Ten dif ferent genoty pes of soy bean were g row n at dif ferent concentration potassium of w hich wascont rolled st rictly in pot .Tolerance limi t of different genotypes of soybean to low potassium in dif ferent g row thperiod w as determiced .The symptoms of lack in potassium of different genoty pes w ere observed and ercordedcarefully .