Evolutionary divergences in root system morphology, allocation, and nitrogen uptake in species from high- versus low-fertility soils

Root morphology and nutrient uptake processes are essential for acquisition of mineral resources from soil. However, our understanding of how root form and function have diverged across environments is limited. In this study, we addressed hypotheses of adaptive differentiation using three pairs of Helianthus species chosen as phylogenetically-independent contrasts with respect to native soil nutrients. Under controlled environmental conditions, root morphology, allocation, and nitrogen (N) uptake (using a 15N tracer) were assessed for seedlings under both high and low N treatments. Species native to low nutrient soils (LNS) had lower total root length than those native to high nutrient soils (HNS), reflecting the slower growth rates of species from less fertile environments. Contrary to expectations, species did not consistently differ in specific root length, root tissue density, or root system plasticity, and species native to LNS had lower root : total mass ratio and higher 15N uptake rates than species native to HNS. Overall, these evolutionary divergences provide support for adaptive differentiation among species, with repeated evolution of slow-growing root systems suited for low resource availability in LNS. However, species native to LNS maintain a high capacity for N uptake, potentially as a means of maximising nutrient acquisition from transient pulses.

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Morphological and Physiological Root Traits and Their Relationship with Nitrogen Uptake in Wheat Varieties Released from 1915 to 2013

Agronomy ◽

10.3390/agronomy11061149 ◽

2021 ◽

Vol 11 (6) ◽

pp. 1149

Author(s):

Guglielmo Puccio ◽

Rosolino Ingraffia ◽

Dario Giambalvo ◽

Gaetano Amato ◽

Alfonso S. Frenda

Keyword(s):

Durum Wheat ◽

Root System ◽

N Uptake ◽

Specific Root Length ◽

Root Traits ◽

Wheat Breeding ◽

N Availability ◽

Wheat Varieties ◽

Uptake Efficiency ◽

Positive Effects

Identifying genotypes with a greater ability to absorb nitrogen (N) may be important to reducing N loss in the environment and improving the sustainability of agricultural systems. This study extends the knowledge of variability among wheat genotypes in terms of morphological or physiological root traits, N uptake under conditions of low soil N availability, and in the amount and rapidity of the use of N supplied with fertilizer. Nine genotypes of durum wheat were chosen for their different morpho-phenological characteristics and year of their release. The isotopic tracer 15N was used to measure the fertilizer N uptake efficiency. The results show that durum wheat breeding did not have univocal effects on the characteristics of the root system (weight, length, specific root length, etc.) or N uptake capacity. The differences in N uptake among the studied genotypes when grown in conditions of low N availability appear to be related more to differences in uptake efficiency per unit of weight and length of the root system than to differences in the morphological root traits. The differences among the genotypes in the speed and the ability to take advantage of the greater N availability, determined by N fertilization, appear to a certain extent to be related to the development of the root system and the photosynthesizing area. This study highlights some variability within the species in terms of the development, distribution, and efficiency of the root system, which suggests that there may be sufficient grounds for improving these traits with positive effects in terms of adaptability to difficult environments and resilience to climate change.

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Barley shoot biomass responds strongly to N:P stoichiometry and intraspecific competition, whereas roots only alter their foraging

Plant and Soil ◽

10.1007/s11104-020-04626-w ◽

2020 ◽

Vol 453 (1-2) ◽

pp. 515-528 ◽

Cited By ~ 1

Author(s):

Amit Kumar ◽

Richard van Duijnen ◽

Benjamin M. Delory ◽

Rüdiger Reichel ◽

Nicolas Brüggemann ◽

...

