provide a good integration of the responses across environments of the entries for the different attributes in the trials. For instance, using yield as the sole criterion, the excellence of the namcala and coker group for quality is overlooked. The analyses point to a decision in favor of either high yields of moderate to good quality lint or moderate yield but superior lint quality. The decisions indicated by the methods confirmed the selections made by the plant breeders. The procedures provide a less subjective, relatively easy to apply and interpret analytical method of describing the patterns of performance and associations in complex multiattribute and multilocation trials. This should lead to more efficient selection among lines in such trials.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00225956
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    The use of matrix specifications in defining gene action in genotypic value models and generation mean analysis (1979)
    Springer
    Theoretical and applied genetics 55 (1979), S. 225-229 
    Details
    ISSN: 1432-2242
    Keywords: Generation means ; Matrices ; Genetics ; Models
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Gene action and interaction have been defined in the literature by the use of a variety of notations (Mather 1949; Hayman 1954, 1955, 1957; Jinks 1954; Kempthorne 1954, 1955). This leads to unnecessary complications in understanding the subject. This paper provides a simple convenient way of translating one parameterization into another and illustrates the simple linear relationship between them. The various notations are written in matrix form by the use of a specification matrix. This provides a convenient compact method of presentation of the relevant Equations. The linear relationship between the genetic parameters enables these to be estimated in the most convenient way and then converted to other parameters for the purposes of comparison. The generation means Equations of Hayman (1958) are derived using the matrix formulation as an illustration of the use of the specification matrix.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00268116
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Classifying genotypic data from plant breeding trials: a preliminary investigation using repeated checks (1992)
    Springer
    Theoretical and applied genetics 85 (1992), S. 461-469 
    Details
    ISSN: 1432-2242
    Keywords: Cluster Analysis ; Genotype x environment interaction ; Heritability ; Repeatability ; Structure-recovery
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Several subjective choices must be made when classifying genotypes based on data from plant breeding trials. One choice involves the method used to weight the contribution each environment makes to the classification. A second involves the use of either genotype-means for each environment or genotypevalues for each block, i.e., considering each block to be a different environment. Another involves whether environments (or blocks) in which genotypes are nonsignificantly different should be included or excluded from such classifications. An alternative to the use of raw or standardized data, is proposed in which each environment is weighted by a discrimination index (DI) that is based on the concept of repeatability. In this study the effect of three weighting methods (raw, standardized and DI), the choice of using environments or blocks, and the choice of including or excluding environments or blocks in which genotypic effects were not significant, were considered in factorial combination to give 12 options. A data set comprised of five check cultivars each repeated six times in each of three blocks at six environments was used. The effect of these options on the ability of a hierarchical clustering technique to correctly classify the repeats into five groups, each consisting of all the six repeats of a particular check cultivar, was investigated. It was found that the DI weighting method generally led to better recovery of the known structure. Using block data rather than environmental data also improved structure recovery for each of the three weighting methods. The exclusive use of environments in which genotypic effects were significant decreased structure recovery while the contrary generally occurred for blocks. The best structure recovery was obtained from the DI weighting applied to blocks (whether genotypes were significant or not).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00222328
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Evaluation of experimental designs and spatial analyses in wheat breeding trials (2000)
    Springer
    Theoretical and applied genetics 100 (2000), S. 9-16 
    Details
    ISSN: 1432-2242
    Keywords: Key words Wheat ; Breeding trials ; Experimental designs ; Spatial analysis ; Selection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Thirty-three wheat breeding trials were conducted from 1994 to 1996 in the Northern Grains Region (QLD and Northern NSW) of Australia to evaluate the influence of experimental designs and spatial analyses on the estimation of genotype effects for yield and their impact on selection decisions. The relative efficiency of the alternative designs and analyses was best measured by the average standard error of difference between line means. Both more effective designs and spatial analyses significantly improved the efficiency relative to the randomised complete block model, with the preferred model (which combined the design information and spatial trends) giving an average relative efficiency of 138% over all 33 trials. When the Czekanowski similarity coefficient was used, none of the studied models were in full agreement with the randomised complete block model in the selection of the top lines. The agreement was influenced by selection proportions. Hence, the use of these methodologies can impact on the selection decisions in plant breeding.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001220050002
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    The effect of the accumulation of disease resistance genes on the long-term association of a global sample of environments for testing spring bread wheat (2000)
    Springer
    Theoretical and applied genetics 101 (2000), S. 1164-1172 
    Details
    ISSN: 1432-2242
