Oxygen distribution and movement, respiration and nutrient loading in banana roots (Musa spp. L.) subjected to aerated and oxygen-depleted environments

E.A. Aguilar, David Turner, D.J. Gibbs, W. Armstrong, K. Sivasithamparam

Research output: Contribution to journalArticle

33 Citations (Scopus)

Abstract

Excessive soil wetness is a common feature where bananas (Musa spp.) evolved. Under O-2 deficiency, a property of wet soils, root growth and functions will be influenced by the respiratory demand for O-2 in root tissues, the transport of O-2 from the shoot to root and the supply of O-2 from the medium. In laboratory experiments with nodal roots of banana, we examined how these features influenced the longitudinal and radial distributions of O-2 within roots, radial O-2 loss, solute accumulation in the xylem, root hydraulic conductivity, root elongation and root tip survival. In aerated roots, the stele respired about 6 times faster than the cortex on a volume basis. Respiratory O-2 consumption decreased substantially with distance from the root apex and at 300-500 mm it was 80% lower than at the apex. Respiration of lateral roots constituted a sink for O-2 supplied via aerenchyma, and reduced O-2 flow towards the tip of the supporting root. Stelar anoxia could be induced either by lowering the O-2 partial pressure in the bathing medium from 21 to 4 kPa (excised roots) or, in the case of intact roots, by reducing the O-2 concentration around the shoot. The root hair zone sometimes extended to 1.0 mm from the root surface and contributed up to a 60% drop in O-2 concentration from a free-flowing aerated solution to the root surface. There was a steep decline in O-2 concentration across the epidermal-hypodermal cylinder and some evidence of a decline in the O-2 permeability of the epidermal-hypodermal cylinder with increasing distance from the root apex. The differences in O-2 concentration between cortex and stele were smaller than reported for maize and possibly indicated a substantial transfer rate of dissolved O-2 from cortex to stele in banana, mediated by a convective water flow component. An O-2 partial pressure of 4 kPa in the medium reduced net nutrient transfer into the vascular tissue in the stele within 1 or 2 h. Hypoxia also caused a temporary decrease in radial root hydraulic conductivity by an order of magnitude. In O-2 deficient environments, the stele would be among the first tissues to suffer anoxia and O-2 consumption within the root hair zone might be a major contributor to root anoxia/hypoxia in banana growing in temporarily flooded soils.
Original languageEnglish
Pages (from-to)91-102
JournalPlant and Soil
Volume253
Issue number1
DOIs
Publication statusPublished - 2003

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Musa
pollution load
bananas
breathing
respiration
oxygen
nutrient
stele
hypoxia
root hydraulic conductivity
cortex
root hairs
anoxia
root tips
distribution
root growth
soil
partial pressure
hair
shoots

Cite this

@article{85f70fa3fd7449a8bce9fcd3b3a2d183,
title = "Oxygen distribution and movement, respiration and nutrient loading in banana roots (Musa spp. L.) subjected to aerated and oxygen-depleted environments",
abstract = "Excessive soil wetness is a common feature where bananas (Musa spp.) evolved. Under O-2 deficiency, a property of wet soils, root growth and functions will be influenced by the respiratory demand for O-2 in root tissues, the transport of O-2 from the shoot to root and the supply of O-2 from the medium. In laboratory experiments with nodal roots of banana, we examined how these features influenced the longitudinal and radial distributions of O-2 within roots, radial O-2 loss, solute accumulation in the xylem, root hydraulic conductivity, root elongation and root tip survival. In aerated roots, the stele respired about 6 times faster than the cortex on a volume basis. Respiratory O-2 consumption decreased substantially with distance from the root apex and at 300-500 mm it was 80{\%} lower than at the apex. Respiration of lateral roots constituted a sink for O-2 supplied via aerenchyma, and reduced O-2 flow towards the tip of the supporting root. Stelar anoxia could be induced either by lowering the O-2 partial pressure in the bathing medium from 21 to 4 kPa (excised roots) or, in the case of intact roots, by reducing the O-2 concentration around the shoot. The root hair zone sometimes extended to 1.0 mm from the root surface and contributed up to a 60{\%} drop in O-2 concentration from a free-flowing aerated solution to the root surface. There was a steep decline in O-2 concentration across the epidermal-hypodermal cylinder and some evidence of a decline in the O-2 permeability of the epidermal-hypodermal cylinder with increasing distance from the root apex. The differences in O-2 concentration between cortex and stele were smaller than reported for maize and possibly indicated a substantial transfer rate of dissolved O-2 from cortex to stele in banana, mediated by a convective water flow component. An O-2 partial pressure of 4 kPa in the medium reduced net nutrient transfer into the vascular tissue in the stele within 1 or 2 h. Hypoxia also caused a temporary decrease in radial root hydraulic conductivity by an order of magnitude. In O-2 deficient environments, the stele would be among the first tissues to suffer anoxia and O-2 consumption within the root hair zone might be a major contributor to root anoxia/hypoxia in banana growing in temporarily flooded soils.",
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Oxygen distribution and movement, respiration and nutrient loading in banana roots (Musa spp. L.) subjected to aerated and oxygen-depleted environments. / Aguilar, E.A.; Turner, David; Gibbs, D.J.; Armstrong, W.; Sivasithamparam, K.

