The genetic improvement of N (EUN) and P (EUP) use efficiency is a less expensive and more sustainable way to obtain satisfactory grain yields. However, the lack of knowledge about the relationship among the determinant characters of nutrient use efficiency has made the use of early and indirect selection difficult. Therefore, the objective of this study was to identify the relationship among the determinant characters of nitrogen and phosphorus use efficiency in maize. In this study, 14 lines and 39 single-cross hybrids were tested in two experiments with low and high N and P availability, in a completely randomized simple factorial design with two replications. The experiments were conducted in a shade house. Were used PVC cylindrical tubes with 4 dm³ capacity filled with two types of substrate, according to the experiment. The nutrient solutions were provided from the seventh day after transplanting, applying 250 ml tube-1 every two days. Plants were harvested at the stage of six fully expanded leaves (V6) to evaluate the traits: shoot dry mass, specific root area, lateral and axial root length and the two components of EUN and EUP, i.e., the utilization (EUt) and uptake efficiency (EAb). According to the analyses of variance and path analysis of the collected data, EUN and EUP were not significantly influenced by the root traits. The main determinant character of EUN and EUP is shoot dry mass, regardless of the nutrient availability.
Zea mays L.; abiotic stress; indirect selection; early selection
