Screening tomato genotypes for early-stage drought tolerance using polyethylene glycol-induced osmotic stress

Drought stress is a major abiotic constraint to tomato (Solanum lycopersicum L.) production, particularly at early developmental stages. Screening genotypes under controlled osmotic stress is crucial for identifying drought-tolerant cultivars. This study evaluated five tomato genotypes Khumal 2, Monoprecos, NGRCO9569, NGRCO9571, and Srijana for germination and seedling performance under polyethylene glycol (PEG)-induced drought stress to identify resilient candidates for breeding programs.

A completely randomized design (CRD) experiment was conducted under three PEG levels (0%, 3%, and 6%). Significant genotype × stress interactions were observed (p < 0.05) across germination and seedling traits. NGRCO9569, Monoprecos, and Khumal 2 maintained high germination rates, seedling vigor, and biomass under stress. In contrast, Srijana exhibited sharp declines in all measured parameters, including complete germination failure at 6% PEG. Vigor index and root-to-shoot ratio increased in tolerant genotypes, indicating effective stress adaptation. Multivariate analyses, including MGIDI and DRI indices, consistently ranked NGRCO9569 and Khumal 2 as top performers. Strong positive correlations were found among plant height, root spread, biomass, and vigor.

NGRCO9569, Monoprecos, and Khumal 2 demonstrated superior drought tolerance under PEG-induced stress and are promising candidates for field validation and breeding. The observed genetic variability highlights potential for drought-resilient tomato improvement. Integrating these genotypes into molecular studies focusing on QTL mapping and gene expression profiling will aid in developing climate-resilient cultivars suited for low-irrigation environments.