Figure 4

Net photosynthesis rate (A) (A), stomatal conductance (gs) (B), transpiration (E) (C) and instantaneous carboxylation efficiency (k = A/Ci) (D) measured on the diagnostic leaf (fifth leaf from the top) of cotton (Gossypium hirsutum) plants grown in nutrient solution containing different concentrations of phosphorus (P) and zinc (Zn) for 90 days. Low P = 0.5 mM; Adequate P = 4 mM; High P = 8 mM; Low Zn = 0.5 µM; Adequate Zn = 4 µM; High Zn = 8 µM. Different letters indicate significant differences for each dependent variable separately (Tukey test at P ≤ 0.05; n = 4). Sigma Plot 11 software (SYSTAT, San Jose, CA, USA) was used to display data.