Search Results (2,272)

The application of slow-release nitrogen fertilizer not only economizes labor input, but also decreases the frequency of use of mechanical intakes, with significant implications in advancing modern intensive agricultural production. Whether slow-release nitrogen fertilizer application can influence the association between microbial diversity and soil multifunctionality remains controversial. This study analyzed the spatial variances of soil environmental factors, soil multifunctionality, and their correlations with bacterial and fungal communities under five nitrogen application rates. The key factors influencing the dominant microbial species and community structures at different spatial locations were determined by the slow-release nitrogen fertilizer application rate, and the driving factors and dominant species of soil multifunctionality were identified. In contrast to the control group, moderate slow-release nitrogen fertilizer application enhanced soil multifunctionality and ameliorated the resilience of microbial diversity loss at diverse spatial locations resulting from irrational nitrogen fertilizer application. The resilience of the fungal community to disturbances caused by fertilization was lower than that of the bacterial community. Bacterial diversity exhibited a significant correlation with soil multifunctionality, and the soil multifunctionality intensity under 240 kg ha⁻¹ treatment increased by 159.01% compared to the CK. The main dominant bacterial communities and the dominant fungal community Ascomycota affected soil multifunctionality through slow-release nitrogen fertilizer application. Structural equation modeling and random forest analysis demonstrated that bacterial community diversity, particularly in bulk soil and the rhizosphere, community composition, and soil nitrogen form are the primary driving factors of soil multifunctionality. Results indicated that the microbial niche alterations induced by slow-release nitrogen fertilizer application positively affect soil multifunctionality. Full article

Kiwifruit Vine Decline Syndrome (KVDS) has become a major concern in Italy, impacting both plant health and production. This study aims to investigate how KVDS affects soil health indicators and the composition of soil microbial communities by comparing symptomatic and asymptomatic areas in two kiwifruit orchards located in Latium, Italy. Soil samples were collected during both spring and autumn to assess seasonal variations in soil physicochemical properties, enzyme activities, and microbial biomass. The results reveal that KVDS influences several soil properties, including pH, electrical conductivity, and the contents of water-soluble carbon and nitrogen. However, these effects varied between orchards and across different seasons. Additionally, KVDS significantly impacts soil enzyme activities and microbial biomass, as assessed through the phospholipid fatty acid (PLFA) analysis, particularly showing an increase in fungal biomass in symptomatic areas. Metabarcoding further demonstrates that microbial communities differ between symptomatic and asymptomatic soils, exhibiting notable shifts in both diversity and relative abundance. Our findings emphasise the complex interactions between plants, soil, and microbial communities in relation to KVDS. This suggests that the syndrome is multifactorial and likely linked to an imbalance in soil microbial communities at the rhizosphere level, which can negatively affect soil health. Full article

Paddy fields are important anthropogenic emission sources of methane (CH₄). However, it is not clear how rice root development and rhizosphere soil properties affect CH₄ emissions. Therefore, we selected rice varieties with similar growth periods but different root traits in the local area. We measured CH₄ emission fluxes, cumulative CH₄ emissions, root dry weight, root length, and the dissolved organic carbon (DOC), microbial biomass carbon (MBC), redox potential (Eh), ammonium nitrogen (NH+ 4–N), and nitrate nitrogen (NO− 3–N) contents in rhizosphere soil. Methanogens and methanotrophs are crucial factors influencing CH₄ emissions; thus, their abundance and community composition were also assessed. The result showed that CH₄ fluxes of each rice variety reached the peak at tillering stage and jointing-booting stage. The CH₄ emissions in tillering stage were the largest in each growth period. CH₄ emissions had negative correlations with root length, root dry weight, Eh NO− 3–N, methanotroph abundance, and the pmoA/mcrA ratio, and positive correlations with NH+ 4–N, MBC, DOC, and methanogen abundance. Path analysis confirmed methanogens and methanotrophs as direct influences on CH₄ emissions. Root development and rhizosphere soil properties affect CH₄ emissions indirectly through these microbes. This study suggests that choosing rice varieties with good root systems and managing the rhizosphere soil can effectively reduce CH₄ emissions. Full article

