Plant-soil Interactions Research Articles

Arctic rooting depth distribution influences modelled carbon emissions but cannot be inferred from aboveground vegetation type.

The distribution of roots throughout the soil drives depth-dependent plant-soil interactions and ecosystem processes, particularly in arctic tundra where plant biomass, is predominantly belowground. Vegetation is usually classified from aboveground, but it is unclear whether such classifications are suitable to estimate belowground attributes and their consequences, such as rooting depth distribution and its influence on carbon cycling. We performed a meta-analysis of 55 published arctic rooting depth profiles, testing for differences both between distributions based on aboveground vegetation types (Graminoid, Wetland, Erect-shrub, and Prostrate-shrub tundra) and between 'Root Profile Types' for which we defined three representative and contrasting clusters. We further analyzed potential impacts of these different rooting depth distributions on rhizosphere priming-induced carbon losses from tundra soils. Rooting depth distribution hardly differed between aboveground vegetation types but varied between Root Profile Types. Accordingly, modelled priming-induced carbon emissions were similar between aboveground vegetation types when they were applied to the entire tundra, but ranged from 7.2 to 17.6 Pg C cumulative emissions until 2100 between individual Root Profile Types. Variations in rooting depth distribution are important for the circumpolar tundra carbon-climate feedback but can currently not be inferred adequately from aboveground vegetation type classifications.

Interspecific interactions between crops influence soil functional groups and networks in a maize/soybean intercropping system

Despite increasing evidence that intercropping systems may increase crop productivity, little is known about whether and how soil biota change under interspecific competition among plants. A field experiment with maize/soybean intercropping and the corresponding monoculture systems was conducted under four nitrogen fertilization regimes to investigate the effects of interspecific plant interactions on grain yield, soil properties (β-glucosidase and water-soluble carbohydrates), and biotic communities (bacteria, fungi, and nematodes). The soils under maize and soybean in the intercropping system were sampled separately to represent intercropped maize and intercropped soybean, respectively. Compared to monocultures, the complexity and robustness of soil networks comprising bacterial, fungal, and nematode communities increased in intercropped maize soils, but densities of plant parasitic nematodes and β-glucosidase activity were reduced. Intercropped soybean soils had lower C availability due to chronic shading by maize, but a significant increase was found in saprophytic fungi, and plant parasitic nematodes compared to soybean monoculture soils. Although intercropped soybean suffered from interspecific competition with maize, the interactions within the fungal community increased for both crop species in the intercropping system. Our study demonstrates that increased carbon uptake in maize due to increased light capture in the intercropping system can facilitate nutrient cycling by altering the abundance of functional groups of soil organisms, such as saprophytic fungi, and enhancing network complexity and stability. We detected a trade-off between productivity and soil nematode diversity in the intercropping system under nitrogen fertilization, the yield of maize increased but soil nematode richness decreased at low nitrogen level, while the yield of soybean decreased but the nematode richness increased at high nitrogen level. These findings show that both trade-offs and benefits occur in intercropping systems and highlight the role of plant-soil biota interactions in such systems.

Soil–Plant Interaction Mediated by Indigenous AMF in Grafted and Own-Rooted Grapevines under Field Conditions

Plant–soil biota represent a unique living system crucial for improving crops’ adaptation to climate change. In vineyards, plant–soil relations are mediated by rootstock–scion interaction, with grafted vines being the main plant material employed in vineyard planting. The interaction between two deeply different biological systems such as Vitis vinifera sativa and the American Vitis species may modify vines’ adaptation to abiotic stress. The aim of this study was to investigate the physiological response (chlorophyll content—CHL; stomatal conductance—gs) of grafted and ungrafted vines and assess the involvement of Arbuscular Mycorrhizal Fungi (AMF) in this response. In two vineyards located in Central Italy, the presence of AMF was assessed in the roots of grafted and ungrafted cv ‘Aleatico’ vines. The morphological traits of AMF and root mycorrhizal colonization differed in the grafted and ungrafted vines. Under limited climate conditions, ungrafted vines showed better leaf resilience traits (high CHL and gs values) and larger AMF storage organs (vesicles). On the other hand, the grafted ones—which are more sensitive to climate conditions (lower gs and CHL)—involved AMF colonization strategies (greater abundance of arbuscoles and mycorrhizal colonization potential) linked to the improved uptake and transport of water from the bulk soil to the vine. Taken together, these findings highlight different mycorrhizal colonization strategies and storage behaviors in grafted and ungrafted vineyards and with respect to different physical and chemical soil traits.