Keyword(s):

Root System ◽

Intraspecific Competition ◽

Root Length ◽

Root Biomass ◽

Specific Root Length ◽

Plant Performance ◽

Shoot Biomass ◽

P Availability ◽

Soil Layers ◽

N:P Stoichiometry

Abstract Aims Root system responses to the limitation of either nitrogen (N) or phosphorus (P) are well documented, but how the early root system responds to (co-) limitation of one (N or P) or both in a stoichiometric framework is not well-known. In addition, how intraspecific competition alters plant responses to N:P stoichiometry is understudied. Therefore, we aimed to investigate the effects of N:P stoichiometry and competition on root system responses and overall plant performance. Methods Plants (Hordeum vulgare L.) were grown in rhizoboxes for 24 days in the presence or absence of competition (three vs. one plant per rhizobox), and fertilized with different combinations of N:P (low N + low P, low N + high P, high N + low P, and high N + high P). Results Shoot biomass was highest when both N and P were provided in high amounts. In competition, shoot biomass decreased on average by 22%. Total root biomass (per plant) was not affected by N:P stoichiometry and competition but differences were observed in specific root length and root biomass allocation across soil depths. Specific root length depended on the identity of limiting nutrient (N or P) and competition. Plants had higher proportion of root biomass in deeper soil layers under N limitation, while a greater proportion of root biomass was found at the top soil layers under P limitation. Conclusions With low N and P availability during early growth, higher investments in root system development can significantly trade off with aboveground productivity, and strong intraspecific competition can further strengthen such effects.

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Impact of Plant Root Morphology on Rooted-Soil Shear Resistance Using Triaxial Testing

Advances in Civil Engineering ◽

10.1155/2020/8825828 ◽

2020 ◽

Vol 2020 ◽

pp. 1-13

Author(s):

Suyun Meng ◽

Guoqing Zhao ◽

Yuyou Yang

Keyword(s):

Internal Friction ◽

Root System ◽

Root Morphology ◽

Root Length ◽

Friction Angle ◽

Plant Roots ◽

Distribution Characteristics ◽

Soil Cohesion ◽

Shearing Strength ◽

Individual Root

Mechanical reinforcement by plant roots increases the soil shearing strength. The geometric and distribution characteristics of plant roots affect the soil shearing strength. Current research on the shear strength of rooted-soil is mostly based on direct shear tests with a fixed shear surface and thus cannot reflect the actual failure state of the rooted-soil. In this study, Golden Vicary Privet was used to create a rooted-soil, and a triaxial test method was used for soil mechanical property analysis. The influence of the root geometry (root diameter and individual root length) and distribution characteristics (root density and root distribution angle) on the rooted-soil shearing strength was studied by controlling the root morphology in the specimens. According to the results, both the root geometry and distribution characteristics affect the rooted-soil shearing strength. For a fixed total length of the roots, the longer the individual root length is, the better the soil shearing strength is. In addition, the reinforcement effect of the root system increases as the angle between the root and the potential failure surface increases. The results also show that the root system significantly enhances the soil cohesion while only minimally affecting the internal friction angle. The maximum rooted-soil cohesion is 2.39 times that of the plain soil cohesion, and the maximum internal friction angle of rooted-soil is 1.24 times that of plain soil. This paper provides an approach for the determination of the rooted-soil strength and a rationale for vegetation selection in ecological slope reinforcement applications.

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Comparative Analysis of Root System Morphology in Tomato Rootstocks

HortTechnology ◽

10.21273/horttech03654-17 ◽

2017 ◽

Vol 27 (3) ◽

pp. 319-324 ◽

Cited By ~ 3

Author(s):

David H. Suchoff ◽

Christopher C. Gunter ◽

Frank J. Louws

Keyword(s):

Image Analysis ◽

Abiotic Stress ◽

Root System ◽

Root Length ◽

Specific Root Length ◽

Root Diameter ◽

Image Analysis System ◽

Ancillary Benefits ◽

Main Effect ◽

Analysis System

At its most basic, grafting is the replacement of one root system with another containing more desirable traits. Grafting of tomato (Solanum lycopersicum) onto disease-resistant rootstocks is an increasingly popular alternative for managing economically damaging soilborne diseases. Although certain rootstocks have demonstrated ancillary benefits in the form of improved tolerance to edaphic abiotic stress, the mechanisms behind the enhanced stress tolerance are not well understood. Specific traits within root system morphology (RSM), in both field crops and vegetables, can improve growth in conditions under abiotic stress. A greenhouse study was conducted to compare the RSM of 17 commercially available tomato rootstocks and one commercial field cultivar (Florida-47). Plants were grown in containers filled with a mixture of clay-based soil conditioner and pool filter sand (2:1 v/v) and harvested at 2, 3, or 4 weeks after emergence. At harvest, roots were cleaned, scanned, and analyzed with an image analysis system. Data collected included total root length (TRL), average root diameter, specific root length (SRL), and relative diameter class. The main effect of cultivar was significant (P ≤ 0.05) for all response variables and the main effect of harvest date was only significant (P ≤ 0.01) for TRL. ‘RST-106’ rootstock had the longest TRL, whereas ‘Beaufort’ had the shortest. ‘BHN-1088’ had the thickest average root diameter, which was 32% thicker than the thinnest, observed in ‘Beaufort’. SRL in ‘Beaufort’ was 60% larger than ‘BHN-1088’. This study demonstrated that gross differences exist in RSM of tomato rootstocks and that, when grown in a solid porous medium, these differences can be determined using an image analysis system.