Biostimulants include a wide array of microorganisms and substances that can exert beneficial effects on plant development and growth, often enhancing nutrient uptake and improving tolerance against abiotic and biotic stress. Depending on their composition and time of application, these products can influence plant physiology directly as growth regulators or indirectly through environmental condition changes in the rhizosphere, such as nutrient and water availability. This review evaluated 48 case studies from 39 papers to summarize the effects of biostimulant application on fruit and tuber yields and on the quality of processing tomato and potato in open field conditions. For potato, PGPR bacteria were the main studied biostimulant, whereas the low number of studies on processing tomato did not permit us to delineate a trend. The yield and quality were greatly influenced by cultivars and biostimulant composition, application method, period, and dose. For processing tomato, a positive effect of the biostimulant application on the marketable yield was reported in 79% of the case studies, whereas for potato, the effect was reported in only 47%. Few studies, on processing tomato and potato, also reported data for quality parameters with contrasting results. The variability of crop response to biostimulant application in open field conditions highlights the need for more comprehensive studies. Such studies should focus on diverse cultivars, deeply understand the interaction of biostimulant application with agronomic management (e.g., irrigation and fertilization), and evaluate yield and quality parameters. This approach is crucial to fully understand the potential and limitations of biostimulant applications in agriculture, particularly regarding their role in sustainable crop production. Full article

The production of wheat is fundamentally interconnected with worldwide food security. The practice of deep tillage (DT) cultivation has shown advantages in terms of soil enhancement and the mitigation of diseases and weed abundance. Nevertheless, the specific mechanisms behind these advantages are unclear. Accordingly, we aimed to clarify the influence of DT on rhizosphere soil (RS) microbial communities and its possible contribution to the improvement of soil quality. Soil fertility was evaluated by analyzing several soil characteristics. High-throughput sequencing techniques were utilized to explore the structure and function of rhizosphere microbial communities. Despite lowered fertility levels in the 0–20 cm DT soil layer, significant variations were noted in the microbial composition of the DT wheat rhizosphere, with Acidobacteria and Proteobacteria being the most prominent. Furthermore, the abundance of Bradyrhizobacteria, a nitrogen-fixing bacteria within the Proteobacteria phylum, was significantly increased. A significant increase in glycoside hydrolases within the DT group was observed, in addition to higher abundances of amino acid and carbohydrate metabolism genes in the COG and KEGG databases. Moreover, DT can enhance soil quality and boost crop productivity by modulating soil microorganisms’ carbon and nitrogen fixation capacities. Full article

Rhizosphere microorganisms are crucial for enhancing plant stress resistance. Current studies have shown that Arbuscular mycorrhizal fungi (AMF) can facilitate vegetation recovery in heavy metal-contaminated soils through interactions with rhizosphere microbiota. However, the mechanisms by which AMF influences rhizosphere microbiota and plant growth under cadmium (Cd) stress remain unclear. In this study, Lolium perenne L. was inoculated with AMF (Rhizophagus irregularis) and grown in soils supplemented with Cd (0 mg kg⁻¹, Cd0; 100 mg kg⁻¹, Cd100). Plant biomass, antioxidant enzyme activities, peroxide content, Cd uptake, and rhizosphere bacterial community composition were evaluated. AMF inoculation reduced Cd influx in aboveground tissues, enhanced nutrient availability in the rhizosphere, and mitigated Cd biotoxicity. Additionally, AMF inoculation improved the scavenging efficiency of reactive oxygen species and alleviated oxidative stress in L. perenne, thereby mitigating biomass reduction. Moreover, AMF treatment increased leaf and root biomass by 342.94% and 41.31%, respectively. Furthermore, under the same Cd concentration, AMF inoculation increased bacterial diversity (as measured by the Shannon index) and reduced bacterial enrichment (as indicated by the ACE index). AMF promoted the enrichment of certain bacterial genera (e.g., Proteobacteria and Actinobacteria) in the Cd100 group. These findings suggest that AMF regulated the composition of the rhizosphere bacterial community and promoted the growth of potentially beneficial microorganisms, thereby enhancing the resistance of L. perenne to Cd stress. Cd contamination in soil severely limits plant growth and threatens ecosystem stability, highlighting the need to understand how AMF and rhizosphere microbes can enhance Cd tolerance in L. perenne. Therefore, inoculating plants with AMF is a promising strategy for enhancing their adaptability to Cd-contaminated soils. Full article

