PHENOTYPIC DIVERSITY OF SWEET POTATO (IPOMOEA BATATAS[L.]LAM.) GERMPLASMUSING QUANTITATIVE TRAITS: A PRE- BREEDING STUDY IN TOGO

Objective: Sweet potato is a root and tuber crop which contribute to food security in Togo. However, little scientific data exists on the genetic variability of cultivars grown in Togo, although this information is a prerequisite for development of new varieties. The objective of this study was to explore the phenotypic diversity within Togos sweet potato cultivars. Materials and Methods: The germplasm is composed of sixty five (65) cultivars from Togo and sixteen (16) exotic varieties introduced from Burkina Faso breeding unit. The experiment was laid out in a 9 x 9 lattice square design with three replicates. In total, sixteen (16) quantitative traits were evaluated using the sweet potato ontology as described by CIP. Results:Descriptive statistics, ANOVA and PCA revealed high variability for traits such as root yield, dry matter content, aboveground biomass, stem length, internode length and stem diameter. Cluster analysis performed on the basis of the Euclidean distance between cultivars using Ward method as aggregation criterion has revealed four phenotypic clusters. Clusters I and II are composed of varieties with low root yield (12.95 and 15.87 t.ha-1) and high dry matter content (29.68 and 26.86%). Clusters III and IV are made of varieties exhibiting high aboveground biomass (37.74 and 50.75 t.ha-1), high fresh root yield (16.06 and 20.18 t.ha-1) and low dry matter content (24.62 and 23.84%). The variability observed in this gene bank constitutes a basis for genetic improvement programmes of sweet potato in Togo.