title: Quantitative Relationship of Soil Texture with the Observed Population Density Reduction of Heterodera glycines after Annual Corn Rotation in Nebraska.
abstract: Soil texture has been commonly associated with the population density of Heterodera glycines (soybean cyst nematode: SCN), but such an association has been mainly described in terms of textural classes. In this study, multivariate analysis and a generalized linear modeling approach were used to elucidate the quantitative relationship of soil texture with the observed SCN population density reduction after annual corn rotation in Nebraska. Forty-five commercial production fields were sampled in 2009, 2010, and 2011 and SCN population density (eggs/100 cm(3) of soil) for each field was determined before (Pi) and after (Pf) annual corn rotation from ten 3 × 3-m sampling grids. Principal components analysis revealed that, compared with silt and clay, sand had a stronger association with SCN Pi and Pf. Cluster analysis using the average linkage method and confirmed through 1,000 bootstrap simulations identified two groups: one corresponding to predominant silt-and-clay fields and other to sand-predominant fields. This grouping suggested that SCN relative percent population decline was higher in the sandy than in the silt-and-clay predominant group. However, when groups were compared for their SCN population density reduction using Pf as the response, Pi as a covariate, and incorporating the year and field variability, a negative binomial generalized linear model indicated that the SCN population density reduction was not statistically different between the sand-predominant field group and the silt-and-clay predominant group.
authors.affiliation: Department of Plant Pathology, University of Nebraska-Lincoln, Lincoln, NE 68583.
authors.forename: Oscar
authors.initials: O
authors.lastname: Pérez-Hernández
authors.affiliation: Department of Plant Pathology, University of Nebraska-Lincoln, Lincoln, NE 68583.
authors.forename: Loren J
authors.initials: LJ
authors.lastname: Giesler
keywords: Heterodera glycines; corn rotation; ecology; multivariate analysis; negative binomial; soil texture; soybean cyst nematode