Plant Health Research Articles

The use of mineral dynamised high dilutions for natural plant biostimulation; effects on plant growth, crop production, fruit quality, pest and disease incidence in agroecological strawberry cultivation

ABSTRACT Strawberries (Fragaria x ananassa) are one of the most important fruit crops worldwide. Most of the strawberries that are produced today rely on the use of pesticides and fungicides, leading the crop to be listed as one of the most contaminated by contentious inputs. Plant biostimulants are used as a plant health strategy focused on stimulating plant growth and development with a low residual impact. The objective of this study was to assess the plant biostimulation effects of strawberry plants treated with mineral dynamised high dilutions (DHDs): Sulphur 12CH, Phosphorus 12CH, Kali carbonicun 12CH, Calcarea carbonica 12CH, Silicea terra 12CH, Natrum muriaticum 12CH and Mercurius solubilis 12 CH, distilled water 12CH and distilled water (control). The experiment was undertaken under greenhouse conditions at the University of Santa Catarina State (UDESC), in Lages, Santa Catarina (SC), Brazil in 2019 and was repeated in 2021 at the Federal University of Santa Catarina (UFSC), in Curitibanos, SC. The experiment used a randomised block design, following double-blind treatment application. Data were analysed by ANOVA and when significant (p ≤ 0.05) by Dunnett’s test. The results showed that plants treated with DHDs of Sulphur 12CH, Phosphorus 12CH and Kali carbonicum 12CH increased plant growth and crop yield and were less affected by leaf spot disease (Mycosphaerella fragariae). Plants treated with Silicea terra 12CH, or with Calcarea carbonica 12CH showed increased development of the root system. The results obtained suggested that mineral DHDs could be used as plant biostimulants to support agroecological strawberry production.

Known distribution of the soybean cyst nematode, Heterodera glycines, in the United States and Canada through 2023

The soybean cyst nematode (SCN), Heterodera glycines, is a major yield-reducing pathogen of soybean ( Glycine max [L.] Merrill) in the United States and Canada, causing twice as much yield loss annually as any other pathogen. Reports of new discoveries of SCN in areas of the United States and Canada that grow the crop can lead to greater awareness of the pathogen and increased efforts to scout for the nematode. Beginning in January 2024, university nematologists, plant pathologists, and agronomists as well as government plant health officials in soybean-producing states in the United States and provinces in Canada were queried about the known distribution of the nematode. This publication contains an updated map of the known distribution of SCN in the United States and Canada through 2023 and a listing of counties and rural municipalities where the nematode initially was identified between 2000 and 2023. In total, there were 31 counties in 10 states in the United States plus three counties total in Manitoba and Ontario and ten rural municipalities in Quebec, Canada in which SCN was first discovered between 2020 through 2023. The results show that the distribution of SCN in the United States and Canada continues to expand, and sustained scouting for the presence of the pathogen is warranted to facilitate management to reduce soybean yield losses.

Above- and below-ground field study on the impacts of conventional and alternative mesoplastics on Hordeum vulgare growth and soil invertebrate communities

Plastic plays an important role in agriculture, but its use has become a concerning source of pollution. While new (bio)degradable, alternative plastics are being developed and used as mulching films, their ecological impacts, in particular under field conditions, are not well understood. Furthermore, there is a notable lack of knowledge on how plastic pollution affects soil invertebrate communities. Most existing studies primarily focus on microplastics, often neglecting the impacts of mesoplastics. This study therefore compared the separate effects of two conventional (polyethylene and polypropylene) and two alternative (polyethylene containing biodegradable additives and compostable polylactic acid) mesoplastic films on plant performance (biomass, seed yield) and soil mesofaunal assemblages in a field experiment. The mesoplastics were applied at 0.1% (w/w), prior to soil being planted with Hordeum vulgare (spring barley), which was grown to maturity, for 11 weeks. Generally, there were no measurable differences between the conventional and alternative plastic treatments, however, barley exposed to mesoplastics showed reduced biomass, seed yield, and chlorophyll content, along with increased oxidative stress. Soil fauna, particularly Collembola, had lower richness and abundance when exposed to both plastic types, but assemblage structure and composition remained unchanged after 11 weeks. This study is pivotal in highlighting that both conventional and alternative plastics can similarly affect plant health and soil ecosystems. The evidence provided is essential for refining future risk assessments of agricultural plastic pollution and underscores the urgent need for more sustainable practices and materials in agriculture.

