Abstract: Taking hydroponically cultured arrow-leaf saltbush (Atriplex triangularis) seedlings as test materials, and using electrical conductivity detector, atomic spectroscopy, and pressure bomb, this paper studied the effects of salt stress on the seedlings root membrane permeability, ion uptake, and reflection coefficient, and analyzed the salt-resistance characteristics and related mechanisms of A. triangularis. The results showed that with increasing salt stress, the root membrane permeability increased, but the reflection coefficient decreased. Salt stress decreased the total K⁺ uptake and increased the total Na⁺ uptake, but the relative amount of absorbed K⁺ increased while that of absorbed Na⁺ decreased. Under salt stress, A. triangularis roots had a higher regulation capability in their ion uptake, and the reduction of root reflection coefficient was favourable to the water absorption by the roots with moderate negative pressure, and accordingly, reduced the danger of xylem cavitation. All these features could be closely related to the higher salt-resistance of A. triangularis.

Key words: Atriplex triangularis, ion uptake, membrane permeability, reflection coefficient, salt stress, cotton, CO₂ concentration, nitrogen fertilizer, biomass, nitrogen absorption, soil urease activity.