Root traits are multidimensional: specific root length is independent from root tissue density and the plant economic spectrum

Abstract. Plant roots usually vary along a dominant ecological axis, the root economics spectrum (RES), depicting a tradeoff between resource acquisition and conservation. For absorptive roots, which are mainly responsible for resource acquisition, we hypothesized that root strategies as predicted from the RES shift with increasing root diameter. To test this hypothesis, we used seven contrasting plant species for which we separated absorptive roots into two categories: thin roots (< 247 μm diameter) and thick roots. For each category, we analyzed a~range of root traits closely related to resource acquisition and conservation, including root tissue density, carbon (C) and nitrogen (N) fractions as well as root anatomical traits. The results showed that trait relationships for thin absorptive roots followed the expectations from the RES while no clear trait relationships were found in support of the RES for thick absorptive roots. Our results suggest divergence of absorptive root strategies in relation to root diameter, which runs against a single economics spectrum for absorptive roots.

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Shifts in fine root traits within and among species along a fine-scale hydrological gradient

Annals of Botany ◽

10.1093/aob/mcaa175 ◽

2020 ◽

Author(s):

Guy M Taseski ◽

David A Keith ◽

Rhiannon L Dalrymple ◽

William K Cornwell

Keyword(s):

Root Traits ◽

Matter Content ◽

Root Tissue ◽

Species Variation ◽

Dry Matter Content ◽

Fine Scale ◽

Trait Variation ◽

Tissue Density ◽

Root Tissue Density ◽

Below Ground

Abstract Background and Aims Lessons from above-ground trait ecology and resource economics theory may not be directly translatable to below-ground traits due to differences in function, trade-offs and environmental constraints. Here we examine root functional traits within and across species along a fine-scale hydrological gradient. We ask two related questions: (1) What is the relative magnitude of trait variation across the gradient for within- versus among-species variation? (2) Do correlations among below-ground plant traits conform with predictions from resource-economic spectrum theory? Methods We sampled four below-ground fine-root traits (specific root length, branching intensity, root tissue density and root dry matter content) and four above-ground traits (specific leaf area, leaf size, plant height and leaf dry matter content) in vascular plants along a fine-scale hydrological gradient within a wet heathland community in south-eastern Australia. Below-ground and above-ground traits were sampled both within and among species. Key Results Root traits shifted both within and among species across the hydrological gradient. Within- and among-species patterns for root tissue density showed similar declines towards the wetter end of the gradient. Other root traits showed a variety of patterns with respect to within- and among-species variation. Filtering of species has a stronger effect compared with the average within-species shift: the slopes of the relationships between soil moisture and traits were steeper across species than slopes of within species. Between species, below-ground traits were only weakly linked to each other and to above-ground traits, but these weak links did in some cases correspond with predictions from economic theory. Conclusions One of the challenges of research on root traits has been considerable intraspecific variation. Here we show that part of intraspecific root trait variation is structured by a fine-scale hydrological gradient, and that the variation aligns with among-species trends in some cases. Patterns in root tissue density are especially intriguing and may play an important role in species and individual response to moisture conditions. Given the importance of roots in the uptake of resources, and in carbon and nutrient turnover, it is vital that we establish patterns of root trait variation across environmental gradients.

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A split supply of bio-organic and chemical fertilizer synergistically affects root system architecture and improves above-ground growth in pear tree (Pyrus pyrifolia Nakai)

10.21203/rs.2.23996/v1 ◽

2020 ◽

Author(s):

Yalong Kang ◽

Xiangrui An ◽

Yanwei Ma ◽

Yan Li ◽

Wenli Wu ◽

...

Keyword(s):

Root System ◽

System Architecture ◽

Root Length ◽

Lateral Root ◽

Organic Fertilizer ◽

Root System Architecture ◽

Chemical Fertilizer ◽

Root Tissue ◽

Tissue Density ◽

Root Tissue Density

Abstract Background: Root system architecture (RSA) is highly plastic, responding to nutrient availability and the heterogeneity of the soil environment. However, the linkage of root morphology to anatomy and root nutrient, and its implication for root function at the heterogeneous application of bio-organic and chemical fertilizer have not yet been defined, especially for pear trees.Results: In this study, a split-root experiment was conducted using 1-year old ‘Cuiguan’ trees. No fertilizer (NF), chemical fertilizer (CF), and bio-organic fertilizer (BIO) were paired to test six combinations: NF-NF, NF-CF, NF-BIO, CF-CF, BIO-BIO, and BIO-CF. Root morphological, anatomical traits and root nutrient concentrations, and their relationships were determined. Trees receiving BIO had significantly higher lateral root numbers, activity, total lateral root length, and specific root length than trees receiving no BIO, while the effects on root tissue density were the direct opposite. Compared with CF-CF treatment, root xylem thickness, stele diameter, vessel diameter, and number of vessels all increased in response to BIO-CF treatment. Root growth was synergistically promoted in BIO-CF, with increased special root length and root nitrogen concentration, but root tissue density and the carbon:nitrogen ratio were reduced. Intriguingly, the synergistic effect resulted in greater trunk girth without sacrificing height, compared to trees receiving CF or BIO alone.Conclusions: The combination of BIO and CF improves root traits and tree growth, suggesting that using bio-organic fertilizer as a supplement to reduce the application rate of chemical fertilizer is beneficial to orchard ecosystems.

