Abstract: The purpose of this paper is to show how the change of transpiration destroys water balance in rice plants. The inhibition of, transpiration was pronounced under the following two conditions: 1) The amount of pollutants accumulated in the roots, stems and leaves of the plant was very large; 2) Any one of the organs, that is, its root, stem or leaf, showed visible injury. The later was the direct cause of the declination of transpiration. Because the absorption and transport of wate were inhibited. With the decline of transpiration, photosynthesis also declined rapidly. Owing to this, the plant grow slowly, with its stem and leaf sparse. Thus the plant phenological period became abnormal and the biomass and production of rice decreased. According to inhibition level of the plan transpiration, the toxicity of the pollutants and the plant resistance could be distinguished.

Key words: Pollutants, Transpiration, Water balance, Rice