Linking root traits to superior phosphorus uptake and utilisation efficiency in three Fabales in the Core Cape Subregion, South Africa

In the low-P soil of the fynbos biome, plants have evolved several morphological and physiological P acquisition and use mechanisms, leading to variable uptake and use efficiencies. We expected that plants grown in low-P soils would exhibit greater P acquisition traits and hypothesised that Aspalathus linearis (Burm. f.) R. Dahlgren, a cluster-root-forming species adapted to drier and infertile soils, would be the most efficient at P acquisition compared with other species. Three fynbos Fabales species were studied: A. linearis and Podalyria calyptrata (Retz.) Willd, both legumes, and Polygala myrtifolia L., a nonlegume. A potted experiment was conducted where the species were grown in two soil types with high P (41.18 mg kg–1) and low P (9.79 mg kg–1). At harvest, biomass accumulation, foliar nutrients and P acquisition mechanisms were assessed. Polygala myrtifolia developed a root system with greater specific root length, root hair width and an average root diameter that exuded a greater amount of citrate and, contrary to the hypothesis, exhibited greater whole-plant P uptake efficiency. However, P. calyptrata had higher P use efficiency, influenced by N availability through N2 fixation. Specific root length, root length and root : shoot ratio were promising morphological traits for efficient foraging of P, whereas acid phosphatase exudation was the best physiological trait for solubilisation of P.

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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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Effect of phosphate solubilising bacteria (Enterobacter cloacae) on phosphorus uptake efficiency in sugarcane (Saccharum officinarum L.)

Soil Research ◽

10.1071/sr18128 ◽

2019 ◽

Vol 57 (4) ◽

pp. 333

Author(s):

Saeed Safirzadeh ◽

Mostafa Chorom ◽

Naeimeh Enayatizamir

Keyword(s):

Root Length ◽

Phosphorus Uptake ◽

Morphological Characteristics ◽

Specific Root Length ◽

Enterobacter Cloacae ◽

P Uptake ◽

Available P ◽

Time Activity ◽

Uptake Efficiency ◽

P Influx

Phosphorus (P) is an essential nutrient in sustainable production of sugarcane. Due to low labile P in soil under sugarcane cultivation, evaluation of the efficiency of P uptake and the application of phosphate solubilising bacteria (PSB) play important roles in management of P fertiliser. To investigate the effect of using PSB on P uptake in sugarcane (variety CP57–614), a pot experiment was conducted with three replications in greenhouse conditions. The treatments were a combination of three P rates (0 (P0), 50 and 100% (~40 mg kg−1) as triple superphosphate, and two PSB strains (Enterobacter cloacae R13 (R13) and R33 (R33)) which were applied independently and simultaneously. Morphological characteristics of sugarcane and some biochemical parameters were evaluated in the rhizosphere at three harvesting times: 60, 95 and 140 days after planting (DAP). Whereas in low available P (P0), bacterial strain R33 improved P uptake along with sugarcane ageing, P uptake was diminished in non-inoculated treatment over time. Activity of PSBs in the rhizosphere (especially strain R33) prevented the sharp fall of P influx after 95 DAP in low available P condition. Indeed, activity of R33 in the rhizosphere decreased the dependence of P uptake on root development via improving P uptake. Therefore, influx was the main mechanism of P uptake in sugarcane. Sugarcane inoculated by PSBs acquired 76 and 81% of total P uptake from non-Olsen-P fraction in P0R13 and P0R33 respectively at 95 DAP. However, this amount was lower (70.4%) in P0R0. Furthermore, strain R33 improved P uptake efficiency in sugarcane by changing root morphology (e.g. specific root length and root length) and reducing soil limitations (e.g. enhancement of P compound solubility and P influx).

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Variation in root morphology and P acquisition efficiency among Trifolium subterraneum genotypes

Crop and Pasture Science ◽

10.1071/cp19078 ◽

2019 ◽

Vol 70 (11) ◽

pp. 1015 ◽

Cited By ~ 2

Author(s):

Jonathan W. McLachlan ◽

Rebecca E. Haling ◽

Richard J. Simpson ◽

Xiaoxi Li ◽

Richard J. Flavel ◽

...

