LAUSR

In this paper, the effect of nitrogen application on nitrate reductase activity of the Sidan 19 maize (Zea mays L.) cultivar was studied. The Sidan 19 maize is a medium maturity maize single variety, which is a hybrid of 44/4 (Huangzao4 improved line) as the female parent and Mo17 as the male parent. It has high average hectare yield, good early-onset, easy to catch seedlings and other excellent properties, so it was selected as a model plant. In order to study the effect of nitrogen application on the activity of nitrate reductase in maize, the method of this paper is to prepare nitrate reductase, extract corn leaves, add trichloroacetic acid solution to stop the enzyme reaction, and use standard curve method to determine the content of maize nitrate reductase. The experimental results show that: (1) N application rate of nitrate reductase activity (NRA) was N300 > N200 > N100 > N0. (2) NRA activity of maize leaves was the lowest at the seedling stage, the highest at heading stage, and then decreased. Under 15% pec-6000 drought stress, 72 mmol/L salt stress and 72 mmol/L Saline-alkali stress, nitrate reductase activity of maize leaves and roots was the highest. (3) Under the same amount of nitrogen application, the nitrate reductase activity of maize roots increased, and the nitrate reductase (NR) activity of leaves was higher than that of roots under the same stress effect. (4) Under the same amount of nitrogen application, the nitrate reductase activity of maize leaves was the highest. At nitrogen levels of N0, N0.1 and N0.5, the activity of nitrate reductase enzymes in roots of each treatment from highest to lowest were sodium nitrate > urea > ammonium chloride. It showed that the activity of nitrate reductase increased with the increase of nitrogen application. The nitrate reductase activity of maize root was the highest at heading stage, and under low nitrogen condition.