Evaluation Of Cold And Drought Resistance Of American Popla Clones Based On Subordinate Function

Populous deltoids is widely distributed in the temperate regions of the Northern Hemisphere.It has extremely rich germplasm resources,large genetic variation within the species,straight trunks of trees,and excellent material quality.It is the most cultivated and used tree species.However,in the northern regions of China,poplars often encounter low temperature and drought stress during the growth process.The resistance of the current fast-growing high-yield clones need to be further optimized.Therefore,it has important scientific value to screen black poplar clones with strong cold resistance and drought resistance through index evaluation system.In this research,five black poplar clones obtained from the hybridization were used as materials,and contrast experiments were conducted to evaluate the cold resistance and drought resistance,which provided a scientific basis for breeding and popularization of fine new varieties.Main conclusions were made as follows:(1)In order to study the cold resistance mechanism of poplar,taking annual dormancy branches of five Populous deltoids and three Populous deltoids control as experimental materials,we studied the changes of conductivity,superoxide dismutase activity,MDA molality,mass fraction of soluble protein and POD activities after the plants had been treated under a series of low temperature(-15?,-20?,-25?,-30?,-35?)for 24 hours and compared and evaluated the differences of the clones in cold resistance by using membership function method.There were obvious differences among the clones of the ability of cold resistance(P<0.05).(2)Through the membership function,the cold resistance of eight species of poplar deltoids clones from strong to weak was Nankang Populus(0.6997),‘08H1-6'(0.5656),‘03S4-1'(0.5339),‘08H11-11'(0.4734),ShanLin NO.3(0.4547),Qinheiyang NO.1(0.4265),69 Populus(0.3865),Qinheiyang NO.2(0.3096).The results showed that the cold resistance of ‘08H1-6',‘03S4-1' and ‘08H11-11' are between Nankang Populus and ShanLin NO.3.(3)The leaf anatomical structures of 11 poplar clones(‘08H11-11',Qinheiyang NO.1,Qinheiyang NO.2,‘08H1-6',‘NanKang',‘03S4-1',I-69,ShanLin No.3,Populus deltoids No.1,Populus deltoids No.2,Populus deltoids No.3)were observed with paraffin sectioning method.Seven xeromorphic indices were measured,such as leaf thickness,thickness of vein,thickness of upper and lower epidermis,thickness of upper and lower palisade tissue and ratio of palisade tissue to leaf thickness etc.An evaluation about this kind of poplar clones were given by the method of subordinate functions.Relationships between anatomical indices and drought resistance were examined by grey correlative analysis.(4)The conclusion showed that the drought resistance capabilities of eleven poplar clones were in an order of ‘NanKang',Populus deltoids No.2,Populus deltoids No.3,Qinheiyang NO.2,Qinheiyang NO.1,‘03S4-1',‘I-69',‘08H11-11',Populus deltoids No.1,ShanLin No.3 and ‘08H1-6'.Studies have shown that the upper and lower palisade tissue thickness,leaf thickness and other indicators can be better used to evaluate the drought resistance of poplar species.