The Physiological Responses Of Endemic Plants Reaumuria Trigyna In Alashan Desert To Salt Tolerance

Reaumuria trigyna is an endemic plant species of narrow area distribute in Eastern Alashan-Western Erdos.It is well adapted to salty deserted land.In this paper, the physiological responses of endemic species Reaumuria trigyna and its widespread congener Reaumuria soongorica to salt tolerance have been studied and discussed. The results are as follows:1.Wild Reaumuria trigyna can live in saline soil,non-salinization soil and heavy solonchack.The maximum osmotic potential at water saturation point(ψ_s^sat and the osmotic potential when a plasmolysis just emerges(ψ_s^tlp) decreased as the salinity of soil increase,Reaumuria trigyna can enhance osmotic adjustment ability by reducing the osmotic potential to adapt different saline habitat.2.Based on three measurements of water parameters of Reaumuria trigyna occurring in four different habitats,Fuzzy mathematics subordination function values analysis were used to estimate water deficit water deficit resistance ability.The results showed that the strongest one is that in heavy solonchack;the modest one is that in non-salinization soil;and the lowest one is that in saline soil.Reaumuria trigyna occurring in heavy solonchack and and non-salinization soil suffered stronger environmental stresses.The water deficit resistance ability of Reaumuria trigyna become more and more stronger by hardening with season(May,july,September).3.Compared with other xerophyte plants,the water parameters of Wild Reaumuria trigyna and R.soongorica appeared particularity,which has strong ability of maintaining large turgor and low water potential with very lowψ_s^sat andψ_s^tlP values.It is possibly correlative with their salt endurance.Compared with the differences of water parameters between these two plants,the salt and drought resistance ability of R.soongorica are stronger than Reaumuria trigyna,which indicated that two plant species,have the differentiation under the long-term natural selection to the environment adaptiveness.This is a possible reason why R. soongorica distributed widespread and Reaumuria trigyna distribute straitly.4.Correlation between(IAA+ZR+GA₃)/ABA and growth vigour is positive. The(IAA+ZR+GA₃)/ABA in wild Reaumuria trigyna varied from strong to weak in heavy solonchack,in non-salinization soil and in saline soil.This is consistent with the results of Reaumuria trigyna population density and the degree of cover that saline soil are biggest,non-salinization soil are modest,heavy solonchack are smallest.Under different concentration of NaCl stress,The tendency of (IAA+ZR+GA₃)/ABA ratio in Reaumuria trigyna seedling and its relative growth rate all showed increased first then decreased later,and reached the maximum When NaCl concentration was 80mmol/L.So speculating that the optimal concentration for seedling growth is 80mmol/L.Reaumuria trigyna had developed an internal adaptation mechanism for living in saline habitat for a long time. Integration regulation of endogenous hormone plays a key role for Reaumuria trigyna growth under salt stress.5.Under the identical habitat,the content of promotion growth hormone IAA, ZR and GA₃ in Reaumuria trigyna is lower than Reaumuria soongorica,but suppressing growth hormone ABA content is contrary.This kind of existence condition of hormone is more advantageous for Reaumuria trigyna growth.Therefore, regulation of endogenous hormone possibly is one of internal reasons that ecology adaptability of Reaumuria trigyna is weaker than Reaumuria soongorica.6.The Enzymatic antioxidant system of Reaumuria trigyna in saline soil existed in a balance:SOD and POD vigor is high,MDA content is low.But the Enzymatic antioxidant system of Reaumuria trigyna in heavy solonchack and non-salinization soil existed in a unbalance and the membrane was damaged seriously.In the acceptability salt stress scope of Reaumuria trigyna seedling(≤80mmol/L),high SOD,POD and CAT vigor can mutually regulate to reduce oxygen free radical to plant cell membrane injury.When NaCl concentration was over 80mmol/L,the activity of antioxidant enzyme all decreased significantly.Then Oxygen free radical accumulated sharply,and cell membrane was damaged seriously.