Lettuce is an important annual leafy vegetable and bitterness is its potent flavor character. Lettuce germplasm differ their phenotypic characters and sesquiterpene lactones (SLs) contents which are important for consumer’s acceptance. This study was carried out to evaluate the phenotypic characters and SLs contents in one hundred lettuce germplasm in Jeonju, Korea. Twenty-three agro-morphological (16 qualitative and 7 quantitative) traits and two SLs (lactucin and lactucopicrin) contents were studied in these germplasm. Germplasm exhibited the variation in qualitative and quantitative characters. Average plant weight was 423.9 g with a range from 116.0 to 905.0 g. Lactucin content was varied from 19.7 (IT 294226) to 194.4 ㎍/g (IT 294298) with an average concentration of 84.7 ㎍/g. Lactucopicrin ranged from 82.5 (IT 300134) to 2228.6 ㎍/g (IT 294210) with an average concentration of 586.3 ㎍/g. Total SLs content was ranged from 120.1 (IT 300134) to 2286.6 (IT 294210) ㎍/g with the average concentration of 671.0 ㎍/g. Significant (p≤0.05) differences were found between crisp head and butter head germplasm for lactucin, lactucopicrin and total SLs content. Crisp head germplasm revealed the highest average lactucin (112.9 ㎍/g), lactucopicrin (734.8 ㎍/g) and total SLs content (847.7 ㎍/g). Crisp head and leafy type germplasm exhibited more total SLs content (847.7 and 744.7 ㎍/g, respectively) than cos (524.9 ㎍/g) and butter head type (519.4 ㎍/g). Principal component analyses of the quantitative traits indicated that the first principal component axis accounted more than 91% of the total variation. This study revealed the ample genetic variation in the agro-morphological traits and SLs contents to support the selection for improved lettuce varieties.

• Jung-Sook Sung(National Agrobiodiversity Center, National Institute of Agricultural Sciences, RDA, Jeonju 54874, Korea)
• On-Sook Hur(National Agrobiodiversity Center, National Institute of Agricultural Sciences, RDA, Jeonju 54874, Korea)
• Kyoung-Yul Ryu(National Agrobiodiversity Center, National Institute of Agricultural Sciences, RDA, Jeonju 54874, Korea)
• Hyung-Jin Baek(National Agrobiodiversity Center, National Institute of Agricultural Sciences, RDA, Jeonju 54874, Korea)
• Susanna Choi(National Agrobiodiversity Center, National Institute of Agricultural Sciences, RDA, Jeonju 54874, Korea)
• Sang-Gyu Kim(National Agrobiodiversity Center, National Institute of Agricultural Sciences, RDA, Jeonju 54874, Korea)
• Binod Prasad Luitel(National Agrobiodiversity Center, National Institute of Agricultural Sciences, RDA, Jeonju 54874, Korea)
• Ho-Cheol Ko(National Agrobiodiversity Center, National Institute of Agricultural Sciences, RDA, Jeonju 54874, Korea)
• Jae-Gyun Gwak(National Agrobiodiversity Center, National Institute of Agricultural Sciences, RDA, Jeonju 54874, Korea)
• Ju-Hee Rhee(National Agrobiodiversity Center, National Institute of Agricultural Sciences, RDA, Jeonju 54874, Korea)