Selection of discrepant maize genotypes for nitrogen use efficiency by a chlorophyll meter

Abstract

The objective of the present study was to verify if it is possible to discriminate maize genotypes for their efficiency of nitrogen use by readings obtained with a portable chlorophyll meter. 76 topcross hybrids and 5 previously tested controls were evaluated without sidedress nitrogen fertilization and 81 S1 families that only differed in relation to nitrogen sidedress fertilization (with and without). Readings were obtained by the chlorophyll meter in the phenological stages of four and eight fully unfolded leaves. Different negative selection pressure was simulated by the chlorophyll meter readings at each phenological stage and the genotypes were screened for grain yield and efficiency of N use. It was verified that the portable chlorophyll meter can be used to eliminate the least productive genotypes before flowering in quick tests, especially in environments without nitrogen sidedress, although the most effective genotypes regarding nitrogen use could not be discriminated this way.