This study investigated the combined effects of novel plant growth-promoting rhizobacteria (PGPR)—Agrobacterium pusense NC2, Kosakonia oryzae WN104, and Phytobacter sp. WL65—and Ascophyllum nodosum seaweed extract (ANE) as biostimulants (PGPR-ANE) on rice growth, yield, and rhizosphere bacterial communities using the RD79 cultivar. The biostimulants significantly enhanced plant growth, shoot and root length, and seedling vigour; however, seed germination was not affected. In pot experiments, biostimulant application significantly increased the richness and evenness of bacterial communities in the rhizosphere, resulting in improvements in rice growth and yield, with increases in plant height (9.6–17.7%), panicle length (14.3–17.9%), and seeds per panicle (48.0–53.0%). Notably, biostimulant treatments also increased post-harvest soil nutrient levels, with nitrogen increasing by 7.7–19.2%, phosphorus by 43.4–161.4%, and potassium by 16.9–70.4% compared to the control. Principal coordinate analysis revealed distinct differences in bacterial composition between the tillering and harvesting stages, as well as between biostimulant treatments and the control. Beneficial bacterial families, including Xanthobacteraceae, Beijerinckiaceae, Acetobacteraceae, Acidobacteriaceae, and Hyphomicrobiaceae, increased in number from the tillering to harvesting stages, likely contributing to soil health improvements. Conversely, methanogenic bacterial families, such as Methanobacteriaceae and Methanosarcinaceae, decreased in number compared to the control. These findings highlight the dynamic responses of the rhizosphere microbiome to biostimulant treatments and underscore their potential benefits for promoting sustainable and productive agriculture. Full article

Arbuscular mycorrhizal fungi (AMF) act as intermediaries between the root systems of host plants and the surrounding soil, offering various benefits to medicinal plants, such as promoting growth and enhancing quality. However, the host range of AMF in medicinal plants and the characteristics of plant–AMF networks in farmland ecosystems remain insufficiently studied. In the present study, we measured AMF colonization, species diversity, and soil properties of 31 medicinal plants at the Anguo Medicine Planting Base in Northwest China. The medicinal plant–AMF network was subsequently analyzed, and the growth-promoting effects of AMF on Astragalus mongholicus were examined. Spore density, species richness, and total colonization exhibited significant variation across different medicinal plant species. Glomus melanosporum, G. claroideum, and Septoglomus constrictum were the dominant species among 61 AMF species. Soil organic matter, phosphatase, available nitrogen, and glomalin-related soil proteins (GRSPs) were the main factors affecting the AMF composition. Structural equation models and a variation partitioning analysis suggested a highly plant species-specific pattern of AMF distribution patterns, where the host identities explained 61.4% of changes in spore density and 48.2% of AMF colonization. The soil nutrient availability and phosphatase activity also influenced AMF colonization. Our results confirmed glomalin as an important contributor to the soil carbon in farmland for cultivating medicinal plants. The medicinal plant–AMF symbiotic network exhibited highly nested patterns, a low specialized structure, high connectance, and low modularity, which suggested saturated AMF colonization and symbiosis stability provided by redundant plant–AMF associations. Despite the wide host range among medicinal plants, AMF inoculation revealed species-specific effects on the growth performance and active ingredient content levels in A. mongholicus, G. claroideum and Sep. constrictum induced the highest biomass and active ingredient content accumulation in A. mongholicus. These findings advance our understanding of AMF community dynamics in the rhizosphere of medicinal plants and offer valuable insights for optimizing medicinal plant cultivation practices. Full article

The prolonged practice of continuous potato cropping, coupled with inadequate field management, disrupts the soil bacterial community equilibrium. Such disturbances compromise the resilience of the soil ecosystem, predisposing it to an increased incidence of potato diseases. However, the effects of the phosphorus fertiliser application rate on the rhizosphere soil bacterial community composition of potatoes and the occurrence of potato common scab (CS) have not been adequately studied. Here, diseased field soils from Dingxi and Huidong Counties were collected for potting tests, and field tests were conducted in Huidong County for validation. An examination of the relationship between the bacterial community composition in the potato rhizosphere soil and potato CS under different phosphate fertiliser treatments was conducted using 16S rRNA high-throughput sequencing. The results show that a lower phosphorus fertiliser application rate was more conducive to maintaining soil bacterial community diversity under different phosphorus fertiliser treatments in different habitats. In addition, the relative abundance of the txtA gene increased significantly (p < 0.05) with the increase in the phosphate fertiliser application rate. Field trials conducted in Huidong revealed that treatments F1, F2, and F3 had respective CS incidence rates of 28.33%, 46.67%, and 59.44%, while their corresponding disease severity indices were 7.67, 17.33, and 29.44. Further analysis revealed that the relative abundance of antagonistic genera of pathogenic S. scabies decreased significantly (p < 0.05) with increases in the phosphorus fertiliser application rate. In summary, the correlation between potato CS and changes in the bacterial community of rhizosphere soil was used to determine the optimal phosphorus application rate during potato production, which can provide a scientific basis for the management of phosphorus fertiliser in potato farmland. Full article

