Effect of salinity on seed germination, growth and survival of paulownia fortunei seedlings under laboratory and greenhouse conditions

Fortune's Empress Tree (Paulownia fortunei) is one of important exotic and fast growing tree species in Iran, that salinity stress can affect its seed germination and seedling growth. In this study, for determining the response of this species under salinity stress, effects of 5 salinity treatments in different NaCl concentrations (0, 50, 100, 150 and 200 mM) on seed germination, survival and growth characteristics of Paulownia fortunei seedlings were investigated under laboratory and greenhouse conditions. In laboratory conditions, seed germination was conducted with 4 replicates and 5 salinity treatments based on a completely randomized design. In the greenhouse conditions, growth and survival of P. fortunei container seedlings were conducted with 6 replicates and 5 salinity treatments, based on a completely randomized design for one growing season. The results showed that in the absence of salinity, germination percentage (GP) and germination speed (GS) of P. fortunei seeds reached to 89% and number of 19 seeds per day, respectively. GP did not significantly decrease until 100 mM NaCl, but GS began to decrease significantly from 50 mM and reached to its lowest value at 200 mM NaCl concentration. Survival of seedlings showed a significant difference with control (non-saline) at 150 and 200 mM NaCl concentrations with 50% and 83.3% reduction, respectively. Moreover, a significant decrease began in vegetative characteristics of seedlings from 50 mM concentration, but there was no significant difference at concentrations of 50 to 150 mM NaCl.