Influence of different nitrogen levels on growth and production parameters in maize plants

The aim of this study was to evaluate (i) the application effect of nitrogen (N) in Zea mays plants cultivated in field conditions, and to investigate the changes (ii) in nitrogen compounds and parameters linked to growth and yield, as well as to determine (iii) optimal nitrogen level to cultivar Pioneer 30F53. Experimental design was in randomized blocks, five repetitions, and six nitrogen levels (0, 40, 80, 120, 160 and 200 kg ha -1 of N). Parameters measured were dry matter of the index leaf, plant height, ear height, ear length, ear diameter, ear dry matter, grain protein content and yield. Levels of nitrate, ammonium and total N of leaves on 38 th and 68 th day after sowing of the experiment were also evaluated. Results reveal that ear diameter, ear dry matter, plant height, and ear height increased with increasing nitrogen level. Ammonium amount was directly influenced by increase in nitrogen rates, while nitrate and total nitrogen presented quadratic response during vegetative and reproductive stages. Grain protein presented an increase until N level of 160 kg ha -1 . In relation to yield occurred increase was promoted by nitrogen. Our study showed two relationships, between nitrogen and plant height, as well as nitrogen and yield.