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Background: Continuous cropping of the same crop leads to land degradation. This is also called the continuous-cropping obstacle. Currently, intercropping tobacco with other crops can serve as an effective strategy to alleviate continuous cropping obstacles. Results: In this study, tobacco K326 and insectary floral plants were used as materials, and seven treatments of tobacco monoculture (CK), tobacco intercropped with Tagetes erecta, Vicia villosa, Fagopyrum esculentum, Lobularia maritima, Trifolium repens, and Argyranthemum frutescens respectively, were set up to study their effects on rhizosphere soil chemical properties and composition and structure of rhizosphere soil microbial community of tobacco. The 16 S rRNA gene and ITS amplicons were sequenced using Illumina high-throughput sequencing. tobacco/insectary floral plants intercropping can influence rhizosphere soil chemical properties, which also change rhizosphere microbial communities. The CK and treatment groups tobacco rhizosphere soil microorganisms had significantly different genera, such as tobacco intercropping with T. repens and A. frutescens significantly increased the number of Fusarium and intercropping T. erecta, V. villosa, L. maritima, T. repens, and A. frutescens significantly increased the number of Sphingomonas and unknown Gemmatimonadaceae. Additionally, intercropping T. erecta, V. villosa and L. maritima changed the rhizosphere fungal and bacteria community and composition of tobacco and the positive correlation between tobacco rhizosphere the genera of fungi and bacterial were greater than CK. The pathway of the carbohydrate metabolism, amino acid metabolism, and energy metabolism in rhizosphere bacteria were significantly decreased after continuous cropping. Fungal symbiotic trophic and saprophytic trophic were significantly increased after intercropping V. villosa, L. maritima and plant pathogen and animal pathogen were increased after intercropping T. repens and A. frutescens. Additionally, bacterial and fungal communities significantly correlated with soil chemical properties, respectively. Conclusion: This study reveals that intercropping tobacco with insectary floral plants, particularly T. erecta, V. villosa, L. maritima and A. frutescens significantly affects soil chemical properties and alters rhizosphere microbial communities, increasing the abundance of certain microbial genera. Additionally, intercropping enhances pathways related to carbohydrate, amino acid, and energy metabolism in rhizosphere bacteria. These findings suggest that intercropping could provide a promising strategy to overcome challenges associated with continuous tobacco cropping by regulating the rhizosphere environment. [ABSTRACT FROM AUTHOR]

Drought can greatly impact the biodiversity of an ecosystem and play a crucial role in regulating its functioning. However, the specific mechanisms by which drought mediate the biodiversity effect (BE) on community biomass in above- and belowground through functional traits remain poorly understood. Here, we conducted a common garden experiment in a greenhouse, which included two plant species richness levels and two water addition levels, to analyze the effects of biodiversity on aboveground biomass (AGB), belowground biomass (BGB) and total biomass (TB), and to quantify the relationship between BEs and functional traits under drought conditions. Our analysis focused on partitioning BEs into above- and belowground complementarity effect (CE) and selection effect (SE) at the species level, which allowed us to better understand the impacts of biodiversity on community biomass and the underlying mechanisms. Our results showed that plant species richness stimulated AGB, BGB and TB through CEs. Drought decreased AGB, BGB and TB, simultaneously. In addition, the aboveground CE was positively associated with the variation in plant height. SEs in above- and belowground were negatively correlated with the community mean plant height and root length, respectively. Furthermore, drought weakened the aboveground CE by decreasing variation in plant height, resulting in a reduction in AGB and TB. Our findings demonstrate that the complementarity of species is an important regulator of community biomass in above- and belowground, the dynamics of biomass under environmental stress are associated with the response of sensitive compartments. [ABSTRACT FROM AUTHOR]

Continuous cultivation of tobacco could cause serious soil health problems, which could cause bacterial soil to change to fungal soil. In order to study the diversity and richness of fungal community in tobacco-growing soil under different crop rotation, three treatments were set up in this study: CK (tobacco continuous cropping); B (barley-tobacco rotation cropping) and R (oilseed rape-tobacco rotation cropping). The results of this study showed that rotation with other crops significantly decreased the soil fungal OTUs, and also decreased the community richness, evenness, diversity and coverage of fungal communities. Among them, B decreased the most. In the analysis of the composition and structure of the fungal community, it was found that the proportion of plant pathogens Nectriaceae decreased from 19.67% in CK to 5.63% in B, which greatly reduced the possibility of soil-borne diseases. In the analysis of the correlation between soil environmental factors and fungal communities, it was found that Filobasidiaceae had a strong correlation with TP and AP, and Erysiphaceae had a strong correlation with TK and AK. NO3−-N and NH4+-N were the two environmental factors with the strongest correlation with fungal communities. The results of this study showed that rotation with other crops slowed down the process of soil fungi in tobacco-growing soil and changed the dominant species of soil fungi community. At the same time, crop rotation changed the diversity and richness of soil fungal community by changing the physical and chemical properties of soil. [ABSTRACT FROM AUTHOR]

Background and Aims Nitrogen enrichment affects biodiversity, plant functional traits and ecosystem functions. However, the direct and indirect effects of nitrogen addition and biodiversity on the links between plant traits and ecosystem functions have been largely overlooked, even though multidimensional characteristics of plant functional traits are probably critical predictors of ecosystem functions. Methods To investigate the mechanism underlying the links between plant trait identity, diversity, network topology and above- and below-ground biomass along a plant species richness gradient under different nitrogen addition levels, a common garden experiment was conducted in which those driving factors were manipulated. Key Results The study found that nitrogen addition increased above-ground biomass but not below-ground biomass, while species richness was positively associated with above- and below-ground biomass. Nitrogen addition had minor effects on plant trait identity and diversity, and on the connectivity and complexity of the trait networks. However, species richness increased above-ground biomass mainly by increasing leaf trait diversity and network modularity, and enhanced below-ground biomass through an increase in root nitrogen concentration and network modularity. Conclusions The results demonstrate the mechanistic links between community biomass and plant trait identity, diversity and network topology, and show that the trait network architecture could be an indicator of the effects of global changes on ecosystem functions as importantly as trait identity and diversity. [ABSTRACT FROM AUTHOR]