Study On Drought Resistance Of Acer Negundo‘ Aurea’and Sambucus Canadensis‘Aurea’

In this paper,Acer negundo‘Aurea’ and Sambucus canadensis‘ Aurea’ were used to study.Drought stress is carried out by pot weighing method,on the seventh,fourteenth,twenty-first,twenty-eighth and thirty-fifth days to collect samples after the beginning of stress.The change of growth index,relative membrane permeability,pigment content,leaf color,organic matter content and photosynthetic characteristics on Acer negundo’Aurea’and Sambucus canadensis‘ Aurea’ were measured in different degree of drought and rehydration.The main results of this study were as follows:1.Drought stress inhibited the gold leafmaple leaf and Sambucus canadensis growth,the effect of mild stress on the Acer negundo‘Aurea’ was not obvious,the leaf water content and leaf area were not significant,the plant height and crown width were 5.11%and 11.40% lower than the control,and the root and crown ratio increased by 1.69%.Under moderate stress,the growth of Acer negundo ‘Aurea’ was inhibited,severe stress inhibited the growth of Acer negundo‘Aurea’,and its plant height,canopy,leaf water content and leaf area decreased by 39.10%,29.62%,13.59% and 70.85% respectively,and the root crown ratio increased by 19.79%,which were significantly different from those of the control;Mild stress had no significant effect on Sambucus canadensis‘ Aurea’,the growth of Sambucus canadensis‘ Aurea’ was obviously inhibited under moderate stress,and severe stress inhibited the growth of Sambucus canadensis‘ Aurea’ The plant height,crown,leaf water content and leaf area decreased by 37.68%,19.83%,8.48% and 70.83% respectively,and the root crown ratio increased by 99.66%,which was significantly different from the control.2.Under drought stress,the contents of chlorophyll and carotenoid were significantly influenced.With the increase of drought level,it first decreased and then increased;The content of chlorophyll and carotenoid in the Sambucus canadensis‘ Aurea’ was not significantly affected by mild stress and moderate stress.The content of chlorophyll was significantly increased under severe stress,and the content of carotenoid decreased significantly.The values of leaf color parameters L* and B* of Acer negundo‘Aurea’ and Sambucus canadensis‘ Aurea’ were decreased with the increase of drought stress,and the decrease of mild stress was small,and the difference was not obvious.Under moderate andsevere stress,the values of L* and B* were significantly lower than those of control,showing a significant decrease in leaf brightness and sharp decline in leaf yellow.3.Under mild stress,the change of soluble sugar content of Acer negundo‘Aurea’ and Sambucus canadensis‘ Aurea’ was not obvious,under moderate and severe stress,it increased significantly.At 35 d,they increased by 35.05%,53.92% and 58.49%,72.43%respectively,the difference is very significant;With the increase of drought stress,the soluble protein content of Acer negundo‘Aurea’ and Sambucus canadensis‘ Aurea’decreased gradually.In the treatment of 35 d,mild,moderate and severe stress decreased by12.71%,19.53%,75.25% and 7.48%,18.36%,44.45% respectively,the difference was significant with the control.4.With the increase of drought degree,the Fo and Fm first decreased and then increased,the Fv/Fm gradually decreased,and the Fv/Fo first increased and then decreased.The light response curve of Acer negundo‘Aurea’ was "single peak",and the net photosynthetic rate,stomatal conductance and intercellular two oxygen carbon concentration under severe drought stress were significantly different from those of the control;The light response curve of Sambucus canadensis‘ Aurea’ was "double peak",net photosynthetic rate under severe stress,stomatal conductance and intercellular carbon dioxide concentration under moderate and severe stress were significantly different from those of control.The light saturation point and light compensation point of Acer negundo‘Aurea’ and Sambucus canadensis‘ Aurea’ gradually decreased with the increase of drought degree,and decreased by 34.43%,63.09% and 16.43% and 12.33% respectively under severe drought stress.5.The water content,relative conductivity,chlorophyll,carotenoid,soluble sugar and soluble protein of plant were restored to some extent after Acer negundo’Aurea’ and Sambucus canadensis‘ Aurea’ rehydration treatment.The treatment of mild drought and moderate drought stress has a strong ability to recover after rehydration and the recovery ability of rehydration was weakened by severe drought treatment.