Peroxidase activity as an indicator of the iron status of conifers

An appraisal has been made of the diagnostic value of leaf peroxidase activity as an indicator of the iron status of conifers. The peroxidase activity in leaves from plants receiving additional iron in a liquid feed increased 11.5-fold compared with that in controls, but the total iron in the leaves increased only 2.6-fold. Furthermore, the enzyme activity increased 29.2-fold in response to additional iron supplied in the base fertilizer, whereas the total iron content increased only 7.5-fold. The peroxidase assay can be completed within 2 h of receiving the leaf samples and could offer a considerably more sensitive and rapid means of assessment of the iron requirements of the plants than the conventional analytical methods currently used.