Phytobiomes: Harnessing the Power of Microbial Communities for Plant Health

Phytobiomes encompass the dynamic ecosystems surrounding plants, which include a diverse range of microbial communities such as fungi, bacteria, algae, viruses, and nematodes. These microorganisms interact intricately with plants, influencing their health, growth, and resilience. Beneficial fungi form symbiotic relationships with plant roots, enhancing nutrient absorption, while bacteria play a role in nitrogen fixation and disease suppression. Algae contribute to soil health and organic matter decomposition, and viruses, though often seen as harmful, can provide resistance to certain pathogens. Nematodes, both beneficial and parasitic, regulate soil nutrient cycles and influence plant growth. Harnessing the potential of these microbial communities offers promising solutions for sustainable agriculture. By promoting beneficial interactions within the phytobiome, it is possible to improve plant productivity, enhance nutrient use efficiency, and increase tolerance to environmental stresses such as drought, salinity, and pathogens. Phytobiome research aims to uncover the complex relationships within these microbial networks to develop novel agricultural practices that reduce reliance on chemical inputs. This holistic approach not only promotes plant health but also ensures ecological balance, contributing to the long-term sustainability of agroecosystems in the face of environmental challenges. Understanding the power of microbial communities within phytobiomes is key to advancing future agricultural innovations.

Production of genetically stable and Odontoglossum ringspot virus-free Cymbidium orchid ‘New True’ plants via meristem-derived protocorm-like body (PLB) subcultures

BackgroundThis study aimed to produce Odontoglossum ringspot virus (ORSV)-free Cymbidium orchid ‘New True’ plants from ORSV-infected mother plants by culturing their meristems and successively repeating subcultures of protocorm-like bodies (PLBs) derived from the meristems.ResultsInitially, ORSV was confirmed as the causative agent of viral symptoms in orchid leaves via reverse transcription-polymerase chain reaction (RT-PCR) analysis. Meristems from infected plants were cultured to generate PLBs, which in sequence were repeatedly subcultured up to four times. RT-PCR and quantitative RT-PCR analyses revealed that while ORSV was undetectable in shoots derived from the first subculture, complete elimination of the virus required at least a second subculture. Genetic analysis using inter-simple sequence repeat markers indicated no somaclonal variation between regenerated plants and the mother plant, suggesting that genetic consistency was maintained.ConclusionOverall, our findings demonstrate that subculturing PLBs for a second time is ideal for producing genetically stable, ORSV-free Cymbidium orchids, thus offering a practical means of generating genetically stable, virus-free plants and enhancing plant health and quality in the orchid industry.

Unveiling Potassium and Sodium Ion Dynamics in Living Plants with an In-Planta Potentiometric Microneedle Sensor.

Potassium and sodium ions (K+ and Na+) play crucial roles in influencing plant growth and health status. Unfortunately, current strategies to determine the concentrations of such ions are destructive for the plants because it is necessary to collect/extract the sap for further analysis and produce either scattered or delayed results. Here, we introduce a new potentiometric dual microneedle sensor for nondestructive, real-time, and continuous monitoring of K+ and Na+ concentrations in living plants. The developed sensors show a response time <5 s, close-to-Nernstian slope (∼55 mV dec-1), resiliency to five insertions on the stem, good repeatability (max. %RSD = 0.3%) and reversibility (max. %RSD = 3%), appropriate continuous operation for 24 h, and linear range of responses that cover expected plant physiological levels (5-50 mM for Na+ and 50-120 mM for K+). Moreover, the accuracy was successfully investigated by comparing the results provided by the microneedle sensors to those obtained by a standard reference method (e.g., ion chromatography). Finally, we demonstrate that the developed analytical device is capable of tracking K+ and Na+ transportation from the hydroponic solution to the stem within 5-10 min. This research will contribute to establishing a new generation of analytical platforms for smart agriculture offering real-time information.

