The maize iron nutrition not obeying the reward descending rule

The effect of different iron levels on the maize seedlings iron nutrition was studied．The results indicate that within the Fe level of 0～0．10／umol/L，the fresh weight of shoots decreases with the increase of Fe concentration．not obeying the reward descending rule of mineral substance nutrition；in the range from 0．10 to 100umol／L of Fe concentration，the fresh weight of shoots increases with the increase of Fe level：the biomass of roots is least in the Fe coneentration of 0．01umol／L；in the Fe level of 0～lumol／L，with the increase of the Fe concentration，the Fe content of maize shoots decreases，the etiolation of leaves aggravates and chlorophyll content decreases，the Fe concentration making the etiolation of the leaves most severely is about lumol／L；in the Fe level of 1～lOOumol／L．the Fe content and chlorophyll content of the shoots increase with the increase of Fe concentration in nutrient solution．The changing trend of Fe content in the roots is similar to that in shoots，but the Fe concentration causing Fe content low in roots is lower than that in leaves．Furthermore，the effect of certain low Fe on the contents of soluble sugar，amino acid，NO₃^--N and total absorbed Fe is more severe than that of Fe deficiency．