Response of chlorophyll fluorescence and growth of Celtis caucasica and Robinia pseudoacacia seedlings to the cadmium stress

The aim of the present study was to determine the effects of cadmium on chlorophyll fluorescence parameters, i.e., Fv/Fm= (Fm−F0)/Fm, Fo and Fm as well as the growth of one-year-old seedlings of Celtis caucasica and Robinia pseudoacacia. The seedlings were sprayed by saline solution Cd during 10 days, 2 times, with different concentrations of Cd (0, 250, 500, 1000 and 2000 mg/litre). Chlorophyll fluorescence was measured every other day. Diameter and height were measured at the end of growing season. The results indicated that Fv/Fm of the both species decreased significantly with increasing of Cd concentrations and significant increase during 10 days by exposure to Cd concentrations was observed. Fo of the both species increased significantly in 2000 mg/liter, Fm decreased significantly in all treatments. Diameter of Celtis seedlings were not affected by the concentrations of 500, 1000 and 2000 mg/liter. Diameter of Robinia decreased significantly. The height of Celtis increased and the height of Robinia decreased significantly in 2000 mg/liter. Results showed fairly similar physiological responses to the cadmium stress by both species and both reacted to the high concentration of Cd.Other physiological characteristics should be considered in future studies while selecting of tree species for afforestation projects in urban polluted areas.