Phosphorus Solubilizing Microorganisms: An Eco-Friendly Approach for Sustainable Plant Health and Bioremediation

Phosphorus Solubilizing Microorganisms: An Eco-Friendly Approach for Sustainable Plant Health and Bioremediation

Design, Synthesis, Antifungal Evaluation, and Three-Dimensional Quantitative Structure-Activity Relationship of Novel 5-Sulfonyl-1,3,4-thiadiazole Flavonoids.

Plant pathogenic fungi frequently disrupt the normal physiological and biochemical functions of plants, leading to diseases, compromising plant health, and ultimately reducing crop yield. This study aimed to address this challenge by identifying antifungal agents with innovative structures and novel mechanisms of action. We designed and synthesized a series of flavonoid derivatives substituted with 5-sulfonyl-1,3,4-thiadiazole and evaluated their antifungal activity against five phytopathogenic fungi. Most flavonoid derivatives demonstrated excellent antifungal activity against Botrytis cinerea (B. cinerea), Alternaria solani (A. solani), Rhizoctorzia solani (R. solani), Fusarium graminearum (F. graminearum), and Colletotrichum orbiculare (C. orbiculare). Specifically, the EC50 values of 38 target compounds against R. solani were below 4 μg/mL, among which the compounds C13 (EC50 = 0.49 μg/mL), C15 (EC50 = 0.37 μg/mL), and C19 (EC50 = 0.37 μg/mL) had the most prominent antifungal activity, superior to that of the control drug carbendazim (EC50 = 0.52 μg/mL). Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images of the cellular ultrastructures of R. solani mycelia and cells after treatment with the compound C19 revealed sprawling growth of hyphae, a distorted outline of their cell walls, and reduced mitochondrial numbers. Studying the 3D-QSAR between the molecular structure and antifungal activity of 5-sulfonyl-1,3,4-thiadiazole-substituted flavonoid derivatives could significantly improve conventional drug molecular design pathways and facilitate the development of novel antifungal leads.

Potential of kaempferol and caffeic acid to mitigate salinity stress and improving potato growth

Salinity stress adversely affects plant growth by disrupting water uptake, inducing ion toxicity, initiating osmotic stress, impairing growth, leaf scorching, and reducing crop yield. To mitigate this issue, the application of kaempferol (KP), caffeic acid (CA), and plant growth-promoting rhizobacteria (PGPR) emerges as a promising technology. Kaempferol, a flavonoid, protects plants from oxidative stress, while caffeic acid, a plant-derived compound, promotes growth by regulating physiological processes. PGPR enhances plant health and productivity through growth promotion, nutrient uptake, and stress mitigation, providing a sustainable solution. However, combining these compounds against drought requires further scientific justification. That’s why the current study was conducted using 4 treatments, i.e., 0, 20 µM KP, 30 μM CA, and 20 µM KP + 30 μM CA without and with PGPR (Bacillus altitudinis). There were 4 replications following a completely randomized design. Results showed that 20 µM KP + 30 μM CA with PGPR caused significant enhancement in potato stem length (14.32%), shoot root, and leaf dry weight (16.52%, 11.04%, 67.23%), than the control. The enrichment in potato chlorophyll a, b, and total (31.86%, 46.05%, and 35.52%) was observed over the control, validating the potential of 20 µM KP + 30 μM CA + PGPR. Enhancement in shoot N, P, K, and Ca concentration validated the effective functioning of 20 µM KP + 30 μM CA with PGPR evaluated to control. In conclusion, 20 µM KP + 30 μM CA with PGPR is the recommended amendment to alleviate salinity stress in potatoes.

Hyperspectral Imaging for Phenotyping Plant Drought Stress and Nitrogen Interactions Using Multivariate Modeling and Machine Learning Techniques in Wheat

