Studies On The Introduction, Selection, Application And Mechanism Of Salt-tolerance And Halophyte Landscape Plants

This research focus on 3 fields, one is the halophyte landscape plants introduced from Italy, the second is halophyte plants resource which planted in our country collected and evaluated, the third is the research on mechanism of salt-tolerance or halophyte plants ,the results were following :1 Plants of greening in salt affected soils in Tanggu Area, Huanghua city and Dongying city have been studied in 2 years. There are 87 species(include variety) ,belong to 34 families. Among them, 63 species have been cultivated ,only 27.5% are middle salt tolerance degree plants, most of them are light salt tolerance degree plants, no species is high salt tolerance, the research also found there are 24 species of wild salt tolerance plants ,10 of them are high valuable plants of greening in salt affected soils and are recommended.2 Wild ground cover plants of 8 species were chosen as experimental materials, the salt resistance of these plants were studied. The salt matrix include NaCl and Na2SO4, the salt content was 0, 0.25%, 0.5% and 1% .The results showed that all the plants can't germinate in the soil that contain 1% salt. All plants could germinate and grow in the saline soil that contain 0.25% salt, in this treatment the most rate of germination is Viola prionantha(46.35% more than control),the salt effect of growth inhabitation on Dianthus plumarius was the smallest ,the biomass decreased 23.6% than the control. When the salt content is 0.5%, only Iris lacteal, Taraxacum mongolicum, Dianthus plumariu, Coronilla varia could germinate and grow, but germination delay, and the rate of germination decrease markedly. Dianthus plumari is the most salt-resistance species. The salt treatment made the proline increase markedly ,but less effect on soluble sugar when treated as 0.25% or 0.5%, when treated as 0.5%, the content of MDA increased markedly .It suggested the it was seriously harmful to plants as salt content 0.5% .3 The cuttings of Parthenocissus Quinquefolia were treated with 0~300 mmol.L-1 NaCl . The growth, and some physiological characteristics were investigated after 7d of treatment . The results showed that plants grow and develop normally in 25 and 50 mmol.L-1 NaCl. When the concentration of NaCl equaled or more than 100 mmol.L-1, the growth of treated plants were inhibited, the rate of photosynthetic , transpiration ,as while as stomata conductance were markedly decreased ; As the same time ,membrane permeability and MDA content markedlyincreased. It is possible that the concentration of NaCl of 100 mmol.L-1 was the key value of salt stress. Under the salt stress, the contents of soluble sugar .proline acid , K+, Ca2+, and Na+ increased, especially when the content of NaCl above 100 mmol.L-1, except proline, the difference of treated plants and control was significant . It is suggested that the adaptation of Parthenocissus Quinquefolia cuttings to the salt stress by increase the content of soluble sugar and K+, Ca2+,and Na+, to adjust the stress of osmotic pressure.4 Crithmum maritimum, Pancratium martimum,Chamaerops humilis ,Atriplex numnularia JErygium martimum and Acacia maligna were introduced from Italy. The result of experiment were as following : Atriplex numnularia, Erygium martimum needed the lest time of germination, it was 13 days;Acacia malignaAcacia maligna needed the longest time of germination, it was 71 days. The highest rate of germination was the species of Crithmum maritimum,it was 95%,the lowest rate of germination was the species of Acacia maligna, it was 2%;among 6 species, Crithmum maritimum grow fastest.5 When Crithmum maritimum, Pancratium martimu and Chamaerops humilis were treated with 100mmol.L-1 NaCl,the photosynthesis was inhibited. To the species of Crithmum maritimum, it was needed to increase the content of soluble sugar to adjust the stress of osmotic pressure , but to the Chamaerops humilis, the content of proline acid increased ;in the same treatment the species of Chamaerops humilis increased the content of soluble sugar and proline acid.6 The salt tolerance of Crithmum maritimum was studied.the resuluts showed us: When the concentration of NaCl less than 200 mmol.L-1,there was not affected on the growth of Crithmum maritimum, 400 mmol.L-1 NaCl inhibited the growth markedly, it suggested that Crithmum maritimum was a most salt tolerance species. When the concentration more than 200 mmol.L-1,the photosynthesis decreased, the content of soluble sugar increased markedly , but there was no obvious change of the content of proline acid .It suggested that when the plant was stressed by high concentration of salt, the synthesis reaction of soluble sugar was startup, the synthesis reaction of proline acid was stopped. When the salt stress, the content of Na+ increased ,the Na+/K+ decreased , it maybe the leaf ,as the concentration of Na+ increased ,Na+ was absorbed into leaf cell, to adjust the osmotic pressure.