Variation in morphological and physiological root traits and organic acid exudation of three sweet potato (Ipomoea batatas) cultivars under seven phosphorus levels

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Abstract

Plants invest their carbon resource in various strategies to enhance phosphorus (P) uptake and use when growing in low P soils. Sweet potato has evolved and persisted in P-impoverished soils, but exhibits highly variable growth and yield. Variation among sweet potato cultivars in ability to access and use P may affect growth and yield: the influence of root system traits in this regard has been little researched. In this study we explored the root traits and rhizosphere chemistry of three sweet potato cultivars under P deficient and sufficient conditions. Three sweet potato cultivars, two native to Papua New Guinea (Tambul Mai and Whagi Besta) and one internationally grown commercial cultivar (Beauregard), were grown with seven levels of P (0–360 mg P kg−1 soil added as KH2 PO4) for 84 days in a glasshouse in low P soil. Dry mass yield, tissue P concentration, root exudation of organic acids, colonisation by arbuscular mycorrhizal fungi (AMF) and root morphological and physiological traits were measured. All cultivars maintained a constant tissue P concentration below 1.0 mg P g −1 DM when P supply was low. There were few distinct differences among the cultivars in the response to P addition for growth, total root length, specific root length, root tissue density, average root diameter, root mass fraction and colonisation by AMF. Four organic acids were exuded by roots. Malate and fumarate were abundant only in cultivars from Papua New Guinea, while citrate and oxalate were common across all cultivars. Under P deficiency, all sweet potato cultivars used internal P efficiently, preferentially allocating carbon to shoots and to supporting AMF and organic acid release, rather than to increasing the root mass or forming specialised root structures. Among the root factors studied, the type of organic acid exuded was noteworthy, with citrate and malate being reported for the first time.

Original languageEnglish
Article number108572
JournalScientia Horticulturae
Volume256
DOIs
Publication statusPublished - 15 Oct 2019

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Ipomoea batatas
exudation
sweet potatoes
organic acids and salts
phosphorus
cultivars
mycorrhizal fungi
Papua New Guinea
malates
citrates
soil
carbon
oxalates
root systems
rhizosphere
chemistry

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title = "Variation in morphological and physiological root traits and organic acid exudation of three sweet potato (Ipomoea batatas) cultivars under seven phosphorus levels",
abstract = "Plants invest their carbon resource in various strategies to enhance phosphorus (P) uptake and use when growing in low P soils. Sweet potato has evolved and persisted in P-impoverished soils, but exhibits highly variable growth and yield. Variation among sweet potato cultivars in ability to access and use P may affect growth and yield: the influence of root system traits in this regard has been little researched. In this study we explored the root traits and rhizosphere chemistry of three sweet potato cultivars under P deficient and sufficient conditions. Three sweet potato cultivars, two native to Papua New Guinea (Tambul Mai and Whagi Besta) and one internationally grown commercial cultivar (Beauregard), were grown with seven levels of P (0–360 mg P kg−1 soil added as KH2 PO4) for 84 days in a glasshouse in low P soil. Dry mass yield, tissue P concentration, root exudation of organic acids, colonisation by arbuscular mycorrhizal fungi (AMF) and root morphological and physiological traits were measured. All cultivars maintained a constant tissue P concentration below 1.0 mg P g −1 DM when P supply was low. There were few distinct differences among the cultivars in the response to P addition for growth, total root length, specific root length, root tissue density, average root diameter, root mass fraction and colonisation by AMF. Four organic acids were exuded by roots. Malate and fumarate were abundant only in cultivars from Papua New Guinea, while citrate and oxalate were common across all cultivars. Under P deficiency, all sweet potato cultivars used internal P efficiently, preferentially allocating carbon to shoots and to supporting AMF and organic acid release, rather than to increasing the root mass or forming specialised root structures. Among the root factors studied, the type of organic acid exuded was noteworthy, with citrate and malate being reported for the first time.",
keywords = "Arbuscular mycorrhizal fungi, Carboxylate exudation, Phosphorus acquisition strategy, Phosphorus use efficiency, Sweet potato cultivars",
author = "David Minemba and Gleeson, {Deirdre B.} and Erik Veneklaas and Ryan, {Megan H.}",
year = "2019",
month = "10",
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TY - JOUR

T1 - Variation in morphological and physiological root traits and organic acid exudation of three sweet potato (Ipomoea batatas) cultivars under seven phosphorus levels

AU - Minemba, David

AU - Gleeson, Deirdre B.

