Biology and Fertility of Soils最新文献

When imidazolinone herbicides persist longer than intended and remain active in the soil, they can have unknown impacts on soil health. This study investigated the impact of simulated soil residues of an imidazolinone herbicide on shoot dry matter and bacterial communities in the bulk and rhizosphere soil in tolerant and susceptible wheat genotypes, at two different crop growth stages. Four levels of gradient increased herbicide residues were applied, and rhizosphere bacterial diversity and community composition were analysed using 16S rRNA gene amplicon sequencing. Our results highlight that the shift in wheat rhizosphere bacteriome is driven more by the crop growth stage and wheat genotype than the presence and level of imidazolinone residues. Results showed a linear trend of increasing alpha diversity with increasing herbicide residues during the early crop growth stage, and a decrease in alpha diversity with increasing herbicide residues during the late crop growth stage, only for the tolerant genotype. The order Betaproteobacteriales in the rhizosphere was increased by herbicide residues to a greater extent than the other taxonomic groups. During the early growth stage, there were more ASV (amplicon sequence variant) enriched by imidazolinone herbicide residues in the rhizosphere of the tolerant genotype compared with the susceptible genotype. Future research work should consider studies with soils that have different physicochemical properties, and focus on other soil microbes of known significance to nutrient cycling and crop growth.

Pursuing sustainable agricultural production necessitates innovative approaches to enhance nutrient use efficiency and mitigate the environmental impact of fertilizer use in cropping systems. Biochar-based controlled-release fertilizers (BCRFs) have emerged as a promising solution to address these challenges. This paper reviews BCRF production methods, nutrient retention mechanisms, and effects on plant growth and the environment compared with conventional fertilizers. Various techniques have been used to improve the fertilizer efficiency of BCRFs, including impregnation, coating, granulation, co-pyrolysis, hydrothermal synthesis, and in-situ pyrolysis, each offering unique advantages in controlling nutrient release. BCRFs facilitate nutrient retention and gradual release, improving soil nutrient use efficiency. The BCRFs also improve soil structure and enhance microbial activities and root growth, thereby fostering resilient and productive crops. BCRFs have considerable potential for carbon sequestration, mitigation of greenhouse gas emissions, reduction in nutrient leaching and environmental impact, contributing to sustainable agricultural practices compared to the use of conventional fertilizers (e.g., synthetic or chemical fertilizers). However, attention is needed to address challenges concerning the economic feasibility, scalability, and regulatory frameworks associated with using BCRFs. BCRFs offer a promising pathway for improving nutrient management in agriculture; however, interdisciplinary efforts are needed to unlock their full potential in enhancing plant growth and environmental sustainability.

Drought stress is a key factor limiting crop growth and production. Although a variety of crops can improve their survival and drought resistance as a result of interactions with their rhizosphere microbiota, the mechanisms related to plant–rhizosphere microbiota interactions under drought stress are not fully understood, especially regarding the mechanisms in habitats with droughts. Here, the molecular mechanisms involving the E. ulmoides rhizosphere microbiota in response to drought stress were systematically analyzed using pot experiments, metagenomic sequencing, and assessment of plant physiological indexes. The results showed that the composition and co-occurrence patterns of the E. ulmoides rhizosphere microbiota were altered under drought stress, and the phylogenetic diversity of the core microbes was increased. Moreover, Betaproteobacteria and Opitutae were significantly enriched in the rhizosphere and their relative abundances were significantly correlated with the levels of superoxide dismutase (SOD) and soluble sugar (SS) in E. ulmoides. Kyoto Encyclopedia of Genes and Genomes (KEGG) functional analysis showed that two-component system, biosynthesis of amino acids, ABC transporters, and ribosome became more abundant in the rhizosphere under drought stress, and were significantly correlated with SOD and SS levels. Similarly, genes encoding Carbohydrate Active Enzymes (CAZymes) activities that auxiliary activities and glycosyl transferases became more abundant and were significantly correlated with SOD and SS levels. In conclusion, the relative abundances of KEGG functions and CAZymes classes in the E. ulmoides rhizosphere microbiota were altered by enrichment of Betaproteobacteria and Opitutae, which in turn affected the host physiological indexes to improve the host’s adaptability to drought. These findings are of great significance for improving plant drought tolerance in order to increase sustainable crop production.

