Phenotypic Characterization of Dioscorea burkilliana J. Miège (Dioscoreaceae) Genetic Resources
I. T. Gbadamosi
Department of Botany, University of Ibadan, Nigeria.
M. Abberton
International Institute of Tropical Agriculture, Ibadan, Nigeria.
A. C. Igwe
Department of Botany, University of Ibadan, Nigeria.
F. Soyode
International Institute of Tropical Agriculture, Ibadan, Nigeria.
O. J. Olawuyi *
Department of Botany, University of Ibadan, Nigeria.
*Author to whom correspondence should be addressed.
Abstract
Aims: This study investigated morphological characterization of eighty accessions of Dioscorea burkilliana obtained from the Genetic Resources Center of International Institute of Tropical Agriculture (IITA) Ibadan, Nigeria.
Study Design and Methods: The experimental field was laid out in a complete randomized design with three replicates on plots of 10 meters length spaced at one meter between rows and one meter within rows (10 m x 1 m x 1 m).
Results: The evaluation of nine qualitative and six quantitative traits revealed phenotypic variations in D. burkilliana accessions using IPGRI’s descriptors. The mature stem colour of spot at spine base (MSCSSB) had the highest mean of 61.73 cm, while young stem with absence or presence of scale leaves (YSA/PSL) had least value of 0.37 cm. The principal component analysis (PCA) produced the highest eigenvector of 3.122 for Prin 1 with highest proportion of 20.81%, while Prin 15 had the least (0.11%). Also, in Prin 1, the mature leaf petiole at base (MLP A), mature leaf petiole at middle ( MLP B) and mature leaf petiole at top (MLP C) were closely related compared to matured leaf measurement MLM-Breadth A, MLM-Breadth B and MSA-PCS. There was positive and strong relationship between mature leaf petiole at base (MLP-A) with mature leaf petiole at middle (MLP-B) (r = 0.84, p< 0.005) and mature leaf petiole at top (MLP-C) (r = 0.75). The dendrogram was delineated into seven cluster groups in which cluster V had 18 accessions which was the highest, while cluster VI had the least with one accession (DbB 222).
Conclusion: The strong positive associations among MLP-A, MLP-B and MLP-C as well as MSS SAB and MSA/PCS suggested the consideration of these traits for future breedings. Accessions DbB 83, DbB 140 and DbB 254 could be recommended as parent material for the improvement of Discorea burkilliana.
Keywords: Dioscorea burkilliana, accessions, morphological character, phenotypic variation, dendrogram.