Potassium fertilization and water depths in maize (Zea mays L.) production used as silage in the Brazilian semiarid region

摘要

The aim of this study was to evaluate corn yield whole plant for silage, submitted at potassium rates and water depths. The experiment was carried in an experimental field, at the city of Sume, Paraiba State, Brazil. The experimental design was a randomized block design in a split-plot with six water depths (in plots) based on crop potential evapotranspiration (ETcp) in levels: 0.25; 0.50; 0.75; 1.00; 1.25 and 1.50 ETcp. and six amounts of potassium (in subplots), 0, 20, 40, 60, 80 and 100 kg Kha~(-1), in four replicates. Manual harvesting of spikes in the green stage occurred 67 days after sowing. Production variables observed were green plant mass along with the spikes (GPMwiths) and the green mass of the plant without the spikes (GPMwithouts). The GPMwiths and GPMwithouts were influenced significantly by factors of water depths, K fertilization and the interaction between the two factors mentioned. The effects of variations in K dose and the level of water depth on the GPMwiths and GPMwithouts were fitted to quadratic regression models. The overall averages observed throughout the experiment were 62.4 and 49.1 t ha~(-1) corresponding to GPMwiths and GPMwithouts, respectively. The water depths for irrigation that maximized the physiological parameters of plants as GPMwiths and GPMwithouts, according to the regression equations were, respectively, 690 mm and 766.7 mm. Quantitative potassium to maximize physiological parameters GPMwiths and GPMwithouts, according to the regression equations were,respectively, 104.75 kg ha~(-1) (73.68 t ha~(-1)) and 52.1 kg ha~(-1) (48.74 t ha~(-1)).