Keyword(s):

Root Hair ◽

Root Length ◽

Morphological Traits ◽

Trifolium Subterraneum ◽

P Uptake ◽

Hair Length ◽

Root Hair Length ◽

P Acquisition ◽

Plant P Uptake ◽

Total Plant

Trifolium subterraneum L. is widely grown in the phosphorus (P) deficient soils of southern Australia. However, this pasture legume has a high critical external P requirement and requires frequent applications of P fertiliser to achieve high productivity. Twenty-six genotypes of T. subterraneum were grown to determine: (i) differences in shoot growth and P acquisition under low-P supply; (ii) the root morphological traits important for P acquisition; and (iii) the feasibility of selection among genotypes for these root morphological traits. Micro-swards of each genotype were grown with a topsoil layer that was either moderately P-deficient or had P supplied in excess of the critical requirement for maximum yield; the subsoil layer was P-deficient. Yield and P content of shoots and roots were determined after 5 weeks’ growth, and root samples were assessed for diameter, length and root hair length. All genotypes were equally highly productive when excess P was supplied. However, relative shoot yield in the moderately P-deficient soil ranged from 38–71%. Total root length ranged from 63–129 m pot–1, and was correlated with total plant P uptake (R2 = 0.78, P < 0.001). Variation was also observed in average root diameter (0.29–0.36 mm) and root hair length (0.19–0.33 mm). These traits were combined with root length to calculate the total surface area of the root hair cylinder, which was also correlated with total plant P uptake (R2 = 0.69, P < 0.001). The results demonstrated that there was significant variation in P acquisition efficiency and shoot yield among genotypes of T. subterraneum when grown in P-deficient soil, and that root length was important for improved P uptake. The results indicate potential to identify superior genotypes that achieve improved P acquisition and higher shoot yields in low-P soil.

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Nitrogen and phosphorus availability affect wheat carbon allocation pathways: rhizodeposition and mycorrhizal symbiosis

Soil Research ◽

10.1071/sr19183 ◽

2020 ◽

Vol 58 (2) ◽

pp. 125 ◽

Cited By ~ 1

Author(s):

Bahareh Bicharanloo ◽

Milad Bagheri Shirvan ◽

Claudia Keitel ◽

Feike A. Dijkstra

Keyword(s):

Microbial Biomass ◽

Grain Yield ◽

Fine Roots ◽

Root Biomass ◽

Root Traits ◽

P Uptake ◽

N Availability ◽

P Availability ◽

Wheat Genotypes ◽

Plant P Uptake

Plants allocate their photosynthetic carbon (C) belowground through rhizodeposition, which can be incorporated into microbial biomass and organic matter, but can also be directly shared with arbuscular mycorrhizal fungi (AMF). In this study, we investigated how both rhizodeposition and AMF colonisation are affected by nitrogen (N) and phosphorus (P) availability in soil systems, and in turn, how these C allocation pathways influenced plant P uptake in four different wheat genotypes with variable root traits. Wheat genotypes (249, Suntop, Scout and IAW2013) were grown in pots and labelled continuously during their growth period with 13CO2 to determine rhizodeposition. We applied two levels of N (25 and 100 kg ha–1) and P (10 and 40 kg ha–1) fertiliser. Plant root traits, plant P content, soil available P and N, microbial biomass C and P, and AMF colonisation were examined. We constructed a structural equation model to show how C allocation to rhizodeposition and AMF colonisation depended on P and N availability, and how these pathways affected plant P uptake and grain yield. Wheat genotypes with fine roots (Suntop, Scout and IAW2013) were associated with AMF colonisation for plant P uptake, and the genotype with the largest root biomass (249) provided more C to rhizodeposition. Both rhizodeposition and AMF colonisation increased plant P and grain yield under low P and high N availability respectively, while root biomass and root traits, such as specific root length and proportion of fine roots, determined which C allocation pathway was employed by the plant.

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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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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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Sex-specifically responsive strategies to phosphorus availability combined with different soil nitrogen forms in dioecious Populus cathayana

Journal of Plant Ecology ◽

10.1093/jpe/rtab025 ◽

2021 ◽

Author(s):

Xiucheng Liu ◽

Yuting Wang ◽

Shuangri Liu ◽

Miao Liu

Keyword(s):

Root Length ◽

Root Length Density ◽

Specific Root Length ◽

P Uptake ◽

Root Tip ◽

P Availability ◽

P Deficiency ◽

Populus Cathayana ◽

Leaf P ◽

P Supply

Abstract Aims Phosphorus (P) availability and efficiency are especially important for plant growth and productivity. However, the sex-specific P acquisition and utilization strategies of dioecious plant species under different N forms are not clear. Methods This study investigated the responsive mechanisms of dioecious Populus cathayana females and males based on P uptake and allocation to soil P supply under N deficiency, nitrate (NO3 −) and ammonium (NH4 +) supply. Important Findings Females had a greater biomass, root length density (RLD), specific root length (SRL) and shoot P concentration than males under normal P availability with two N supplies. NH4 + supply led to higher total root length, RLD and SRL but lower root tip number than NO3 − supply under normal P supply. Under P deficiency, males showed a smaller root system but greater photosynthetic P availability and higher leaf P remobilization, exhibiting a better capacity to adaptation to P-deficiency than females. Under P deficiency, NO3 − supply increased leaf photosynthesis and PUE but reduced RLD and SRL in females while males had higher leaf P redistribution and photosynthetic PUE than NH4 + supply. Females had a better potentiality to cope with P deficiency under NO3 − supply than NH4 + supply; the contrary was true for males. These results suggest that females may devote to increase in P uptake and shoot P allocation under normal P availability, especially under NO3 − supply, while males adopt more efficient resource use and P remobilization to maximum their tolerance to P-deficiency.

