Ecological Adaptation Of Phalaris Arundinacea In Poyang Lake Wetland

Poyang Lake is the largest freshwater lake in China, and one of the six major wetlands in the world. Seasonal water level changes affect the plant survival of the Poyang Lake wetland. Phalaris arundinacea is one of the main dominant plants in Poyang Lake. In this paper, we explored how Phalaris arundinacea adapt to the environment of Poyang Lake Wetland by field investigation on distribution of Phalaris arundinacea, simulated water stress experiment, the production of paraffin sections, the determination of the growth dynamic, vegetative reproduction and seed germination experiments of Phalaris arundinacea.The main results are as follows:1.Phalaris arundinacea is mainly distributed in the range of8.5-13meters high level and grow along the waterside with less human disturbance. It is often accompany to Polygonum barbatum or Carex and form a mixed community with Polygonum barbatum or Carex.2.Phalaris arundinacea growth in good condition during the dry period of Poyang Lake. The change of height and biomass of Phalaris arundinacea in different month appears S-curve. Sexual reproduction growth makes significant changes in all aspects.3. The seed of Phalaris arundinacea is light neutral, its optimum germination temperature is25℃. Seed germination is sensitive to low water potential conditions. Overall, germination rate of Phalaris arundinacea seed is low. The rapid expansion and reproduction of Phalaris arundinacea population mainly through the tiller as a kind of vegetative propagation method to adapt to the Poyang Lake seasonal flooding.4. Phalaris arundinacea have evolved well-developed aerenchyma in roots, stems, and leaves. The basic tissue cells of the stem can regain the ability of cell division to grow new adventitious roots. Endodermis of roots has Casparian strips with a horseshoe-shaped five surface thickening. It is shows that the adaptation of anatomical structure of Phalaris arundinacea for Poyang Lake wetland.5. In condition of drought or flooding stress, the activity of POD and CAT, soluble protein content showed varying degrees of rise with the time and stress intensity to protect the plant tissue. Soluble sugar content in Phalaris arundinacea showed distribution change. Soluble sugar content reduced in roots and leaves, increased in stems. MDA content changed little overall. Drought and flooding stress on Phalaris arundinacea membrane peroxidation injury is not obvious. When the water stress is removed, the recovery of Phalaris arundinacea were not very well. Processing time and stress intensity had a significant effect on the physiological indicators of Phalaris arundinacea. Overall, Phalaris arundinacea could be well adapted to drought and flooding condition.