Response Ability Of Male And Female Humulus Scandens(Lour.) Merr.to Low Temperature Stress And The Difference Between Coping Strategies

Aiming at the restoration of damaged habitats and slope management,the dioecious climbing herb Humulus scandens(Lour.)Merr.was selected as the test material,and the indoor test of seeds and seedlings with different low temperature treatments and low temperature stress were set up.Outdoor experiments of Humulus scandens under different supports were used to determine the relevant indexes of Humulus scandens seed germination,seedling component traits,biomass structure,physiological response and other indexes.Combining the differences in the effects of low temperature on male and female Humulus scandens plants under different supports,analyze the gender response of low temperature to male and female Humulus scandens plants,and study the influence of low temperature on germination characteristics,as well as the differences in the growth,physiological response and survival strategies of seedlings and adult plants..Explore the effects of low temperature on male and female Humulus scandens under different supports,in order to provide high-quality materials for ecological management under low temperature,and provide theoretical basis for the selection of cold-resistant varieties,planting management and sustainable utilization of Humulus scandens.The main results are as follows:(1)Low temperature has an extremely significant effect on the germination characteristics of Humulus scandens seeds(P<0.01).Humulus scandens seeds have the shortest germination days at 6?,and the highest germination rate,germination vigor,vigor index and germination index.There is no significant difference between 3? and9?(P>0.05).The germination characteristics are significantly higher under low temperature treatment.Control group at room temperature.This shows that low temperature promotes seed germination.(2)Low temperature has a very significant effect on the roots,stems,leaves and biomass distribution of Humulus scandens seedlings(P<0.01).As the temperature decreases,the leaf length,leaf width,single leaf area and total leaf area of Humulus scandens seedlings decrease.Humulus scandens seedlings responded to low temperature stress by reducing plant height and stem thickness.The order of low temperature treatment on stem and root characters was: basal stem diameter>plant height>root length.It indicated that Humulus scandens seedlings showed significant differences in their component traits under low temperature.The lower the temperature,the lower the leaf biomass allocation ratio,the higher the stem and root biomass allocation ratio,and the lower the total biomass.(3)The Chla,Chlb,Chl(a+b),Chla/Chlb and other indicators of Humulus scandens seedlings under low temperature have extremely significant effects(P<0.01),indicating that low temperature will affect the synthesis of Chl in the seedlings.Low temperature has a significant effect on the antioxidant enzyme system and osmotic regulation mechanism(P<0.05),and the enzyme activity increases with the decrease of temperature.The order of influence of active metabolism and membrane damage is:SOD>POD>MDA>CAT;the order of influence of osmotic adjustment mechanism is:SS>SP>Pro.(4)Low temperature had extremely significant effects on the leaf and stem characteristics of Humulus scandens under different supports(P < 0.01).The heterogeneity of the support had an effect on the leaf thickness,single leaf area,dead leaf rate and internode length of male and female Humulus scandens plants.All have significant effects(P < 0.05),have extremely significant effects on the thickness of secondary branches,single leaf area,stem length(P<0.01),and have significant effects on the floral traits of female and male plants and secondary branches(P<0.05).The support reduces the number of flower spikes in male plants.The flower cob axis length and flower spike stalk length of the male secondary branches increase.The plant changes the component traits to increase the number of pollen,and also provides better material conditions for the spread of pollen..The biomass distribution of Humulus scandens plants was affected by different supports and showed significant gender differences.The distribution of stems and flowers of Humulus scandens female plants was significantly higher than that of male plants(P<0.05).(5)Low temperature has significant differences in SOD and POD activities under different supports(P<0.05),but there is no significant difference in CAT activities(P>0.05).The total treatment of Humulus scandens has a very significant effect on SOD and POD activities(P<0.01)),but there was no significant difference between CAT activities(P>0.05).The order of the effect of low temperature on Humulus scandens enzyme activity under the support is: POD>SOD>CAT.There were significant differences in SOD between male and female plants of Humulus scandens under different supports(P<0.05),and there were significant differences in POD enzyme activity between sexes(P<0.05).Supports and gender have extremely significant differences in membrane damage and osmotic adjustment substance content such as MDA,Pro,SP,SS(P<0.01).There was a significant difference between sex and MDA content(P<0.01).The MDA content of male plants of Humulus scandens was significantly higher than that of female plants(P<0.05),and the MDA content of male plants reached the peak with the support of trees.Gender had a significant effect on the Pro content(P<0.05).The Pro content of the male plants of Humulus scandens was significantly higher than that of the female plants(P<0.05),and the Pro content of the male plants reached the maximum under the control treatment.(6)Low temperature has a very significant effect on the photosynthetic pigment content of male and female Humulus scandens plants under different supports(P<0.01).The content of Chla and Chlb is very significant under the support,and the content of Chla and Chlb under flat ground without support is significant.It is greater than the content supported by shrubs and trees(P<0.05).The net photosynthetic rate(Pn),intercellular CO2 concentration(Ci),transpiration rate(Tr),and stomatal conductance(Gs)of Humulus scandens are significantly different under different supports(P<0.05).By increasing the height of the support,Make the values of Pn,Gs,Tr all decrease first and then increase,Ci first increase and then decrease,Pn,Gs,Tr reach the maximum when there is no support on flat ground,and Ci reach the maximum when the bush supports.In summary,low temperature has obvious effects on the germination of Humulus scandens seeds,seedling component traits and physiological responses,and the growth and development and physiological responses of male and female Humulus scandens plants under heterogeneous support conditions,and there are significant gender differences between males and females.Humulus scandens responds to low temperature by adjusting its morphological plasticity,changing the way of biomass allocation,regulating photosynthetic pigments and photosynthetic parameters,and changing the physiological metabolism speed,resisting low temperature to activate the antioxidant enzyme system and increase permeability.In this experiment,the female Humulus scandens plants showed stronger cold-resistant morphology and physiological basis than the male plants in terms of structural traits,photosynthetic characteristics,antioxidant enzyme system and osmotic substances.Therefore,more consideration should be given to gender differences in cold resistance when breeding ecological restoration varieties,soil consolidation and slope protection,and formulation of greening measures to avoid unnecessary economic losses and ecological risks.