Characterisation And Determination Of Virus Resistance Among Cowpea [Vigna Unguiculata (L.) Walp.] Genotypes

Show simple item record Tettey, C.K. 2018-05-04T09:54:28Z 2018-05-04T09:54:28Z 2017-07
dc.description Thesis (MPhil) en_US
dc.description.abstract Several households in Ghana feed on cowpea [Vigna unguiculata (L.) Walp.] which serves as good source of protein. However, cowpea viral diseases and the lack of adaptable cultivars have become a limiting factor in cowpea production. This work therefore sought to explore morphogenetic diversity and viral resistance traits in cowpea germplasm to improve productivity. Thirty-eight exotic and local cowpea genotypes were cultivated at the Teaching and Research Field of the School of Agriculture, the University of Cape Coast. Two plants were maintained per stand at planting distance of 50 cm x 30 cm with three replications in a randomized complete block layout during the major (June – September) and minor seasons (November – February). The cowpea genotypes were characterised using both morphological and molecular methods to assess diversity in the coastal savanna agro-ecological zone of Ghana. They were also screened for resistance to cowpea viruses using visual scale on-field and DAS-ELISA protocol. The cowpeas showed significant (P < 0.05) variations in plant height, canopy diameter, number of branches, area of leaf, days to 50% flowering, days to pod maturity, pod length, number of seeds per pod and hundred seed weight. There were significant and positive correlations between pod weight and seed yield (r = 0.985, P < 0.05), plant height and canopy diameter (r = 0.576, P < 0.05), canopy diameter and number of branches (r = 0.576) as well as pod length and the number of seeds per pod (r = 0.530, P < 0.05). Hundred seed weight ranged from 10.03 g to 22.7 g. On the whole, 23 quantitative and qualitative parameters differentiated the cowpea genotypes into two main clusters with sub-clusters. Genomic analysis involving nine polymorphic SSR primers showed a mean genetic diversity of 0.7, polymorphic information content of 0.67 and allele frequency of 0.4 among the cowpea genotypes, which were differentiated into two main clusters with sub-clusters. Incidence and severity of cowpea viruses in both the major and minor seasons were significantly (P < 0.05) different among the cowpea genotypes as well as between the two seasons with the minor season showing the higher mean incidence (53.1%) and severity (1.99) compared to 30.9% incidence and 1.49 mean severity recorded for the major season. Of the four cowpea viruses screened on 15 best performing cowpea genotypes using DAS-ELISA, two viruses, Cowpea severe mosaic virus (CPSMV) (1/15) and Cucumber mosaic virus (CMV) (13/15) were detected with one mixed infection CPSMV/CMV recorded in the local genotype Padi-tuya. IT04K-321-2 alone was devoid of viruses and could be resistant but requires further confirmation prior to incorporation into future breeding programmes. en_US
dc.language.iso en en_US
dc.publisher University of Ghana en_US
dc.subject Characterisation en_US
dc.subject Determination en_US
dc.subject Virus Resistance en_US
dc.subject Cowpea [Vigna Unguiculata (L.) Walp.] en_US
dc.subject Genotypes en_US
dc.title Characterisation And Determination Of Virus Resistance Among Cowpea [Vigna Unguiculata (L.) Walp.] Genotypes en_US
dc.type Thesis en_US

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