Stochastic processes in the structure and functioning of soil biodiversity

Ecologists are increasingly recognizing the importance of stochastic processes in generating spatial and temporal variation in biological communities. This variation is very high in soil, which hosts not <¼ of all biodiversity on Earth and is central to how terrestrial ecosystems respond to perturbations. Measurement errors, demographic stochasticity (individual variability in traits such as birth and death rates), and environmental stochasticity (fluctuations in environmental properties) are the three main sources of stochasticity in ecology. Here, we synthesize how these three sources of stochasticity are quantified and incorporated in the study of soil biodiversity, highlighting current limits, possible solutions, and future research needs. We stress the relevance of all these factors to our future understanding of terrestrial ecosystems via plant-soil and soil-climate interactions and feedbacks. In soil, measurement errors are due to the small size, high abundance, and broad distributions of soil organisms, which limit sampling in space and especially over time. We argue that positive autocorrelation is a main characteristic of soil environmental properties, which may have important consequences on the response of soil biota to perturbations. At a local scale, large populations of soil organisms also imply a minor role of demographic stochasticity. Despite demographic stochasticity being a less significant source of variability than environmental stochasticity, we show that demographic stochasticity can be sizeable, but that within soil systems, stochasticity of environmental conditions must be accounted for. Explicit consideration of stochastic processes in soil biodiversity research is essential to our future understanding of the processes that control soil biodiversity. In classical ecology, stochasticity implies probabilistic predictions in terms of population growth, extinction, species coexistence, and community diversity. In soil, stochasticity implies very variable responses to climate change and the soil-climate feedback. Future studies will have to identify the major sources of environmental stochasticity with a particular focus on the interaction between multiple global change factors.

Effects of cowpea (Vigna unguiculata) inoculation on nodule development and rhizosphere carbon and nitrogen content under simulated drought

AimsInoculation with climate-adapted rhizobia is able to increase legume productivity in drought-prone regions of Sub-Saharan Africa. Enhanced nodulation might additionally affect plant-soil interactions and control rhizosphere carbon (C) and nitrogen (N) pools.MethodsWe investigated inoculation effects on nodulation and biological N2 fixation (BNF) of Vigna unguiculata and consequent effects on C and N pools in two Namibian soils. Three treatments (Bradyrhizobium sp.1–7 inoculant, non-inoculated, N-fertilised with 50 kg N ha−1) were applied in rhizoboxes at 45% and 20% maximum water holding capacity. Nodule development was photo-documented, and rhizobia-DNA sequences were identified. BNF was assessed by δ15N enrichment, and organic C and N pools were analysed in bulk and root adherent soil.ResultsPlant growth initially enhanced mineral N losses from the rhizosphere at flowering stage (6 weeks growth), but led to a re-increase of N, and organic C contents after ripening (10 weeks). Inoculation had no effect on nodulation and soil C and N pools, indicating that both soils contained sufficient indigenous rhizobia to allow effective nodulation. However, the inoculant strain was more competitive in establishing itself in the root nodules, depending on the local conditions, showing a need for regional adjustment of inoculation strategies.ConclusionWater stress was the main limitation for nodulation and, in combination with soil type, substantially affected rhizosphere and bulk soil C and N contents. The temporally enhanced rhizodeposition after ripening could be able to maintain soil C and N pools after legume cultivation.

Root-Soil Interactions for Pepper Accessions Grown under Organic and Conventional Farming.

