Abstract: Six rice cultivars with different Zn efficiency were cultivated at different Zn2+ activities (pZn2+9. 7, pZn2+11.0 and pZn2+11. 5) in nutrition solution. Their growth and some physiological characters were studied in responses to different Zn2+ activities. It was found that the ability of rice tolerance to Zn deficiency significantly differed among the rice cultivars. Dry matter(DW) accmulation of roots increased when Zn2+ activities were lower than pZn2+ 11. 5 for all the cultvars tested. However,Shoot DW of Zn-efficient rice genotypes significantly decreased but their root DW significantly increased when pZn2+ decreased from 9. 7 to 11.0. Shoot DW of Zn-inefficient rice genotypes significantly decreased and no increase in root DW were observed when pZn2+ decreased from 9. 7 to11.0 Therefore, the DW of whole plant for Zn-efficient rice. genotypes had not significantly decreased while that for Zn-inefficient rice genotypes had significantly decreased at relatively low Zn2+ activities.At pZn2+ 11. 5, the DW of all rice genotypes significantly decreased, especially for Zn-inefficient rice genotypes. There were obvious differences in growth rates of leaves among the cultivars at low Zn2+ activities. The Zn-inefficient rice genotypes could only grow up to 3. 5 leaves and Zn-efficient rice genotypes could grow to 4. 5 leaves at pZn2+11. 5. The chlorophyll content slightly increased at pZn2+ deceased up to 11.0, but decreased at pZn2+ 11. 5. Root oxidizing power (ROP) considerably increased at severe Zn deficiency (pZn2+ 11.5. At seedling age of 39, it was interesting that ROP decreased about one-fold for the Zn-efficient cultivars but increased markedly for Zn-inefficient cultivars when plants were grown at pZn2+11.0.The water content of rice seedling slightly decreased when Zn2+ activities decreased. It could be concluded that at relaive low Zn activity the Zn-efficient cultivars could increase root growth, lower root oxidizing power, maintain leaf growth rate and leaf photosynthetic capacity and thus reach homeostasis in adaptation to low Zn.