Phosphate nutrition of Australian heath plants. I. The importance of proteoid roots in Banksia (Proteaceae)

Abstract

The proteoid roots of Banksia ornata were examined in the laboratory and in the field for any special features of phosphate metabolism. It was found that these roots were particularly efficient at absorbing phosphate, but this feature was possibly allied with a high root surface area rather than with a metabolic factor. Both proteoid and non-proteoid roots formed the same proportion of polyphosphate and other phosphorus fractions. In the field, even during winter, the proteoid root layer was shown to be active in absorbing phosphate. Evidence pointing to polyphosphate formation was also obtained. It was shown that the extensive carpet of these roots at or near the soil surface could constitute an effective nutrient-trapping organ.