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Effect of Penicillium bilaii inoculation and phosphorus fertilisation on root and shoot parameters of field-grown pea

Canadian Journal of Plant Science ◽

10.4141/p00-083 ◽

2001 ◽

Vol 81 (3) ◽

pp. 361-366 ◽

Cited By ~ 29

Author(s):

J. Kevin Vessey ◽

Krista G Heisinger

Keyword(s):

Pisum Sativum ◽

Root Morphology ◽

Root Length ◽

Specific Root Length ◽

Dry Weight ◽

Western Canada ◽

Microbial Inoculants ◽

P Nutrition ◽

P Content ◽

Phosphorus Fertilisation

The mechanisms underlying the stimulating effect of Penicillium bilaii inoculation on the growth of crop plants are not clear. The effect of P. bilaii inoculation on root morphology [dry weight (DW), length and specific root length) and other root and shoot parameters of pea were investigated at two field sites in western Canada in 1996. Pea (Pisum sativum L.) was grown at three levels of P fertilization (0, 6.4 and 19.3 kg ha–1) at Ellerslie, AB, and Outlook, SK. Shoot dry matter, P concentrations, P content and nodulation were also measured in pea plants harvested at the seven- to nine-node stage. Soil cores were used to sample roots. Although plants were responsive to P fertiliser at both sites, P. bilaii inoculation affected pea growth at the Ellerslie site only. At this site, P. bilaii inoculation increased root length by 48%, specific root length (m g–1 root DW) by 21%, root DW by 13%, and shoot P concentration by 13% in treatments that received no P fertiliser. We suggest that the stimulating effect of P. bilaii inoculation on crop P nutrition is partly explained by increases in root absorptive capacity in the presence of the fungus. However, this effect was only significant under P-limited conditions. Key words: Microbial inoculants, Pisum sativum, Penicillium bilaii, phosphorus, root length, root morphology

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Root system architecture in winter varieties of spelt (TriticumspeltaL.)

BIO Web of Conferences ◽

10.1051/bioconf/20181001019 ◽

2018 ◽

Vol 10 ◽

pp. 01019

Author(s):

Andrzej Żabiński ◽

Urszula Sadowska

Keyword(s):

Root System ◽

Root Length ◽

Root Length Density ◽

Computer Software ◽

Morphological Structure ◽

Specific Root Length ◽

Dry Mass ◽

Root System Architecture ◽

Root Diameter ◽

Soil Core

The objective of the study was determination of the variability of morphometry and comparison of the morphological structure of the root system in winter cultivars of spelt. Four spelt cultivars were used in the study: Frankencorn, Oberkulmer Rotkorn, Schwabenkorn and Ostro. The material for the study originated from a field experiment. The roots were collected using the soil core method to the depth of 30 cm, from the rows and inter-rows, then the roots were separated using a semi-automatic hydropneumatic scrubber. The cleaned roots were manually separated and scanned, obtaining their digital images. Image analysis was performed using the Aphelion computer software. In order to characterize the root system of the spelt cultivars included in the study, values of the following indexes were determined: root dry mass (RDM), root length density (RLD), specific root length (SRL), mean root diameter (MD). Based on the obtained results it was determined that the RDM, MD and RLD indexes in all spelt cultivars attain the highest values in the row, at the depth 0–5 cm.The highest value of the RDM and MD indexes characterized the root system of the Ostro cultivar at the depth 0–5 cm. The Oberkulmerrotkorn spelt cultivar was distinguished among the tested objects by the highest value of the SRL index.

