| This study comprehensively analyzed the genetic differences of water-soluble vitamin content in potato varieties (lines), evaluated the effect of genotype-by-environment interactions (GEI) on vitamin content, and assessed the adaptability and stability under multiple environments. The ultimate aim was to select the excellent potato varieties with high and stable water-soluble vitamin content, providing a scientific basis for breeding high-nutrition potato cultivars. A total of 26 potato varieties cultivated over two years at three locations were used as materials, and the content of ten water-soluble vitamins in potato tubers (ascorbic acid, thiamine, riboflavin, niacinamide, nicotinic acid, pantothenic acid, pyridoxine, pyridoxamine, biotin, and folic acid) was determined using liquid chromatography-mass spectrometry (LC-MS). The genetic variation, environmental adaptability, and stability of water-soluble vitamin content in different ecological regions were investigated with the variance analysis and the Genotype + Genotype × Environment Interaction (GGE) biplot method. Combined with membership function method, the comprehensive evaluation was conducted to screen potato varieties (lines) with excellent performance. There were extremely significant differences in the genotype effect, environmental effect, GEI effect, year -environment interaction effect, and genotype-year-environment interaction effect in ascorbic acid, thiamine, riboflavin, nicotinamide, niacin, pyridoxine, and pyridoxamine content, respectively. The GGE biplot analysis indicated that C3 exhibited the highest adaptability at Weiyuan and Shandan, while H1 performed the best at Yongchang. The higher and stable vitamin content was identified in C2, H1, and G57 for ascorbic acid; A7, H1, and A4 for thiamine; H2, H7, and G57 for riboflavin; G25, G23, and C5 for nicotinamide; G25, C7, and G23 for niacin; H2, C4, and C7 for pantothenic acid; G23, H6, and A3 for pyridoxine; H5, C3, and H6 for pyridoxamine; G1, A5, and G25 for biotin; C3, A1, and H3 for folic acid. The discriminative ability of trial sites ranked as follows: Weiyuan in 2022 > Yongchang in 2023 > Shandan in 2022, with Weiyuan in both two years being the most representative. The integration of GGE model and membership function method facilitated a comprehensive evaluation of water-soluble vitamin content in potato cultivars (lines). H1, C3, H3, G23, and A5 showed the best overall performance under three environments. Weiyuan was identified as the ideal site for screening excellent genotypes under multi-environment conditions, while Yongchang and Shandan were more suitable for selecting genotypes with specific water-soluble vitamins. |