FIGURE 5 Content of total polysaccharides secreted by roots in culture media. (a), (b), and (c) respectively represent the changes in polysaccharide content under the superimposed environmental factors of nitrogen, phosphorus and nitrogen-phosphorus deficit stress. (d) indicates the changes in polysaccharide content under superimposed drought and high temperature. * indicating a significant difference to the N, P, NP, D, and CK treatment, p < 0.05.