Authors: Eulalio Morel L&opez, Florencio David Valdez Ocampo, Am&ilcar Isidro Serv&in Niz, Modesto Osmar Da Silva Oviedo, Oscar Caballero Casuriaga, Wilfrido Lugo Pereira, Derlys Fernando L&opez &Avalos, Carlos Alberto Mongelos Barrios, Edith Ruiz D&iaz, Ruth Ester Pistilli
Corn is a crop of high productive potential, but to achieve this, it is essential to apply production technologies, especially fertilizers with a high level of nitrogen. The objective of this work was to evaluate the influence of nitrogen fertilizer in different phenological stages on corn production. The experiment was installed in the experimental plot of the Facultad de Ciencias Agrarias, Universidad Nacional de Concepción, Concepción Department, Paraguay. The experimental design was randomized blocks, with 5 treatments and 4 repetitions. The treatments consisted of the application of nitrogenous fertilizer in the phenological stages V0, V3, V5, V7 and V9. Number of leaves on and below the spike, number of seed lines per spike, plant height, spike height and yield were evaluated. The obtained data was subjected to the analysis of variance by Fisher's test at 5%, when significant differences was detected, it was proceeded to compare the means obtained by the effect of the treatments using the Tukey test at 5% of significance. The results indicate that the application of nitrogen in different phenological stages of corn cultivation influenced the height of the plant, height of insertion of the spike and yield; not so, for: number of leaves above and below the spike and number of seed lines per spike. It is concluded that the application of nitrogen in different phenological stages of corn, has influence on productive characteristics of the crop. It was recommended that it should be done in phenological stage V5, to achieve maximum efficiency. Key words: Zea mays L., phenological stages, nitrogen, fertilization.