The influence of nitrogen, phosphorus, iron and silicon nutrition on the growth rate of Amprhora exigua was studied by single factor and orthogonal experiment. The results showed that Amprhora exigua well utilized by sodium nitrate and ferric citrate did not differ significantly in Kˊ from urea solution and ferric chloride, respectively. The optimum concentration FeC6H5O7-Fe and Na2SiO3-Si were 0.1~0.5 mg/L and 0.8~1.6 mg/L, respectively. The orthogonal test of the four factors of nitrogen, phosphorous, iro...