Journal of Applied Biosciences (J. Appl. Biosci.) [ISSN 1997 - 5902]
Volume 45: 3045 - 3058. Published September 29, 2011.
Diversity of the morphological traits of yam (Dioscorea spp.) genotypes from Sierra Leone
*P.E. Norman1, P. Tongoona2 and P.E. Shanahan3
1Njala Agricultural Research Center (NARC), PMB 540, Freetown, Sierra Leone. 2Africa Center for Crop Improvement (ACCI), University of KwaZulu-Natal, Private Bag X01, Scottsville 3209, South Africa. 3Agricultural Plant Sciences, University of KwaZulu-Natal, South Africa.
Corresponding author email: penorman2008@yahoo.com
ABSTRACT
Objective: The aim of this study was to explore morphological variability existing within germplasm and to characterize 52 yam genotypes using 28 morphological traits.
Methodology and results: A total of 52 yam genotypes from Sierra Leone were grown in a randomized complete block design with three replications during year 2010 at the University of KwaZulu-Natal, Pietermaritzburg, South Africa. Twenty-eight morphological traits measured from the genotypes were analysed using principal component analysis (PCA) and cluster analysis (CA). The first 10 principal components (PCs), which had eigen-values >0.6 explained 86.61% of the total variability. The PCA results indicating traits that largely contributed to the variability within and between the species included: number of days to shoot emergence, shoot traits (position, shape, size, density, vein colour and measurements of leaves; shoot growth rate) and tuber traits (shape and flesh colour). The two-dimensional plots of the first two PCs grouped the accessions according to their species, whereas some of the genotypes within species were grouped according to the various tuber shapes: irregular, oblong, oval-oblong, round and cylindrical. Genotypes WR 07/024, SR 07/075, 07/073, ER 07/032 and NR 07/042 overlapped in sub-groups B1 and B2; whereas genotypes WR07/010, NR 07/041, ER 07/038 and NR 07/067 overlapped in sub-groups B1 and B3. This indicated the possibility of duplication of genotypes in the germplasm. The dendrogram of the CA showed six major groups, which also supported groupings in the PCA.
Conclusion and potential application of results: This study revealed that wide genetic diversity exists in yam production cultivars grown in Sierra Leone which could be used to breed high yielding genotypes and other desired traits such as resistance to local pests and diseases. Findings would also be useful for genetic improvement and conservation planning of yams using molecular techniques to confirm the diversity observed.
Key words: Dioscorea, agro-morphological diversity, genotypes, characterization
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