scholarly journals Plants in constrained canopy micro-swards compensate for decreased root biomass and soil exploration with increased amounts of rhizosphere carboxylates

2017 ◽  
Vol 44 (5) ◽  
pp. 552 ◽  
Author(s):  
Robert P. Jeffery ◽  
Richard J. Simpson ◽  
Hans Lambers ◽  
Daniel R. Kidd ◽  
Megan H. Ryan
Keyword(s):  
Specific Root Length ◽  
Root Traits ◽  
Trifolium Subterraneum ◽  
Arbuscular Mycorrhizal ◽  
Dry Mass ◽  
Root Diameter ◽  
Soil P ◽  
Fungal Colonisation ◽  
P Concentration ◽  
Foraging Ability

Root traits related to phosphorus (P) acquisition are used to make inferences about a species’ P-foraging ability under glasshouse conditions. However, the effect on such root traits of constrained canopy spread, as occurs in dense pasture swards, is unknown. We grew micro-swards of Trifolium subterraneum L. and Ornithopus compressus L. at 15 and 60 mg kg–1 soil P in a glasshouse. Shoots either spread beyond the pot perimeter or were constrained by a cylindrical sleeve adjusted to canopy height. After 8 weeks, shoot and root dry mass (DM), shoot tissue P concentration, rhizosphere carboxylates, arbuscular mycorrhizal (AM) fungal colonisation, total and specific root length (TRL and SRL respectively), average root diameter (ARD) and average root hair length (ARHL) were measured. In all species and treatments, constrained canopy spread decreased root DM (39–59%), TRL (27–45%) and shoot DM (10–28%), and increased SRL (20–33%), but did not affect ARD, ARHL and AM fungal colonisation. However, shoot P concentration and content increased, and rhizosphere carboxylates increased 3.5 to 12-fold per unit RL and 2.0- to 6.5-fold per micro-sward. Greater amounts of rhizosphere carboxylates when canopy spread was constrained appeared to compensate for reduced root growth enabling shoot P content to be maintained.

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

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.

Influence of arbuscular mycorrhizae on soil P dynamics, corn P-nutrition and growth in a ridge-tilled commercial field

2008 ◽  
Vol 88 (3) ◽  
pp. 283-294 ◽  
Author(s):  
Christine P Landry ◽  
Chantal Hamel ◽  
Anne Vanasse
Keyword(s):  
Arbuscular Mycorrhizae ◽  
Arbuscular Mycorrhizal ◽  
Am Fungi ◽  
Dry Mass ◽  
Soil Disturbance ◽  
P Uptake ◽  
P Nutrition ◽  
Soil P ◽  
High Yields ◽  
Ridge Tillage

Ridge-tilled corn (Zea mays L.) could benefit from arbuscular mycorrhizal (AM) fungi. Under low soil disturbance, AM hyphal networks are preserved and can contribute to corn nutrition. A 2-yr study was conducted in the St. Lawrence Lowlands (Quebec, Canada) to test the effects of indigenous AM fungi on corn P nutrition, growth, and soil P in field cropped for 8 yr under ridge-tillage. Phosphorus treatments (0, 17, 35 kg P ha-1) were applied to AM-inhibited (AMI) (fungicide treated) and AM non-inhibited (AMNI) plots. Plant tissue and soil were sampled 22, 48 and 72 days after seeding (DAS). P dynamics was monitored in situ with anionic exchange membranes (PAEM) from seeding to the end of July. AMNI plants showed extensive AM colonization at all P rates. At 22 DAS, AMI plants had decreased growth in the absence of P inputs, while AMNI plants had higher dry mass (DM) and P uptake in unfertilized plots. The PAEM was lower in the AMNI unfertilized soils in 1998 and at all P rates in 1999, indicating an inverse relationship between P uptake and PAEM. At harvest, grain P content of AMNI plants was greater than that of AMI plants. In 1998, only AMI plants had decreased yield in the absence of P fertilization. In 1999, AMNI plants produced greater grain yield than AMI plants at all P rates. AM fungi improve the exploitation of soil P by corn thereby maintaining high yields while reducing crop reliance on P inputs in RT. Key words: Arbuscular mycorrhizae, ridge-tillage, soil P dynamics, corn, P nutrition

