Multivariate analysis unveils antioxidant-nutrient trade-offs in Maize Hybrids: A hierarchical framework for acid soil tolerance evaluation

Background and Aims Acid soils, characterized by nutrient deficiencies and metal ion toxicity, severely limit maize yields. Cultivating acid soil tolerant maize represents a promising strategy to address these edaphic constraints. Methods Through controlled pot experiments, 50 maize hybrids were subjected to acidic soil stress (AS) and optimal soil conditions (CK), evaluating 15 morpho-physiological traits at the V5 stage. Multivariate statistical approaches were employed to identify critical tolerance indicators, with subsequent field validation conducted on four selected genotypes. Results Acidic soil stress induced significant alterations across all measured parameters compared to control conditions and revealed substantial genotypic variation in stress responses. Cluster analysis classified the 50 hybrids into five distinct tolerance categories, with two predominant adaptation strategies. Antioxidant-dependent resistance characterized by elevated peroxidase (POD), ascorbate peroxidase (APX), and catalase (CAT) activities. This strategy prioritized oxidative defense at the expense of biomass production (acid-sensitive varieties). Nutrient optimization strategy demonstrated by superior nitrogen and phosphorus acquisition efficiencies, enabling sustained growth under stress conditions (acid-tolerant varieties). Stepwise regression identified six critical evaluation parameters: plant height, fresh weight, stem diameter, leaf area, total nitrogen and phosphorus accumulation, complemented by antioxidant enzyme profiles and reactive oxygen species levels. Conclusion This study establishes a comprehensive evaluation framework incorporating 11 validated indicators for screening adaptive maize varieties in acid soil conditions. Field validation confirmed the accuracy of multivariate analysis in selecting acid soil tolerant varieties.