Genetic diversity and clustering of tomato(Lycopersicum lycopersicum (L.) Karsten) successions in Laos based on morphological traits

Traditional (63), introduced (4) and locally improved (2) varieties of tomato collected from Central, Southern and Northern provinces of Laos were characterized based on their morphological traits to assess the genetic diversity using the Shannon-Weaver Diversity index. At similarity coefficient of 12.56, the dendogram generated six clusters. Only one accession, XKH100, from central Laos was assigned to Cluster 1, indicating that it is widely different from the rest of the accessions. Two introduced varieties (HHRCS and HHRC6) from Asian Vegetable Research and Development Center (AVRDC) belonged to Cluster 2. VTC25 was the lone accession assigned to Cluster 3, and was significantly different from the 18 genotypes collected from the same area. Cluster 4 included two sub-clusters with four accessions sourced from the three different areas. Cluster V had also four accession collected from the same site. Fifty-seven accessions were assigned to Cluster 6. Accessions under Cluster 1, 2 and 3 can be hybridized with those in Clusters 4, 5, and 6. Sixteen accessions had shorter maturity period (82 days) which is a preferred characteristic for hybrid production. High percentage fruit setting under high temperature conditions was observed in 2 accessions. Most of them had sparse leaf density. Fruits that are red, either slightly flattened, rounded, high rounded, or heart-shaped and with thicker fruit wall are desirable, these being preferred by the Laos market. All accession had small fruits based on International Plant Genetic Resources Institute (IPGRI) descriptor. High yield were obtained in 12 accessions indicating good performance. The 15 accessions with good potential for F1 tomato hybrid production were: BKX40, HHRC 5, HHRC 6, HHRC DK, HHRC MT, KHM 76, KHM 77, VTC21, VTC23, VTC32, VTC35, VTC 42, VTC 69, XKH100, and XYB106. These accessions possess two-fourths desirable traits based on the presumption that parents with good performances in most aspects usually produce a larger proportion of the progenies with better performance.