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Long‐distance abscisic acid signalling under different vertical soil moisture gradients depends on bulk root water potential and average soil water content in the root zone
Author(s) -
PUÉRTOLAS JAIME,
ALCOBENDAS ROSALÍA,
ALARCÓN JUAN J.,
DODD IAN C.
Publication year - 2013
Publication title -
plant, cell and environment
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.646
H-Index - 200
eISSN - 1365-3040
pISSN - 0140-7791
DOI - 10.1111/pce.12076
Subject(s) - abscisic acid , water content , xylem , shoot , soil water , dns root zone , chemistry , water potential , root hair , moisture , agronomy , root system , horticulture , botany , environmental science , soil science , biology , geology , biochemistry , geotechnical engineering , organic chemistry , gene
To determine how root‐to‐shoot abscisic acid ( ABA ) signalling is regulated by vertical soil moisture gradients, root ABA concentration ([ ABA ] root ), the fraction of root water uptake from, and root water potential of different parts of the root zone, along with bulk root water potential, were measured to test various predictive models of root xylem ABA concentration [ RX‐ABA ] sap . Beans ( P haseolus vulgaris L . cv. N assau ) were grown in soil columns and received different irrigation treatments (top and basal watering, and withholding water for varying lengths of time) to induce different vertical soil moisture gradients. Root water uptake was measured at four positions within the column by continuously recording volumetric soil water content ( θ v ). Average θ v was inversely related to bulk root water potential ( Ψ root ). In turn, Ψ root was correlated with both average [ ABA ] root and [ RX‐ABA ] sap . Despite large gradients in θ v , [ ABA ] root and root water potential was homogenous within the root zone. Consequently, unlike some split‐root studies, root water uptake fraction from layers with different soil moisture did not influence xylem sap ( ABA ). This suggests two different patterns of ABA signalling, depending on how soil moisture heterogeneity is distributed within the root zone, which might have implications for implementing water‐saving irrigation techniques.