Modern agriculture has boosted the production of food based on the use of pesticides and fertilizers and improved plant varieties. However, the impact of some such technologies is high and not sustainable in the long term. Although the importance of rhizospheres in final plant performance, nutrient cycling, and ecosystems is well recognized, there is still a lack of information on the interactions of their main players. In this paper, four accessions of pepper are studied at the rhizosphere and root level under two farming systems: organic and conventional. Variations in soil traits, such as induced respiration, enzymatic activities, microbial counts, and metabolism of nitrogen at the rhizosphere and bulk soil, as well as measures of root morphology and plant production, are presented. The results showed differences for the evaluated traits between organic and conventional management, both at the rhizosphere and bulk soil levels. Organic farming showed higher microbial counts, enzymatic activities, and nitrogen mobilization. Our results also showed how some genotypes, such as Serrano or Piquillo, modified the properties of the rhizospheres in a very genotype-dependent way. This specificity of the soil-plant interaction should be considered for future breeding programs for soil-tailored agriculture.

The Complex, Unique, and Powerful Imaging Instrument for Dynamics (CUPI2D) at the Spallation Neutron Source (invited).

The Oak Ridge National Laboratory is planning to build the Second Target Station (STS) at the Spallation Neutron Source (SNS). STS will host a suite of novel instruments that complement the First Target Station's beamline capabilities by offering an increased flux for cold neutrons and a broader wavelength bandwidth. A novel neutron imaging beamline, named the Complex, Unique, and Powerful Imaging Instrument for Dynamics (CUPI2D), is among the first eight instruments that will be commissioned at STS as part of the construction project. CUPI2D is designed for a broad range of neutron imaging scientific applications, such as energy storage and conversion (batteries and fuel cells), materials science and engineering (additive manufacturing, superalloys, and archaeometry), nuclear materials (novel cladding materials, nuclear fuel, and moderators), cementitious materials, biology/medical/dental applications (regenerative medicine and cancer), and life sciences (plant-soil interactions and nutrient dynamics). The innovation of this instrument lies in the utilization of a high flux of wavelength-separated cold neutrons to perform real time in situ neutron grating interferometry and Bragg edge imaging-with a wavelength resolution of δλ/λ ≈ 0.3%-simultaneously when required, across a broad range of length and time scales. This manuscript briefly describes the science enabled at CUPI2D based on its unique capabilities. The preliminary beamline performance, a design concept, and future development requirements are also presented.

Plant–Soil Interactions in Karst Regions

Karst regions have a shallow soil layer, discontinuous soil cover, high rock exposure rate, calcium-rich and alkaline soil, and a fertile but small total soil [...]

Drought neutralizes positive effects of long‐term grazing on grassland productivity through altering plant–soil interactions

Abstract Livestock grazing is among the most intensive land‐use activities in grasslands, and can affect plant communities directly or indirectly via grazing‐induced soil legacies. Under climate change, grasslands are threatened globally by recurrent drought. However, the extent to which drought influences grazing‐induced soil legacy effects on plant biomass production and community composition remains largely unexplored. We grew five naturally co‐occurring plant species (three dominants and two subordinates) in mixed communities in a glasshouse experiment in live and sterilized soil that had or had not been subjected to 19 years of grazing; these plant communities were then exposed to a subsequent drought. We tested the treatment effects on plant community biomass, proportional above‐ground biomass of individual species, arbuscular mycorrhizal (AM) fungal root colonization, and soil nutrient availability. Under drought‐free conditions, soils from grazed plots produced significantly higher plant above‐ground and total community biomass compared to soils from ungrazed plots. In contrast, plant above‐ground and total community biomass were similar between grazed and ungrazed soils under drought conditions. Similarly, soils from grazed plots increased the proportional biomass of dominant species but decreased the proportion of subordinate species; however, the proportional biomass of dominant and subordinate species was similar between grazed and ungrazed soils under drought conditions. Soil NO3−‐N in grazed soil was significantly higher compared to ungrazed soil. Drought dramatically increased soil NO3−‐N in sterilized soil and had a more pronounced increase in grazed soil than in ungrazed soil. Arbuscular mycorrhizal fungal root colonization from grazed soil was lower compared to ungrazed soil. Drought significantly increased the soil available phosphorus concentration, as well as plant community AM fungal root colonization. Synthesis. Our study suggests that drought can neutralize positive grazing effects on plant community biomass production via altered plant–soil interactions. Also, we found that drought can alleviate the negative effects of grazing legacies on subordinate species by reducing competitiveness of dominant species. Our study provides new insights for understanding the underlying mechanisms of grazing effects on grassland productivity under climate change. Read the free Plain Language Summary for this article on the Journal blog.

