Study On Germplasm Resources Investigation And Salt Tolerance Physiology Of Chimonanthus Praecox In Beijing Areas

Chimonanthus praecox,which blossoms in winter and early spring,is a aromatic plants in China.It has high ornamental value,applied value and cultural value.In this paper,the resources of Ch.Praecox in various gardens in Beijing were investigated and classified.Further,physiology of salt tolerance were studied.It is of great significance in guiding the cultivation and application of Ch.praecox in Beijing.Based on record standards of cultivars classification developed by Chen Longqing,the cultivars of Ch.praecox in Beijing areas had been investigated longitudinally for two consecutive years.The preliminary results were as follows:There were 32 cultivars of Ch.Praecox,including 8 concolor cultivars,7 intermedius cultivars and 17 patens cultivars,of which 12 cultivars were named firstly in this paper.And the classification table for Ch.praecox was developed.When the seed of Ch.Praecox 'Xiaoqingkou' was ripe in June,we sowed seeds immediately after harvesting seeds.Then the seed germination experiment was carried out with different concentrations of salt stress(0-1.2%).The results showed that low salt stress(0.2%)hadn't significant effect on seed germination and seedling growth of Ch.praecox,and Ch.Praecox seeds can tolerate low salt stress.With the increase of salt concentration,the difference of the threat index was significant.Simultaneously,the 1-year-old's,3-year-old's and 5-year-old's Ch.Praecox 'Yipin Wanhuang'potted seedlings had been tested for 40 days under 0,0.3%,0.6%,0.9%and 1.2%salt stress.The growth,morphological,physiological and chlorophyll fluorescence parameters of Ch.praecox were observed,to investigate the morphological and physiological responses to salt stress.The main results were as follows:(1)After 40 days of salt stress,Ch,praecox appeared some phenomenons such as turnning yellow of leaves,curling,plant death and root reduction.When the salt concentration was 0.30/o,the 1-year-old's,3-year-old's and 5-year-old's survival rate was respectively 40%,50%,100%.When the salt concentration was 1.2%,the survival rate was 0.This indicated that Ch.Praecox had a certain salt tolerance,but not suitable for growth in saline soil.(2)Under salt stress,there was a significant negative correlation between the growth of different organs with salt concentration(P<0.01).(3)By measuring the relevant physiological indicators,the results showed:When the salt concentration was 0.3%,the 1-year-old's and 3-year-old's leaf water content were significantly higher than that the blank's at 40 days(P<0.05),and there was no significant difference in 5-year-old Ch.Praecox;SP and SS presented a tendency to decrease firstly and then increase with the extension of stress time;POD,SOD,MDA and Pro increased gradually with the extension of stress time on the whole;the relative conductivity increased with the extension of stress time,and under 0.3%salt stress,the relative conductivity value was always lower than 50%.(4)By measuring chlorophyll fluorescence parameters,the results showed that the differences of Fv/Fm,Y(?),qP and rETR with salt concentration,salt stress time and the interaction effect were significant(P<0.01),So the chlorophyll fluorescence parameterscan reflect the response mechanism of leaf photosynthetic capacity to salt stress.(5)Through principal component analysis,the results showed that the water content,POD,MDA,relative conductivity and chlorophyll fluorescence parameters Fv/Fm,Y(?),qP,and rETR were the main evaluation index of salt tolerance of Ch.Praecox;SOD,SP,SS,Pro can be used as a reference index.