Journal of Applied Biosciences (J. Appl. Biosci.) [ISSN 1997 - 5902]
Volume 45: 3059 - 3070. Published September 29, 2011.
Determination of interrelationships among agro-morphological traits of yams (Dioscorea spp.) using correlation and factor analyses
*P.E. Norman1, P. Tongoona2 and P.E. Shanahan3
11Njala Agricultural Research Center (NARC), PMB 540, Freetown, Sierra Leone.
2Africa Center for Crop Improvement (ACCI), University of KwaZulu-Natal P.O.Box Private Bag X01, Scottsville 3209, South Africa. 3Agricultural Plant Sciences, University of KwaZulu-Natal, South Africa.
Corresponding author email: penorman2008@yahoo.com
ABSTRACT
Objective: To determine the interrelationships existing among agro-morphological traits of yams using correlation and factor analyses.
Methodology and results: A total of 52 yam genotypes from Sierra Leone were grown in a randomized complete block design with three replications in 2010 at the University of KwaZulu-Natal, Pietermaritzburg, South Africa. Twenty-eight morphological traits measured from the genotypes were analysed using correlation and factor analysis (FA). Traits that discriminated the most between the accessions were: the number of days to emergence, shoot traits (absence or presence of wings, leaf colour, density, lobation, position, shape and size of leaf, number of stems and branches) and below ground traits (tuber shape and flesh colour of central cross section of tuber). Factor analysis had six factors, which explained 75% of the total genetic variation in the dependence structure. Factor 1 was strongly associated with absence or presence of wings, distance between lobes, leaf apex shape, leaf colour, leaf density, leaf margin colour, leaf length-2 leaf vein colour of the upper surface, number of branch, number of stem, stem colour and tip length of mature leaf; factor 2 with leaf density, leaf length-1, leaf vein colour of lower surface, petiole wing colour, tip colour, wing colour and flesh colour of central cross section of tuber; factor 3 with absence or presence of wings and leaf width-1; factor 4 with leaf width-2; factor 5 with stem colour; and factor 6 with number of days to emergence. Other factors (>7) explained the rest of the genetic variation and may not be important in yam breeding programmes.
Conclusion and potential application: This study revealed that wide genetic diversity exists in yam 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 variation observed.
Key words: Dioscorea, agro-morphological diversity, genotypes, interrelationships
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