Study On The Adaptability Of Three Populus Deltoides Seedlings To Drought And Waterlogging

P.deltoides cv.'Zhonghong' and P.deltoidescv.'Quanhong' are bud mutation red leaves varieties of the American Populus '2025'(P.deltoidescv.'Lux'(1-69/55)x P.deltoidescv.'Shan Hai Guan '),they are fast growing and high yield of colorful landscape trees,in view of the two red leaves poplar as new varieties,its adaptability isn't known,we studied the changes in the growth and physiological and biochemical index on the 2025 and one year old grafted seedlings of its two bud mutation varieties'quanhong','zhonghong' under sustained drought and waterlogging stress,the drought,waterlogging tolerance evaluation was made of these three polar varieties by using membership function method and gray relational analysis method,to provide scientific foundation for the popularization and application of the red leaves varieties.The main results are as follows:(1)The leaf Pn and Tr of the three poplar varieties had a significant positive correlation with the soil water content,and the determination coefficient R2 of the Pn,Tr simulation equation was greater than 0.6,and the significant was caused by the significant decrease in the SWC The main reason for the change of leaf Pn was continuous decline of SWC and Tr.(2)Under sustained drought stress,the chlorophyll content,Pn and Tr of leaves were decreased significantly,had extremely significant difference with CK(P<0.01),the difference of chlorophyll content was significant(P<0.05),Pn and Tr had no significant difference(P>0.05)among the three varieties.(3)Under sustained drought stress,the relative permeability of leaf membrane,the content of MDA and The soluble sugar content of the three poplar cultivars were significantly increased,had extremely significant difference with CK(P<0.01);the trend of CAT activity and the soluble protein content was decreased,had extremely significant difference with CK(P<0.01);SOD activity and the content of proline in the leaves increased first and then decreased,continued to decline,had extremely significant difference with CK(P<0.01).(4)During the process of mild flooding to moderate flooding,the chlorophyll and carotenoids in the leaves of three poplar varieties increased.Chla,chlb,total chlorophyll and chla/b ratio decreased with the increase of flooding time,chla decreased more than chlb.Compared with the CK,the difference was extremely significant(P<0.01),but there was no significant difference among the three clones(P>0.05).(5)Under the continued waterlogging stress,the leaf Pn of three poplar varieties showed a downward trend,with extremely significant difference(P<0.01),the difference was significant among the three poplar varieties(P<0.05);Tr in leaves of 3 poplar varieties were extremely significant lower than the CK;early stress,Tr of P.deltoides cv.'Zhonghong' and Populus '2025' was extremely significantly higher than that of P.deltoides cv.'Quanhong'(P<0.01);the late stress,Tr of P.deltoides cv.' Zhonghong ' was significantly higher than that of P.deltoides cv.'Quanhong ' and Populus '2025'.(6)With the waterlogging stress sustained,the activity of SOD,the relative permeability of leaf membrane,the content of MDA,the content of proline and the soluble sugar content of the three poplar cultivars showed an increasing trend,were extremely significantly higher than the control group(P<0.01);the change trend of CAT activity and the soluble protein content of the three poplar varieties was different,was extremely significantly lower than the control(P<0.01).(7)The comprehensive evaluation of drought resistance and waterlogging tolerance of cultivars was carried out by using the average value of membership function.The results showed that the drought resistance of P.deltoides cv.'Quanhong'was significantly lower than that of P.deltoides cv.'Zhonghong ' and Populus '2025'(p<0.05),and there was no significant difference between P.deltoides cv.'Zhonghong 'and Populus '2025'(P<0.05);anti waterlogging ability of P.deltoides cv.'Quanhong 'was weakest among the three clones,was significantly lower than that of P.deltoides cv.'Zhonghong ' and Populus '2025'(p<0.05),and there was no significant difference between P.deltoides cv.'Zhonghong ' and Populus '2025'(P<0.05).Analysis of resistance related physiological indexes based on grey system theory,proline was main index for evaluating drought resistance of three poplar varieties,the relative permeability was main index for evaluating waterlogging resistance of three poplar varieties.