Using seedlings of Malus baccata, M. xiaojinensis and M. zumi with different salt-tolerance as the experimental materials, physiological and biochemical mechanism of Malus was comparatively studied. The results showed that the main Na+exclusion localization of Malus was roots and stem base, and Na+ exclusion capability in roots and stem base of salt-tolerant species was obviously higher than that of salt-sensitive ones. Whole Na+exclusion capability of salt-sensitive species was about 65 %, middl...