Nutrient uptake, cluster root formation and exudation of protons and citrate in Lupinus albus as affected by localized supply of phosphorus in a split-root system

Summary

This hydroponic split-root experiment demonstrated that localised phosphorus supply to white lupin plants regulates cluster root formation and citrate exudation primarily through effects on shoot phosphorus concentration, rather than solely in response to local phosphorus availability. Proton exudation was inhibited by localised phosphorus supply through altered balance of anion and cation uptake, and approximately 19% of phosphorus taken up in the phosphorus-supplied root half was translocated to the phosphorus-deficient root half, suggesting systemic regulation of root adaptation responses.

Regional applicability

This laboratory experiment using hydroponic culture provides mechanistic insights into phosphorus acquisition strategies relevant to understanding crop performance on phosphorus-deficient soils. The findings on lupin's cluster root physiology may inform breeding and management strategies for phosphorus-efficient crops in the United Kingdom and other temperate regions, though direct field applicability requires validation under soil-based conditions.

Key measures

Shoot and root dry weight; tissue phosphorus, potassium, magnesium and sulphur concentrations; cluster root number; exudation rates of protons, citrate and acid phosphatase; pH of nutrient solution compartments; nutrient translocation between root halves

Outcomes reported

The study measured nutrient uptake (P, K, Mg, S), cluster root formation, and root exudation rates of protons, citrate and acid phosphatase in white lupin under localised phosphorus supply using a split-root system. Shoot and root dry weight, tissue nutrient concentrations, and pH changes were also quantified.

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