Activity of the enzyme reductase nitrate in corn cultivated under different levels of nitrogen and potassium fertilization

Because of the use in human feeding, animal, and high productive potential, corn is considered to be one of the most important cultivated and commercialized cereals in the world. The aim of this research was to evaluate the effect of different potassium doses and nitrogen in the activity of the enzyme nitrate reductase in the corn culture in a greenhouse environment. Five dosages of nitrogen (0; 50; 100; 150 and 200kg ha(-1)) and five potassium dosages (0; 40; 80; 120 and 160kg ha(-1)) were used. The activity of the nitrate reductase was esteemed, in vivo after the plants reached four leaves totally unfolded. The method that was used is based on the principle of the amount of nitrite liberated by fragments of alive tissue in a buffer in the presence of a permanent agent and substrate, reflects the potential in situ activity of the enzyme nitrate reductase. The activity of the enzyme nitrate reductase suffered significant influence of the f nitrogen and potassium dosage interaction, where the interaction N=100kg ha(-1) and K=40kg ha(-1) provided the best medium of the experiment. From this dosage on, the increase of nitrogen and potassium supplement caused a reduction of the enzymatic activity.