| The poplars have many characteristics, such as good quality, growing fast, beautifulshape, high social, economical and environmental efficiency, and they play irreplaceable rolesin the constructions of ecological forest and industrial forest of our country. At present thesaline-alkali soil of our country is deteriorating, so that to study salt tolerance of poplars hasimportant practical significances for saline-alkali land improvement and greening. But it isgenerally belived that the salt tolerance of poplar is not higher than0.2%. With the scienceand technology improving, the varieties of salt-tolerant poplars were reported more and morethrough kinds of breeding methods, but most of them were compared with non-salt-tolerantpoplars, the comparation among different salt-tolerant poplars is lack; and differents includingthe experiment methods and evaluation indexs lead uncomparable among different species.On the other hand, the evaluation indexs system was still not perfect, and the mechanisms ofsalt resistance were not clear, both of them played restricting effects on the progress of thestudy of salt-tolerant poplars. The membership function and cluster analysis were used in thisarticle to evaluate the salt tolerance of popoars through indoor hydroponic experiment and potexperiment. The physiological and biochemical responses of salt-tolerant poplar under potexperiment condition were also measured, which was intended to explore the salt-tolerantevaluation index and mechanism. The purposes of this article were to sift several highsalt-tolerance poplars, and to provide the theoretical basis for the introduction ofsalt-tolerance poplars and the soil improvement. The main conclusions were as follows:(1)30varieties of poplars were selected for the hydroponics experiment under NaClsalt-stress, and the growth indexs were measured, such as survival rate, biomass, root shootratio, salt injury grade, membrance permeability etc. The poplars were classified and rankedby the salt resistance:①the high salt tolerance group: JY-1, JY-34, JY-44, JY-46, the salttolerance threshold value is5g/L;②the intermiddle group: JY-8, JY-24, JY-26, JY-33, JY-39,JY-41, JY-51, the salt tolerance threshold value is between4g/L~5g/L;③the low salttolerance group: JY-3, JY-4, JY-5, JY-6, JY-9, JY-10, JY-13, JY-14, JY-16, JY-18, JY-21, JY-28,JY-29, JY-30, JY-31, JY-40, the salt tolerance threshold value was less than4g/L;④thenon-salt tolerant group: JY-2, JY-23, JY-27.(2)After removing2varieties of poplars from the30carieties through hydroponicsexperiment, the selected28varieties of salt tolerant poplars were used to do port underdifferent salt concentration conditions. The growth indexes of the28species were determined,such as survival rate, shoot growth, salt damage grade etc. The poplars were also classifiedand ranked by the salt resistance:①the high salt tolerant group were JY-9, JY-30, JY-31,JY-34, JY-44, and the salt tolerance threshold value was5g/Kg；②the intermeddle group wereJY-3, JY-4, JY-10, JY-13, JY-14, JY-16, JY-23, JY-39, JY-40, JY-41, JY-46, JY-51, and the salt tolerance threshold value was4～5g/Kg;③the low salt tolerant group were JY-18, JY-24,JY-26, JY-27, JY-28, JY-33, and salt tolerance threshold value was less than4g/Kg;④thenon-salt tolerant group were JY-1, JY-2, JY-5, JY-6, JY-21.(3)5varieties of high salt tolerant poplars in pot experiment were used to study thephysilolgical changes as membrane permeability; SOD, POD, CAT activities; proline, MDA,chlorophyll contents, etc. The conclusions were as follows: the growth indexes andphysiological indexes had good consistencies; poplar grew rapidly but weak salt tolerance;transgenic and intersectional hybrids showed promising prospects.(4)The results of the hydroponics and pot experiments showed that JY-34, JY-44, JY-46had high salt tolerance and rooting ability, and could be planted in the field where saltcontention was as high as0.5%. JY-24, JY-26, JY-33, JY-39, JY-41, JY-51could be planted inthe field where salt contention was0.4%. |
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