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Xylem sap calcium concentrations do not explain liming-induced inhibition of legume gas exchange

Research output: Contribution to Journal/MagazineJournal articlepeer-review

<mark>Journal publication date</mark>09/2014
<mark>Journal</mark>Plant and Soil
Issue number1-2
Number of pages14
Pages (from-to)17-30
Publication StatusPublished
<mark>Original language</mark>English


Liming is considered normal agricultural practise for remediating soil acidity and improving crop productivity; however recommended lime applications can reduce yield. We tested the hypothesis that elevated xylem sap Ca2+ limited gas exchange of Phaseolus vulgaris L. and Pisum sativum L. plants that exhibited reduced shoot biomass and leaf area when limed.

We used Scholander and whole-plant pressure chamber techniques to collect root and leaf xylem sap, a calcium-specific ion-selective electrode to measure xylem sap Ca2+, infra-red gas analysis to measure gas exchange of limed and unlimed (control) plants, and a detached leaf transpiration bioassay to determine stomatal sensitivity to Ca2+.

Liming reduced shoot biomass, leaf area and leaf gas exchange in both species. Root xylem sap Ca2+ concentration was only increased in P. vulgaris and not in P. sativum. Detached leaves of both species required 5 mM Ca2+ supplied to via the transpiration stream to induce stomatal closure, however, maximum in vivo xylem sap Ca2+ concentrations of limed plants was only 1.7 mM and thus not high enough to influence stomata.

We conclude that an alternative xylem-borne antitranspirant other than Ca2+ decreases gas exchange of limed plants.