Abstract: A pot experiment was conducted in a net room to study the growth responses and related mechanisms of Apocynum venetum treated with different concentrations (100-400 mmol·L^-1) of NaCl for 30 days. The biomass accumulation, growth rate, root vigor, salt ion content and mineral ion uptake and distribution were measured. Compared with the control, treatment 100 mmol·L^-1 NaCl had lesser effects on the plant dry mass, but decreased the plant fresh mass and growth rate significantly. With increasing NaCl concentration in the medium, the plant dry mass, fresh mass, and growth rate all decreased significantly. The plant root vigor was obviously higher under 100 and 200 mmol·L^-1 NaCl stress, but decreased significantly under 300-400 mmol·L^-1 NaCl  stress. With the increase of NaCl concentration in the medium, the Na⁺ content in A. venetum roots, stems and leaves increased gradually while the K⁺ content had a slow decrease, the Ca²⁺ and Mg²⁺contents in leaves decreased obviously, and the Ca²⁺ content in stems and the Mg²⁺ content in roots increased in different degree. Under NaCl stress, the K⁺/Na⁺, Ca²⁺/Na⁺, and Mg²⁺/Na⁺ ratios in roots, stems, and leaves decreased markedly, while the selective absorption and transportation of K⁺ and Ca²⁺ increased significantly. The stronger ability of salt exclusion and zhe higher selective absorption and transportation of K⁺ and Ca²⁺ were the key adaptive mechanisms of high salt-tolerance of A. venetum.

Key words: salt stress, Apocynum venetum, biomass, ionic homeostasis, ionic selective absorption and transportation, carbon and nitrogen storage,  age dynamics, Cupressus chengiana plantation, arid valley.