Three leaf stage seedlings were investigated for intake rates of potassium in each 11 genotypes of O.japonica O.indica and O.indica hybrid at different K⁺ levels according to ion depletion.Potassium utilization efficiencies at 3 leaf stage were compared with those at 5 leaf stage to screen efficient genotypes.The suitable potassium levels were 0.2mmo1/L for both O.japonica and O.indica and 0.4mmo1/L for O.indica hybrid.Five leaf stage was much better than 3 leaf stage for comparison of genotypic differences in K utilization efficieny.