Integrated Morpho-Physiological and Biochemical Markers Rank Wheat Genotypes for Salinity and Drought Tolerance at the Seedling Stage

Salinity and drought are major constraints to wheat productivity, affecting growth, photosynthesis, and cellular homeostasis. While many studies have examined responses to these stresses individually, comparative evaluation of genotypes under both stresses using an integrated physiological, biochemical, and multivariate framework remains limited. Here, six wheat genotypes were evaluated at the seedling stage under controlled salinity and drought treatments to identify key morphological and physio-biochemical markers associated with stress resilience. Both stresses reduced shoot and root growth, biomass, gas exchange, and photosynthetic pigments, with drought causing stronger inhibition. Among genotypes, Akbar-2019 exhibited the greatest tolerance, maintaining higher growth, pigment stability, photosynthetic performance, and membrane integrity, whereas Subhani-2021 was the most sensitive. Stress-induced osmotic adjustment was evident from increased proline, soluble sugars, and free amino acids, particularly in Akbar-2019. Antioxidant enzymes (SOD, POD, CAT, APX) were elevated under both stresses; Akbar-2019 combined stronger antioxidant activity with lower malondialdehyde and hydrogen peroxide levels, indicating effective mitigation of oxidative damage. Multivariate analyses (PCA, heatmap clustering, and MGIDI) consistently ranked Akbar-2019 as the most resilient genotype. These findings provide a novel, integrative framework for screening wheat under multiple abiotic stresses, identify promising genotypes for breeding and cultivation in stress-prone environments, and highlight combined morpho-physiological stability, osmolyte accumulation, and antioxidant capacity as informative markers for stress tolerance.