On the relative importance of resource availability and habitat connectivity as drivers of soil biodiversity in Mediterranean ecosystems

Abstract Soil biota influences nutrient cycling and climate regulation and represents an important fraction of global biodiversity, yet we know very little about how this soil biota responds to habitat fragmentation and degradation of habitat quality. We studied the response of different soil trophic groups (microbes and soil fauna), and their trophic structure, to changes in their habitat derived from forest long‐term management and extensive tree die‐off in a Mediterranean ecosystem. Specifically, we evaluated changes in (i) habitat size, (ii) habitat resource availability and heterogeneity and (iii) habitat connectivity. To do this, we sampled the soil biota of 43 holm oak trees (and five open interspaces) differing in size, quality, heterogeneity, connectivity and the effect of die‐off (healthy or affected). We sorted soil biota by trophic group and related their richness to habitat characteristics. Seven of the 12 trophic groups evaluated increased their species richness with soil organic carbon content, which was the most frequently selected driver of soil biota (both microbial and faunal richness). Habitat connectivity positively affected the richness of larger organisms (fauna) and plant attributes (richness, productivity and specific leaf area) also showed significant but contrasting effects depending on the group evaluated. Due to the idiosyncratic responses of different groups, the entire trophic structure (microbes and fauna) was affected by a more complex set of factors than most trophic groups in isolation, including interactions between habitat size and resource availability or connectivity. A major factor influencing habitat resource availability was the die‐off of the dominant tree species (drastically altering tree productivity). We found weaker and more negative relationships between trophic groups under trees suffering from die‐off than beneath healthy trees, particularly between microbial rather than faunal groups. Synthesis. We provide a comprehensive assessment of the response of key members of the soil food web to habitat fragmentation and tree die‐off (landscape‐level plant–soil interactions), illustrating the major role of soil carbon, habitat connectivity and tree die‐off in driving soil biodiversity and trophic structure.

Plant Traits Variably Respond to Plant–Soil Interactions during Secondary Succession on the Loess Plateau

Knowledge of plant photosynthesis, biomass, and stress resistance could contribute to exploring the growth and restoration of vegetation. However, the response of these plant traits to plant–soil interactions at different successional stages remains poorly understood, which limits the understanding of secondary succession. A greenhouse experiment was designed to test the effects of rhizosphere soils collected from early- (EarlySoil), mid- (MidSoil), and late-successional (LateSoil) plant communities on plant traits of early-, mid-, and late-successional species (EarlySp, MidSp, and LateSp, respectively). We found that plant traits reacted in a specific direction to plant–soil interactions at different successional stages. Specifically, compared with treatments of plants growing in their own soil, the net photosynthetic rate and single-photon avalanche diode significantly increased in LateSp–EarlySoil (treatment of plants growing in soil) (20%–31%) and LateSp–MidSoil (10%–18%); the maximum quantum efficiency of photosystem II increased in MidSp–EarlySoil (1%) and LateSp–MidSoil (4%); belowground soluble sugar concentrations decreased in LateSp–EarlySoil (33%) and LateSp–MidSoil (45%); leaf, stem, and root biomass increased in MidSp–EarlySoil (76%–123%), LateSp–EarlySoil (180%–342%), and LateSp–MidSoil (83%–137%), and in turn they decreased in EarlySp–MidSoil (40%–73%) and EarlySp–LateSoil (53%–67%). The results indicated that soil conditioned by pre-successional species (early- or mid-successional species) would be conducive to plant functional traits of subsequent successional species (mid- or late-successional species). Constrained redundancy analysis and path analysis suggested that water-soluble ammonium N, total N, and available N concentrations were key soil factors affecting early-, mid-, and late-successional species, respectively. Our findings confirm the directionality of succession and provide new information for plant population dynamics during secondary succession.

