active Fe content的用法和样例：
- Highly significant correlations were found between SPAD value and chlorosis score, active Fe content and pod yield at early growth stage.
- At early growth stage, SPAD value and active Fe content in young leaves of iron-resistant cultivars were significantly higher than those of iron-susceptible ones.
- Flowering stage was the most sensitive period to iron deficiency when the most severe chlorosis was observed, and the lowest SPAD value and active Fe content in young leaves were tested.
- The Curie temperature and saturation magnetization increase with the Fe content.