Agronomic and spectral performance of corn varieties submitted to different levels nitrogen

Corn production in Brazil has been increasing over the past decade. Despite the growing increase in production in the Cerrado biome, it is challenging to obtain profitable cultivation in these areas of remarkably low natural fertility. Nitrogen (N) is the nutrient absorbed in greater quantity, and that most influences the productivity of the corn grains. Th research hypothesized that different levels of nitrogen topdressing canaffect the agronomic performance of corn. The objective was to evaluate the agronomic traits and the vegetation indices of corn varieties submitted to different nitrogen levels . Each experiment was conducted in a randomized block design with three replicates in a factorial scheme, replicated for two crop seasons in 2017/2018 and 2018/2019. The first factor was composed of 11 open-pollinated varieties of corn. The second factor was composed of two contrasting nitrogen levels (60 kg ha-1 - low and 180 kg ha-1 - high). Leaf nitrogen content, plant height, ear insertion height, stem diameter, vegetation index by normalized difference (NDVI) and red Rdge by normalized difference (NDRE), ear length, number of ear and grains per row and yield were evaluated. analysis of variance and a network of correlations were made to analyze the variations. In the correlation network it can be noted that NDVI and NDRE correlated positively with each other. The nitrogen correlated positively with plant height, ear length, number of grains per row and number of ear per row. It can be concluded that a high dose of nitrogen in coverage provides better agronomic and spectral performance in corn, regardless of the variety used. Such results proved the dependence of variables such as plant height, ear length, number of grains per row and number of ear per row of the nitrogen content present in the leaves. The BRSGorotuba variety has the highest grain yield regardless of the level of nitrogen fertilization topdressing level.