Genetic effects of physiological and morpho-agronomic traits in popcorn under water stress

Understanding the genetic basis of agronomic, morphological and physiological traits in popcorn is key to developing effective breeding strategies under water-limited conditions. This study evaluated additive and dominance effects on 25 traits in 10 S7 inbred lines and their 45 diallel hybrids under water-stressed and well-watered conditions. Water stress was applied 15 days before male flowering by ceasing irrigation. Significant genetic variability was observed, with reductions in grain mass and popping expansion under water stress. Normalized difference vegetation index and relative chlorophyll content effectively detected phenotypic differences during critical growth stages, while canopy temperature depression provided insights into stomatal closure. Some genotypes possessed greater drought resilience, maintaining high chlorophyll levels, associated with the stay-green trait, extending active photosynthesis and increasing biomass accumulation. Dominance effects were predominant for most traits, except for popping expansion and stem diameter, where additive effects were slightly higher under both water regimes. Lines L76, L61 and P3 had high potential for grain yield and drought tolerance. Hybrids L61 × L76 and L71 × L76 performed well under both watering treatments, underscoring the role of heterosis due to dominant allelic interactions. This research highlights the importance of exploring genetic variation for yield and drought-related traits, offering insights for developing popcorn cultivars resilient to water stress.