Using trace kinetics to study the effect of heavy metal stress on the transportation and allocation of photosynthate in wheat

The trace kinetics was used to study the effect of different concentration of Cu2+, Cd2+, Hg2+ stress on the transportation and allocation of photosynthate in wheat. The results showed as follows. (1) With the concentration of Cu2+, Cd2+ and Hg2+ increasing, the export rate constant of photosynthate in the first leaf from top of wheat decreased. The export rate constant of photosynthate in the second leaf from top of wheat increased when Cu2+, Cd2+ and Hg2+ was in lower concentration range, and it decreased when the Cu2+, Cd2+ and Hg2+ was in higher concentration range, indicating that Cu2+, Cd2+, Hg2+ stress might affect the export of photosynthate in the leaves of wheat. (2) The lower concentration (50 mg/L) of Cu2+ and Cd2+ stress caused the k21 and k12 of the first and second leaf from top to decrease significantly, especially with the Cu2+ concentration of 150 mg/L. The k21 and k12 of the first and second leaf from top decreased to 0.100 mg/L Hg2+ stress caused the k21 and k12 of the first leaf from top to decrease significantly. 50 mg/L Hg2+ stress also caused the k21 of the second leaf from top to decrease significantly, indicating that Cu2+, Cd2+, Hg2+ stress might also affect the metabolism and allocation of photosynthate in the leaves of wheat. (3) Cu2+, Hg2+ and Cd2+ stress could inhibit the accumulation of photosynthate in roots