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Abscisic acid signalling when soil moisture is heterogeneous:decreased photoperiod sap flow from drying roots limits abscisic acid export to the shoots

Dodd, Ian C. and Egea, Gregorio and Davies, William J. (2008) Abscisic acid signalling when soil moisture is heterogeneous:decreased photoperiod sap flow from drying roots limits abscisic acid export to the shoots. Plant, Cell and Environment, 31 (9). pp. 1263-1274. ISSN 0140-7791

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Abstract

To investigate the contribution of different parts of the root system to total sap flow and leaf xylem abscisic acid (ABA) concentration ([X-ABA](leaf)), individual sunflower (Helianthus annuus L.) shoots were grafted onto the root systems of two plants grown in separate pots and sap flow through each hypocotyl measured below the graft union. During deficit irrigation (DI), both pots received the same irrigation volumes, while during partial root zone drying (PRD) one pot ('wet') was watered and another ('dry') was not. During PRD, once soil water content (theta) decreased below a threshold, the fraction of sap flow from drying roots declined. As theta declined, root xylem ABA concentration increased in both irrigation treatments, and [X-ABA](leaf) increased in DI plants, but [X-ABA](leaf) of PRD plants actually decreased within a certain theta range. A simple model that weighted ABA contributions of wet and dry root systems to [X-ABA](leaf) according to the sap flow from each, better predicted [X-ABA](leaf) of PRD plants than either [X-ABA](dry), [X-ABA](wet) or their mean. Model simulations revealed that [X-ABA](leaf) during PRD exceeded that of DI with moderate soil drying, but continued soil drying (such that sap flow from roots in drying soil ceased) resulted in the opposite effect.

Item Type: Article
Journal or Publication Title: Plant, Cell and Environment
Uncontrolled Keywords: Helianthus annuus ; ABA modelling ; deficit irrigation ; grafting ; irrigation scheduling ; partial root zone drying ; root-to-shoot signalling ; soil moisture heterogeneity
Subjects: G Geography. Anthropology. Recreation > GE Environmental Sciences
Departments: Faculty of Science and Technology > Lancaster Environment Centre
ID Code: 30904
Deposited By: Mr Richard Ingham
Deposited On: 10 Dec 2009 14:19
Refereed?: Yes
Published?: Published
Last Modified: 17 Sep 2013 08:20
Identification Number:
URI: http://eprints.lancs.ac.uk/id/eprint/30904

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