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dc.contributor.advisorRooney, William Len_US
dc.creatorMateo Moncada, Rafael Arturoen_US
dc.date.accessioned2007-04-25T20:11:13Z
dc.date.available2007-04-25T20:11:13Z
dc.date.created2006-12en_US
dc.date.issued2007-04-25
dc.identifier.urihttp://hdl.handle.net/1969.1/4874
dc.description.abstractSorghum (Sorghum bicolor [L] Moench) was first introduced to the United States in the 1800s. These introductions consisted of tropical varieties with a short day photoperiod response that limited their use in temperate hybrid breeding programs. Commercial exploitation of F1 hybrids in grain sorghum started by the mid 1950s with the use of cytoplasmic male sterility system CMS (A1). Even though other CMS are available, most sorghum hybrid seed production still relies on the A1 system. Genetic gain in most agronomic crop species is limited by several factors. In the specific case of sorghum, the uniform use of the CMS (A1) system and the recent introduction of sorghum to the United States have resulted in a reduction of its genetic base. In order to create enough genetic variability, plant breeders might utilize exotic non adapted material, exotic adapted material or existing elite material as a source of new alleles that will protect and improve genetic gain through selection. This study provides an estimate of the genetic diversity existing in a set of sorghum conversion lines. The objectives of this study were: (1) to estimate the genetic diversity present among a set of 16 sorghum conversion lines; (2) to classify this set of lines based on genetic similarities estimated using AFLP markers and (3) to estimate heterosis, general and specific combining ability for grain yield among the set of conversion lines. Genetic diversity was present in the set of conversion lines evaluated. For the lines included only in this study, Caudatum was the most homogenous race (average GS = 0.69), and this race was closely related to the Durra race (Average GS = 0.66). Two other homogenous races were Bicolor and Kafir with average GS of 0.67. Highest GCA effects were obtained from the Kafir and Caudatum races. Good heterotic responses were obtained from DurraKafir races and CaudatumKafir races. Estimation of SCA, MPH and BPH identified specific crosses that were numerically superior than those of the checks. The use of AFLP markers allowed the identification of five strong clusters through estimates of genetic similarities. This classification did not group the lines by either their genetic background or their fertility reaction. This study provides information to identify specific combinations that would help to understand heterotic relationships in sorghum, and support the suggestions made by Menz and Gabriel that races in sorghum are not well defined.en_US
dc.format.extent869808 bytes
dc.format.mediumelectronicen_US
dc.format.mimetypeapplication/pdf
dc.language.isoen_USen_US
dc.publisherTexas A&M Universityen_US
dc.subjectSorghumen_US
dc.subjectBreedingen_US
dc.subjectConversionen_US
dc.subjectGeneticen_US
dc.subjectDiversityen_US
dc.titleGenetic diversity and combining ability among sorghum conversion linesen_US
dc.typeBooken
dc.typeThesisen
thesis.degree.departmentSoil and Crop Sciencesen_US
thesis.degree.disciplinePlant Breedingen_US
thesis.degree.grantorTexas A&M Universityen_US
thesis.degree.nameDoctor of Philosophyen_US
thesis.degree.levelDoctoralen_US
dc.contributor.committeeMemberKevin, Crosbyen_US
dc.contributor.committeeMemberKing, Stephenen_US
dc.contributor.committeeMemberMenz, Monicaen_US
dc.type.genreElectronic Dissertationen_US
dc.type.materialtexten_US
dc.format.digitalOriginborn digitalen_US


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