Deciphering genotypic variation in maize (Zea mays l.) during reproductive stage under moisture stress condition through integrative multivariate analysis

A field evaluation was conducted during the 2025 summer season at Bihar Agricultural University, Sabour, to assess the drought tolerance of twenty maize (Zea mays L.) genotypes under well-watered and drought stress conditions imposed at knee-high (V6–V8; 35 DAS) and tasselling (VT; 60 DAS) stages. Episodic drought significantly reduced leaf area (–14.1%), root volume (–23.5%), plant height (–16.6%), leaf area index (–17.1%), net assimilation rate (–26.0%), and crop growth rate (–25.0%). However, tolerant genotypes such as VMH 1695, DHM 117, and SKM 1 displayed adaptive plasticity through minimal reductions in growth traits and increased root elongation, facilitating improved water uptake. Biochemically, proline accumulation and enhanced catalase and peroxidase activities were consistently higher in tolerant lines, underscoring their role in osmotic adjustment and oxidative stress mitigation. Reproductively, drought delayed tasselling and silking, lengthened anthesis–silking interval, and impaired floral synchrony in sensitive genotypes (e.g., SML 25, SML 212), whereas tolerant entries maintained reproductive stability and yield resilience. Grain yield declined severely in sensitive genotypes (up to –59.3%), but tolerant lines sustained comparatively higher productivity (–14–18% reduction) through efficient canopy retention, assimilate partitioning, and reproductive synchrony. Correlation analysis identified crop growth rate (r=0.97), net assimilation rate (r=0.90), proline (r=0.77), catalase (r=0.71), and cob traits as major contributors to yield under stress, while prolonged anthesis–silking interval correlated negatively (r=–0.71). Principal component analysis explained 69.8% of total variation, with the first two axes distinguishing tolerant from susceptible genotypes and differentiating biochemical from morphological adaptation strategies. Hierarchical clustering and MGIDI analysis consistently grouped DHM 117, VMH 1695, and SKM 1 as ideotype-proximal entries, integrating superior growth performance, antioxidant defenses, reproductive synchrony, and yield stability. Collectively, the study highlights the complementary roles of structural and biochemical resilience in drought adaptation and identifies DHM 117, VMH 1695, and P 3526 as promising donors for breeding drought-resilient maize cultivars