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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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Water and phosphorus uptake by upland rice root systems unraveled under multiple scenarios: linking a 3D soil-root model and data

10.1101/2020.01.27.921247 ◽

2020 ◽

Author(s):

Trung Hieu Mai ◽

Pieterjan De Bauw ◽

Andrea Schnepf ◽

Roel Merckx ◽

Erik Smolders ◽

...

Keyword(s):

Upland Rice ◽

Phosphorus Uptake ◽

Root Systems ◽

Multiscale Model ◽

P Uptake ◽

Water Dynamics ◽

Small Scale ◽

P Availability ◽

P Deficiency ◽

Plant P Uptake

AbstractBackground and aimsUpland rice is often grown where water and phosphorus (P) are limited and these two factors interact on P bioavailability. To better understand this interaction, mechanistic models representing small-scale nutrient gradients and water dynamics in the rhizosphere of full-grown root systems are needed.MethodsRice was grown in large columns using a P-deficient soil at three different P supplies in the topsoil (deficient, suboptimal, non-limiting) in combination with two water regimes (field capacity versus drying periods). Root architectural parameters and P uptake were determined. Using a multiscale model of water and nutrient uptake, in-silico experiments were conducted by mimicking similar P and water treatments. First, 3D root systems were reconstructed by calibrating an architecure model with observed phenological root data, such as nodal root number, lateral types, interbranch distance, root diameters, and root biomass allocation along depth. Secondly, the multiscale model was informed with these 3D root architectures and the actual transpiration rates. Finally, water and P uptake were simulated.Key resultsThe plant P uptake increased over threefold by increasing P and water supply, and drying periods reduced P uptake at high but not at low P supply. Root architecture was significantly affected by the treatments. Without calibration, simulation results adequately predicted P uptake, including the different effects of drying periods on P uptake at different P levels. However, P uptake was underestimated under P deficiency, a process likely related to an underestimated affinity of P uptake transporters in the roots. Both types of laterals (i.e. S- and L-type) are shown to be highly important for both water and P uptake, and the relative contribution of each type depend on both soil P availability and water dynamics. Key drivers in P uptake are growing root tips and the distribution of laterals.ConclusionsThis model-data integration demonstrates how multiple co-occurring single root phene responses to environmental stressors contribute to the development of a more efficient root system. Further model improvements such as the use of Michaelis constants from buffered systems and the inclusion of mycorrhizal infections and exudates are proposed.

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Phosphorus-acquisition strategies of canola, wheat and barley in soil amended with sewage sludges

Scientific Reports ◽

10.1038/s41598-019-51204-x ◽

2019 ◽

Vol 9 (1) ◽

Cited By ~ 10

Author(s):

C. Nobile ◽

D. Houben ◽

E. Michel ◽

S. Firmin ◽

H. Lambers ◽

...

Keyword(s):

Soil Phosphorus ◽

Specific Root Length ◽

Cropping System ◽

Root Traits ◽

Sewage Sludges ◽

P Acquisition ◽

Acquisition Strategies ◽

P Content ◽

P Fertilizer ◽

Available Soil Phosphorus

Abstract Crops have different strategies to acquire poorly-available soil phosphorus (P) which are dependent on their architectural, morphological, and physiological root traits, but their capacity to enhance P acquisition varies with the type of fertilizer applied. The objective of this study was to examine how P-acquisition strategies of three main crops are affected by the application of sewage sludges, compared with a mineral P fertilizer. We carried out a 3-months greenhouse pot experiment and compared the response of P-acquisition traits among wheat, barley and canola in a soil amended with three sludges or a mineral P fertilizer. Results showed that the P-acquisition strategy differed among crops. Compared with canola, wheat and barley had a higher specific root length and a greater root carboxylate release and they acquired as much P from sludge as from mineral P. By contrast, canola shoot P content was greater with sludge than with mineral P. This was attributed to a higher root-released acid phosphatase activity which promoted the mineralization of sludge-derived P-organic. This study showed that contrasted P-acquisition strategies of crops allows increased use of renewable P resources by optimizing combinations of crop and the type of P fertilizer applied within the cropping system.

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