Study Of The Landscape Application Evaluation And Salt Tolerance Of Sedum Spp.

The increasing population and the rapid development of industy have caused a lot of land salinization.The plants,belonging to Sedum,have the advantages of high ornamental value and fairly strong resistance.It is of scientific and practical significance to explore the salt-tolerant cultivars to improve soil physical and chemical properties and enrich the diversity of plant landscape in salted areas.Therefore,in this study,based on the investigation and collection of the planting resources of Sedum in Beijing and abroad,the AHP comprehensive evaluation model was established to access the landscape application value of 30 sedums.On the basis,the salt-tolerant physiologiacal mechanism and the range of salt adaptation of eight species of Sedum were studied in depth,from which to screen out the suitable species for saline regions landscaping.The conclusions are as follows:1)This paper proposed a comprehensive evaluation model by AHP to access the landscape application value of 30 sedums investigated and collected in Beijing area.Flower ornamental value,leaf characteristics,remained ornamental value and landscape application potential were selected to define an 18 evaluation index in 4-grade to build the model.The results showed that,first grade(?4.0)included 3 kinds of sedums(Sedum spectabile 'Rosenteller',Sedum lineare 'Variegatum',Sedum spectabile'Autumn Joy'),11 in the second grade(3.5^4.0),12 in the third grade(3.0?3.5)and 4 in the fourth grade(?3.0).According to the comprehensive evaluation,results of each level,ornamental characteristics,purpose of landscape construction and nursery production supply,the suitable Sedums was recommended for different forms of green space.The study provides a scientific reference for the landscape application of Sedums in Beijing area and the north area of China.2)NaCl stress had a significant inhibitory effect on the growth and development of sedums in this study,and the inhibitory effect was more obvious with the increase of NaCl concentration.The results showed that the plant height,crown width,ground diameter,flowering stalk size,leaf number and relative biomass of eight sedums were significantly decreased,and the specific leaf area increased.Differences in the amount of biotic changes in root and shoots of different species under salt stress are different.It showed two different trends of the change of Root-canopy radio,one is that the ratio went up firstly and then went down,the other is that the ratio kept going down.3)Sedum species are relatively salt-tolerant plants,according to the morphological manifestations and growth indexes of various sedums under NaCl stress,8 species(cultivars)sedums were determined to have fine ornamental value under NaCl concentration less than 100mmol·L-1 in 40 days.In the 10th day of salt stress,the stress symptoms were observed under the condition of NaCl concentration of 200mmol·L-1,and the symptoms of salt injury increased with the prolongation of time.However,the plants still maintained a slow growth state.Under 400 mmol·L-1 NaCl stress,the indicators showed that Sedum plants were shrinking,chlorotic,stem and broken,almost without any ornamental value,some of which S.telephium 'Purple Emperor' plants died.4)The contents of water,soluble sugar,proline,Na+,K+,Mg2+,Ca2+ and MDA,relative conductivity,SOD,POD and CAT activities,Chlorophyll content,Fv/Fo and Fv/Fm of eight sedums were all significantly changed under the salt stress.It is suggested that Sedum could resist a certain degree of salt stress through the mechanism of water regulation,osmotic adjustment mechanism,membrane system and photosynthetic system in salted environment.5)In this paper,the comprehensive salt tolerance of eight species sedum was obtained by membership function method:S.spectabile'Rosenteller'>S.'Vera Jameson'>S.spectabile'Brilliant'>S.spectabile'Carl'>S.spectabile>S.'Joice Henderson'>S.hybrid'Autumn Joy'>S.telephium'Purple Emperor'.It is same as the result of salt tolerance evaluation form.6)Three main components of salt tolerance were proposed by principal component analysis of 11 resistant physiological indexed,The first principal component mainly contains soluble sugar,proline and SOD activity,the second principal component mainly contains conductivity and CAT activity,and the third mainly contains malondialdehyde content.Through the system cluster analysis,8 sedums were divided into three categories,one is relatively strong salt tolerance plants,including S.spectabile,S.'Joice Henderson',S.spectabile'Rosenteller',S.spectabile'Brilliant',S.spectabile'Carl',and S.'Vera Jameson',the other is not salt-resistant plants,including S.teleph ium'Purple Emperor',S.hybrid'Autumn Joy' belongs to the middle type.