Influence of cadmium stress on chlorophyll fluorescence characteristics in Populus x canescens

Young Populus x canescens plants were grown by hydroponic method and exposured to four Cd2+ concentrations of (10, 30, 50 and 70 mu M) in contrast to the control (non-Cd) for 7, 14, 21 and 28 days.Chlorophyll fluorescence parameters were very sensitive to Cd stress in grey poplar. F-v/F-a and F-v/F-m ratio generally declined with increasing Cd levels at the 7, 14, 21 and 28 clays. Increasing cadmium concentration up to 70 mu M resulted in a greater suppression of (Phi PSII activity; the F-v/F-m and F-o/F-v ratio, q(N), and q(p) decreased. In conclusion, the initial level of chlorophyll fluorescence intensity (F-v/F-m and F-o/F-v ratio, q(N) and q(p)) remained almost unaffected by cadmium treatment.