A salt stress on seedlings of a white poplar hybrid clone B430, P. tomentosa, P. bolleana, and hybrid of P. tomentosa and P. bolleana was made in pots, with the NaCl solution concentration of 0.10%, 0.30%, 0.60%, 0.90% and a pure water control. Each pot was watered respectively with 2L corresponding salt solution every 10 day. The content of K+, Na+, Ca ++ in root, stem and leaf of the seedlings and the selectivity (RS K,Na, RS Ca, Na) to ions of transportation to above-ground part were determined an...