Accurate detection of drought stress in plants is essential for water use efficiency and agricultural output. Hyperspectral imaging (HSI) provides a non-invasive method in plant phenotyping, allowing the long-term monitoring of plant health due to sensitivity to subtle changes in leaf constituents. The broad spectral range of HSI enables the development of different vegetation indices (VIs) to analyze plant trait responses to multiple stresses, such as the combination of nutrient and drought stresses. However, known VIs may underperform when subjected to multiple stresses. This study presents new VIs in tandem with machine learning models to identify drought stress in wheat plants under varying nitrogen (N) levels. A pot wheat experiment was set up in the glasshouse with four treatments: well-watered high-N (WWHN), well-watered low-N (WWLN), drought-stress high-N (DSHN) and drought-stress low-N (DSLN). In addition to ensuring that plants were watered according to the experiment design, photosynthetic rate (Pn) and stomatal conductance (gs) (which are used to assess plant drought stress) were taken regularly, serving as the ground truth data for this study. The proposed VIs, together with known VIs, were used to train three classification models: support vector machines (SVM), random forest (RF), and deep neural networks (DNN) to classify plants based on their drought status. The proposed VIs achieved more than 0.94 accuracy across all models, and their performance further increased when combined with known VIs. The combined VIs were used to train three regression models to predict the stomatal conductance and photosynthetic rates of plants. The random forest regression model performed best, suggesting that it could be used as a stand-alone tool to forecast gs and Pn and track drought stress in wheat. This study shows that combining hyperspectral data with machine learning can effectively monitor and predict drought stress in crops, especially in varying nitrogen conditions.

Increasing Fertilization Efficiency of Biomass Ash by the Synergistically Acting Digestate and Extract from Water Plants Sequestering CO2 in Sorghum Crops.

The utilization of biomass ash in sustainable agriculture and increasing its fertilizing efficiency by biological agents, potentially sequestering CO2, have become important issues for the global economy. The aim of this paper was to investigate the effects of ash from sorghum (Sorghum bicolor L. Moench) and Jerusalem artichoke (Helianthus tuberosus L.) biomass, a biogas plant digestate, and a Spirodela polyrhiza extract, acting alone or synergistically, on soil fertility and the development, health and physiological properties of sorghum plants. The results show novel information concerning differences in the composition and impact of ash, depending on its origin, soil properties and sorghum plant development. Sorghum ash was more effective than that from Jerusalem artichoke. Ash used alone and preferably acting synergistically with the digestate and Spirodela polyrhiza extract greatly increased soil fertility and the growth, biomass yield and health of sorghum plants. These improvements were associated with an increased chlorophyll content in leaves, better gas exchange (photosynthesis, transpiration, stomatal conductance), greater enzyme activity (acid and alkaline phosphatase, RNase, and total dehydrogenase), and a higher biomass energy value. The developed treatments improved environmental conditions by replacing synthetic fertilizers, increasing the sequestration of CO2, solving the ash storage problem, reducing the need for pesticides, and enabling a closed circulation of nutrients between plant and soil, maintaining high soil fertility.

Response of Integrated Nutrient Management (INM) Practice on Growth, Yield and Quality Parameters of Fenugreek (Trigonella corniculate L.)

Integrated nutrient management methods assist improve fenugreek (Trigonella corniculate L.) development and yield by integrating the use of organic and inorganic fertilizers. These methods enhance soil fertility, increase nutrient availability, and improve plant health, all of which lead to increased crop yield, growth and quality. Future policies must place a high priority on the economical, sustainable, and efficient use of nutrient resources for the purpose to increase agricultural output. Thus, proper crop, water, soil, and land management along with integrated nutrient management are necessary for sustainable agriculture. Improved soil qualities and increased nutrient availability for agricultural plants come from the use of organic manures in conjunction with inorganic fertilizers. This enhances fenugreek growth, yield, and quality measures. The synthesis of carbohydrates, phytohormones, and even biofertilizers is enhanced by a nutritious diet. It also builds up the soil's organic status, which raises the availability of other nutrients and contributes to the maximum growth of crops. Vermicompost, farmyard manure, rhizobium, phosphorus- and potassium-soluble bacteria (PSB) are among the materials used in methi cultivation that support sustainable agriculture by enhancing soil fertility, nutrient availability, and general crop health, all of which lead to higher methi yields and quality. Organic matter is a storehouse of nutrients; applying both organic and inorganic fertilizer together can boost yields, improve soil fertility, raise crop input-use efficiency, and reduce the need for expensive fertilizers. This crop responds effectively to N provided through a combination of organic and inorganic sources. Majority of the nitrogen applied from different sources is not used by the first crop and is always reflected in the crop that follows. Therefore, it is necessary to assess how integrated nutrition management affected fenugreek's yield and nutrient uptake.

