Figure 7.

Effect of spraying glycerol on NO₃-N (a,d), total nitrogen content (b,e) and soluble protein content (c,f) in burley tobacco seedlings under different nitrogen conditions. CK: control; Gl: glycerol. TN: total nitrogen content. Error bars indicate standard error of the means (n = 3). Symbols ** ¹indicate that the significant differences between treatment of control and treatment of spraying glycerol under sufficient nitrogen condition (N100) are at 0.01. Symbols ** ²and * ²indicate that the significant differences between treatment of control and treatment of spraying glycerol under 20% less nitrogen application condition (N80) are at 0.01 and 0.05, respectively. (a–c), TN90; (d–f), TN86.