Nodal root diameter and node number in maize (<i>Zea mays</i> L.) interact to influence plant growth under nitrogen stress

Schneider, Hannah; Yang, Jennifer T.; Brown, Kathleen M.; Lynch, Jonathan P.

doi:10.1002/pld3.310

Cited by 24 publications

(24 citation statements)

References 56 publications

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“…The percentage of roots with root hairs was not affected by the amounts of applied N (N0 and N227), but N0 led to a decrease in both root number and root hair length in all maize genotypes. Schneider et al (2021) found that maize lines with few-thick nodal roots had smaller total axial root lengths in N0, while lines with many-thin developed a greater total axial root length in N0. The phenotype of fewer, thicker nodal roots was associated with deeper root distribution and resulted in an increased shoot growth under N deficiency.…”

Section: Root Diameter Root Diameter Distribution and Specific Root L...mentioning

confidence: 89%

Nutrient deficiency effects on root architecture and root-to-shoot ratio in arable crops

et al. 2023

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Plant root traits play a crucial role in resource acquisition and crop performance when soil nutrient availability is low. However, the respective trait responses are complex, particularly at the field scale, and poorly understood due to difficulties in root phenotyping monitoring, inaccurate sampling, and environmental conditions. Here, we conducted a systematic review and meta-analysis of 50 field studies to identify the effects of nitrogen (N), phosphorous (P), or potassium (K) deficiencies on the root systems of common crops. Root length and biomass were generally reduced, while root length per shoot biomass was enhanced under N and P deficiency. Root length decreased by 9% under N deficiency and by 14% under P deficiency, while root biomass was reduced by 7% in N-deficient and by 25% in P-deficient soils. Root length per shoot biomass increased by 33% in N deficient and 51% in P deficient soils. The root-to-shoot ratio was often enhanced (44%) under N-poor conditions, but no consistent response of the root-to-shoot ratio to P-deficiency was found. Only a few K-deficiency studies suited our approach and, in those cases, no differences in morphological traits were reported. We encountered the following drawbacks when performing this analysis: limited number of root traits investigated at field scale, differences in the timing and severity of nutrient deficiencies, missing data (e.g., soil nutrient status and time of stress), and the impact of other conditions in the field. Nevertheless, our analysis indicates that, in general, nutrient deficiencies increased the root-length-to-shoot-biomass ratios of crops, with impacts decreasing in the order deficient P > deficient N > deficient K. Our review resolved inconsistencies that were often found in the individual field experiments, and led to a better understanding of the physiological mechanisms underlying root plasticity in fields with low nutrient availability.

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Section: Root Diameter Root Diameter Distribution and Specific Root L...mentioning

confidence: 89%

Nutrient deficiency effects on root architecture and root-to-shoot ratio in arable crops

et al. 2023

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“…The results suggest ethylene‐induced root thickening may be node‐specific as well as genetically variable. Recent studies have demonstrated root anatomy and architectural traits are node specific and may be under distinct genetic control (Schneider et al, 2021 ; Schneider et al, 2021 ; Schneider, Yang, Brown, & Lynch, 2021 ; Yang, Schneider, Brown, & Lynch, 2019 ).…”

Section: Discussionmentioning

confidence: 99%

Soil penetration by maize roots is negatively related to ethylene‐induced thickening

Vanhees

Schneider

Sidhu

et al. 2021

Plant Cell & Environment

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Radial expansion is a classic response of roots to a mechanical impedance that has generally been assumed to aid penetration. We analysed the response of maize nodal roots to impedance to test the hypothesis that radial expansion is not related to the ability of roots to cross a compacted soil layer. Genotypes varied in their ability to cross the compacted layer, and those with a steeper approach to the compacted layer or less radial expansion in the compacted layer were more likely to cross the layer and achieve greater depth. Root radial expansion was due to cortical cell size expansion, while cortical cell file number remained constant. Genotypes and nodal root classes that exhibited radial expansion in the compacted soil layer generally also thickened in response to exogenous ethylene in hydroponic culture, that is, radial expansion in response to ethylene was correlated with the thickening response to impedance in soil. We propose that ethylene insensitive roots, that is, those that do not thicken and can overcome impedance, have a competitive advantage under mechanically impeded conditions as they can maintain their elongation rates. We suggest that prolonged exposure to ethylene could function as a stop signal for axial root growth.

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“…These observations align with the hypothesized advantages of the ‘steep, deep, cheap’ ideotype for improved N capture proposed by Lynch (2013) , where exploration of deeper soil domains improves the acquisition of mobile resources such as nitrate. The fitness benefits of this foraging strategy have also been demonstrated in vivo where maize genotypes that produced few, thick nodal roots had a deeper distribution of root length and greater shoot growth under N deficit compared with genotypes that produced many, thin nodal roots ( Schneider et al , 2021 b ). Compaction can lead to decreased, constant or even increased root numbers ( Bushamuka and Zobel, 1998 ; Grzesiak et al , 2014 ; Colombi and Walter, 2016 ).…”

Section: Discussionmentioning

confidence: 98%

Theoretical evidence that root penetration ability interacts with soil compaction regimes to affect nitrate capture

et al. 2021

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Background and Aims Although root penetration of strong soils has been intensively studied at the scale of individual root axes, interactions between soil physical properties and soil foraging by whole plants are less clear. Here we investigate how variation in the penetration ability of distinct root classes and bulk density profiles common to real-world soils interact to affect soil foraging strategies. Methods We utilize the functional-structural plant model OpenSimRoot to simulate the growth of maize (Zea mays) root systems with variable penetration ability of axial and lateral roots in soils with 1) uniform bulk density, 2) plow pans, and 3) increasing bulk density with depth. We also modify the availability and leaching of nitrate to uncover reciprocal interactions between these factors and the capture of mobile resources. Key Results Soils with plow pans and bulk density gradients affected overall size, distribution, and carbon costs of the root system. Soils with high bulk density at depth impeded rooting depth and reduced leaching of nitrate, thereby improving the coincidence of N and root length. While increasing penetration ability of either axial or lateral root classes produced root systems of comparable net length, improved penetration of axial roots increased allocation of root length in deeper soil, thereby amplifying N acquisition and shoot biomass. Although enhanced penetration ability of both root classes was associated with greater root system carbon costs, the benefit to plant fitness from improved soil exploration and resource capture offset these. Conclusions While lateral roots comprise the bulk of root length, axial roots function as a scaffold determining the distribution of these laterals. In soils with high soil strength and leaching, root systems with enhanced penetration ability of axial roots have greater distribution of root length at depth, thereby improving capture of mobile resources.

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Nodal root diameter and node number in maize (Zea mays L.) interact to influence plant growth under nitrogen stress

Cited by 24 publications

References 56 publications

Nutrient deficiency effects on root architecture and root-to-shoot ratio in arable crops

Nutrient deficiency effects on root architecture and root-to-shoot ratio in arable crops

Soil penetration by maize roots is negatively related to ethylene‐induced thickening

Theoretical evidence that root penetration ability interacts with soil compaction regimes to affect nitrate capture

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