Genetic Diversity of Tomato Germplasm in Ghana using Morphological Characters

Tomatoes constitute an important fruit vegetable crop in Ghana. However, its diversity is low and may be associated with numerous biotic stresses that pose serious threat to production.
Aim: To characterize 216 germplasm gathered from Korea (RDA), Taiwan (AVRDC), Burkina Faso and Ghana based on their morphological characters.
Study Design: An augmented randomized complete block design with six blocks and three checks.
Place and Duration of Study: Crops Research Institute, Kwadaso station, Kumasi- Ghana, from August 2012 to November 2012.
Methodology: Two hundred and sixteen tomato germplasm were planted in single rows at spacing of 100cm by 50cm. Each row had 12 plants per accession.
Data on morphological variables were measured using AVRDC descriptor list which was then subjected to multivariate analysis using Principal Component Analysis (PCA) and Clustering Criterion.
Results: Characters contributing most to variability were stem and fruit pubescence, leaf attitude, style, stamen length, colour of immature fruit, fruit skin colour, folia density, ease of fruit wall to peel and plant habit. Scores of the first principal component (PC-1) accounted for 11.88% of the total variation were highly correlated (correlation coefficient >0.3) to characters related in number of days to first flowering, number of days to 50% flowering and that of number of days to 100% flowering. The pruned dendogram generated through agglomerative hierarchical clustering based on the similarity matrix revealed two main groups according to the major morphological characters associated with them.
Conclusion: This study has shown that there is a wide variability in the accessions assembled. These can be used to breed high yielding varieties and/or screen for tomato fruits resistance to pest and disease infestation. The results of this study would be useful for conservation set up and genetic improvement, however, additional confirmation research is required using molecular tools to scrutinize the diversity detected.