Multi-year characterization of CIMMYT wheat germplasm for drought resilience: identifying key water-retention and photosynthetic traits for pre-breeding

Recurrent drought threatens wheat production in semi-arid regions, prioritizing the identification of resilient genetic resources for pre-breeding. This study characterized 60 CIMMYT CIMCOG genotypes for drought resilience, evaluating them under well-watered and water-deficient conditions across two seasons (2023–2024) in a multiyear field design. Leaf water status traits (RWC, IWC, WSD, RSD, LWC, RWL, ELWR) and chlorophyll fluorescence traits (SPAD, PI, Fv/Fm) were assessed alongside grain yield, with genotypes ranked using integrated selection tools (BLUPs, YSI, MFV, and PCA). Water deficit reduced photosynthetic efficiency and yield, though genotypic variation was substantial. RWC, SPAD, PI, and ELWR showed high heritability and were positively associated with GY under stress; PCA confirmed these traits clustered with GY. Based on YSI and MFV rankings, nine genotypes (CIMCOG 59, 8, 50, 30, 22, 33, 25, 34, 55) performed consistently well across stability indices and are proposed as candidate donors for further evaluation. This work extends prior CIMCOG characterization by combining excised-leaf water retention with chlorophyll-fluorescence traits and integrated stability metrics, identifying RWC, SPAD, PI, and ELWR as heritable physiological traits associated with yield stability under drought. As findings rest on two- season correlations, further multi-environment validation is needed though results support these traits as screening tools for semi-arid environments.