Crown roots dominate nitrate uptake in maize (Zea mays) under varying soil moisture conditions

Abstract

Background and Aims: Nitrate (NO3−) uptake is primarily driven by soil water flow and varies among maize root types. This study quantified NO3− uptake by embryonic (primary and seminal) and crown roots under contrasting soil water conditions to determine their relative contributions to total plant N acquisition during early vegetative growth.

Methods: Maize was grown in a split-root pot that segregated the embryonic and crown roots. The sandy-loam soil was moistened to water potentials of either −5 kPa (wet) or −30 kPa (relatively dry). A partial N mass balance was made by destructively sampling shoots, roots, and soils after 0, 24, and 48 h following 15N-KNO3 injection at the V3 (three-leaf) and V6 (six-leaf) stages. Root hydraulic conductance was quantified using an osmotic-driven root exudation method. Gross nitrification was assessed using a 15N isotope dilution technique.

Key Results: At the V3 stage, crown roots had 202 % more N uptake than embryonic roots in wet soil (−5 kPa). However, in relatively dry soil (−30 kPa) N uptake was similar for embryonic and crown roots, and crown root hydraulic conductance was 80 % lower than in wet soil. By the V6 stage, crown roots dominated N uptake, with embryonic roots supplying <20 % of N uptake. Gross nitrification rates did not differ significantly between root types.

Conclusions: Maize NO3− uptake depends primarily on the crown roots, due to their capacity to extract water and NO3− from soil, even under dry conditions.

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BibTeX RIS

BibTeX

@article{jiang2026crown,
  title = {{Crown roots dominate nitrate uptake in maize (Zea mays) under varying soil moisture conditions}},
  author = {Yutong Jiang and Joann K Whalen},
  journal = {Annals of Botany},
  year = {2026},
  month = jul,
  doi = {10.1093/aob/mcag197},
  url = {https://doi.org/10.1093/aob/mcag197},
  note = {CC BY 4.0},
}

RIS

TY  - JOUR
TI  - Crown roots dominate nitrate uptake in maize (Zea mays) under varying soil moisture conditions
AU  - Yutong Jiang
AU  - Joann K Whalen
PY  - 2026
DA  - 2026/07/07
JO  - Annals of Botany
DO  - 10.1093/aob/mcag197
UR  - https://doi.org/10.1093/aob/mcag197
AB  - Background and Aims: Nitrate (NO3−) uptake is primarily driven by soil water flow and varies among maize root types. This study quantified NO3− uptake by embryonic (primary and seminal) and crown roots under contrasting soil water conditions to determine their relative contributions to total plant N acquisition during early vegetative growth.  Methods: Maize was grown in a split-root pot that segregated the embryonic and crown roots. The sandy-loam soil was moistened to water potentials of either −5 kPa (wet) or −30 kPa (relatively dry). A partial N mass balance was made by destructively sampling shoots, roots, and soils after 0, 24, and 48 h following 15N-KNO3 injection at the V3 (three-leaf) and V6 (six-leaf) stages. Root hydraulic conductance was quantified using an osmotic-driven root exudation method. Gross nitrification was assessed using a 15N isotope dilution technique.  Key Results: At the V3 stage, crown roots had 202 % more N uptake than embryonic roots in wet soil (−5 kPa). However, in relatively dry soil (−30 kPa) N uptake was similar for embryonic and crown roots, and crown root hydraulic conductance was 80 % lower than in wet soil. By the V6 stage, crown roots dominated N uptake, with embryonic roots supplying <20 % of N uptake. Gross nitrification rates did not differ significantly between root types.  Conclusions: Maize NO3− uptake depends primarily on the crown roots, due to their capacity to extract water and NO3− from soil, even under dry conditions.
SN  - 0305-7364
SN  - 1095-8290
ER  -

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