Evaluation of Horticulture Performance and Genetic Diversity of 72 Mini Cucumber Varieties Adapting to Off‐Season Production in High‐Altitude Taibai County of Shaanxi Province, China

Cucumber is an economically important vegetable crop cultivated and consumed worldwide. The high‐altitude region of Taibai County in China offers an ideal environment for high‐quality vegetable production, especially during the summer season of lowland areas. However, suitable cucumber cultivars for Taibai County with high‐quality, such as Mini cucumber (the Beit Alpha type), are still lacking. To diversify local cucumber production of Taibai County, this study introduced 72 Mini cucumber cultivars and evaluated their adaptability and genetic diversity. We assessed key morphological traits, including sex expression, fruit shape index (FSI), immature fruit rind color, and downy mildew resistance under local growing conditions. Significant phenotypic variation was observed for these cucumbers. There were 50% of lines that were gynoecious or subgynoecious. The FSI of these Mini cucumbers ranged from 1.4 to 7.5. Besides, the downy mildew resistance also varied widely, with several lines showing promising resistance. Genetic analysis using 19 polymorphic SSR markers revealed moderate diversity across the panel, with an average polymorphism information content of 0.29. Population structure analysis divided the accessions into two distinct groups, with Group I enriched for gynoecious lines. The genetic data, combined with phenotypic evaluations, identified superior lines such as the downy mildew‐resistant mini044 and the short‐fruited mini047, and mini033. This study provides a valuable foundation for breeding and selecting Mini cucumber cultivars adapted to high‐altitude production systems, supporting the diversification and sustainability of vegetable cultivation in these unique agro‐ecological niches.