The Competitive Ability Research Of Elodea Nuttallii

Elodea nuttallii has been increasingly broad introductived in China, but some studies show that it is a certain eco-invasive, and from the time of other invasive species outbreaks, it may be in the eve of the outbreak. In order to use the species more rational, and to research, evaluate and predict its existing ecological risk, from three different aspects of the competitiveness between the native species and E. nuttalli, this study is carried out understand their competitiveness, and to prevent the risk. Inter-specific competitive ability of plants, including its breeding, artificial diffusion, the ability to use nutrients and allelopathy, etc., from the dehydration tolerance, nitrogen use and long-term competition, E. nuttallii and other native species is used in this study.1,The water loss rate and the survival rate of E. nuttallii, Ceratophyllum demersum and Myriophyllum verticillatum in the same dehydration time. In order to kown the water deficit stress effects when E. nuttallii may encounter in the artificial diffusion, this study researched when encounter the no-water environment, water deficit stress of E. nuttallii, C. demersum and M. verticillatum, and they are used to measured their water loss rate in the same dehydration time. The results is showed that in the condition of there is no water lost, the survival rate of three plants in order is C. demersum≈E. nuttallii > M. verticillatum. When the dehydration time is 10 minutes, the water loss rate in order is M. verticillatum≈C. demersum < E. nuttallii; the survival rate in order is C. demersum > M. verticillatum≈E. nuttallii; When the dehydration time is 20 minutes, the water loss rate in order is C. demersum≈M. verticillatum > E. nuttallii, the survival rate in order is C. demersum≈M. verticillatum < E. nuttallii, When the dehydration time is 30 minutes, the water loss rate in order is C. demersum< E. nuttallii < M. verticillatum and the survival rate in order is C. demersum > M. verticillatum≈E. nuttallii. Thus available for a long time in the no-water environment, C. demersum suffered minimal damage, followed by M. verticillatum, E. nuttallii has the weakest resistance in the no-water environment, and suffered the greatest restrictions in the artificial diffusion.2,The ammonium nitrogen and nitrate nitrogen uptake kinetics of E. nuttallii, Hydrilla verticillate and C. demersumAs experimental materials,E. nuttallii, H. verticillate and C. demersum is used to study the NO3--N and NH4+-N uptake kinetics under the different concentrations of nitrogen and phosphorus levels (high nutrition: TN 8.866mg/L, TP 1.033mg/L; in Nutrition: TN 0.886mg/L, TP 0.103mg/L; low-nutrition: TN 0.296mg/L, TP 0.034mg/L). The results showed that: In the high nutrient treatment, the order of the absorptive capacity of nitrate nitrogen is: E. nuttallii > C. demersum≈H. verticillate; the absorptive capacity of ammonium nitrogen in order is C. demersum > H. verticillate > E. nuttallii. In the middle nutrient treatment, the order of the absorptive capacity of nitrate nitrogen is: E. nuttallii > H. verticillate≈C. demersum; the absorptive capacity of ammonium nitrogen in order is H. verticillate≈E. nuttallii> C. demersum. In the low nutrient treatment, the order of the absorptive capacity of nitrate nitrogen is: H. verticillate > E. nuttallii≈C. demersum; he absorptive capacity of ammonium nitrogen in order is E. nuttallii≈H. verticillate > C. demersum. From the point of the water purification, E. nuttallii can be able to purify the water which is at the high level of nitrate nitrogen more better, C. demersum can be easy to purify the water which is at the high level of ammonium nitrogen, and H. verticillate can adaptat the broadest range of the nitrate nitrogen and ammonium nitrogen in the water. From the point of the in-terspecific competition, in the high concentration of ammonium nitrogen, C. demersum has the higher ability to compete, and in the high concentration of nitrate nitrogen, E. nuttallii is stronger in this competition.3,The long-term competitive test of E. nuttallii, C. demersum, M. verticillatum and Vallisneria natansE. nuttallii, C. demersum, M. verticillatum and V. natans is used to study their competitiveness in the long-term of competitive test. The results is in summer, their ability to compete is M. verticillatum > V. natans > E. nuttallii >C. demersum, and in autumn, their ability to compete is E. nuttallii > M. verticillatum > V. natans > C. demersum. Overall, because of its reproductive capacity and the relatively good cold capacity, E. nuttallii occupy a certain advantage in the long-term competitive.