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

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

Response of Acacia mangium to vesicular – arbuscular mycorrhizal inoculation, soil pH, and soil P concentration in an oxisol

1996 ◽  
Vol 74 (2) ◽  
pp. 155-161 ◽  
Author(s):  
M. Habte ◽  
M. Soedarjo
Keyword(s):  
Soil Ph ◽  
Acacia Mangium ◽  
Arbuscular Mycorrhizal ◽  
Mn Toxicity ◽  
Soil P ◽  
P Concentration ◽  
Vesicular Arbuscular ◽  
Host Growth ◽  
High Concentrations ◽  
Vamf Colonization

The vesicular–arbuscular mycorrhizal (VAM) fungus Glomus aggregatum and the legume species Acacia mangium were grown together in a manganese-rich oxisol at pH 4.3 to 6.0 and at soil P concentrations favorable for VAM-host growth (0.02 mg ∙ L−1) and sufficient for non-VAM host growth (0.8 mg ∙ L−1). At the lower P concentration, vesicular–arbuscular mycorrhizal fungal (VAMF) colonization of roots increased as soil pH increased from 4.3 to 5.0. However, colonization of roots was not significantly influenced by further increases in pH. Growth of A. mangium at 0.02 mg P/L in the presence of G. aggregatum was inferior to that observed at 0.8 mg P/L, suggesting that there was some degree of host–endophyte incompatibility. Increasing P concentration from 0.02 to 0.8 mg P/L increased target soil pH in the unlimed soil from 4.3 to 4.8 and reduced the concentration of available soil Mn from 13.2 to 2.1 mg ∙ L−1. Thus, the better plant growth observed at the higher P concentration at pH < 5 was mainly due to the alleviation of Mn toxicity due to the precipitation of the cation directly by excess phosphate and (or) phosphate-induced elevation of soil pH. The poor VAMF inoculation effect observed at the lower soil P level in the unlimed soil was thus largely due to the toxicity of high concentrations of Mn2+ and H+ ions. Keywords: hydrogen ion, calcium, manganese-rich, manganese toxicity, pinnule P, soil acidity, VAMF colonization, VAMF effectiveness.

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

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.

scholarly journals Targeting Low-Phytate Soybean Genotypes Without Compromising Desirable Phosphorus-Acquisition Traits

2020 ◽  
Vol 11 ◽  
Author(s):  
Mireadili Kuerban ◽  
Wenfeng Jiao ◽  
Jiayin Pang ◽  
Jingying Jing ◽  
Li-Juan Qiu ◽  
...  
Keyword(s):  
Genotypic Variation ◽  
Root Traits ◽  
Dry Weight ◽  
Root Surface ◽  
Root Surface Area ◽  
Soil P ◽  
P Acquisition ◽  
P Concentration ◽  
Soybean Genotypes ◽  
Food And Feed

Phytate-phosphorus (P) in food and feed is not efficiently utilized by humans and non-ruminant livestock, potentially contributing to high losses of P to the environment. Crops with high P-acquisition efficiency can access soil P effectively. It remains elusive whether crop genotypes with high P-acquisition efficiency can also have low seed phytate concentrations. A core collection of 256 soybean [Glycine max (L.) Merr.] genotypes from China with diverse genetic background were grown in the same environment and seeds were sampled to screen for seed phytate-P concentration. Some of these genotypes were also grown in a low-P soil in the glasshouse to measure root morphological and physiological traits related to P acquisition. Large genotypic variation was found in seed phytate-P concentration (0.69–5.49 mg P g–1 dry weight), total root length, root surface area, rhizosheath carboxylates, and acid phosphatase activity in rhizosheath soil. Geographically, seed phytate-P concentration was the highest for the genotypes from Hainan Province, whereas it was the lowest for the genotypes from Inner Mongolia. Seed phytate-P concentration showed no correlation with any desirable root traits associated with enhanced P acquisition. Two genotypes (Siliyuan and Diliuhuangdou-2) with both low phytate concentrations and highly desirable P-acquisition traits were identified. This is the first study to show that some soybean genotypes have extremely low seed phytate concentrations, combined with important root traits for efficient P acquisition, offering material for breeding genotypes with low seed phytate-P concentrations.

