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Multivariate analysis of turfgrass cell wall components and relationship with black cutworm larval develpment. S.C. Hong and R.C. Williamson The Dept. Entomology Univ. Wisconsin-Madison. Objectives.
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Multivariate analysis of turfgrass cell wall components and relationship with black cutworm larval develpment S.C. Hong and R.C. Williamson The Dept. Entomology Univ. Wisconsin-Madison
Objectives • To examine multi-dimensional relationship between cell wall components of turfgrasses and black cutworm larval development • To compare multivariate analyses
Turfgrass species and cultivars • Creeping bentgrass (cbe) • Reveillie (tbr): The hybrid of Kentucky bluegrass and Texas bluegrass • Kentucky bluegrass • Challenger (chl) • Julia (jla) • Midnight (mid) • Monopoly (mono) • South Dakota (sd) • Young vs. Old based on planting dates • Young: less than 60 d • Old: greater than 365 d
Cell wall components • Dry matter • Acid detergent fiber (adf) • Neutral detergent fiber (ndf) • Lignin • Ash • Total nitrogen • Leaf toughness • Larval weight (lw) from non-choice feeding assay
Multivariate analysis • Fisher’s discriminant analysis • Cluster analysis • Hierarchical clustering method • Kruskal’s non-metric multidimensional scaling • Factor analysis
Fisher’s discriminant analysis • Objective: • To describe graphically the different features of observations from populations • To classify turfgrasses into groups based on collected variables.
Cluster analysis • Exploratory data analysis tool • Sorting different objects into groups in a way that the degree of association between two objects is maximal. • Kruskal’s non-metric multidimensional scaling (MDS) • Hierarchical clustering method (HCM)
Factor analysis • Objective: • To discover if the observed variables can be explained in terms of a much smaller number of variables called ‘factors’ • To fix collinearity • Regression analysis using the result of factor analysis
Factor analysis • ntmlw: log-transformed larval weight • ntmfa1: new data calculated from the first factor loadings and cell wall data • ntmfa2: new data calculated from the second factor loadings and cell wall data
Summary • Discriminant and Cluster analysis • Useful to describe graphically the features of cell wall data • Discriminant analysis and two cluster analyses show similar grouping pattern. • Group one: intratypes • Group two: Young vs. old
Summary • Factor analysis • Remedy for collinearity among some variables (ADF, NDF, lignin, and leaf toughness) • Fitted model with larval weight has a negative coefficient for factor 1 (fa1).
Acknowledgements • United States Golf Association • Amber Klawitter • Dow AgroSciences