Drought is a significant climatic factor that significantly affects the production of Chinese cabbage, a crop that is highly susceptible to drought stress. The development and cultivation of drought-tolerant varieties could be a viable strategy to minimize the damage caused by climate change and ensure stable production of Chinese cabbage. This requires the implementation of technologies for early evaluation and selection of a plethora of resources. In this study, we screened 100 varieties and breeding resources for drought tolerance under a water deficit treatment at the seedling stage. We also evaluated the growth response of Chinese cabbage varieties and breeding resources under water deficit treatment and selected drought-tolerant Chinese cabbage genotypes. We confirmed that the visual score for wilting, which evaluates the wilting response during the recovery process of Chinese cabbage seedlings through water deficit treatment and re-watering, can be used as an indicator for evaluating tolerance to drought stress. The visual score for wilting showed a high correlation with major traits representing drought tolerance. Our findings highlight the need for an integrated approach that considers various environmental conditions, varieties, and lines to select and develop drought-tolerant varieties. We selected ‘18-FH112-1’ and ‘18-FH112-1-2’ among others, and these germplasms will be useful resources for drought tolerance breeding. This study provides a foundation for future efforts to develop drought-tolerant Chinese cabbage varieties, thereby contributing to the stable production of this crucial crop.

This study aimed to develop drought tolerance indicators in kimchi cabbage (Brassica rapa ssp. pekinensis) seedlings by integrating chlorophyll fluorescence (CF) imaging parameters with morphological and physiological traits during post-drought recovery. Seedlings of two cultivars, 'Bulam3ho' and 'Hwipalam', were exposed to 5 days of water deficit treatment followed by 12 days re-watering period. Drought stress markedly reduced plant leaf area, plant fresh weight, and leaf water content, while increasing dry matter content. Gas exchange traits, including the net photosynthetic rate, transpiration, and stomatal conductance, declined significantly, whereas the intercellular CO 2 concentration increased under drought stress and gradually decreased during the recovery period, indicating a transition from stomatal to non-stomatal limitation of photosynthesis. CF parameters, particularly F v /F m and F v /F 0 , decreased under drought but gradually recovered upon re-irrigation, which indicated reversible photoinhibition of photosystem II. Following re-irrigation, the two cultivars showed distinct recovery dynamics. 'Bulam3ho' recovered more rapidly in terms of growth, development, and photosynthetic activity, whereas 'Hwipalam' recovered slowly with greater photochemical stability. These results demonstrate distinct recovery strategies between the two cultivars, reflecting their different physiological responses to drought. Moreover, significant correlations among CF indices, gas exchange traits, and morphological parameters demonstrate that CF imaging parameters serve as reliable and non-destructive indicators of drought response and recovery. These findings highlight the potential of CF-based phenotyping for high-throughput screening and breeding of drought-resilient kimchi cabbage cultivars.