Enhancing drought tolerance in cumin through physiological and genetic insights from a synthetic variety

Developing drought-tolerant crop varieties is essential for sustainable agriculture and food security, particularly in arid and semi-arid regions. This study introduces a newly developed cumin variety (Cuminum cyminum L.), a high-value medicinal plant, bred for enhanced resilience against drought stress. The synthetic variety was evaluated over three growing seasons under normal irrigation (field capacity) and severe drought stress (30% of field capacity) conditions. Results indicated that the synthetic variety exhibited a 71.59% higher seed yield, 46.53% greater chlorophyll a content, 24.03% more total chlorophyll, and a 52.90% increase in proline accumulation under drought stress compared to parental genotypes. Under drought stress conditions, the enzymatic activity of catalase, peroxidase, and ascorbate peroxidase was 131.81%, 122.05%, and 264.78% higher, respectively, in the synthetic variety compared to the parental genotypes, contributing to its improved drought tolerance. Furthermore, the synthetic variety demonstrated a 95.02% increase in essential oil content and favorable shifts in essential oil composition under stress conditions. Molecular analysis using ISSR markers revealed significant genetic diversity with polymorphic percentages ranging from 66.67 to 100%. Clustering and principal coordinates analysis (PCoA) confirmed clear distinctions between the synthetic variety and its parental genotypes. These findings highlight the synthetic cumin variety as a promising candidate for sustainable agriculture in water-limited regions, combining drought tolerance with superior agricultural productivity.