Response of salt-tolerant tree species to different levels of soil salinity

Abstract

To identify the response of salt-tolerant tree species to different soil salinity, four tree species including Rhus trilobata, Gleditsia triacanthos, Acer negundo and Acer ginnala were introduced and a lysimeter experiment with five soil salinity treatments (CK, 1, 3, 5 and 7%) was conducted in Nanjing, south of China. 1% soil salinity had no significant effect on the relative seedling rate and the seedling height of different tree species, the obvious decrease of relative seedling rate and seedling height of the seedlings firstly appeared at 3% salinity level. Salt stress significantly influenced the photosynthetic indexes of the seedlings, and the net photosynthetic rate, stomatal conductance and transpiration rate of the seedlings were significantly decreased by the high soil salinity; comparing the four tree species, photosynthetic indexes of R. trilobata were less affected by the salt stress. The seedlings of R. trilobata and G. triacanthos absorbed K+ and discharged Na+ when facing with high soil salinity, while other tree species like A. ginnala was significantly influenced by the increasing of Na+, leading to the obvious decline of K+ absorption. Fully considering the evaluation indexes including seedling rate, seedling height, photosynthetic indexes and Na+ and K+ absorption of different tree species under the salt stress condition, and by the calculations of projection pursuit model, R. trilobata was believed to own the most satisfactory salt tolerance and recommended as the preferable tree species for planting in coastal areas of south-eastern China.