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ASSOCIATION OF KENTUCKY BLUEGRASS CHARACTERISTICS WITH BLUEGRASS BILLBUG

ARTHUR HENRY BRUNEAU, University of Nebraska - Lincoln

Abstract

Anatomical, morphological, and physiological characteristics of 12 Kentucky bluegrass (Poa pratensis L.) cultivars were studied and analyzed to: (1) determine criteria for selecting billbug resistant cultivars and (2) identify mechanisms of resistance. Injury rating exhibited a positive (r = 0.52) correlation with shoot size, but a negative (r = 0.53) correlation with shoot density. Larval density exhibited a negative (r = 0.54) correlation with percent lignified leaf tissue, but a positive (r = 0.74) correlation with shoot size. A negative correlation was found between total cell wall content of field grown plants harvested and larval density (r = 0.88) or injury (r = 0.70). Cellulose appeared to be the primary constituent responsible for this relationship. An Instron Universal Testing Instrument was used to measure the force required to shear and puncture individual shoots. A negative correlation (r = 0.60) was found between shoot shear strength for spring harvested field grown plants and larval density. A positive correlation was noted between etiolated shoot weight and larval density (r = 0.75) or injury rating (r = 0.50). Discriminant analysis was used as an allocation and separatory technique. Discriminant analysis was useful because overestimation of variable information content and dimensionality of data was reduced. Separatory discrimination suggested that highly and moderately resistant cultivars possessed tougher tissue but lower recuperative potential than susceptible or tolerant cultivars. Ability to conceal billbug injury appeared to distinguish tolerant and highly resistant cultivars from susceptible and moderately resistant cultivars, respectively. Development of a classification procedure appeared promising with correct prediction ranging from 67 to 98% depending upon number and type of discriminating variables analyzed. Correct prediction was enhanced by increasing discriminating variable number or by jointly analyzing variables measured under different growing conditions. Most promising classification techniques involved analyses of variables associated with greenhouse (etiolated shoot weight, root regrowth, and etiolated shoot number) and field grown (shoot strength and size, epidermal short cell and prickle hair count, and total cell wall content) plants. More extensive tests are needed before definitive conclusions can be made.

Subject Area

Agronomy

Recommended Citation

BRUNEAU, ARTHUR HENRY, "ASSOCIATION OF KENTUCKY BLUEGRASS CHARACTERISTICS WITH BLUEGRASS BILLBUG" (1983). ETD collection for University of Nebraska-Lincoln. AAI8318651.
https://digitalcommons.unl.edu/dissertations/AAI8318651

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