Genetic Variation of Iranian Lettuce Genotypes Based on Morphological Traits

Lettuce (Lactuca sativa L.) is one of the major leaf and salad vegetables. Identification of the genetic potential of lettuce germplasm is crucial in the breeding programs and introduction of new cultivars. Assessment of genetic diversity of Iranian lettuce germplasm collected from different provinces was conducted in the research field of Seed and Plant Improvement Institute, Karaj, Iran in 2010. Genotypes were sown on rows with the length and spacing 3 m and 60 cm, respectively. Morphological characteristics were evaluated based on IPGRI descriptors. Results revealed high variability among genotypes. Three types of lettuce including stem, leaf and romaine were identified for the first time in Iranian lettuce. There were significant positive correlations between growth period to bolting and flowering in genotypes. Qom genotype and lines no. 15 and 25 of Mazandaran were sensitive to bolting, and Pich-e-Ahvaz, Siah-e-Dezful, Sefid-e-Neishabour, Siah-e-Neishabour and Varamin 3 were resistant. Genotypes were separated into three groups based on cluster analysis in which some groups had above average values for some traits. Factor analysis reduced the 17 evaluated traits to six components which justified 71.8% of changes. Distribution diagram based on the first and second components separated the genotypes into three groups. To conclude, genotypes with desirable characteristics can be used in breeding programs of lettuce in Iran.