Year of Publication

2008

Document Type

Dissertation

College

Agriculture

Department

Crop Science

First Advisor

T.D. Phillips

Abstract

One of the principle factors that limits the areas to which seeded bermudagrass can be adapted is low temperature. Therefore, increasing the winter tolerance of seeded bermudagrass cultivars has been a goal of turfgrass breeders for many years. Design of an efficient breeding method for developing cultivars with increased tolerance to cool and freezing temperatures could be enhanced by having heritability estimates for cold tolerance traits. Additionally, the identification of correlated traits can be useful in improvement of cultivar development. Heritability estimates for winter tolerance can be obtained from cold treatments imposed artificially or from observations made in the field. Parental clones and their respective polycross half-sib families were established in a randomized complete block design with four replications in 2004 in Lexington, KY. Differences in spring green up and fall dormancy measured in 2006 were detected between genotypes within the progeny and parental groups. These same lines were subjected to 15 replications of a freezing treatment in a freeze chamber. Differences in spring green up and fall dormancy were detected between genotypes within the progeny and parental groups. Differences in freeze response were also detected using the artificial freeze treatment. Broad-sense heritabilities were estimated to be 0.895 and 0.573 for spring green-up and fall dormancy respectively. Narrow-sense heritability estimates were found to be 0.885 and 0.265 for these same traits. These results indicate that this population could be improved for cold tolerance using phenotypic recurrent selection. Freeze response was found to be positively correlated to winter hardiness and seed yield in the parent group.

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