Figure 2

Root length (cm), surface area (cm²), and volume (cm³) of cotton plants under different types of salt–alkali stress (NaCl (CS), Na₂SO₄ (SS), and Na₂CO₃ + NaHCO₃ (AS)). Columns with bars represent the mean ± standard error (n = 3). Asterisks indicate a significant difference between the control (CK) and the salt–alkali stress (*p < 0.05; **p < 0.01). (a–c) indicate the root length in NaCl, Na₂SO₄, and Na₂CO₃ + NaHCO₃ stress, respectively. (d–f) indicate the surface area in NaCl, Na₂SO₄, and Na₂CO₃ + NaHCO₃ stress, respectively. (g–i) indicate the root volume in NaCl, Na₂SO₄, and Na₂CO₃ + NaHCO₃ stress, respectively.