Na <sub> 2 </ Sub> Co <sub> 3 </ Sub>, Nacl And Peg Tenuiflora Seedlings K ~ +, Na ~ + Metabolism,

The relationship between osmotic regulation mechanism of leaves and chlorophyll fluorescence kinetics and its ability of suffering salt and alkali of P. tenuiflora seedlings under different Na₂CO₃ ,NaCl and PEG stress which had the same osmotic potential were investigated in the article. Systemic determination and analysis are carried on chlorophyll fluorescence kinetics parameter, membrane leakage, osmotic potential of leaves and culture solution, Na⁺ and K⁺ concentration of culture solution, Na⁺ and K⁺ concentration on leaves , Na⁺ and K⁺ concentration of leaves, Na⁺ and K⁺ excreting and absorbing of Na⁺ and K⁺ of P. tenuiflora seedlings. The results showed:The result showed that PH of Na₂CO₃ stress culture solution was significantly higher than that of NaCl and PEG stress culture solution under iso-osmotic stress. Compared with NaCl ,PEG stress, under Na₂CO₃ stress, the osmotic potential and water content of seedling leaves of P. tenuiflora decreased greater. The variety of EL was similar in all 3 stress,but EL under NaCl stress was greater than under Na₂CO₃ and PEG stress.In this article ,the results showed Na⁺ concentration of culture solution of Na₂CO₃ and NaCl were comparative,but pH of Na₂CO₃ culture solution was further lager than NaCl culture solution. Na₂CO₃ damaged plants because it has three stree including ion stress,pH stress and osmotical stress.When osmotic potential of culture solution (OPCS)was more than -2.5bar , under iso-osmotic stress of NaCl and Na₂CO₃ , the ability of potential heat dissipation of PSⅡwas stronger.And in stronger light,it can be protected from light restration and light oxidation by avoiding absotbing too much light.It's regulation ability was greater than that in PEG stress.When -5.3bar-2.5bar, K⁺/ Na⁺ both in NaCl and Na₂CO₃ changed little,which suggest in low salt and alkali stress, P. tenuiflora seedlings were influenced little.And osmotic potential stress had main effect. When OPCS>-2.5bar, K⁺/ Na⁺ both in NaCl and Na₂CO₃ changed greater, which suggest alkali stress had main effect.The pervation regulation ability of P. tenuiflora seedlings decreased. When osmotic potential was lower(-3.2bar2CO₃ and NaCl stress,the absorbing of Na⁺ was similar.But in PEG stress,the absorbing of Na⁺ was most.Tt was guseed Na⁺ entered as osmotical regulation matter to maintain osmotical balance and absorb water .But in high ion and low osmotical potential stress(OPCS<-4.4bar), P. tenuiflora seedlings may metabolize in other ways to matain its natural activities.