scholarly journals Breeding against mycorrhizal symbiosis: modern cotton (Gossypium hirsutum L.) varieties perform more poorly than older varieties except at very high phosphorus supply

2021 ◽  
Author(s):  
Xinxin Wang ◽  
Min Zhang ◽  
Jiandong Sheng ◽  
Gu Feng ◽  
Thomas W. Kuyper
Keyword(s):  
Gossypium Hirsutum ◽  
Mycorrhizal Fungi ◽  
Root Traits ◽  
Arbuscular Mycorrhizal ◽  
Root Diameter ◽  
Mycorrhizal Symbiosis ◽  
Crop Species ◽  
Lower Productivity ◽  
Mycorrhizal Plants ◽  
P Supply

Abstract Background and aims Cotton (Gossypium hirsutum L.) is an important cash fiber crop species, but its root traits related to phosphorus (P) acquisition have been poorly understood. Methods Eight cotton varieties that were released between 1950 and 2013 were grown in pots with or without arbuscular mycorrhizal fungi (AMF) at three P supply levels. Eleven root traits were measured and calculated after seven weeks of growth. Results At the lower two P levels mycorrhizal plants acquired more P and produced more biomass than non-mycorrhizal plants. At the highest P level mycorrhizal plants took up more P than non-mycorrhizal plants, but there was no difference in biomass. At the intermediate P level, root diameter was significantly positively correlated with biomass, P concentration and P content of mycorrhizal plants. More recent accessions had smaller root diameters, acquired less P and obtained less biomass, indicating (inadvertent) varietal selection for thinner roots that provided less cortical space for AMF, which increased the need for high P fertilizer. Conclusion Our study provides support for the importance of the outsourcing model of nutrient acquisition in the root economics space framework. Inadvertent varietal selection in the last decades, resulting in thinner roots and a lower benefit from mycorrhizal colonization, has caused a lower productivity of cotton varieties at moderate P supply, indicating the need to rethink cotton breeding efforts in order to achieve agricultural sustainability.

scholarly journals Spore communities of arbuscular mycorrhizal fungi and mycorrhizal associations in different ecosystems, south Australia

2002 ◽  
Vol 26 (3) ◽  
pp. 627-635 ◽  
Author(s):  
Z. I. Antoniolli ◽  
E. Facelli ◽  
P. O'Connor ◽  
D. Miller ◽  
K. Ophel-Keller ◽  
...  
Keyword(s):  
Arbuscular Mycorrhizal Fungi ◽  
Mycorrhizal Fungi ◽  
Plantago Lanceolata ◽  
Trifolium Subterraneum ◽  
Arbuscular Mycorrhizal ◽  
Soil P ◽  
Permanent Pasture ◽  
Mycorrhizal Associations ◽  
Sampling Times

Communities of arbuscular mycorrhizal fungi (AMF) were surveyed in different South Australian ecosystems. The soil was wet-sieved for spore extraction, followed by the determination of presence and abundance of AMF species as well as the percentage of root colonization. Mycorrhizal associations were common and there was substantial fungal diversity in different ecosystems. Spores were most abundant in the permanent pasture system and less abundant under continuous wheat. The incidence of mycorrhizal associations in different plant species and the occurrence of Arum and Paris type colonization generally conformed with previous information. Spores of seventeen AMF were verified throughout seasonal changes in 1996 and 1997 in the permanent pasture and on four host species (Lolium perenne, Plantago lanceolata, Sorghum sp. and Trifolium subterraneum) , set up with the same soils under greenhouse conditions. Glomus mosseae was the dominant spore type at all sampling times and in all trap cultures. Mycorrhizal diversity was significantly affected by different sampling times in trap cultures but not in field-collected soil. P. lanceolata, Sorghum sp. and T. subterraneum as hosts for trap cultures showed no differences in richness and diversity of AMF spores that developed in association with their roots. Abundance and diversity were lowest, however, in association with L. perenne , particularly in December 1996. Results show that the combination of spore identification from field-collected soil and trap cultures is essential to study population and diversity of AMF. The study provides baseline data for ongoing monitoring of mycorrhizal populations using conventional methods and material for the determination of the symbiotic effectiveness of AMF key members.

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

Botany ◽  
2011 ◽  
Vol 89 (6) ◽  
pp. 397-403 ◽  
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.

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

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 (&lt;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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