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Alternation of wet and dry sides during partial rootzone drying irrigation alters root-to-shoot signalling of abscisic acid.

Dodd, Ian C. and Theobald, Julian C. and Bacon, Mark A. and Davies, William J. (2006) Alternation of wet and dry sides during partial rootzone drying irrigation alters root-to-shoot signalling of abscisic acid. Functional Plant Biology, 33 (12). pp. 1081-1089. ISSN 1445-4408

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Abstract

Partial rootzone drying (PRD) is an irrigation technique where water is distributed unevenly to the root system such that part is irrigated while the remainder is allowed to dry the soil. Tomato (Lycopersicon esculentum Mill.) plants were grown with their roots in two soil columns to compare the physiological consequences of alternation of wet and dry columns during PRD irrigation (alternate PRD, PRD-A) with retention of the same wet and dry columns (fixed PRD, PRD-F). When PRD plants received 50% less water than well-watered (WW) plants, xylem ABA concentration ([X-ABA]) increased and stomatal conductance decreased relative to WW plants. Although both sets of PRD plants received the same amount of water, [X-ABA] of PRD-A plants increased up to 2-fold above that of PRD-F plants, which further decreased stomatal conductance. Differences in [X-ABA] were detected within an hour of alternation, but did not persist beyond the photoperiod of alternation. [X-ABA] increased linearly as whole-pot soil water content (θpot) and leaf water potential (Ψleaf) declined, but the difference in [X-ABA] between the two sets of PRD plants was not due to differences in either θpot or Ψleaf. In PRD-F plants, the unwatered part of the root system contributes proportionally less to the transpiration stream as the soil progressively dries (Yao et al. 2001, Plant, Cell & Environment 24, 227–235). In PRD-A plants, we hypothesise that re-watering the dry part of the root system allows these roots to contribute proportionally more to total sap flux, thus liberating a pulse of ABA to the transpiration stream as the root ABA pool accumulated during soil drying is depleted. Since the enhancement of [X-ABA] caused by PRD-A increased as θpot and Ψleaf declined, an optimal frequency of alternation to maximise the cumulative physiological effects of this ABA pulse must consider possible negative impacts of leaf water deficit as soil water status declines.

Item Type: Article
Journal or Publication Title: Functional Plant Biology
Uncontrolled Keywords: irrigation scheduling ; soil drying ; stomatal conductance.
Subjects: Q Science > QK Botany
Departments: Faculty of Science and Technology > Lancaster Environment Centre
Faculty of Science and Technology
VC's Office
ID Code: 33921
Deposited By: Dr Julian C Theobald
Deposited On: 28 Jul 2010 16:26
Refereed?: Yes
Published?: Published
Last Modified: 06 Sep 2013 20:16
Identification Number:
URI: http://eprints.lancs.ac.uk/id/eprint/33921

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