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Testing deep placement of an 15N tracer as a method for in situ deep root phenotyping of wheat, barley and ryegrass

Plant Methods ◽

10.1186/s13007-019-0533-6 ◽

2019 ◽

Vol 15 (1) ◽

Cited By ~ 2

Author(s):

Si Chen ◽

Simon Fiil Svane ◽

Kristian Thorup-Kristensen

Keyword(s):

Root System ◽

Spring Barley ◽

N Uptake ◽

Stress Gradient ◽

15N Tracer ◽

Tracer Method ◽

Measurement Variability ◽

Deep Placement ◽

Deep Root ◽

Root Phenotyping

Abstract Background Deep rooting is one of the most promising plant traits for improving crop yield under water-limited conditions. Most root phenotyping methods are designed for laboratory-grown plants, typically measuring very young plants not grown in soil and not allowing full development of the root system. Results This study introduced the 15N tracer method to detect genotypic variations of deep rooting and N uptake, and to support the minirhizotron method. The method was tested in a new semifield phenotyping facility on two genotypes of winter wheat, seven genotypes of spring barley and four genotypes of ryegrass grown along a drought stress gradient in four individual experiments. The 15N labeled fertilizer was applied at increasing soil depths from 0.4 to 1.8 m or from 0.7 to 2.8 m through a subsurface tracer supply system, and sampling of aboveground biomass was conducted to measure the 15N uptake. The results confirm that the 15N labeling system could identify the approximate extension of the root system. The results of 15N labeling as well as root measurements made by minirhizotrons showed rather high variation. However, in the spring barley experiment, we did find correlations between root observations and 15N uptake from the deepest part of the root zone. The labeled crop rows mostly had significantly higher 15N enrichment than their neighbor rows. Conclusion We concluded that the 15N tracer method is promising as a future method for deep root phenotyping because the method will be used for phenotyping for deep root function rather than deep root growth. With some modifications to the injection principle and sampling process to reduce measurement variability, we suggest that the 15N tracer method may be a useful tool for deep root phenotyping. The results demonstrated that the minirhizotrons observed roots of the tested rows rather than their neighboring rows.

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Improvements in the Root Morphology, Physiology, and Anatomy of Platycladus orientalis Seedlings from Air-root Pruning

HortScience ◽

10.21273/hortsci13375-18 ◽

2018 ◽

Vol 53 (12) ◽

pp. 1750-1756

Author(s):

Zhipei Feng ◽

Xitian Yang ◽

Hongyan Liang ◽

Yuhua Kong ◽

Dafeng Hui ◽

...

Keyword(s):

Root System ◽

Surface Area ◽

Root Length ◽

Specific Root Length ◽

Experimental Period ◽

Root Surface ◽

Root Surface Area ◽

Root Pruning ◽

Root Tips ◽

Platycladus Orientalis

Air-root pruning (AP) has been identified as an effective technique for enhancing root growth and development. However, little information is available regarding the temporal changes in the root system of Platycladus orientalis (L.) Franco under AP. We performed integrated morphological, physiological, and anatomical analyses of the roots in P. orientalis seedlings that had been air-root pruned for 120, 150, and 190 days. Our results found that the whole root length, number of root tips, and root surface area of AP seedlings at 120, 150, and 190 days were higher than those of the non–root-pruned (NP) seedlings (P < 0.05), but the average root diameter did not differ significantly between the treatments. Compared with NP treatment, AP increased the root length, surface area, number of tips, and specific root length of the ≤0.5 mm diameter roots in P. orientalis during the experimental periods (P < 0.05), but those of 0.5- to 1-mm-diameter roots were only increased on day 190 (P < 0.05). The AP plants also exhibited higher root vitality and proportion of live fine roots than the NP plants (P < 0.05). Our anatomical evaluation of the ≤0.5 mm roots and taproots revealed features that could account for the morphological differences found between the AP and NP plants. In conclusion, our results indicate that air-root pruning induced changes in the roots that promote the root system development in P. orientalis compared with the NP treatment during the experimental period. These results thus provide experimental evidence to support the use of AP in P. orientalis seedlings.

