Genotype-Specific Responses to Drought During Seed Production in Carrot: Biochemical, Physiological, and Seed Quality Evaluation

Drought stress during the reproductive phase substantially reduces seed yield and quality, posing a major challenge to sustainable crop production under climate change. This study investigated the effects of drought stress at the flowering stage on selected biochemical and physiological parameters in 18 carrot accessions. To describe the long-term consequences of drought comprehensively, we examined seed quality parameters. Our analyses revealed that stress responses are highly dependent on the genotype and the parameter examined. Regarding antioxidant responses and potential tissue damage caused by drought, 'Dolanka', DC97, DC265, DC359, DC522, DC701, DC704, and DC720 exhibited the highest tolerance. The photosynthetic apparatus and pigments were maintained under stress in DC233, DC522, DC717, and DC728. Germination parameters served as reliable indicators of stress tolerance in DC97, DC359, DC432, DC522, DC701, and DC722 accessions. Based on these findings and detailed discussion of the results, we conclude that tolerance/sensitivity assessment of carrot genotypes should consider the holistic response of the plant rather than individual parameters. Through overall assessment, we recommended DC522 accession as the most drought-tolerant, given its enhanced ROS (Reactive Oxygen Species) scavenging mechanisms, increased chloroplast pigments accumulation, and superior germination parameters under drought conditions. Conversely, DC295 should not be cultivated under water-deficient conditions due to its impaired ability to detoxify ROS, altered photosynthetic activity, and disrupted seed germination under such conditions. These results collectively highlight the potential for selecting drought-tolerant carrot genotypes in breeding programs targeting improved seed performance under water-limited conditions, thereby supporting the development of resilient cultivars adapted to future climate challenges.