THESIS

MATERIALS AND METHODS
1. Investigation of major groups and their association with geographical origin
of Southeast Asian Solanum based on morphological characteristics
1.1 Characterization and determination of major groups of Solanum accessions
originating from Southeast Asia using a standard set of descriptors
The 94 accessions of Solanum spp. were obtained from the Genetic
Resource and Seed Unit (GRSU), Asian Vegetable Research and Development Center
(AVRDC) - The World Vegetable Center, Tainan, Taiwan. These germplasm were
originally collected from six Southeast Asian countries including Cambodia, Laos,
Malaysia, Myanmar, Thailand and Vietnam (Table 1). The seeds of those accessions
were sown in seedling trays inside the greenhouse. Sixteen seedlings per accession
were transplanted to the field under the net cages at 30 days after sowing. The
characterization data were based on seedling, vegetative part, inflorescence, fruit and
seed, following the IBPGR descriptors (IBPGR, 1990) modified by AVRDC
(Appendix A). Species identification is based upon the work of Backer and
Bakhuizen (1965) and Blomqvist and Ban (1999).
1.2 Association of morphological traits and geographical origin of Southeast
Asian Solanum
The characterization data of 89 accessions of Solanum spp. (Appendix
Table A2) originally collected from Southeast Asia were used for cluster analysis.
Morphological characterization of the accessions was based on a standard set of
descriptors developed by the IBPGR and modified by AVRDC. This record sheet was
composed of 61 descriptors with 36 nominal (qualitative) and 25 ratio scale
(quantitative) traits. Data analysis was divided into two steps, preliminary analysis
and cluster analysis. The preliminary analysis based on ratio scale (quantitative) traits
using SAS Software Release 6.03 (SAS, 1999). The cluster analysis was further
divided into individual analyses based on the ratio scale (quantitative) and nominal
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