Abstract: Two low potassium tolerant rice(Oryza sotiva L.)genotype, N18 and N19, and their recipient,N27(control) were used in this experiment to investigate the effects of low potassium stress on the growth and changes of several physiological indexes of different rice genotypes at seedling stage. The results showed that under low potassium stress, the height, fresh and dry weight of shoots of the recipient depressed greater than that of low potassium tolerant rice genotypes. Under low potassium stress, root length, root dry weight, root volume and root vigor of all genotypes were decreased, which were more significantly of N18 and N19 than those in N27 respectively. Furthemore, low potassium stress increased the ratio of root/shoot, but the differences in it were inconspicuous among the three genotypes tested. Under low potassium stress, free amino acid contents and soluble suger content in leaves of all genotypes were increased, the increases of which were less in N18 and N19 than in N27. Under low potassium stress, soluble protein contents in leaves were decreased, reductions of which were more in N27 than in N18 and N19.

Key words: rice, low potassium stress, genotypic difference, physiological index