Comparison between Co(II) and Ni(II) cycling at goethite-water interfaces: Interplay with Fe(II)-catalyzed recrystallization

Cobalt (Co) and nickel (Ni) are critical metals for modern renewable energy technologies as well as essential micronutrients for terrestrial plant health and marine primary production. Both metals are commonly surface-adsorbed onto and/or structurally-incorporated into iron (oxyhydr)oxide minerals, such as goethite (α-FeOOH), that are ubiquitously present in soils and sediments at the Earth’s surface. In sub- and anoxic environments, aqueous ferrous iron (Fe(II)) generated from dissimilatory Fe(III) reduction can induce the recrystallization of goethite and subsequently influences the speciation and mobilization of associated metals, e.g., Co(III) being reduced to Co(II). While it is generally considered that divalent Co and Ni behave similarly at goethite-water interfaces, there lacks a direct comparison of their cycling through goethite in response to Fe(II)-catalyzed recrystallization. Here, under circumneutral anoxic conditions with and without addition of aqueous Fe(II), we performed batch reaction experiments on Co(II)-substituted goethite and Co(II) and Ni(II) sorption experiments on pure goethite. The redox state and coordination environment of Co associated with goethite were determined using high energy resolution fluorescence detected X-ray absorption spectroscopy at the Co K-edge, and the distribution of solid-bound Co and Ni in goethite following sorption was revealed by sequential dissolution. Our results show that substitution of Co(II) for Fe(III) in goethite has less negative feedback on Fe(II)-catalyzed recrystallization than Ni(II), which may be related to their differing structural distortions as evidenced by EXAFS. In the absence of Fe(II), aqueous Co(II) is more favourably adsorbed onto and incorporated deeper into goethite than Ni(II), suggesting that Co(II) is more structurally compatible with goethite. The presence of Fe(II) markedly enhances the structural incorporation of both Co(II) and Ni(II) as a result of goethite recrystallization, which in turn can be inhibited by the accumulation of metals at the mineral surface. Furthermore, structurally-incorporated Co(II) is more difficult to be released back into solution (i.e. sum of aqueous and extract fractions) than Ni(II) during Fe(II)-catalyzed goethite recrystallization. Overall, our work highlights the significant differences between Co(II) and Ni(II) in their cycling at goethite-water interfaces and intricate interplay with Fe(II)-catalyzed recrystallization. This improves our understanding of their mobilization and distribution in anoxic goethite-rich systems and can provide useful insights for their enrichment and extraction from natural and artificial laterites generated from the enhanced weathering of ultramafic mine tailings.

Plant probiotic microbes – trending microbes for plant growth and value addition of compost- a review

New agricultural approaches, including natural and organic farming, have developed organic and microbiological goods. Beneficial microbes known as plant probiotic microorganisms (PPM) are primarily found in soil and have coevolved with plants in a symbiotic or free-living relationship. By encouraging plant growth and health, these bacteria lessen the need for artificial fertilizers, support environmentally friendly agricultural practices, and improve plant health. Agroecosystem vigour, biodiversity, biological cycles, and soil biological activity are all enhanced by using plant probiotic bacteria in biologically based agriculture. By using beneficial bacteria to support the health and function of the host organism, plant probiotics aim to lessen the demand for toxic pesticides and fertilizers. Using these probiotic microorganisms will have a synergistic and advantageous effect on crop production. Plant probiotic microorganisms improve the overall quality of compost throughout the composting process by accelerating the breakdown of organic materials and introducing helpful bacteria. This rich compost adds beneficial bacteria to the soil, creating a healthy and productive environment. This review looks at the common plant probiotic bacteria, how they work, how they complement each other to improve compost quality and plant growth, how they might be used in agriculture, and how they could change how composting is done.

