To achieve coordinated improvement in yield and nutritional quality, the GGE (genotype+genotype×environment interaction) biplot method was employed to systematically dissect the genetic differences, environmental adaptability, and trait stability of potato yield and flavonoid content across different ecological regions. The core objective was to screen elite genotypes with high yield, high flavonoid content, and stability adapted to specific ecological zones, thereby providing theoretical support for breeding nutritionally enhanced potato varieties. A total of 130 potato varieties (lines) were tested in a two-year (2021-2022), 3-location trial conducted in three ecological regions of Gansu province: Weiyuan county, Anding district, and Yongchang county. Plot yield and contents of catechin, rutin, nicotiflorin, quercetin, and kaempferol were measured after harvest. Joint analysis of variance and GGE biplot were used to analyze the genotype×environment interaction for yield and quality traits. The ANOVA showed that, except for plot yield which had no significant year effect, the effects of genotype, environment, and genotype×environment interaction were highly significant (P < 0.01) for all traits. Plot yield, catechin content, and rutin content were mainly influenced by genotype, whereas nicotiflorin, quercetin and kaempferol contents were predominantly affected by genotype×environment interaction. GGE analysis for plot yield indicated that G122 had the highest yield at Anding (2021, 2022), Weiyuan (2022), and Yongchang (2022). G27 had the highest yield at Yongchang in 2021, G36 had the highest yield at Weiyuan in 2021. C18, G122, C6, G102, G42, G49, C3, and G9 were high-yielding and stable. The discriminative power of test locations ranked as Yongchang > Anding > Weiyuan, with the Anding being the most representative. GGE analysis of flavonoid content revealed that G79 had the highest catechin content across all three locations, the highest kaempferol content at Anding and Weiyuan, and the highest nicotiflorin content at Yongchang. C16 had the highest rutin and nicotiflorin contents at Anding and Weiyuan. G37, G4, and G46 had the highest rutin, quercetin, and kaempferol contents, respectively, at Yongchang. G32 had the highest quercetin content at Anding and Weiyuan. G98, G63, G1, G129, and G102 had high and stable catechin content. G37, G113, G49, C11, and G93 had high and stable rutin content. G37, G122, G13, and G21 had high and stable nicotiflorin content. G46, G71, G124, and G79 had high and stable quercetin content. G9, C5, and G27 had high and stable kaempferol content. The discriminative power of test locations ranked as Yongchang > Weiyuan > Anding, with the Yongchang being the most representative for flavonoid traits. Using the GGE model combining plot yield and flavonoid content, elite lines (G122, G102, G49, and G93) were identified as high-yielding, high in flavonoid content, and stable. Considering both discriminatory power and representativeness, Anding is recommended as an ideal environment for yield evaluation, while Yongchang is more suitable for screening varieties (lines) for both yield and flavonoid content under specific environments.
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