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Influence of arbuscular mycorrhizae on biomass and root morphology of selected strawberry cultivars under salt stress

Botany ◽

10.1139/b11-028 ◽

2011 ◽

Vol 89 (6) ◽

pp. 397-403 ◽

Cited By ~ 22

Author(s):

Li Fan ◽

Yolande Dalpé ◽

Chengquan Fang ◽

Claudine Dubé ◽

Shahrokh Khanizadeh

Keyword(s):

Salt Stress ◽

Root Morphology ◽

Root Length ◽

Mycorrhizal Fungi ◽

Arbuscular Mycorrhizae ◽

Specific Root Length ◽

Arbuscular Mycorrhizal ◽

Root Diameter ◽

Root Tissue ◽

Sustainable Horticulture

To investigate the influence of arbuscular mycorrhizal fungi (AMF) on biomass and root morphology, a greenhouse experiment was conducted using three elite strawberry ( Fragaria × ananassa Duch.) cultivars (‘Kent’, ‘Jewel’, and ‘Saint-Pierre’). They were subjected to three NaCl levels (0, 30, and 60 mmol/L) and were inoculated and noninoculated (control) with AMF Glomus irregulare . The presence of AMF significantly changed root morphology and increased root-length percentages of medium (0.5 mm < root diameter φ ≤ 1.5 mm) and coarse (φ > 1.5 mm) roots, shoot and root tissue biomass, root to shoot ratio (R/S ratio), and specific root length (SRL), regardless of cultivar and salinity. In contrast, salt alone changed root morphology and decreased shoot and root tissue biomass, R/S ratio, and SRL. The AMF colonization rates were reduced linearly and significantly with increasing salinity levels. Cultivars responded differently to AMF than to salt stress. ‘Saint-Pierre’ seemed to be the most tolerant cultivar to salinity, while ‘Kent’ was the most sensitive. Consequently, AMF symbiosis highly enhanced salt tolerance of strawberry plants, which confirmed the potential use of mycorrhizal biotechnology in sustainable horticulture in arid areas.

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Influence of fine root traits on in situ exudation rates in four conifers from different mycorrhizal associations

Tree Physiology ◽

10.1093/treephys/tpaa051 ◽

2020 ◽

Vol 40 (8) ◽

pp. 1071-1079

Author(s):

Maiko Akatsuki ◽

Naoki Makita

Keyword(s):

Root System ◽

Root Morphology ◽

Fine Root ◽

Root Exudation ◽

Specific Root Length ◽

Root Traits ◽

Root Diameter ◽

Small Scale ◽

Exudation Rate

Abstract Plant roots can exude organic compounds into the soil that are useful for plant survival because they can degrade microorganisms around the roots and enhance allelopathy against other plant invasions. We developed a method to collect carbon (C) exudation on a small scale from tree fine roots by C-free filter traps. We quantified total C through root exudation in four conifers from different microbial symbiotic groups (ectomycorrhiza (ECM) and arbuscular mycorrhiza (AM)) in a cool-temperate forest in Japan. We determined the relationship of mass-based exudation rate from three diameter classes (<0.5, 0.5–1.0, and 1.0–2.5 mm) of the intact root system with root traits such as morphological traits including root diameter, specific root length (SRL), specific root area (SRA), root tissue density (RTD) and chemical traits including root nitrogen (N) content and C/N. Across species, the mass-based root exudation rate was found to correlate with diameter, SRA, RTD, N and C/N. When comparing mycorrhizal types, there were significant relationships between the exudation and diameter, SRL, SRA, root N and C/N in ECM species; however, these were not significant in AM species. Our results show that relationships between in situ root exudation and every measured trait of morphology and chemistry were strongly driven by ECM roots and not by AM roots. These differences might explain the fact that ECM roots in this study potentially covaried by optimizing the exudation and root morphology in forest trees, while exudation in AM roots did not change with changes in root morphology. In addition, the contrasting results may be attributable to the effect of degree and position of ECM and AM colonization in fine root system. Differences in fine root exudation relationships to root morphology for the two types of mycorrhizae will help us better understand the underlying mechanisms of belowground C allocation in forest ecosystems.

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