Effects Of Environmental Factors On Germination And Seedling Growth Of Triarrhena Lularioriparia

Poyang Lake,the largest freshwater lake in China,its annually seasonal water level variation have a great impact on the survival of Poyang Lake wetland plants.In this paper,we used the dominant plant of Poyang Lake�Triarrhena lularioriparia as the research object,artificial simulation of seed germination under different moisture/temperature conditions and seedling growth experimrnt under waterlogging stress,analyzed the effect of moisture/temperature on its seed germinating period and the effect of waterlogging enviroment on its seedling growth porcess.Discussed the physiological response and adaptive strategy of Triarrhena lularioriparia seed germination to different temperature conditions/arid environment and its seedling growth to waterlogging environment.(1)Under different temperature conditions,the optimum temperature for germination of Triarrhena lularioriparia seed is 25 �C.The ambient temperature above or below 25 �C has a significant inhibitory effect on the germination of Triarrhena lularioriparia seed.(2)Under drought stress,12.5 % ~ 17.5 % concentration of PEG-6000 were conducive to promoting Triarrhena lularioriparia seed germination,and Triarrhena lularioriparia seed had strongest ability to cope with drought stress at 12.5 %concentration.The other concentration gradients all inhibited the germination of Triarrhena lularioriparia seed,and with the increased of drought stress,the inhibition of seed germination was stronger,the change trend was: the germination coefficient increased first then decreased.The drought resistance of Triarrhena lularioriparia seed in different treatment groups was: 12.5 % > 15 % > 17.5 % > 0 % > 2.5 % >5 % > 7.5 % > 10 % > 20 %.Under the 12.5% concentration of PEG-6000,the drought-resistant of Triarrhena lularioriparia seed reached the maximum.(3)Under waterlogging conditions,Triarrhena lularioriparia seedling can not survive in more than 50 cm waterlogging environment.In the process of seedling growth,Triarrhena lularioriparia seedling would adapt to the flooding environment through the change of morphology(root growth,adventitious roots,etc.),but with the increased of water depth and the prolongation of waterlogging time,the growth rate slowed and the membrane grew.The degree of lipid peroxidation was increased,the antioxidant enzyme protection system was destroyed,and root activity was decreased.As the water depth increased,the plant growth rate decreased,the number of leavesdecreased,and the relative content of chlorophyll decreased.The activity of MDA and each antioxidant enzyme increased first then decreased,soluble protein content decreased first then increased,the root activity after waterlogging has been significantly reduced.With the waterlogging time prolonged,the activity of MDA,SOD and POD of Triarrhena lularioriparia increased continuously.(4)The Triarrhena lularioriparia seedling water level ecological amplitude was determined to be [-38.62 cm,41.07 cm],and the optimal water level ecological amplitude was [-11.04 cm,20.15 cm].The general elevation of Triarrhena lularioriparia community is mainly located at 12 ~ 17 m.