FIGURE 4.

Effects of alkali stress on the total relative concentration of organic acids/amine (A), sugars and poly-sugars (B), amino acids (C), and nucleotide derivatives (D) in young and old leaves of cotton seedlings. The values are the means ± SE of five biological replicates, and each replicate consisted of a pool of five plants. Significant difference between organs under similar stress condition was determined by T-test and marked as ^∗P < 0.05 and ^∗∗P < 0.01. The seedlings were subjected to 80 mM alkali stress (NaHCO₃:Na₂CO₃ = 9:1; pH = 9.06) for 6 days.