| Chimonanthus praecox is one of the important traditional flowers of China,which has beautiful forms,color and flower fragrance in winter.The saline-alkali tolerance physiology of the seeds and the 2-year-old’s seedings of Ch.Praecox was studied in order to provide theoretical basis for its application on saline-alkali land.1 The seeds of Ch.Praecox ’Xiaoqingkou’ was used as test material.,Nacl,Na2SO4,NaHCO3 and Na2CO3 were divided into five treatment groups(pH 7.22-10.4)in which the proportion of alkaline salts gradually increased.Five concentration gradients(concentration 0.2%-1.0%)were set up in each treatment group.A total of 25 saline-alkali conditions were simulated.The germination rate and physiological indexes of Ch.Praecox seeds under saline-alkali stress were measured to explore the physiological response of Ch.Praecox seeds to saline-alkali tolerance.The main results were as follows:(1)Under five types of saline-alkali stress,with the increase of salt concentration,the germination rate of Ch.Praecox seeds decreased as a whole;SOD activity,POD activity and free proline content increased first and then decreased;soluble sugar content and MDA content increased;soluble protein content in treatment A,B and C(pH 7.22-8.78)increased as a whole,while that of treatment D and E(pH 9.65,10.4)with alkaline salt proportion showed an upward trend and then a downward trend.(2)The comprehensive evaluation of saline-alkali tolerance of Ch.Praecox seeds by membership function law showed that the damage degree of Ch.Praecox seeds under different types of saline-alkali stress was in the order of E treatment group>D treatment group>B treatment group>A treatment group>C treatment group.2 Using two-year-old Ch.Praecox ’Xiaoqingkou’ as test material,Nacl,Na2SO4,NaHCO3 and Na2CO3 were mixed in different proportions to simulate 30 different saline-alkali conditions(pH 7.22-10.4,concentration 0.2-1.2%).To observe the morphological,growth and physiological indexes of Ch.Praecox under saline-alkali stress,and to explore the physiological response mechanism of Ch.Praecox to saline-alkali stress.The main results were as follows:(1)Under five types of saline-alkali stress,with the increase of salt concentration,Ch.Praecox showed an upward trend in salt damage index,salt damage grade and salt damage rate,Ch.Praecox responded earlier to the stress of D and E treatments(pH 9.65,10.4)with higher alkaline salt proportion.Salt tolerance thresholds of Ch.Praecox to five types of saline-alkali stress(A,B,C,D,E)were 0.322%,0.311%,0.340%,0.271%and 0.230%,respectively.Leaf length growth,leaf width growth and shoot growth showed a downward trend,among which the growth of C treatment(pH 8.78)decreased slightly,while the growth of D,E treatment(pH 9.65,10.4)with higher alkaline salt proportion decreased significantly.(2)Under five types of saline-alkali stress,with the increase of salt concentration and the prolongation of stress time,chlorophyll content and leaf tissue water content of Ch.Praecox showed a downward trend as a whole.;soluble protein content,free proline content,relative conductivity,MDA content,and soluble sugar content showed an upward trend;SOD activity and POD activity showed a first upward trend and then downward trend;Fv/Fm,Yield,qP,ETR,Pn,Gs and Tr showed a downward trend,while Ci showed an upward trend.(3)Stepwise regression analysis of the salt tolerance coefficient of 20 single items was made.We ultimately screened shoot growth,qP,chlorophyll and POD as appraisal indicators of the salt resistance of Ch.Praecox.(4)The stress severity of different types of saline-alkali on Ch.Praecox was in order of:treatment E>treatment D>treatment B>treatment A>treatment C.In summary,the physiological mechanism of saline-alkali tolerance of Ch.Praecox was preliminarily analyzed in this experiment.At the same time,the main identification indicators for salt and alkali tolerance evaluation of Ch.Praecox were screened,and the tolerance of Ch.Praecox to different types of salt and alkali stress was evaluated,which provided a theoretical basis for promoting the application of Ch.Praecox on saline-alkali land. |
