Growth, production and water and nitrogen use efficiency of maize under water depths and nitrogen fertilization

Crescimento, produção e eficiências do uso de água e nitrogênio do milho sob lâminas e adubações nitrogenadas

ABSTRACT

The objective of this study was to evaluate the growth, the production components and the water (WUE) and nitrogen use efficiency (NUE) in maize (Zea mays L.), as function of water depths and nitrogen doses. The experimental design was randomized blocks in a split-plot scheme with four repetitions. The irrigation treatments applied in the plots were composed of four water depths: 80, 90, 100 and 110% of the water requirement, based on the soil field capacity, while the N doses, distributed in the subplots, were 0, 60, 120 and 180 kg ha^-1. Increases in water depths and in N doses promote linear increases in plant height and leaf area index. For cycle I (2015) the maximum yield (16,778.3 kg ha^-1) was reached with the irrigation depth of 538.1 mm and nitrogen dose of 180 kg ha^-1; and for cycle II (2016), the maximum yield was reached with the irrigation depth corresponding to 505 mm and N dose of 180 kg ha^-1, yielding 17,819.5 kg ha^-1. The highest values of WUE (4.1 and 3.8 kg m^-3) were estimated in cycle I (2015) for 432.7 mm and in cycle II (2016) for 359.6 mm, respectively; while the highest values of NUE (67.5 and 65.3 kg kg^-1) were estimated in cycle I (2015), for the water depth of 555.7 mm and nitrogen dose of 113.3 kg ha^-1, and in cycle II (2016), for the water depth of 506 mm and nitrogen dose of 107.7 kg ha^-1.

Key words:
Zea mays L.; irrigation management; mineral fertilization