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dc.creatorGomez, Martha I.
dc.descriptionDue to the character of the original source materials and the nature of batch digitization, quality control issues may be present in this document. Please report any quality issues you encounter to, referencing the URI of the item.en
dc.descriptionIncludes bibliographical references.en
dc.description.abstractThe main objectives of this study were to: 1) develop improved methods for flow cytometric determination of nuclear DNA content in G. hirsutum L., and 2) determine the extent of variation in DNA content among different race stocks of G. hirsutum. Flow cytometric determinations of DNA were performed in 32 races of the tetraploid cotton, Gossypium hirsutum L. About 19% variation in mean DNA content was found among the races of cotton analyzed. The range of mean DNA content was from 2C=5.08 pg to 2C=6.05 pg. A general ANOVA was performed, and significant interaction race-leaf effect was present. This indicated that leaf to leaf variation in DNA content was present at least in some of the races analyzed. An individual ANOVA was run for each of the races. The leaf effect was limited to a subset of varieties. Linear and quadratic regression analyses were performed for each of the races. The ones that showed linear, and/or quadratic effects from subset, were the small group of races that presented a significant leaf ef f ect. The origin of the leaf-to-leaf variability in DNA content within plants of some cotton races is an interesting phenomenon that will require further investigation. It could be due to any or a combination of environmental, technical, physiological, or genetics factors including activity of retrotransposons. Grouping of races according to Tukey's multiple range test was performed individually for the first, third and fifth leaves. This was necessary when all the races were included in the ANOVA and a significant leaf-race interaction effect was present. High overlapping of groups was present indicating a high homogeneity in DNA content among races for each of the leaves. Furthermore, more variability in DNA content was observed for the first leaf compared to the third and fifth leaf stages. An ANOVA was performed for the group of races that lacked leaf effect, and no leaf-race interaction was observed. A general Tukey's multiple range analyses was performed for the group of races lacking the leaf effect. Four groups were present. The 19% variation in mean DNA content among these races of cotton is not high compared to other species that have been investigated.en
dc.publisherTexas A&M University
dc.rightsThis thesis was part of a retrospective digitization project authorized by the Texas A&M University Libraries in 2008. Copyright remains vested with the author(s). It is the user's responsibility to secure permission from the copyright holder(s) for re-use of the work beyond the provision of Fair Use.en
dc.subjectMajor genetics.en
dc.titleGenome size variation of Gossypium hirsutumen
dc.format.digitalOriginreformatted digitalen

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