    Keywords: Keywords CIMMYT ; ISWYN ; Mega-environments ; Retrospective analysis ; Pattern analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  CIMMYT (the International Maize and Wheat Improvement Center) has routinely conducted international wheat yield trials to study the adaptation of spring bread wheat. The first of these, the International Spring Wheat Yield Nursery (ISWYN), was conducted for 31 years from 1964 to 1994 inclusive (30 cycles were conducted as no nursery was distributed in 1993 because of Karnal Bunt). Recently, pattern analysis methods have been developed and a set of computer programs written, which enable retrospective analyses of such historical databases to appraise the relationships among test environments in a way that discriminates among genotypes. Such an analysis was conducted on the 30 years of yield data from ISWYN and the classification derived from these analyses was compared with an agroecological classification of spring wheat test environments derived by CIMMYT. The incidence of foliar diseases (stem rust, leaf rust, yellow rust, Septoria spp. and Fusarium spp.) was important in the distinction between the high-rainfall low-latitude (mega-environment 2) and the high-input-irrigated low-latitude (mega-environment 1) environment types. The accumulation of resistance genes for these diseases has been an objective of the CIMMYT wheat breeding program. It was hypothesized that, as the relevant resistance genes were successfully pyramided into the germplasm, the distinction between these two mega-environment types would disappear. The results of the retrospective analyses support this hypothesis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001220051593
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    Patterns of diversity in fatty acid composition in the Australian groundnut germplasm collection (1995)
    Springer
    Genetic resources and crop evolution 42 (1995), S. 243-256 
    Details
    ISSN: 1573-5109
    Keywords: Classification ; genetic diversity ; groundnut ; linoleic acid ; oleic acid ; ordination
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Knowledge of the amounts and types of fatty acids in groundnut oil is beneficial, particularly from a nutritional standpoint. Germplasm evaluation data for fatty acid composition on 819 accessions of groundnut (Arachis hypogaea L.) from the Australian Tropical Field Crops Genetic Resource Centre, Biloela, Queensland were examined. Data for eight quantitative fatty acid descriptors have been documented. Statistical assessment, via methods of pattern analysis, summarised and described the patterns of variation in fatty acid composition of the groundnut accessions in the Australian germplasm collection. Presentation of the results from principal components analysis and hierarchical cluster analysis using a biplot was shown to be a very useful interpretative tool. Such a biplot enables a simultaneous examination of the relationships among all the accessions and the fatty acids. Unlike that information available via database searches, the results from contribution analysis together with the biplot provide a global picture of the diversity available for use in plant breeding programs. The use of standardised data for eight fatty acids, compared to using three specific fatty acids, provided a better description of the total diversity available because it remains relevant with possible changes in the nutritional preferences for fatty acids. Fatty acid composition was found to vary in relation to the branching pattern of the accessions. This pattern is generally indicative of the botanical types of groundnuts; Virginia (alternate) compared to Spanish and Valencia (sequential) botanical types.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02431259
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    Colonization of perspex strips by larvae of Austrosimulium bancrofti (Taylor) near Ipswich, Queensland (1991)
    Springer
    Hydrobiologia 218 (1991), S. 255-263 
    Details
    ISSN: 1573-5117
    Keywords: blackfly larvae ; Simuliidae ; substrate colonization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Larvae of the Taxon Austrosimulium bancrofti (Taylor) were collected from perspex strips placed in rapids of the Brisbane River during January (summer) and October (spring). Separation of larvae according to the mixture approach to clustering demonstrated that: a) October cluster I larvae were larger and underwent an additional cluster to those collected in January, b) there was an additional cluster of larvae in each month, which correlated with the percentage of A. bancrofti Ipswich B that were identified cytologically, and c) greater numbers of later cluster larvae were collected from the strips than early clusters. Multivariate analysis demonstrated that distance from the lip of the rapids, strip texture and water velocity had a significant effect on the number of larvae colonizing perspex strips. Numbers increased with: a) decreasing distance from the lip of the rapids, b) increasing surface area of roughened strips and c) water velocity in the range 1.00 〈 X ≤1.38ms−1. The influence of adult female oviposition behaviour, larval behaviour, sampling time and technique are discussed in relation to the parameters that influenced the colonization of artificial substrates.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00038839
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    An investigation of multi-attribute genotype response across environments using three-mode principal component analysis (1989)
    Springer
    Euphytica 44 (1989), S. 109-123 
    Details
    ISSN: 1573-5060
    Keywords: three-mode principal component analysis ; soybean lines ; ordination ; multivariate analysis ; genotype-environment interaction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The usefulness of three-mode principal component analysis to explore multi-attribute genotype-environment interaction is investigated. The technique provides a general description of the underlying patterns present in the data in terms of interactions of the three quantities (attributes, genotypes, and environments) involved. As an example, data from an Australian experiment on the breeding of soybean lines are treated in depth.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00022605
    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...