An agroecological structure model of compost—soil—plant interactions for sustainable organic farming

Compost is used worldwide as a soil conditioner for crops, but its functions have still been explored. Here, the omics profiles of carrots were investigated, as a root vegetable plant model, in a field amended with compost fermented with thermophilic Bacillaceae for growth and quality indices. Exposure to compost significantly increased the productivity, antioxidant activity, color, and taste of the carrot root and altered the soil bacterial composition with the levels of characteristic metabolites of the leaf, root, and soil. Based on the data, structural equation modeling (SEM) estimated that amino acids, antioxidant activity, flavonoids and/or carotenoids in plants were optimally linked by exposure to compost. The SEM of the soil estimated that the genus Paenibacillus and nitrogen compounds were optimally involved during exposure. These estimates did not show a contradiction between the whole genomic analysis of compost-derived Paenibacillus isolates and the bioactivity data, inferring the presence of a complex cascade of plant growth-promoting effects and modulation of the nitrogen cycle by the compost itself. These observations have provided information on the qualitative indicators of compost in complex soil-plant interactions and offer a new perspective for chemically independent sustainable agriculture through the efficient use of natural nitrogen.

Exploiting crop genotype-specific root-soil interactions to enhance agronomic efficiency

Challenges of soil degradation and changing climate pose major threats to food security in many parts of the world, and new approaches are required to close yield and nutrition gaps through enhanced agronomic efficiency. Combined use of mineral fertilizers, organic inputs, improved germplasm and adaptation of these practices to local contexts through improved agronomy can promote efficiency whilst building stocks of soil organic matter (SOM). Within this framework, recent attention has turned to the nature of plant-soil interactions to increase response to mineral fertilizer inputs through utilisation of nutrients from SOM that are replenished through management. This utilisation has been shown in barley and maize to vary with genotype and to be related to root physiological traits associated with rhizodeposition. The identification of candidate genes associated with rhizodeposition takes this a step closer towards the possibility of breeding for sustainability. Here we discuss this potential and feasibility in the context of maize cropping systems, and explore the potential for a combined approach that optimises utilisation of SOM nutrients together with enhanced biological nitrification inhibition to further improve agronomic efficiency.

Source apportionment and controlling mechanisms of nitrogen leaching from bioretention systems

Nitrogen (N) leaching has attracted concerns in bioretention systems (BRSs), while regulation of N leaching in BRSs is a challenge. In this study, N leached from BRSs with three plants (Phragmites australis, Acorus calamus L. and Cana indices L.) has for the first time been apportioned between three types of sources: immediate, fast and slow leaching based on 15N labeling. Results indicated that: fast leaching mainly comes from the previous four rainfall-runoffs, while slow leaching accounts for the largest proportion in total leaching; immediate leaching is mainly as NO3-, fast leaching mainly as NO3- and dissolved organic nitrogen (DON), and slow leaching mainly as DON and NH4+; BRSs with different plants vary in source compositions of N leaching. Meanwhile, N fates, transformation rates, and functional genes were constrained to explain the controlling mechanisms of each source of N leaching: immediate leaching mainly relates to soil characteristics and root morphology (e.g. type, surface area and diameter) that can influence adsorption, preferential flow and plant uptake; fast leaching mainly relates to soil N transformation during the dry periods that can influence the availabilities of NO3- and DON; slow leaching mainly relates to plant uptake and soil retention, soil N transformation and plant-soil interactions can influence the availabilities and stability of DON and NH4+. This study provides insights into the source compositions of N leaching, the long-term N legacy effect and controlling mechanisms of N leaching in BRSs-like engineering systems, which will imply future improvements in design and risk assessment of green infrastructure.

