Nitrogen impacts on maize yield in contrasting stress environments

Nitrogen (N) fertilization and drought stress have large influence on maize grain yield, thus studies about genotypes and management technologies are very important to increase maize production. This study is presented in three chapters; the first two were undertaken in the United States of America and the third one in Brazil. The objectives were: to understand which traits, if any, differ between similar-maturity tolerant and non-drought tolerant hybrids that govern nutrient uptake and concentrations under different management treatments (varied plant densities (PD) and N rates) and their influence on grain yield (GY). To investigate the physiological and yield responses of comparable-maturity drought and non-drought tolerant hybrids to varied plant density and N rates. And to investigate the responses of maize to sidedress N applications, using isotopically labeled urea fertilizer (15N), at different development stages.