Abstract: Rice seeds were treated with a range of concentration of diethyl sulphate (dES) or sodium azide (NaN₃) after having been presoaked for 16—18 hours with water. The respiratory intensity was determined on second day (seed germinating for 48 hours) and activity of cytochrome oxidase was determined on fourth day (seedling growing for 4 days). The respiratory intensity of germinating seeds and activity of cytochrome oxidase of seedlings decline with the increase of the concentration of dES or NaN₃, and germination rate and germination power of seed, seedling height, root vigor decrease consequentially. The experimental results show that the decreases of germination rate of seed, seedling height, and root vigor are closely linked to the respiratory intensity and activity of cytochrome oxidase in cells in early development of rice. Both dES and NaN₃ at first inhibit the respiration in cells, therefore the changes in seed viability, seedling height, root vigor are caused.