Among the long-term sustainable solutions to mitigate saline stress on plants, the use of plant growth promoting microorganisms (PGP) is considered very promising. While most of the efforts have been devoted to the selection and use of bacterial PGPs, little has been proposed with yeast PGP (PGPYs). In this study, three PGPY strains belonging to Naganishia uzbekistanensis, Papiliotrema terrestris and Solicoccozyma phenolica were employed singularly and in a consortium to mitigate salt stress of zucchini (Cucurbita pepo). The results demonstrated that these yeasts, when applied to salt-amended soil, mitigated the growth inhibition caused by NaCl. Among the three species, N. uzbekistanensis and P. terrestris showed the most significant improvements in plant performance, with N. uzbekistanensis exhibiting hormetic effects under salt stress by improving root length and dry plant biomass. In general, the root system was the most affected part of the plants due to the presence of the yeasts. The entire rhizosphere bacterial microbiota was significantly influenced by the addition of PGPYs, while the mycobiota was dominated by the introduced yeasts. Metabolomic fingerprinting using FTIR revealed modifications in hemicellulose and silica content, indicating that PGPY inoculation impacts not only the plant but also the soil and rhizosphere microorganisms.

Disease-resistant wheat cultivars exhibited significantly lower infection rates in field conditions, associated with higher microbial diversity in key compartments such as the rhizosphere soil and phylloplane. Microbial community analysis revealed compartment-specific selection effects, with significant horizontal microbial transfers noted across plant tissues, suggesting a strong compartment-dependent selection from soil microbiomes. Further, resistant varieties were enriched of potential beneficial microbial taxa that contribute to plant health and disease resistance from seedling to adult stages. This was verified by rhizosphere microbiome transplantation experiment, where the inoculation of the rhizosphere microbiome of resistant cultivars suppressed pathogen infection and enhanced plant growth, indicating that wheat resistance to soil-borne virus disease depended on the interaction of the host with the microbial community around it. Our results also demonstrated that the microbial composition and network at the seedling stage predicted wheat health and pathogen susceptibility. Disease infection simplified the intra-kingdom networks and increased potentially beneficial taxa such as Massilia, Bacillus, and Pseudomonas within the microbiome. Overall, our findings provide novel insights into the microbial dynamics influenced by host traits and their implications for disease resistance and plant health, offering potential strategies for agricultural biocontrol and disease management.

Bacillus amyloliquefaciens is a widely used plant growth-promoting rhizobacterium. To investigate its role and mechanisms in selenium (Se) biofortification in crops, a pot experiment with four treatments including no application of Se fertilizer and B. amyloliquefaciens (control), B. amyloliquefaciens application (BA), Se fertilizer application (Se), and combined B. amyloliquefaciens and Se fertilizer application (BA + Se) was conducted. The results showed that, BA + Se treatment significantly increased total biomass of tea seedling compared with control, BA and Se treatments. Additionally, compared with Se treatment, BA + Se treatment significantly increased the Se concentrations in root and leaf, and Se content in the whole tea seedling by 101.4%, 34.5%, and 149.5%, respectively; BA + Se treatment also significantly increased the soil exchangeable Se and total available Se concentrations. Compared with control, BA treatment upregulated the expression level of CsPHT1;2b; Se treatment upregulated the expression levels of CsSULTR1;1, CsSULTR1;2, CsPHT1;2a and CsPHT1;2b; BA + Se treatment upregulated the CsSULTR1;1 and CsPHT1;2a expression levels in tea seedling roots. The 16S rRNA indicated that BA and Se treatments had no effects on the diversity of rhizosphere bacterial community, but altered bacterial community composition. Soil pH was the most important environmental factor affecting rhizosphere bacterial community composition. BA + Se treatment significantly increased soil pH and the complexity of rhizosphere bacterial symbiotic network, compared with other three treatments. Furthermore, comparative analysis about rhizosphere soil properties and bacterial community composition and function between Se and BA + Se treatments, suggested that BA + Se treatment promoted soil Se availability by recruiting g_Sinomonas species and regulating the abundance of Se reductase in the rhizosphere.

