Genotype × water deficit interactions drive contrasting phenotypic responses and production outcomes in brazilian and andean maize

Abstract

Water deficit is one of the main constraints to maize (Zea mays L.) productivity, highlighting the need to understand genotype × environment interactions to develop resilient cultivars and efficient management strategies. In this study, two contrasting genotypes, INIA 618 (Andean genotype) and B2782PWU (Brazilian genotype), were evaluated under two water regimes: Well Watered (100% WW) and Water Deficit (50% WD) during the V14 stage. An integrative approach was applied (physiological, biochemical, anatomical, and biometric) combined with multivariate analyses and the Multivariate Plasticity Index (MVPi). The results revealed contrasting strategies. In INIA 618, physiological plasticity was the most prominent (MVPi = 148.65 ± 74.33), with a 2.07-fold increase in proline and a 2.20-fold increase in soluble sugars under water deficit. At the biometric level, shoot biomass increased 1.07-fold and root biomass 1.16-fold, whereas plant height decreased 0.92-fold. In the reproductive component, grain area decreased 0.61-fold and grain number 0.90-fold, resulting in a reduction of the harvest index (0.70-fold). These adjustments reflect a conservative strategy prioritizing physiological and anatomical stability over reproductive efficiency. In contrast, B2782PWU exhibited lower physiological (MVPi = 17.58 ± 8.84) and anatomical plasticity (7.35 ± 3.80), but greater biometric plasticity (6.19 ± 3.24). This genotype maintained stable plant height (1.00-fold) and grain number (1.00-fold), preserving 3.7 times more grains than INIA 618 under water deficit. However, it experienced a sharp reduction in root biomass (0.56-fold), reflecting a maintenance strategy that safeguards productivity at the expense of belowground development. The harvest index decreased only 0.82-fold, remaining 2.7 times higher than INIA 618 under stress. These findings demonstrate that physiological plasticity may entail a productive cost, whereas biometric plasticity supports yield stability. From an applied perspective, INIA 618 appears more suitable for environments with severe and recurrent drought, while B2782PWU shows advantages under moderate or intermittent water deficit. The use of MVPi enables anticipation of trade-offs between plasticity and productivity, providing a practical tool for genotype selection and management decisions under water scarcity.