Abstract:The objective was to determine the mechanism of the alteration of photosynthetic electron transport, light energy transformation and utilization of tea tree leaves under K deficiency. Vegetative propagated 10-month-old tea [Camellia sinensis (L.) O. Kuntze cv. Ruixiang] seedlings grown in pots were fertilized three times weekly for 24 weeks with different nutrient solution contents, 0, 100, 200, 600 and 2000 μmol/L potassium. The results show that OJIP transients from the K-deficiency leaves display the decreased P-step and the increased O-step, and as well as two new steps at about 150 μs (L-step) and 300 μs (K-step) in the different spectra compared with the control. The RC/CSo, TRo/ABS (or Fv/Fm), ETo/ABS, REo/ABS, PIabs and PIcs are decreased in the K-deficiency leaves, while VJ, VI and dissipated energy are increased. In conclusion, The K deficiency decreases photosynthetic electron transport capacity by impairing the whole electron transport chain from PSII donor side up to the PSI. Enhanced energy dissipation protects the leaves of K-deficiency plants from photo-oxidative damage in high light.