If calcifuges are forced to grow on a calcareous soil, they usually develop chlorosis. However, total leaf iron (Fe) does not often correlate well with Fe deficiency symptoms. The extraction of 'active' Fe by 1 M HCl or Fe chelators, e.g., 1,10-phenanthroline, may reflect the relation between chlorosis and Fe-concentration in the leaves better than total Fe does. Extraction of 'active' Fe from leaves of wild plants by 1,10-phenanthroline, citric acid and HCl was compared. The 1,10-phenanthroline was chosen for further methodological studies. All samples were extracted at indoor light conditions and analyzed by AAS because dark incubation did not influence the oxidation state of Fe and non-specific light absorbance seemed to be high in colorimetric analysis. Washing of leaf material with H2O seemed to clean the leaf surfaces equally well as with 0.1 M HCl. Only fresh leaf material was extracted, as pretreatment (freezing or drying) changed the extractability of Fe. An extraction time of 16 h was adequate for the herbaceous plants tested but not for Carer pilulifera, where extracted Fe increased linearly with time. The age of the extractant solution may play a role because 1,10-phenanthroline had lost part of its chelation capacity after 6 weeks. The ratio of leaf weight:extractant volume did not influence the amount of Fe extracted, provided the same amount of chelator was supplied. The 1,10-phenanthroline did not interfere with the Fe determination by AAS, and HCl pH 3 as used for the preparation of the extractants had only a marginal influence on Fe extractability compared to 1,10-phenanthroline at pH 3. To get comparable results the extraction method should be standardized as much as possible. Samples can be stored in the refrigerator for several hours before adding the extractant and the extracts can be stored for a few days or frozen and measured on the same day, with the same instrument setting.
|Tidskrift||Communications in Soil Science and Plant Analysis|
|Status||Published - 2000|
Bibliografisk informationThe information about affiliations in this record was updated in December 2015.
The record was previously connected to the following departments: Plant Ecology and Systematics (Closed 2011) (011004000)