The use of plant growth-promoting rhizobacteria (PGPR) for the bioremediation of heavy metal cadmium (Cd) and for enhancing plant growth in Cd-polluted soil is widely recognized as an effective approach. This study aimed to isolate Cd-resistant bacteria with plant growth-promoting (PGP) traits from the rhizosphere of vegetables subjected to metal contamination and to investigate the mechanisms associated with Cd adsorption as well as its impact on Cd uptake in lettuce. Six Cd-resistant bacterial strains were isolated from rhizosphere soil, among which the R27 strain exhibited the highest tolerance to Cd (minimum inhibitory concentration of 2000 mg/L) along with PGP traits, including phosphate solubilization (385.11 mg/L), the production of indole-3-acetic acid (IAA) (35.92 mg/L), and siderophore production (3.34 mg/L). Through a range of physiological, biochemical, and molecular assessments, the R27 strain was classified as Bacillus siamensis. This strain demonstrated notable efficiency in removing Cd²⁺ from the growth medium, achieving an efficacy of 80.1%. This removal was facilitated by cell surface adsorption through functional groups such as O–H, C=O, –CO–NH–, and C–O, alongside intracellular Cd accumulation, as evidenced by SEM, TEM, EDX, and FTIR analyses. Pot culture experiments indicated that R27 significantly promoted lettuce seedling growth and helped plants tolerate Cd stress, with the underlying mechanisms likely involving increased antioxidant activities for scavenging reactive oxygen species (ROS) induced by Cd stress, and reduced Cd²⁺ levels in lettuce seedlings to mitigate Cd²⁺ toxicity. These physiological changes were further supported by the down-regulation of genes associated with cadmium transport, including IRT1, Nramp1, HMA2, HMA4, ZIP4, and ZIP12, as well as the significantly reduced root bio-concentration factor (BCF) and translocation factor (TF). In summary, the R27 strain offers considerable potential in the bioremediation of Cd-polluted soils and can serve as a bio-fertilizer to enhance plant growth. Full article

Intercropping affects soil microbial community structure significantly; however, the effects on understory medicinal plants in karst areas remain unclear. We investigated the effects of four intercropping systems (Moso bamboo, Chinese fir, bamboo-fir mixed forest, and forest gap) on the rhizosphere microbial communities of giant lily (Cardiocrinum giganteum), an economically important medicinal plant in China. We assessed the intercropping impact on rhizosphere microbial diversity, composition, and co-occurrence networks and identified key soil properties driving the changes. Bacterial and fungal diversity were assessed by 16S rRNA and ITS gene sequencing, respectively; soil physicochemical properties and enzyme activities were measured. Moso bamboo system had the highest fungal diversity, with relatively high bacterial diversity. It promoted a distinct microbial community structure with significant Actinobacteria and saprotrophic fungi enrichment. Soil organic carbon, total nitrogen, and available potassium were the most influential drivers of microbial community structure. Co-occurrence network analysis revealed that the microbial network in the Moso bamboo system was the most complex and highly interconnected, with a higher proportion of positive interactions and a greater number of keystone taxa. Thus, integrating Moso bamboo into intercropping systems can enhance soil fertility, microbial diversity, and ecological interactions in the giant lily rhizosphere in karst forests. Full article

Saline soils exert persistent salt stress on plants that inhibits their ability to carry out photosynthesis and leads to photosynthetic carbon (C) scarcity in plant roots and the rhizosphere. However, it remains unclear how a rhizosphere environment is shaped by photosynthetic C partitioning under saline conditions. Given that sucrose is the primary form of photosynthetic C transport, we, respectively, created sucrose transport distorted (STD) and enhanced (STE) rice lines through targeted mutation and overexpression of the sucrose transporter gene OsSUT5. This approach allowed us to investigate different scenarios of photosynthate partitioning to the rhizosphere. Compared to the non-saline soil, we found a significant decrease in soil dissolved organic carbon (DOC) in the rhizosphere, associated with a reduction in bacterial diversity when rice plants were grown under moderate saline conditions. These phenomena were sharpened with STD plants but were largely alleviated in the rhizosphere of STE plants, in which the rhizosphere DOC, and the diversity and abundances of dominant bacterial phyla were measured at comparable levels to the wildtype plants under non-saline conditions. The complexity of bacteria showed a greater level in the rhizosphere of STE plants grown under saline conditions. Several salt-tolerant genera, such as Halobacteroidaceae and Zixibacteria, were found to colonize the rhizosphere of STE plants that could contribute to improved rice growth under persistent saline stresses, due to an increase in C deposition. Full article