Biochar application on heavy metal immobilization in unsaturated soil with vegetation: a review

ABSTRACT Biochar, a type of soil amendment, is widely used in heavy metal–polluted soil. It is also effective in enhancing plant performance. However, how biochar affects the soil heavy metal toxicity considering the plant–soil interactions is not well summarized. Therefore, this paper aims to review and summarize the effects of biochar on heavy metal availability in vegetated unsaturated soil. First, this review summarizes the effects of biochar on key parameters of unsaturated soil, including pore size distribution, water permeability, water retention curve, nutrient cycling and soil biota. Then, the mechanism of biochar for managing heavy metals in soil with vegetation is discussed, with a focus on both physical and biochemical aspects. Additionally, the impact of biochar-induced plant growth on the availability of heavy metals in the plant–soil system is explored. Finally, suggestions for future research and applications of biochar are provided. This paper supplies novel outlooks for further study and practice.

Plant-soil interactions in the communities dominated by alien and native plants

It has been established by research on plant invasions that soil biota and availability of nutrients affect the processes of alien species establishment and spread. So far, attention was mainly on alien invaders, although some native species (expansive), vigorously spread in human-influenced landscapes and also transform the habitats they colonize. Based on indirect gradient ordination analysis of vegetation relevés dominated by five native (Calamagrostis epigejos, Filipendula ulmaria, Phalaris arundinacea, Rubus idaeus, Urtica dioica) and five alien taxa (Impatiens glandulifera, Lupinus polyphyllus, Telekia speciosa, Reynoutria sp., Solidago canadensis agg.) in the Czech Republic, Central Europe, we identified pairs of species differing by origin (native vs alien) and growing in similar habitats. In the resulting 10 pairs, we tested the net effect of species origin on the following soil characteristics: (i) physical properties, (ii) nutrient availability, and (iii) biological activity. We found that the impact of alien invasive and native expansive species on soil cannot be explained simply by species’ origin as a factor. Regardless of the origin, a statistically significant effect was recorded only for factors expressing nitrogen supply at the peak of the vegetation season and soil biological activity. Differences in impacts attributable to origin were only verified for individual pairs, being most pronounced between the alien Lupinus and its native counterparts Calamagrostis and Filipendula, and least between Solidago vs Calamagrostis, and Telekia vs Rubus. Both invasive alien and expansive native dominant plants can alter the rate of decomposition by changing the litter quality and availability of nutrients, mainly inorganic nitrogen. Therefore, management actions to preserve or restore diversity and mitigate the negative impacts of dominant species should be focused both on native and alien species.

Water use patterns of dominant species of riparian wetlands in arid areas

AbstractWater resource shortage in arid areas is the main cause of ecological problems. Understanding plant water use patterns is essential for understanding soil–plant interactions and assessing the adaptability of plants in ecosystems with limited water resources. Riparian wetlands are functional transition areas connecting aquatic ecosystems and terrestrial ecosystems. Wetland vegetation restoration is of great significance to water conservation and ecological balance. Using isotope tracing method, our study clarified the water use patterns of dominant plants in typical riparian wetlands in arid areas. The results showed that the dominant herbal species ofSalsola affinismainly used 0–60 cm soil water (48.96%).Salsola affinis, which continuously obtains water from shallow soil, may be difficult to survive in extreme drought conditions. If it withered significantly aged in the dry season, it would have a negative ecological impact. The dominant tree species ofSalix matsudanaKoidz mainly used 20–100 cm soil water (43.99%) and groundwater (23.16%). With increasing water stress,S. matsudanaKoidz had a greater degree of ecological plasticity and can use water from deeper soils. However,S. matsudanaKoidz can continuously obtained water from deep soil and groundwater, which may weaken the water and soil conservation capacity of the wetland. In addition, the lc‐excess value of soil water showed that the soil evaporation intensity of grassland was higher than that of forest land, and the surface evaporation depth reached 60 cm. Our findings will help better understand the impact of vegetation restoration plan (artificial forest land and natural grassland) on the hydrological process of riparian wetland in arid areas, and provide reference for plant species selection and water resources management.

