Abstract: Physiological characteristics of rice at different Zn2+levels [pZn2+＞11.5, 11.3, 11.0, 10.6, 10.3, 9.7] were studied with the Znefficient rice cultivars IR34, IR36, IR8192, and Zninefficient rice cultivars IR26, Ce 64-7, Biyuzaonuo, which grew in chelatorbuffered nutrient solution. There were significant differences in tolerance to zinc deficiency among different rice genotypes. Obvious effects of low zinc activity on the physiological characteristic of rice seedlings were noted. There were significant differences in chlorophyll content, photosynthesis rate, MDA concentration in rice leaf, and H+ excretion of root. As pZn2+ decreased, chlorophyll content and photosynthesis rate decreased at a slower pace in Znefficient cultivars compared to Zninefficient ones, MDA concentration increased slower while H+ excretion of root increased faster in Znefficient cultivars than those in Zninefficient ones. It was suggested that the above indications could be used as indexes to Znefficiency of rice.

Key words: rice, genotype, zinc, physiological characteristic, nutrient efficiency