In this paper a new modeling approach for denitrification and similar processes, which depend on the geochemical gradient between the air-filled larger pores in a soil and a water-filled matrix, is presented. The new modeling approach is capable of taking soil structural properties (obtained e.g. from X-ray CT) into account without requiring a high-resolution simulation. The model approach is explained and its application is demonstrated by simulating denitrification experiments conducted with repacked soil samples to assess the challenges and possibilities of the new approach. The main result of the modeling is that the nitrous oxide emission measured in the experiment can not be explained by a limited supply with oxygen alone at a carbon turnover rate derived from carbon dioxide emissions. It is additionally necessary that the microbial activity is concentrated in localized hot spots to create anaerobic conditions. This is confirmed by analytical solutions.

Untreated chicken manure causes a large amount of antibiotics and heavy metals to enter the soil environment. Currently, there is limited research on antibiotic resistance genes (ARGs) and heavy metal resistance genes (HMRGs) in soil profile. In this study, we conducted a preliminary investigation on the soil profile of vegetable field contaminated by chicken manure. The results showed that the absolute abundance of some resistance genes was higher at the 20–60 cm. Subsequently, we further analyzed the vertical migration of bacteria bearing ARGs and HMRGs through a soil profile as affected by manure using metagenomic sequencing. The findings revealed that long-term application of chicken manure significantly increased the alpha (α) diversity of the 0–20 cm soil layer ARGs and HMRGs, the plasmids relative abundance of soil profile substantially increased. Furthermore, long-term application of chicken manure changed the community composition of the 0–20 cm soil layer resistance genes, and also affected the community composition of the 20–40 cm soil layer with the increase of manure rates. Additionally, long-term application of chicken manure significantly increased the α diversity of the 0–20 cm soil layer bacteria. Structural equation modeling (SEM) further analysis revealed that bacterial relative abundance was the primary driving factor for the distribution of ARGs in vertical space, while mobile genetic elements (MGEs) were the main driving factor for HMRGs. This study strengthens our understanding of the vertical spatial distribution of soil resistance genes following long-term application of chicken manure, and also provides the basis for the management of subterranean environment.

The recalcitrant nature of wheat (Triticum aestivum L.) straw, one of the most abundant agricultural residues, presents challenges for efficient decomposition, limiting nutrient release and organic matter retention in soils. Understanding the effects of tillage practices on wheat straw decomposition and shaping associated microbial communities is essential for enhancing microbial-mediated breakdown and optimizing residue management to enhance soil health, nutrient cycling, and sustainability in agricultural systems. In this study, the effect of different tillage practices on wheat straw decomposition and associated bacterial and fungal community compositions during non-growing and growing seasons were studied. To simulate tillage, litter bags filled with wheat straw were placed at respective soil depths for conventional (22–24 cm) and reduced (8–10 cm) tillage, and on the surface for the no-tillage treatment. The subsets of the litter bags were randomly retrieved after 145 days and at the end of the experiment after 290 days. Statistical analysis revealed that tillage treatments significantly influenced the decomposition rate and nutrient release over time. Overall, the alpha diversity of the decomposition-associated microbial community was not substantially affected by different tillage treatments, while beta diversity exhibited distinct microbial community compositions in relation to tillage practices. The results of this study contribute to a deeper understanding of wheat straw decomposition-associated bacterial and fungal communities’ response to different tillage treatments, with observations made at two distinct sampling times (non-growing and growing seasons) under certain edaphic and climatic conditions.

Little is known about how seedlings sense new soil environments and how the rhizosphere bacteriome changes accordingly. It is important to elucidate these changes to better understand feedbacks that contribute to nutrient cycling and plant fitness. Here, we explored how the tomato rhizosphere bacteriome developed weekly throughout the vegetative developmental stage and with variable nitrogen (N) fertilizer additions. Bacterial communities expressing diverse functions highly fluctuated in the first and second week after planting, and these fluctuations diminished progressively after the third week. Bacteria capable of biocontrol stabilized after the fourth week, while those involved in nutrient cycling continued to change in abundance week-to-week. Thus, bacterial specialization may be concomitant with bacteriome stabilization. With N fertilizer application, bacteria with diverse functions continued to fluctuate through the fifth week. However, regardless of fertilization, bacterial communities stabilized by the sixth week. It may take two weeks for roots to select for soil bacteria to assemble a specific rhizosphere bacteriome, but when N is applied, this period extends. Subsequently, roots may select for bacteria that are already established in the rhizosphere rather than from the bulk soil. This study showcases the dynamics of rhizosphere assemblage and how this process is affected by N additions.