In: Plant and Soil, Vol. 253, No. 1, 2003, p. 91-102.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Oxygen distribution and movement, respiration and nutrient loading in banana roots (Musa spp. L.) subjected to aerated and oxygen-depleted environments

AU - Aguilar, E.A.

AU - Turner, David

AU - Gibbs, D.J.

AU - Armstrong, W.

AU - Sivasithamparam, K.

PY - 2003

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N2 - Excessive soil wetness is a common feature where bananas (Musa spp.) evolved. Under O-2 deficiency, a property of wet soils, root growth and functions will be influenced by the respiratory demand for O-2 in root tissues, the transport of O-2 from the shoot to root and the supply of O-2 from the medium. In laboratory experiments with nodal roots of banana, we examined how these features influenced the longitudinal and radial distributions of O-2 within roots, radial O-2 loss, solute accumulation in the xylem, root hydraulic conductivity, root elongation and root tip survival. In aerated roots, the stele respired about 6 times faster than the cortex on a volume basis. Respiratory O-2 consumption decreased substantially with distance from the root apex and at 300-500 mm it was 80% lower than at the apex. Respiration of lateral roots constituted a sink for O-2 supplied via aerenchyma, and reduced O-2 flow towards the tip of the supporting root. Stelar anoxia could be induced either by lowering the O-2 partial pressure in the bathing medium from 21 to 4 kPa (excised roots) or, in the case of intact roots, by reducing the O-2 concentration around the shoot. The root hair zone sometimes extended to 1.0 mm from the root surface and contributed up to a 60% drop in O-2 concentration from a free-flowing aerated solution to the root surface. There was a steep decline in O-2 concentration across the epidermal-hypodermal cylinder and some evidence of a decline in the O-2 permeability of the epidermal-hypodermal cylinder with increasing distance from the root apex. The differences in O-2 concentration between cortex and stele were smaller than reported for maize and possibly indicated a substantial transfer rate of dissolved O-2 from cortex to stele in banana, mediated by a convective water flow component. An O-2 partial pressure of 4 kPa in the medium reduced net nutrient transfer into the vascular tissue in the stele within 1 or 2 h. Hypoxia also caused a temporary decrease in radial root hydraulic conductivity by an order of magnitude. In O-2 deficient environments, the stele would be among the first tissues to suffer anoxia and O-2 consumption within the root hair zone might be a major contributor to root anoxia/hypoxia in banana growing in temporarily flooded soils.

AB - Excessive soil wetness is a common feature where bananas (Musa spp.) evolved. Under O-2 deficiency, a property of wet soils, root growth and functions will be influenced by the respiratory demand for O-2 in root tissues, the transport of O-2 from the shoot to root and the supply of O-2 from the medium. In laboratory experiments with nodal roots of banana, we examined how these features influenced the longitudinal and radial distributions of O-2 within roots, radial O-2 loss, solute accumulation in the xylem, root hydraulic conductivity, root elongation and root tip survival. In aerated roots, the stele respired about 6 times faster than the cortex on a volume basis. Respiratory O-2 consumption decreased substantially with distance from the root apex and at 300-500 mm it was 80% lower than at the apex. Respiration of lateral roots constituted a sink for O-2 supplied via aerenchyma, and reduced O-2 flow towards the tip of the supporting root. Stelar anoxia could be induced either by lowering the O-2 partial pressure in the bathing medium from 21 to 4 kPa (excised roots) or, in the case of intact roots, by reducing the O-2 concentration around the shoot. The root hair zone sometimes extended to 1.0 mm from the root surface and contributed up to a 60% drop in O-2 concentration from a free-flowing aerated solution to the root surface. There was a steep decline in O-2 concentration across the epidermal-hypodermal cylinder and some evidence of a decline in the O-2 permeability of the epidermal-hypodermal cylinder with increasing distance from the root apex. The differences in O-2 concentration between cortex and stele were smaller than reported for maize and possibly indicated a substantial transfer rate of dissolved O-2 from cortex to stele in banana, mediated by a convective water flow component. An O-2 partial pressure of 4 kPa in the medium reduced net nutrient transfer into the vascular tissue in the stele within 1 or 2 h. Hypoxia also caused a temporary decrease in radial root hydraulic conductivity by an order of magnitude. In O-2 deficient environments, the stele would be among the first tissues to suffer anoxia and O-2 consumption within the root hair zone might be a major contributor to root anoxia/hypoxia in banana growing in temporarily flooded soils.

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M3 - Article

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