Management of Rhizoctonia blight of groundnut using antagonistic effects of bioagents and organic amendments

Rhizoctonia blight disease caused by Rhizoctonia solani in groundnut crop is one of the most devastating diseases occurring worldwide. The disease affects the morphological and physiological parameters of the crop leading to reduction in pod yield as well as oil yield. The pathogen was isolated locally and identified as Rhizoctonia solani based on molecular characterization. The efficacy of different bioagents in reducing the radial growth of pathogen was tested in vitro and highest mycelia growth inhibition was recorded by Trichoderma asperellum (89.07 %). Among the fungicides tested, 100 % mycelial growth inhibition was observed by use of Carbendazim 50 WP, Tebuconazole 25.9 % EC, Hexaconazole 5 % suspension concentrate (SC) and Tebuconazole 50 % + Trifloxystrobin 25 % water-dispersible granule (WG). Among different organic substances tested in vitro, neem seed cake achieved maximum mycelial growth inhibition of 50.74 % and 54.08 % at 10 % and 20 % concentrations respectively. In the field experiment, treatment with application of neem seed cake to the soil at 500 kg/ha + application of mustard seed cake to the soil at 500 kg/ha + treatment of seeds with Tebuconazole at 1.5 g/kg of seed + treatment of seeds with T. asperellum at 10 g/kg of seed was found to be the best in enhancing plant health, growth promotion and oil yield. The combined treatment of bioagent, fungicide and organic amendment recorded maximum number of branches (14.00), number of leaves (668.33), plant dry weight (64.17 g), 100 pod weight (65.00 g) and oil yield (47.33 %) compared to the control and other treatments along with reduction of the disease (59.61 %). In the physiological parameters study, the same treatment also recorded maximum pigment contents viz. Chlorophyll a (1.843 mg/g), Chlorophyll b (0.555 mg/g), total chlorophyll (2.397 mg/g) and carotenoid content (0.084 mg/g) but with minimum phenol content (1.693 mg/g). Thus, it can be concluded that integration of selective inputs in the combined treatment of Neem seed cake, Mustard seed cake, Tebuconazole and T. asperellum could enhance the plant health, morphological growth and physiological parameters and increased the oil yield in groundnut along with reduction of the disease.

The Isolation and Characterization of Novel Caulobacter and Non-Caulobacter Lysogenic Bacteria from Soil and the Discovery of Broad-Host-Range Phages Infecting Multiple Genera.

To explore how microbial interactions within the rhizosphere influence the diversity and functional roles of bacterial communities, we isolated 21 bacterial strains from soil samples collected near Rocky Branch Creek on the University of South Carolina campus. Our findings revealed that a significant proportion of the isolated bacterial strains are lysogenic. Contrary to predictions of a narrow host range, most of the bacteriophages derived from these lysogenic bacteria demonstrated the ability to infect a broad range of bacterial strains. These results suggest that the bacterial community shares a complex phage community, creating an intricate web of interactions. This study enhances our understanding of the relationships between phages and their bacterial hosts in soil ecosystems, with implications for ecological balance and agricultural practices aimed at improving plant health through microbial management strategies.

Phylogenetic analyses show the Select Agent Coniothyrium glycines represents a single species that has significant morphological and genetic variation

ABSTRACT Soybean red leaf blotch (RLB), caused by the fungus Coniothyrium glycines, represents a foliar disease of soybean that is thus far restricted to Africa. The fungus is listed as a Select Agent by the Federal Select Agent Program because it could pose a severe threat to plant health were it to establish in the United States. Previous work uncovered tremendous molecular diversity at the internal transcribed spacer region, suggesting that there may be multiple species causing RLB. To determine whether multiple species cause RLB, we reconstructed the phylogeny of C. glycines and taxonomic allies using sequence data from four genes. We included 33 C. glycines isolates collected from six African countries and determined that all isolates form a well-supported, monophyletic lineage. Within this lineage there are at least six well-supported clades that largely correspond to geography, with one clade exclusively composed of isolates from Ethiopia, another exclusively composed of isolates from Uganda, and four composed of isolates from southern Africa. However, we did not detect any concordance for these clades between the four genes, indicating that all isolates included in this analysis are representative of a single species. Isolates in the Ethiopia clade are morphologically distinct from isolates in the other clades, as they produce larger sclerotia and smaller pycnida and more sclerotia in planta. Additionally, ancestral range estimations suggest that the C. glycines lineage emerged in southern Africa. These results show that there is significantly more genetic and morphological diversity than was initially suspected with this high-consequence fungal plant pathogen.

