1. Awad F, Römheld V and Marschner H 1988 Mobilization of ferric iron from a calcareous soil by plant-borne chelators (phytosiderophores). J. Plant Nutr. 11, 701–713.
2. Clark R B, Römheld V and Marschner H 1988 Iron uptake and phytosiderophore release by roots of sorghum genotypes. J. Plant Nutr. 11, 663–676.
3. Crowley D E, Reid C C P and Szaniszlo P J 1987 Microbial siderophores as iron sources for plants. In Iron Transport in Microbes, Plants and Animals. Eds. G Winkelmann, D Van der Helm and J B Neilands. pp 375–386. VCH Verlagsges., Weinheim, FRG.
4. Crowley D E, Reid C P P and Szaniszlo P J 1988 Utilization of microbial siderophores in iron acquisition by oat. Plant Physiol. 87, 680–685.
5. Häussling M, Leisen E, Marschner H and Römheld V 1985 An improved method for non-destructive measurements of the pH at the root-soil interface (rhizosphere). J. Plant Physiol. 117, 371–375.