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Experimentally altered rainfall regimes and host root traits affect grassland arbuscular mycorrhizal fungal communities

10.32942/osf.io/cu4jh ◽

2019 ◽

Author(s):

Coline Deveautour ◽

Suzanne Donn ◽

Sally Power ◽

Kirk Barnett ◽

Jeff Powell

Keyword(s):

Fungal Community ◽

Community Assembly ◽

Root Length ◽

Specific Root Length ◽

Root Traits ◽

Arbuscular Mycorrhizal ◽

Fungal Communities ◽

Rainfall Regime ◽

Precipitation Regimes ◽

Rainfall Regimes

Future climate scenarios predict changes in rainfall regimes. These changes are expected to affect plants via effects on the expression of root traits associated with water and nutrient uptake. Associated microorganisms may also respond to these new precipitation regimes, either directly in response to changes in the soil environment or indirectly in response to altered root trait expression. We characterised arbuscular mycorrhizal (AM) fungal communities in an Australian grassland exposed to experimentally altered rainfall regimes. We used Illumina sequencing to assess the responses of AM fungal communities associated with four plant species sampled in different watering treatments and evaluated the extent to which shifts were associated with changes in root traits. We observed that altered rainfall regimes affected the composition but not the richness of the AM fungal communities, and we found distinctive communities in the increased rainfall treatment. We found no evidence of altered rainfall regime effects via changes in host physiology because none of the studied traits were affected by changes in rainfall. However, specific root length was observed to correlate with AM fungal richness, while concentrations of phosphorus and calcium in root tissue and the proportion of root length allocated to fine roots were correlated to community composition. Our study provides evidence that climate change and its effects on rainfall may influence AM fungal community assembly, as do plant traits related to plant nutrition and water uptake. We did not find evidence that host responses to altered rainfall drive AM fungal community assembly in this grassland ecosystem.

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Root Phenotyping for Drought Tolerance: A Review

Agronomy ◽

10.3390/agronomy8110241 ◽

2018 ◽

Vol 8 (11) ◽

pp. 241 ◽

Cited By ~ 32

Author(s):

Allah Wasaya ◽

Xiying Zhang ◽

Qin Fang ◽

Zongzheng Yan

Keyword(s):

Drought Tolerance ◽

Crop Yield ◽

Root Length ◽

Root Length Density ◽

Canopy Temperature ◽

Specific Root Length ◽

Root Traits ◽

Three Dimensions ◽

Invasive Approach ◽

Root Phenotyping

Plant roots play a significant role in plant growth by exploiting soil resources via the uptake of water and nutrients. Root traits such as fine root diameter, specific root length, specific root area, root angle, and root length density are considered useful traits for improving plant productivity under drought conditions. Therefore, understanding interactions between roots and their surrounding soil environment is important, which can be improved through root phenotyping. With the advancement in technologies, many tools have been developed for root phenotyping. Canopy temperature depression (CTD) has been considered a good technique for field phenotyping of crops under drought and is used to estimate crop yield as well as root traits in relation to drought tolerance. Both laboratory and field-based methods for phenotyping root traits have been developed including soil sampling, mini-rhizotron, rhizotrons, thermography and non-soil techniques. Recently, a non-invasive approach of X-ray computed tomography (CT) has provided a break-through to study the root architecture in three dimensions (3-D). This review summarizes methods for root phenotyping. On the basis of this review, it can be concluded that root traits are useful characters to be included in future breeding programs and for selecting better cultivars to increase crop yield under water-limited environments.

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Novel approaches to improving growth of pasture legumes at low phosphorus levels

Proceedings of the New Zealand Grassland Association ◽

10.33584/jnzg.2014.76.2952 ◽

2014 ◽

Vol 76 ◽

pp. 197-202

Author(s):

S.N. Nichols ◽

J.R. Crush

Keyword(s):

