| The mountainous riverside wetland is an important transitional zone connecting land and rivers.However,due to factors such as rapid population growth and rapid industrialization,the ecological environment in mountainous areas has become more fragile.Good vegetation conditions are the foundation for maintaining the structural stability and functional integrity of wetlands.As a direct part of the connection between plants and wetlands,the growth of roots is one of the key factors affecting the absorption of soil nutrients by plants.In addition,root penetration and other methods will also change the rhizosphere soil structure.Root redundancy is manifested as excessive root growth,which is a special manifestation of root plasticity.By regulating influencing factors reasonably,it can strengthen root redundancy development and change the root configuration of wetland plants,which is of great significance for restoring or rebuilding wetland plant belts and slowing down the degradation process of mountainous riverside wetlands.The paper studies the feasibility of applying the cultivation technology based on redundancy theory to induce root redundancy development and form root mats in rapid restoration of mountainous riverside wetlands.Firstly,a culture method was established to enhance the redundant development of wetland plant roots by inducing exogenous hormone ethephon(100mg/L,300mg/L,500mg/L)and limiting vertical root space(4cm,8cm)in ectopic soil culture.Secondly,the caisson method was used for transplantation to investigate the changes in growth and metabolism of rushes and cattails under different flooding conditions,and the impact of redundant root morphology on the stability of wetland substrate was analyzed.This paper can provide new ideas and methods for the rapid restoration of riverside wetlands in mountainous areas.The main research results and conclusions obtained are as follows:(1)When determining the appropriate induction concentration of ethephon,it was found that the application of ethephon could reduce the accumulation of reactive oxygen species(ROS)and malondialdehyde(MDA)under flooding conditions,significantly increase the content of catalase(CAT),peroxidase(POD),superoxide dismutase(SOD)and total antioxidant capacity(T-AOC)(P≤0.05),and when the applied concentration of rushes was 500 mg/L,and the applied concentration of cattail was 300 mg/L,the content of CAT,POD The increase in SOD and T-AOC was the largest,while the decrease in SPAD value was the smallest,indicating that ethephon can effectively enhance the adaptability and antioxidant capacity of rushes and cattails in flooded environments,and improve their photosynthetic capacity.In addition,the increase in root porosity and ethylene release rate is the largest,while the decrease in root activity and root oxygen secretion rate is the smallest,indicating that ethephon treatment can alleviate the damage to plant roots caused by flooding to a certain extent and improve the ability of root growth and metabolic activity.(2)A root redundancy induction method was constructed based on the combination of ethephon induction and root vertical spatial restriction induction.Using 500mg/L ethephon to induce rushes and 300mg/L ethephon to induce cattails,and combining with vertical root space limitations(5cm,10cm),the plants were treated.After 50 days of cultivation,a 4cm thick root pad and an 8cm thick root pad were successfully cultivated.The root to shoot ratio of the 4cm and 8cm thick root pads was significantly higher than that of plants grown under natural conditions.(3)The experiment on the waterlogging resistance characteristics of different root types of plants showed that under waterlogging conditions after transplantation,the overall ROS content in the leaves of rush and cattail increased first and then stabilized with the prolongation of waterlogging time,and the MDA content increased first and then decreased with the prolongation of waterlogging time.The T-AOC content and CAT activity of rush and cattail showed a trend of increasing first and then decreasing with the prolongation of waterlogging time,while the SPAD value of the leaves decreased with the prolongation of waterlogging time,There was no significant difference(P>0.05)in MDA,ROS,T-AOC,and CAT at each flooding depth.Using root mat planting technology can improve the root crown ratio,enhance root vitality,and oxygen secretion rate of plants,thereby promoting plant growth.Overall,the root pad planting method can improve the antioxidant capacity of rushes and cattails,reduce cell membrane lipid peroxidation damage,and enhance photosynthesis.Among them,the 8cm thick root pad planting method has the best effect.(4)The single root tensile test of rushes and cattails showed that the use of root pad planting method significantly improved the tensile strength of the roots of rushes and cattails.The average tensile strength of a single root under the 4cm root pad planting method was slightly higher than that under the 8cm thick root pad planting method.The root diameter of Juncus effusus and Typha typha under the root cushion planting mode is significantly smaller than that under the natural state planting mode,and the root diameter under the 4cm thick root cushion planting mode is significantly smaller than that under the 8cm thick root cushion planting mode.The root tensile strength of Juncus effusus is positively correlated with the root diameter as a power function,while the single root tensile strength of Typha typha is linearly positively correlated with the root diameter,and the single root tensile strength of Juncus effusus and Typha typha is negatively correlated with the root diameter as a power function.(5)Through the shear test of root soil complex of different root type plants,the shear characteristics of root soil complex were proved.The direct shear test showed that under the same axial vertical load,the shear strength of root soil complex formed by three root type plants in the shallow soil layer was higher than that of the corresponding root soil complex in the deep soil layer.The shear strength of the root soil complex was improved mainly by increasing the cohesion and internal friction angle.The improvement of the shear resistance of the root soil composite by cattail is mainly achieved by enhancing the root mass density in the soil to enhance the cohesion of the root soil composite.Compared to the 4cm root pad planting method and the natural state planting method,the cohesion value of rush grass and cattail under the 8cm root pad planting method is greater,that is,the root soil composite shear strength of rush grass and cattail under the 8cm root pad planting method is greater.Optimizing planting methods and improving root mass density can effectively improve the shear resistance of root soil composites.Under the 8cm thick root pad planting method,rushes and cattails have better structural advantages in enhancing soil cohesion and improving soil shear resistance,which is more conducive to the resistance of plants to water flow impact and the close integration of roots and riverbed after transplanting to rivers. |
