Nitrogen and potassium fertilization on the yield and intensity of the maize white spot

Abstract

A plant’s nutritional balance can influence its resistance to diseases. In order to evaluate the effect of increasing
doses of N and K on the yield and severity of the maize white spot, two experiments were installed in the field, one
in the city of Ijaci, Minas Gerais, and the other in the city of Sete Lagoas, Minas Gerais. The experimental delimitation
was in randomized blocks with 5 x 5 factorial analysis of variance, and four repetitions. The treatments consisted of
five doses of N (20; 40; 80; 150; 190 Kg ha-1 of N in the experiments 1 and 2) and five doses of K (15; 30; 60; 120;
180 Kg ha-1 of K in experiment 1 and 8.75; 17.5; 35; 50; 100 Kg ha-1 of K in experiment 2). The susceptible cultivar
30P70 was planted in both experiments. The plot consisted of four rows 5 meters long, with a useful area consisting
of two central rows 3 meters each. Evaluations began 43 days after emergence (DAE) in the first experiment and 56
DAE in the second one. There was no significant interaction between doses of N and K and the disease progress. The
effect was only observed for N. The K did not influence the yield and the severity of the disease in these experiments.
Bigger areas below the severity progress curve of the white spot and better yield were observed with increasing
doses of N. Thus, with increasing doses of N, the white spot increased and also did the yield.