Residues of Symbiont Cover Crops Improving Corn Growth and Soil-Dependent Health Parameters

Cover crops have emerged as a crucial tool in promoting sustainable agricultural practices, particularly in improving soil quality and soil–plant health. This study investigates the impact of single cover crop plants each with varying fungal and/or bacterial symbiosis capacities in a pot experiment. The growth of non-symbiont Ethiopian mustard (Brassica carinata), the associative bacterium symbiont black oat (Avena strigosa) and the double (fungus–bacterium) endosymbiont broad bean (Vicia faba) was studied on three distinct soil types, namely a less-fertile sandy soil (Arenosol), an average value of loam soil (Luvisol) and a more productive chernozem soil (Chernozem). Beside the biomass production, nitrogen content and frequency of AM fungi symbiosis (MYCO%) of cover crops, the main soil health characteristics of electrical conductivity (EC), labile carbon (POXC) and fluorescein diacetate enzyme activity (FDA) were assessed and evaluated by detailed statistical analysis. Among the used soil types, the greatest biomass production was found on Chernozem soil with the relatively highest soil organic matter (2.81%) content and productivity. Double symbiotic activity, assessed by soil nitrogen content and mycorrhiza frequency (MYCO%), were significantly improved on the lowest-quality Arenosols (SOM 1.16%). In that slightly humous sandy soil, MYCO% was enhanced by 45%, indicating that symbiosis was crucial for plant growth in the less-fertile soil investigated. After the initial cover crop phase, the accumulated biomass was incorporated into the Luvisol (SOM 1.64%) soil, followed by the cultivation of corn (Zea mays, DK 3972) as the main crop. The results indicate that incorporating cover crop residues enhanced labile carbon (POXC) by 20% and significantly increased the FDA microbial activity in the soil, which positively correlated with the nutrient availability and growth of the maize crop. This study emphasizes the importance of selecting suitable cover crops based on their symbiotic characteristics to improve soil quality and enhance soil–plant health in sustainable agricultural systems.

Rhizospheric bacterial communities against microplastics (MPs): Novel ecological strategies based on the niche differentiation

Considerable amounts of microplastics (MPs) are stocked in plant rhizospheres, yielding adverse effects on rhizospheric microorganisms and threatening plant health. However, the adaptation of the rhizospheric microbiota for MPs remains largely unknown. Here, to evaluate the adaptive strategies of rhizospheric bacterial communities against MPs, we characterized the spatial dissimilarities in MPs properties and bacterial communities from mangrove non–rhizosphere to rhizosphere to root hair sediments. Consequently, two strategies were uncovered: (1) Bacterial communities showed significant niche differentiation induced by the increasingly enriched MPs evaluated by piecewise structural equation modeling (piecewise SEM), as increasing specialization (10.2 % to 19.4 % to 23.0 % of specialists) and decreasing generalization (10.4 % to 10.2 % to 8.7 % of generalists). (2) A self–remediation strategy of enhancing microbial plastic–degrading potentials was determined in bacterial communities, tightly coupled to the increase of specialists (linear regression analysis, R2 = 0.54, P < 0.001) and increasing MPs weathering degrees visualized by the scanning electron microscopy (SEM) from non–rhizosphere to rhizosphere to root hair regions. Our study provides a novel insight into the ecological strategies that rhizospheric microbes utilize against MPs, and broadens our knowledge of the interaction between soil microbes and global MPs pollution.

Free-Riding in Plant Health: A Social-Ecological Systems Approach to Collective Action.

Plant disease epidemics often transcend land management boundaries, creating a collective-action problem where a group must cooperate in a common effort to maximize individual and group benefits. Drawing upon the social-ecological systems framework and associated design principles, we review variables of resource systems, resource units, actors, and governance systems relevant to collective action in plant health. We identify a need to better characterize how attributes of epidemics determine the usefulness of collective management, what influences actors' decisions to participate, what governance systems fit different plant health threats, and how these subsystems interact to lead to plant health outcomes. We emphasize that there is not a single governance structure that ensures collective action but rather a continuum of structures that depend on the key system variables identified. An integrated social-ecological systems approach to collective action in plant health should enable institutional designs to better fit specific plant health challenges.