Author:

Keywords:

Science & Technology, Life Sciences & Biomedicine, Plant Sciences, Citrate sampling, diffusive gradients in thin films, phosphorus deficiency, rhizotron, root exudates, white lupin, ORGANIC-ACIDS, CLUSTER ROOTS, THIN-FILMS, PERFORMANCE-CHARACTERISTICS, DIFFUSIVE GRADIENTS, LUPINUS-ALBUS, TRACE-METALS, PHOSPHORUS, EXUDATION, RHIZOSPHERE, Citrates, Citric Acid, Diffusion, Phosphorus, Plant Breeding, Soil, 0604 Genetics, 0607 Plant Biology, 0703 Crop and Pasture Production, Plant Biology & Botany, 3004 Crop and pasture production, 3101 Biochemistry and cell biology, 3108 Plant biology

Abstract:

The reliable sampling of root exudates in soil-grown plants is experimentally challenging. This study aimed at developing a citrate sampling and mapping technique with millimetre-resolution using DGT (diffusive gradients in thin films) ZrOH-binding gels. Citrate adsorption kinetics, DGT capacity, and stability of ZrOH gels were evaluated. ZrOH gels were applied to generate 2D maps of citrate exuded by white lupin roots grown in a rhizotron in a phosphorus-deficient soil. Citrate was adsorbed quantitatively and rapidly by the ZrOH gels; these gels can be stored after sampling for several weeks prior to analysis. The DGT capacity of the ZrOH gel for citrate depends on the ionic strength and the pH of the soil solution, but was suitable for citrate sampling. We generated for the first time 2D citrate maps of rhizotron-grown plants at a millimetre resolution to measure an illustrated plant response to phosphorus fertilization, demonstrating that DGT-based citrate sampling is suitable for studying root exudation in soil environments, at high spatial resolution. The change of binding material would also allow sampling of other exudate classes and exudation profiles of entire root systems. These aspects are crucial in cultivar breeding and selection.