AU - Veneklaas, Erik

AU - Ryan, Megan H.

PY - 2019/10/15

Y1 - 2019/10/15

N2 - Plants invest their carbon resource in various strategies to enhance phosphorus (P) uptake and use when growing in low P soils. Sweet potato has evolved and persisted in P-impoverished soils, but exhibits highly variable growth and yield. Variation among sweet potato cultivars in ability to access and use P may affect growth and yield: the influence of root system traits in this regard has been little researched. In this study we explored the root traits and rhizosphere chemistry of three sweet potato cultivars under P deficient and sufficient conditions. Three sweet potato cultivars, two native to Papua New Guinea (Tambul Mai and Whagi Besta) and one internationally grown commercial cultivar (Beauregard), were grown with seven levels of P (0–360 mg P kg−1 soil added as KH2 PO4) for 84 days in a glasshouse in low P soil. Dry mass yield, tissue P concentration, root exudation of organic acids, colonisation by arbuscular mycorrhizal fungi (AMF) and root morphological and physiological traits were measured. All cultivars maintained a constant tissue P concentration below 1.0 mg P g −1 DM when P supply was low. There were few distinct differences among the cultivars in the response to P addition for growth, total root length, specific root length, root tissue density, average root diameter, root mass fraction and colonisation by AMF. Four organic acids were exuded by roots. Malate and fumarate were abundant only in cultivars from Papua New Guinea, while citrate and oxalate were common across all cultivars. Under P deficiency, all sweet potato cultivars used internal P efficiently, preferentially allocating carbon to shoots and to supporting AMF and organic acid release, rather than to increasing the root mass or forming specialised root structures. Among the root factors studied, the type of organic acid exuded was noteworthy, with citrate and malate being reported for the first time.

AB - Plants invest their carbon resource in various strategies to enhance phosphorus (P) uptake and use when growing in low P soils. Sweet potato has evolved and persisted in P-impoverished soils, but exhibits highly variable growth and yield. Variation among sweet potato cultivars in ability to access and use P may affect growth and yield: the influence of root system traits in this regard has been little researched. In this study we explored the root traits and rhizosphere chemistry of three sweet potato cultivars under P deficient and sufficient conditions. Three sweet potato cultivars, two native to Papua New Guinea (Tambul Mai and Whagi Besta) and one internationally grown commercial cultivar (Beauregard), were grown with seven levels of P (0–360 mg P kg−1 soil added as KH2 PO4) for 84 days in a glasshouse in low P soil. Dry mass yield, tissue P concentration, root exudation of organic acids, colonisation by arbuscular mycorrhizal fungi (AMF) and root morphological and physiological traits were measured. All cultivars maintained a constant tissue P concentration below 1.0 mg P g −1 DM when P supply was low. There were few distinct differences among the cultivars in the response to P addition for growth, total root length, specific root length, root tissue density, average root diameter, root mass fraction and colonisation by AMF. Four organic acids were exuded by roots. Malate and fumarate were abundant only in cultivars from Papua New Guinea, while citrate and oxalate were common across all cultivars. Under P deficiency, all sweet potato cultivars used internal P efficiently, preferentially allocating carbon to shoots and to supporting AMF and organic acid release, rather than to increasing the root mass or forming specialised root structures. Among the root factors studied, the type of organic acid exuded was noteworthy, with citrate and malate being reported for the first time.

KW - Arbuscular mycorrhizal fungi

KW - Carboxylate exudation

KW - Phosphorus acquisition strategy

KW - Phosphorus use efficiency

KW - Sweet potato cultivars

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U2 - 10.1016/j.scienta.2019.108572

DO - 10.1016/j.scienta.2019.108572

M3 - Article

VL - 256

JO - Scientia Horticulturae: an international journal

JF - Scientia Horticulturae: an international journal

SN - 0304-4238

M1 - 108572

ER -