Effects of Different Levels of Nitrogen Supply on Key Enzyme Activities of Nitrogen Metabolism and Growth Stimulation of Endive (Cichorium endivia L.)

In recent decades, people have blindly pursued increased yield; the excessive use of fertilizer not only causes widespread waste resources but also puts great pressure on environmental protection. this study, to find out optimum nitrogen application endive crops under hydroponic conditions, experiment was conducted investigate changes in nitrate reductase (NR), nitrite (NiR), glutamine synthetase (GS), and glutamate dehydrogenase (GDH) activities different supply levels, fit equations between levels aboveground dry matter accumulation, yield crops. The results showed that key enzymes metabolism were higher at concentrations 8 11 mmol·L−1. accumulation analyzed with logistic model; theoretical found be highest 9.935~11.448 mmol·L−1 two fertility trials by function fitting.