Índice MGIDI na seleção de genótipos de milho com melhor eficiência no uso de nitrogênio e tolerância à salinidade

Abstract

Maize (Zea mays L.) plays a fundamental role in the economy and society, being widely used for human consumption and animal feed. In semi-arid regions, high evapotranspiration rates favor salt accumulation in the soil, making salinity a recurrent problem and one of the main limiting factors for agricultural production. This stress negatively affects nutrient uptake and assimilation by plants, especially nitrate, the main form of nitrogen available in the soil, compromising maize growth, development, and productivity. Despite the relevance of this topic, studies aimed at identifying genotypes that combine nitrogen use efficiency and salinity tolerance, particularly under semi-arid conditions, are still scarce. In this context, the objective of this study was to select maize half-sib progenies with superior performance regarding nitrogen use efficiency and salinity tolerance using the MGIDI index (Multi-Trait Genotype-Ideotype Distance Index). The experiments were conducted during the 2024 growing season at the Experimental Farm of the Federal University of Sergipe (UFS), Sertão Campus, under two experimental conditions: irrigated environment (greenhouse) and rainfed condition (field). In the greenhouse experiment, a randomized block design was adopted in a 21 × 2 factorial scheme (genotypes × salinity levels), with three replications. In the field experiment, a randomized block design with split plots was used in a 35 × 2 factorial scheme (genotypes × nitrogen levels), also with three replications. In the greenhouse, morphological and physiological traits were evaluated, while in the field, morphophysiological and postharvest traits were analyzed. The data were subjected to analysis of variance, factor analysis, and application of the MGIDI index. The analysis of variance indicated significant differences for the interaction between genotypes and salinity levels in the greenhouse experiment, as well as for the sources of variation genotype and nitrogen levels in the field experiment. Factor analysis grouped the variables into two factors for the greenhouse experiment and three factors for the field experiment, explaining 82.80% and 80.60% of the total data variance, respectively. In the greenhouse experiment, genotype G9_C2 stood out for presenting greater physiological tolerance to salinity. In the field, genotypes G27, G4, G35, and G31 showed high productive performance and greater agronomic nitrogen use efficiency under contrasting nitrogen availability conditions. Multivariate selection using the MGIDI index proved to be efficient in identifying superior genotypes, highlighting the potential of the selected genotypes for maize breeding programs focused on nitrogen use efficiency and salinity tolerance.