| The moisture variation is the key ecological factor which affect the growth and distribution of plants in the interlaced zone of rivers and lakes.In this research,we used dominant plant of P.arundinacea of Poyang Lake as the research object.Artificial simulating water stress experiment was conducted by seed germination and rhizome cultivation,and the water was analyzed in different growth periods(seed germination and seedling growth)of P.arundinacea.To study the influence of life history process on the responses to drought stress and seedling growth to submergence environment and adaptive strategies.At the same time,the environmental impact was analyzed by monitoring the growth dynamics of Nanji Mountain wetland.The influence of factors(precipitation,soil water content,Poyang Lake water level,and temperature)on the growth of grasses in the wild reveals the dynamic changes in the growth of P.arundinacea.The results are as follows:(1)Under drought stress,the 10% PEG-6000 solution promoted the germination of seed,and seed at this concentration had the strongest ability to deal with drought stress.With the concentration of PEG-6000 solution increasing,the seed germination process was stronger by inhibition,the trend of was: germination rate,germination potential,daily germination rate and germination value decreased,germination index increased first then decreased,while the average germination rate increased.The drought resistance of different treatments seed: 10%> 0%> 12.5%> 15%> 17.5%>20%> 22.5%,it weakened with the increase of PEG-6000 concentration.(2)Under waterlogging stress,P.arundinacea cannot survive in environment where waterlogging is more than 50 cm.In the process of growth,the seedlings of P.arundinacea will increase their adaptability to the waterlogging environment through changes in morphology(widening of the leaves,root growth and adventitious roots,etc.),but with the increase of water depth and waterlogging time,the growth of P.arundinacea is mainly for the slow growth rate,the degree of membrane lipid peroxidation intensified,the antioxidant enzyme system was destroyed,the root activity decreased.The response of the growth characteristics and physiological characteristics of P.arundinacea to waterlogging environment was as follows: With the increase of the water depth,the growth rate and the number of leaves decreased,chlorophyll relative content decreased.With the extension of waterlogging time,theleaf width and root length increased continuously,the change of leaf length and leaf surface increased first then decreased,the root-shoot ratio showed anti-parabolic change.With the extension of waterlogging time,the content of MDA in each group increased continuously.When water depth was 0-30 cm,SOD and POD increased,CAT increased first then decreased.When water depth was 40-60 cm,SOD and CAT increased,POD decreased first then increased.The root activity decreased continuously in each group,and the rotten roots appeared at 60 cm depth.The content of soluble protein increased,but the impact of waterlogging stress on P.arundinacea soluble protein content is not significant.Above 50 cm depth of waterlogging,the root-shoot ratio was the largest at this depth,the root activity was the lowest,and the black roots and rotted roots were found.(3)Under the effect of monthly mean temperature,monthly mean precipitation and Poyang Lake water level,the P.arundinacea community appeared the phenomenon which opposite to the typical "S" curve of limited growth.The population density of P.arundinacea had the trend of decreased first then increased in growth history,which was consistent with the self-thinning rule.Due to the soil moisture content above 48% in the observational sample plot and the P.arundinacea has a certain degree of resistance to soil moisture supersaturation in the mid-growth stage,the soil moisture content had little effect on the growth dynamics of P.arundinacea,it is not a restrictive environmental factor for the growth of P.arundinacea in Nanji Mountain. |
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