Sat, 26 Jul 2008 08:10:38 BST CiteULike: vrich's cda http://www.citeulike.org/user/vrich/tag/cda CiteULike.org en-gb Copyright © 2004-2008 citeulike.org http://www.citeulike.org/user/vrich/article/2775775 <i>Crop Sci, Vol. 44, No. 1. (1 January 2004), pp. 185-189.</i><br /><br />For improvement of hairy vetch (Vicia villosa Roth) as a winter cover crop, it is necessary to gain insight into the magnitude of variability present in the species. This study was conducted to assess the sources of genetic and phenotypic variability of V. villosa accessions. Thirteen morphological and agronomic traits were measured on 42 populations of V. villosa and two populations of V. pannonica Crantz in field studies at Urbana, IL, for 2 yr. These measurements include initial seed weight, germination, stem length, stem width, leaf length, and leaf width in the fall and spring, winter survival, biomass, and a ratio of organic C to total N (C:N ratio) of the plants. The multivariate data set was analyzed by canonical discriminant analysis (CDA) in combination with a clustering procedure. In this analysis, the first two canonical variates were significant and accounted for 94% of the among-accession variability. The canonical variates indicated that fall and spring measurements of the leaf and stem, and C:N ratio are the most differentiating traits among the accessions. The canonical variates were used to cluster the accessions into four subgroups on the basis of the differentiating traits. Canonical discriminant analysis was useful in identifying the genetic variation and the traits that better describe the variation among hairy vetch populations. Cluster analysis was successful in differentiating the accessions into similar subgroups on the basis of the measured traits. Plant breeders can use the information on variation among Vicia accessions and focus on traits of particular significance. Assessment of Genetic Variation in Hairy Vetch Using Canonical Discriminant Analysis Kathleen Yeater German Bollero Donald Bullock Lane Rayburn Sandra Rodriguez-Zas Crop Sci, Vol. 44, No. 1. (1 January 2004), pp. 185-189. 2008-05-09T12:54:55-00:00 2004 Crop Sci 44 1 185 189 cda http://www.citeulike.org/user/vrich/article/2746821 <i>The American Statistician, Vol. 46, No. 3. (1992), pp. 217-225.</i><br /><br />Canonical discriminant functions are defined here as linear combinations that separate groups of observations, and canonical variates are defined as linear combinations associated with canonical correlations between two sets of variables. In standardized form, the coefficients in either type of canonical function provide information about the joint contribution of the variables to the canonical function. The standardized coefficients can be converted to correlations between the variables and the canonical function. These correlations generally alter the interpretation of the canonical functions. For canonical discriminant functions, the standardized coefficients are compared with the correlations, with partial t and F tests, and with rotated coefficients. For canonical variates, the discussion includes standardized coefficients, correlations between variables and the function, rotation, and redundancy analysis. Various approaches to interpretation of principal components are compared: the choice between the covariance and correlation matrices, the conversion of coefficients to correlations, the rotation of the coefficients, and the effect of special patterns in the covariance and correlation matrices. Interpretation of Canonical Discriminant Functions, Canonical Variates, and Principal Components Alvin Rencher doi:10.2307/2685219 The American Statistician, Vol. 46, No. 3. (1992), pp. 217-225. 2008-05-02T18:54:10-00:00 1992 The American Statistician 46 3 217 225 American Statistical Association analysis cda stats