Mejoramiento de la tolerancia a estrés hídrico en maíz en un programa de mejoramiento público

World maize production is mainly carried out in rainfed systems in which the main limitation to grain yield is usually water availability. In maize, the anthesis-silking interval (ASI, in days) is proved to be a useful secondary trait as it is highly correlated with improved grain yield in drought-prone environments, has high heritability and can be fast and accurately measured in the field. The objective of this work was to characterize and select a set of inbred lines for their tolerance to water stress. To achieve this, 240 inbred lines of the INTA Pergamino Temperate Maize Breeding Program were field grown during the 2019-20 season at high planting density (16 pl.m-2) in a randomized complete block design with 2 replicates. A subset of 50 inbreds was sown in the same site during the dry 2020-21 growing season. Inbreds were characterized for ASI and defensive traits, such as root and stalk lodging. High stand density promoted the expression of significant genotypic differences in ASI (p < 0.05, mean: 2.3 d, range: -3 to +9 d), root (p < 0.05, mean: 26.5%, range: 0 to 100%) and stalk lodging (p < 0.05, mean: 5.3%, range: 0 to 80%). Heritabilities values were 63, 51 and 64 for ASI, root and stalk lodging, respectively. In 2020-21, the 50 inbreds with the lowest ASI values (mean = 0.52), and with less than 20% and 5% root and stalk lodging, respectively were evaluated again, finding significant differences between inbreds (for ASI: p<0.05, mean: 1.8, range: -3 to +6 days). Based on the data obtained in both years, a set of inbreds representative of the different heterotic groups of the breeding program was selected to make biparental crosses and develop new inbreds with shorter ASI, and therefore, with better performance under stressful conditions. For this, the inbreeding from the S0 generation and the evaluation of inbreds in hybrid combination will be carried out at high planting density (16 pl.m-2). This selection method will allow the development of stress-tolerant germplasm.