Niche theory for positive plant-soil feedbacks.

Interactions between plants and the soil are an important ecological process in terrestrial ecosystems as they affect plant community structure: when and where we find different plant species. Those interactions are typically thought of as one-directional: local soil conditions filter through dispersing species to produce a community of locally adapted plants. However, plants can modify local physicochemical soil conditions via their roots and associations with soil microbes. These may in turn affect the local fitness of other plants, making plant-soil interactions bidirectional. In order to understand how they differ from other ecological processes that structure plant communities, we need a theory connecting these individual-level plant-soil feedbacks to community-level patterns. Here, we build this theory with a mathematical model of plant community dynamics in which soil conditioning is explicitly modeled over time and depends on the density of the plants. We analyze this model to describe the long-term composition and spatial distribution of the plant community. Our main result is that positive plant-soil feedbacks will create clustering of species with similar soil preferences. The composition of these clusters is further influenced by niche width and conditioning strength. In contrast with competitive dynamics driven by niche overlap, only species belonging to the same cluster can maintain high relative abundance in the community. Spatial heterogeneity in the form of an environmental gradient generates patches, each representing a single cluster. However, such patchiness is disfavored when species differ in dispersal ability. We show that stronger dispersers cannot take over the habitat as long as an exogenous driver favors soil conditions that benefit the other species. If exogenous drivers supersede soil conditioning by plants, we retrieve classic habitat filtering, where species are selected based on their suitability to the local environment. Overall, we provide a novel mathematical model for positive plant-soil feedback that we use to describe the spatial patterns of plant abundance and traits related to soil preference and conditioning ability.

Monitoring soil–plant interactions and maize yield by satellite vegetation indexes, soil electrical conductivity and management zones

Monitoring soil–plant interactions and maize yield by satellite vegetation indexes, soil electrical conductivity and management zones

Experimental evidence root‐associated microbes mediate seagrass response to environmental stress

Abstract Below‐ground microbiota play an important role in mediating environmental conditions with important consequences for plant performance. Micro‐organisms involved in plant–soil interactions may be associated with roots or bulk soil; however, the relative influence of these below‐ground microbial assemblages on plant performance is poorly known, particularly for marine plants. We separately manipulated the root and sediment microbial assemblages of the seagrass Zostera muelleri in a fully factorial experiment to determine how these assemblages determined plant response (e.g. growth) to nutrient enrichment, a major stressor in marine systems. Under ambient nutrient conditions, seagrass growth was maintained regardless of root microbial assemblage disruption. Under high nutrient stress, however, seagrasses with disrupted root microbiota had reduced growth, whereas growth was maintained in seagrasses with an intact root microbiota. Disruption of bulk‐sediment microbiota did not affect seagrass growth. Nutrient elevation was correlated with enhanced abundances of several putatively beneficial microbial taxa (e.g. sulphide‐oxidising Beggiatoaceae and denitrifying Geofilum rubicundum) associated with roots. Synthesis. Our results suggest that under ambient nutrient conditions micro‐organisms play a reduced role in influencing plant performance, but under more stressful conditions positive plant–root micro‐organism interactions strengthened. These results are among the first to experimentally determine that interactions between marine plants and the root‐associated microbiota are key drivers of seagrass performance under human‐induced environmental changes. This suggests that as in terrestrial systems, marine plant resilience depends on the stress‐mitigating functions of their root‐associated microbiota and disturbance to those plant–microbiota interactions can be deleterious for plant performance. Improving our understanding of these plant–micro‐organism interactions may be critical for understanding the functioning and resilience of threatened marine plants and developing more effective restoration strategies for them.