The effect of lanthanide chloride on abscisic acid and electron-transport activity of some crops

The abscisic acid (ABA) content of the root tips of four crops grown in lan thanide chloride solution and their root lengths had been determined. At la nthanide concentrations of 5 and 10 ppm, these crops all grew well and the ABA decreased. At higher lanthanide concentrations (100-500 ppm), the ABA i s increased again. At these concentrations of lanthanum chloride, the photo systems I and II (PSI and PSII) and whole electron chain transport activiti es were inhibited. PSII was more sensitive than PSI, and it is concluded th at La3+ acts on the diphenylcarbazide (DPC) action place of PSII oxidizing site.