Abstract: A pot experiment was conducted to study the influence of different concentration (0, 50, 100, 200, and 400 mg·kg^-1) Ni and Cu on the growth, photosynthesis, and chlorophyll fluorescence characteristics of Peganum harmala seedlings. With increasing concentration Ni in the medium, the seedlings growth parameters, photosynthetic pigment content, net photosynthetic rate (P_n), stomatal conductance (G_s), transpiration rate (T_r), maximal photochemical efficiency of PSⅡ (F_v/F_m), quantum efficiency of electric transport of PSⅡ(Φ_PSⅡ), and coefficient of photochemical quenching (q_P) of P. harmala decreased significantly, while the intercellular CO₂ concentration (C) and the coefficient of non-photochemical quenching (q_N) were in adverse. The decrease of P_n under Ni stress was mainly caused by non-stomatal limitation. At 50 mg·kg^-1 Cu, the growth parameters, photosynthetic pigment content, P_n, G_s, T_r, C_i, F_v/F_m, Φ_PSⅡ, and q_P reached their peak values; at 100 mg·kg^-1 Cu, the growth parameters, chlorophyll a and b contents, P_n, G_s, T_r,C, and F_v/F_m were still slightly higher than the control; while with the further increasing Cu concentration in the medium, all the test indices except q_N tended to decrease. The decrease of P_n under Cu stress was mainly caused by stomatal limitation. 

Key words: photosynthesis, chlorophyll fluorescence, Peganum harmala, nickel, copper