Effects Of Water Condition On The Growth And Physiology Of Arundo Donax Var.versicolor

With the continuous change of global climate,extreme weather often occurs,and the wetland hydrological conditions change drastically,affecting the growth of wetland plants.This paper takes the wetland plant A.donax var.versicolor as the research object,sets up different water gradients and flooding gradients,analyzes the growth physiological characteristics of A.donax var.versicolor under different water conditions,studies its response characteristics under different water conditions,establishes a model to explore the water level ecological amplitude of A.donax var.versicolor,and provides reference for the construction of wetland.The main conclusions are as follows:(1)After drought stress,A.donax var.versicolor seedlings can gain more dry matter and biomass by thickening the basal stem and increase plant height and root length.Stress can be dealt with by reducing leaf area,accelerating the shedding of old leaves and concentrating water mainly on new leaves.The plant height,basal stem,root length,leaf morphological characteristics and biomass of A.donax var.versicolor seedlings showed an upward trend and then a downward trend with increasing drought.The seedlings of A.donax var.versicolor grew well when the soil moisture content was 30%-50%.When the soil moisture content was less than 20%,the seedlings of A.donax var.versicolor died of drought after 30 days of the experiment.After rewatering,there was no significant increase in each morphological index.The fastest accumulation rate of A.donax var.versicolor biomass was the 0 to 35 day of the experiment.(2)Under drought stress,the synthesis of photosynthetic pigments in the leaves of A.donax var.versicolor is inhibited,but it can coordinate its own antioxidant enzymes to remove reactive oxygen in a timely manner,and resist the drought induced oxidative damage by accumulating soluble protein content.As the stress level deepened,the chlorophyll content decreased,and the carotenoid content showed an upward trend in the early stage of the experiment and a downward trend in the late stage;SOD activity showed an upward trend,and POD and CAT activities both increased first and then decreased;soluble protein and MDA both increase with the degree of stress.After rehydration,all physiological indexes can be restored to the control level.(3)After suffering flooding stress,A.donax var.versicolor obtains oxygen by increasing plant height and number of leaves,obtains nutrients required for growth by increasing root length and growing indefinite roots at the base stem,adapts to adversity by reducing leaf length,leaf width and leaf area and other ways.In addition,each treatment group did not die after 100 days of flooding.With the increase of the depth of flooding,the plant height and basal stem of the seedlings showed a single peak pattern,the root length showed a rising trend,the leaf length,leaf width and leaf area showed a downward trend,and the number of leaves and leaf water content showed an increasing trend and then decreasing trend.Aboveground biomass showed a bimodal change trend,while underground biomass and total biomass showed a general downward trend.The fastest accumulation rate of A.donax var.versicolor biomass was from the 0th to the 50 days of the experiment.(4)Under flooding stress,the chlorophyll synthesis of A.donax var.versicolor is inhibited,but it can coordinate the antioxidant enzyme system to scavenge active oxygen free radicals,and at the same time actively accumulate soluble proteins to maintain a low osmotic type of cells and enhance root vitality against stress.With the increase of the depth of flooding,the chlorophyll content of the leaves of A.donax var.versicolor showed a trend of increasing first and then decreasing,and the content of carotenoids showed a trend of decreasing first and then increasing.The MDA content showed an upward trend,and the root vitality showed a single peak change trend.(5)According to the model study,the ecological range of the water level of A.donax var.versicolor seedlings is [-59.09,61.37] cm,and the optimal water level is [-13.87,10.44] cm.