Assessment of salt tolerance in Populus alba clones using chlorophyll fluorescence

Cuttings of five Populus alba clones (S 18 F1-26, Al29 F8-35, J3 F 1-4, GUI F16-36, PO9 F21-88), Populus euphratica, and Populusxeuramericana (I-214) were submitted during 45 d to regular watering with NaCl solutions of electrical conductivity of 7 and 14 dS m(-1). Chlorophyll a fluorescence in response to the salinity stress was assessed, using F-0 and F-v/F-m. Differences in reaction to the salt were found in P. alba clones, F-0 and F-v/F-m being the fluorescence parameters used to check out this stress. Minimal constant fluorescence of dark-adapted plants (F-0) showed a better correlation with the disease index exhibited by plants and also with salinity dose than the parameter F-v/F-m. Some of the P. alba clones showed the same behaviour, assessed through fluorescence parameters, as P. euphratica, which was previously defined as salt tolerant, while the rest exhibited the same characteristics as I-214, which was very sensitive.