Physiological responses of Populus euphratica seedlings under flooding stress with saline and fresh waters

Populus euphratica is one of species growing naturally in arid and semi-arid regions in riparian habitats. The purpose of this study was to investigate the physiological responses including photosynthesis، stomatal conductivity، transpiration، water potential، and relative water content of leaf of one-year Populus euphratica potted seedlings under flooding-salinity combined stress. Saline-flooding treatments in 5 levels including control (without saline-flooding) flooding (irrigation 4 cm above soil surface) with salinity in concentrations 0، 50، 100، and 150 mM NaCl were applied. This experiment was conducted as completely randomized design in a period of 60 days in greenhouse environment. Results showed that survival in all treatments was about 100%. Saline-flooding treatment had a significant effect on photosynthesis، stomatal conductivity، transpiration، water potential، and relative content of leaf water، so that the increase of salinity in flooding conditions led to decreased in all characteristics measured compared to control treatment. Generally، the results of this research revealed that in spite of reduced physiological measures with increased salinity، P. caspica seedlings are able to maintain the survival under mentioned stresses. With continuing of the research in next growing seasons by the researchers، responses physiological characteristics and particularly survival and growth of these seedlings to above mentioned stresses will be further revealed.