White Clover ◽

Root Length ◽

Specific Root Length ◽

Root Traits ◽

Dry Weight ◽

Root Weight ◽

Soil P ◽

P Acquisition ◽

Shoot Dry Weight ◽

Use Efficiency

Abstract Strategies to reduce the economic and environmental costs of phosphate (P) fertiliser use in mixed pastures through plant breeding are focussed on inefficiencies in the legume component. One approach is breeding within white clover for root systems with improved P acquisition properties. Selection for root length per unit root weight (specific root length, SRL) showed that higher SRL plants could retain more biomass in the above ground fraction with decreasing soil P, whereas plants with lower SRL diverted more biomass to roots. Back cross 1 (BC1) generation interspecific hybrids between white clover and a wild relative, Trifolium uniflorum L., may possess additional root traits influencing P acquisition. In glasshouse experiments, some T. repens × T. uniflorum hybrids, back-crossed to white clover, also exhibited higher shoot dry weight than their white clover cultivar parents at low nutrient supply levels and low to intermediate soil Olsen P. This, combined with low internal P concentrations, suggests some BC1 hybrids may be more tolerant of low soil P than white clover. Differences in both P acquisition ability and internal P use efficiency may contribute to the observed yield differences. There are good prospects for delivery of new-generation clover cultivars with improved phosphate use efficiency to New Zealand farmers. Keywords: phosphorus, white clover, Trifolium uniflorum, interspecific

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Root Porosity Contributes to Root Trait Space of Wetland Monocotyledons Independently of Economics Traits.

10.21203/rs.3.rs-325043/v1 ◽

2021 ◽

Author(s):

Ziqi Ye ◽

Peter Ryser

Keyword(s):

Lateral Roots ◽

Interspecific Variation ◽

Wetland Plants ◽

Root Tissue ◽

Root Porosity ◽

Tissue Density ◽

Adaptive Trait ◽

Root Tissue Density ◽

Air Space ◽

Trait Space

Abstract Aims Root aerenchyma, a key adaptive trait to anoxic soils has rarely been integrated into trait-based plant ecology. This study aims to evaluate the relationship between root porosity and root economics-related traits among wetland plants, focusing on the effect of aerenchyma on root tissue density, a central trait in plant economics spectrum.Methods Root porosity, root tissue density with air-space included or excluded (RTD and RTDA), and other root economics-related traits were measured separately for basal and lateral roots of 16 garden-grown Ontario wetland monocots with contrasting root longevities.Results Interspecific variation in root porosity was unrelated to root economics traits and did not differ between species with long-lived or short-lived roots. Consequently, RTDA better differentiated between species with contrasting root longevities than RTD did, consistently both for basal and lateral roots. Root dry matter content (RDMC) accurately predicted RTDA. A principal component analysis showed that in the root adaptive trait space of wetland plants, the first dimension is defined by economics-related traits, the second dimension by lateral root porosity and the ratio of lateral to basal root length, and the third dimension by basal root porosity.Conclusions Interspecific variation in the aerenchyma content is independent of root economics: Wetland plants can construct economically conservative or acquisitive roots of any porosity. Consequently, to consistently express root functional relationships among wetland plant species, root tissue density should be expressed with RTDA, i.e., excluding the air space, or with the more easily measured RDMC.

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Lateral Root Traits of Taxodium Hybrid ‘Zhongshanshan 406’ in Response to Drought Stress

HortScience ◽

10.21273/hortsci12387-17 ◽

2018 ◽

Vol 53 (4) ◽

pp. 547-551

Author(s):

Qin Shi ◽

Yunlong Yin ◽

Zhiquan Wang ◽

Wencai Fan ◽

Jinbo Guo ◽

...

Keyword(s):

Drought Stress ◽

Surface Area ◽

Root Length ◽

Lateral Root ◽

Plant Root ◽

Lateral Roots ◽

Specific Root Length ◽

Root Traits ◽

Root Tip ◽

Root Surface Area

Roots are vital organs for resource uptake. However, the knowledge regarding the extent by which responses in roots influence plant resistance is still poorly known. In this study, we examined the morphological and physiological responses of lateral roots of Taxodium hybrid ‘Zhongshanshan 406’ (Taxodium mucronatum♀ and Taxodium distichum♂, T. 406) to 8 (DS-8) and 12 days (DS-12) drought. Control plants (CK-8 and CK-12) were well-watered throughout the experiment. Results indicated that drought resulted in significantly decreased root length, surface area, volume, and biomass and a relatively high death rate of roots (>2 mm). Specific root length (SRL) and specific root surface area (SRA) of drought-stressed T. 406 plants were reduced to enhance resource uptake. Meanwhile, root relative water content (RWC) of T. 406 plants in CK-12 treatment was 5.81 times of those in DS-12 treatment. Under drought stress and root superoxide dismutase and ascorbic acid (ASA) activities, proline and hydrogen peroxide (H2O2) contents consistently increased to benefit the elimination of O2−. At the ultrastructural level, the organelle structure of T. 406 plant root tip was visibly damaged because of dehydration. The nucleus swelled and then exhibited uncommon features of disorganization and disruption. In short, our results provided substantial information about lateral root traits of T. 406 plants in response to drought stress, which is crucial to improve the drought resistance of Taxodium hybrid in the future breeding.

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