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University of Namibia (2015)

The genetic diversity of Pennisetum Glaucum (L.) R BR. (Pearl Millet) Landraces in Namibia

Mcbenedict, Billy M.

Titre : The genetic diversity of Pennisetum Glaucum (L.) R BR. (Pearl Millet) Landraces in Namibia

Auteur : Mcbenedict, Billy M.

Université de soutenance  : University of Namibia

Grade : Master of Science (MS) 2015

Résumé
The current Pennisetum glaucum (L.) R. Br. cultivars in Namibia have overall poor performance and this poses a threat to the nation’s food security because this crop is staple for over 70% of the Namibian population. The crop suffers from a range of undesirable production traits such as ; susceptibility to diseases, low yield and prolonged reproductive cycle due to lack of genetic diversity. This study was aimed at understanding the genetic diversity of the crop in Namibia by means of Internal Transcribed Spacer (ITS) sequence data analysis, and SSR and RAPD techniques, and evaluating the most informative technique of the three. A total of 1441 genotypes were collected from the Gene Bank representing all the Namibian landraces. Samples of 96 genotypes were further analyzed using the Shannon-Wiener diversity index and revealed values of 0.45 for SSR and 0.7 for RAPD indicating low genetic diversity. Ordination results using Principal Coordinate Analysis (PCoA) for RAPD, morphology and SSR data confirmed the same clusters as generated by Un-weighted Pair Group Method with Arithmetic Mean (UPGMA) for the same data sets. UPGMA generated phenograms of 29 morphological characterized genotypes were generated for SSR, RAPD and morphology data. The ITS sequences of the same 29 accessions were used to construct a phylogenetic tree. This tree revealed clades with highest similarity with the phenogram generated from morphology (78%) data, followed by the SSR data (68%), and lastly the RAPD (50%) data. Lodging susceptibility, tillering attitude, spike density, bristle length, fodder yield potential, early vigour, number of nodal tillers and spike shape were identified as the phenotypic characters upon which some clusters were based in all data sets used. It is recommended that efforts be made to widen the available gene pool in order to increase genetic diversity in Namibia by introducing genetically diverse accessions from other countries and maintaining the diversity through breeding programs.

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Page publiée le 27 novembre 2018