Research On Influence Factors Of Rhizome Sprouting And Seedling Growth Of Phragmites Australis In Saline-alkali Wetland

The severe degradation of saline-alkali wetland caused by global climate change and human activities makes its restoration a key problem to be solved urgently.One of this work is vegetation restoration of which the core is seedling formation and growth.Therefore,it's important to study the influence factors of formation and growth of seedlings of typical plants.We investigated growth characteristics of Phragmites austrilias in Songnen Plain,for determinating its suitable habitat conditions.On this basis,the effects of different biological and environmental limiting factors on rhizome sprouting and seedling growth were analyzed,to determine the optimal biological control condition and resource limiting factor ratio,providing scientific basis for rapid propagation and restoration of saline-alkali wetland plants.The results show that:1)The population height and aboveground biomass of Phragmites austrilias increased significantly with water depth while decreased with electrical conductivity and p H.The population coverage decreased with water depth,electrical conductivity,p H and total nitrogen.2)With increase of rhizome length of Phragmites austrilias,the germination percentage increased,the germination time decreased,while the relative growth rate first increased and then decreased significantly.The germination percentage,survival rate and relative growth rate were higher at 20 cm treatments where the germination time was shortest.Moreover,the germination percentage and survival rate increased with salinity.0~10 cm water depth was suitable for rhizome sprouting in spring.The interaction of depth and salinity affected the germination time significantly.The sprouting of Phragmites austrilias rhizome was better at 0 cm depth and 5 � salinity.3)With the increase of transplanting density,the individual height,number of ramets,buds,nodes,total rhizome length,aboveground,belowground and total biomass of the seedlings decreased significantly.With increase of initial height,the individual height,number of ramets,nodes,aboveground,belowground and total biomass increased significantly while the relative growth rate and leaf area decreased.The total rhizome length increased first and then decreased while interaction had significant influence on number of rhizome nodes,total rhizome length,aboveground and total biomass.The growth of Phragmites austrilis seedlings was better when transplanting one seedling at 30 cm height per pot.4)With increase of N addition,the individual height,relative growth rate,leaf area,number of ramets,buds,nodes,total rhizome length,aboveground,belowground and total biomass of the seedlings increased significantly.With the increase of salinity,the individual height,relative growth rate,leaf area and speacial leaf area decreased significantly.The growth of Phragmites australis seedling was better when salinity was 0~5 � and NH4NO3 concontration was 11.25~90 g/m~2.