To investigate the soil-specific metabolites of Codonopsis pilosula under different stubble management practices, this study analyzed differentially abundant metabolites in the rhizosphere soils of rotational (DS) and continuous (LS) cropping systems via liquid chromatography–tandem mass spectrometry (LC–MS/MS)-based metabolomic approaches. The results revealed that 66 metabolites, including amino acids and their derivatives, nucleic acids, alcohols, organic acids, amines, fatty acids, purines, and sugars, were significantly different (p < 0.05) between the DS and LS groups. Under continuous cropping, the levels of amines, fatty acids, organic acids, and sugars in the rhizosphere soil were significantly greater (p < 0.05) than those under rotational cropping, whereas the levels of amino acids and their derivatives, nucleic acids, and purines and pyrimidines were significantly lower (p < 0.05). KEGG pathway enrichment analysis revealed that these differentially abundant metabolites were enriched in metabolic pathways such as amino acid metabolism (e.g., alanine, aspartate, and glutamate metabolism), carbon metabolism, the cAMP signaling pathway, ABC transporter proteins, phenylalanine metabolism, and the biosynthesis of plant secondary metabolites. These metabolic pathways were involved in osmoregulation, energy supply, and resilience in plants. In conclusion, inter-root soil metabolites in rotational and continuous cropping of Codonopsis pilosula were able to influence soil physicochemical properties and microbial populations by participating in various biological processes. Full article

The current study was carried out to characterize chalky soil bacteria obtained from the rhizosphere of Acacia species growing in Abardae, Maekel Region of Eritrea. This study collected three chalky soil samples from the rhizosphere of Acacia ethibica, Acacia origena, and non-rhizospheric soil. The samples contained 1.42 × 10¹⁰, 5.35 × 10⁹, and 5.68 × 10⁷ cfu/g of culturable bacteria, respectively. A total of 80 bacterial strains were isolated, with ten selected for further study based on their distinct morphology. The researchers examined the cell morphology and the antimicrobial and plant growth-promoting activity of the chosen bacterial isolates. The study’s findings identified that the aerial mycelium of the strain EAE-1 displayed a unique and previously unreported arrangement of hyphae-bearing spores. The antimicrobial test results also showed that bacterial strains EAE-1, EAE-3, EAE-14, EAE-15, EAE-40, and EAO-24 displayed a wide range of antimicrobial activity against the examined phytopathogens. Furthermore, the seed germination result showed that the majority of bacterial strains had a positive effect on wheat growth, with strains EAE-40 and EAO-17 particularly enhancing maize growth. To sum up, the substantial capabilities of these strains position them as promising candidates for biotechnological applications. This study also represents the preliminary analysis of the microbial composition of Eritrean soil. Full article

Atractylodes macrocephala, a perennial herb widely used in traditional Chinese medicine, is highly prone to root rot, which significantly reduces its yield and quality. This study compared the physicochemical properties of soil from healthy and diseased A. macrocephala plants and analyzed the microbial diversity in the endophytic, rhizosphere, and root zone soils. The results showed that the diseased plants had higher levels of available potassium and electrical conductivity in the rhizosphere, both positively correlated with the severity of root rot, while soil pH was negatively correlated. The diversity and richness of endophytic bacterial and fungal communities were significantly reduced in diseased plants. Additionally, root rot led to major changes in the rhizosphere microbial community, with an increased abundance of Proteobacteria and Ascomycota, and a decrease in Firmicutes, Bacteroidetes, Actinobacteria, and Basidiomycota. Fusarium oxysporum, Fusarium solani, and Fusarium fujikuroi were identified as key pathogens associated with root rot. This study enhances our understanding of the microbial interactions in soils affected by root rot, offering a foundation for developing soil improvement and biological control strategies to mitigate this disease in A. macrocephala cultivation. Full article