Liming can decrease legume crop yield and leaf gas exchange by enhancing root to shoot ABA signalling.
To meet future requirements for food production, sustainable intensive agricultural systems need to optimize nutrient availability to maximize yield, traditionally achieved by maintaining soil pH within an optimal range (6-6.5) by applying lime (calcium carbonate). However, a field trial that applied recommended liming rates to a sandy loam soil (increasing soil pH from 5.5 to 6.2) decreased pod yield of field bean (Vicia faba L. cv. Fuego) by ~30%. Subsequent pot trials, with liming that raised soil pH to 6.3-6.7, reduced stomatal conductance (g(s)) by 63, 26, and 59% in V. faba, bean (Phaseolus vulgaris), and pea (Pisum sativum), respectively. Furthermore, liming reduced shoot dry biomass by 16-24% in these species. Ionomic analysis of root xylem sap and leaf tissue revealed a decrease in phosphorus concentration that was correlated with decreased g(s): both reductions were partially reversed by adding superphosphate fertilizer. Further analysis of pea suggests that leaf gas exchange was reduced by a systemic increase (roots, xylem sap, and leaves) in the phytohormone abscisic acid (ABA) in response to lime-induced suboptimal plant phosphorus concentrations. Supplying synthetic ABA via the transpiration stream to detached pea leaves, at the same xylem sap concentrations induced by liming, decreased transpiration. Furthermore, the g(s) of the ABA-deficient mutant pea wilty was unresponsive to liming, apparently confirming that ABA mediates some responses to low phosphorus availability caused by liming. This research provides a detailed mechanistic understanding of the physiological processes by which lime application can limit crop yields, and questions the suitability of current liming recommendations.
The Lancaster Environment Centre, Lancaster University, Lancaster LA1 4YQ, UK s.rothwell1@lancaster.ac.uk.
Shane A
SA
Rothwell
Myerscough College, Bilsborrow, Preston PR3 0RY, UK.
E David
ED
Elphinstone
The Lancaster Environment Centre, Lancaster University, Lancaster LA1 4YQ, UK.
Ian C
IC
Dodd
D000040:Abscisic Acid / Q000378:metabolism*; D018533:Biomass; D017610:Calcium Compounds / Q000494:pharmacology*; D002245:Carbon Dioxide / Q000378:metabolism; D018556:Crops, Agricultural / Q000187:drug effects / Q000254:growth & development*; D005740:Gases / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007477:Ions; D010087:Oxides / Q000494:pharmacology*; D010758:Phosphorus / Q000378:metabolism; D010788:Photosynthesis / Q000187:drug effects; D018515:Plant Leaves / Q000187:drug effects / Q000378:metabolism*; D018517:Plant Roots / Q000187:drug effects / Q000378:metabolism*; D018520:Plant Shoots / Q000187:drug effects / Q000378:metabolism*; D054046:Plant Stomata / Q000187:drug effects / Q000502:physiology; D015398:Signal Transduction / Q000187:drug effects; D012987:Soil; D031307:Vicia faba / Q000187:drug effects / Q000254:growth & development*; D052584:Xylem / Q000187:drug effects / Q000378:metabolism
D017610:Calcium Compounds; D005740:Gases; D007477:Ions; D010087:Oxides; D012987:Soil; D002245:Carbon Dioxide; D010758:Phosphorus; D000040:Abscisic Acid; C016538:lime
Abscisic acid; ionome; liming; phosphorus; stomatal conductance; wilty.