Abstract

Natural water hydrodynamic conditions play an important role in the nutrients transport among water, soil and plants. Meanwhile, aquatic plants affect the water flow characters and pollutants purification capability. However, there are limited studies on how these conditions affects the nutrient uptake and physiological response of aquatic plants. From May 18 to June 28, 2007, a kind of submerged plant, Vallisneria spiraslis L, was selected to observe the difference in nitrogen accumulation and antioxidant system and their changes in both shoots and roots of the plant between hydrodynamic condition (D flume) and relative hydrostatic condition (S flume). The results showed that under hydrodynamic conditions, the nitrogen accumulation in shoots increased rapidly, and maintained a higher level of nitrogen accumulation than that of the hydrostatic flume. Furthermore, in the initial stage of the experiment, the total chlorophyll of V. spiraslis in the D flume decreased because of the hydrodynamic stress inhibition, while Chl a and b appeared to be a little synthesized in the S flume. Moreover, rapid induction in antioxidant enzyme activity occurred in shoots of the plant in the D flume, and the activity levels of POD and GSH were significantly higher than those of the S flume.

Key words: running water, Vallisneria spiraslis L, nitrogen accumulation, chlorophyll, antioxidant defense.