FIGURE 2 Roots in the culture medium secrete the activity of
enzymes related to nitrogen metabolism. (a), (b), and (c) respectively
represent the changes in nitrogen metabolism-related enzymes under the
superimposed environmental factors of nitrogen, phosphorus and
nitrogen-phosphorus deficit stresses. (d) indicates the changes in
nitrogen metabolism-related enzymes under the superimposed drought and
high temperature. * indicating a significant difference to the N, P, NP,
D, and CK treatment, p < 0.05.