The application of organic fertilizers affects the physiological and biochemical activities of plants, thereby altering the expression of relevant internal genes and metabolites. Nonetheless, most previous research has primarily examined how organic fertilizers influence soil physicochemical properties, microbial community composition, and overall crop physiological metabolism. Therefore, this study used tobacco as the research object to elucidate the intrinsic mechanism of the effects of different amounts of cattle manure on the resistance of tobacco leaves. The research results show that the CM2 treatment significantly increased the density of leaf glandular trichomes, while the CM3 mainly promoted the accumulation of diterpenoid secretions in glandular trichomes. Through multi-omics analysis, it systematically elucidated for the first time that cattle manure activates the endogenous hormone signaling pathways within tobacco leaves, strengthens basic metabolism, and specifically upregulates the expression of key genes (HMGR, SDX, F5H) in the the diterpene and phenylpropanoid biosynthetic pathways, thereby coordinately regulates glandular trichome development and secretion synthesis, ultimately enhancing the plant's biological defense ability. This study elucidates the intrinsic mechanism by which different doses of cattle manure influence tobacco glandular trichome development and resistance by regulating endogenous hormones, basic metabolism, and secondary metabolic pathways, providing a theoretical basis for the rational application of cow manure to improve crop resistance and quality in organic agriculture.

Hyperspectral remote sensing provides a rapid and non-destructive approach for monitoring plant nutrient status; however, its application for magnesium (Mg) estimation in flue-cured tobacco remains limited. In this study, two cultivars, Yunyan 87 and Zhongyan 100, were grown in a hydroponic system with five Mg concentration gradients (0, 0.2, 1, 5, and 25 mmol L-1). Hyperspectral reflectance data of fresh leaves were collected at different growth stages. Three preprocessing methods, including first derivative (FD), standard normal variate (SNV), and multiplicative scatter correction (MSC), were applied, and partial least squares regression (PLSR) was used to identify the optimal preprocessing strategy. Characteristic wavelengths were selected using competitive adaptive reweighted sampling (CARS), successive projections algorithm (SPA), and genetic algorithm (GA), and were further combined with extreme learning machine (ELM), support vector regression (SVR), and radial basis function (RBF) neural network models to estimate Mg content. The results showed that spectral preprocessing significantly improved the relationship between hyperspectral data and Mg content, with optimal methods varying across cultivars and growth stages. Selected wavelengths were mainly located in the near-infrared region. The developed models achieved high prediction accuracy, particularly during the middle and late growth stages, where the coefficients of determination (R2) of all test sets exceeded 0.90. In addition, Yunyan 87 exhibited higher prediction accuracy than Zhongyan 100. These findings demonstrate that hyperspectral technology combined with feature wavelength selection and machine learning enables accurate and non-destructive estimation of Mg content in flue-cured tobacco leaves, providing a reliable tool for Mg nutrition diagnosis and precision management. However, further validation under diverse field conditions is required to enhance model robustness.

Soil bulk density (BD) acts as a fundamental physical constraint that regulates the rhizosphere microenvironment and plant development. In this study, we conducted an in-situ pot-in-field experiment with five distinct soil bulk density gradients (0.5, 0.8, 1.1, 1.4, and 1.7 g·cm⁻³), where pots were embedded into field furrows to ensure natural environmental conditions. We systematically investigated the effects of soil BD on flue-cured tobacco root morphology, anatomy, soil physicochemical properties, enzyme activities, and rhizosphere microbial community structure. Our results demonstrated a non-linear response to soil compaction: while extreme compaction (T5, 1.7 g·cm⁻³) maximized soil moisture, it severely restricted gas exchange and inhibited root expansion. Conversely, an optimal soil BD of 1.1 g·cm−3 (T3) balanced capillary porosity and aeration, facilitating the largest stele diameter, a highly developed phloem system, and vigorous root hair production. This optimal physical state (1.1 g·cm⁻³) significantly enhanced root morphology-characterized by a complex dichotomous branching pattern—and promoted the recruitment of beneficial rhizosphere microbiomes compared to compacted or excessively loose soils. Structural equation modeling (SEM) revealed that soil BD influences plant performance through a cascaded pathway: modifying soil physical and biological properties, which subsequently dictates root anatomical plasticity and topological architecture. These findings challenge the "lower is better" paradigm of soil compaction management and identify 1.1 g·cm−3 as the threshold for optimal tobacco growth. Our study provides a mechanistic framework for understanding how physical soil constraints modulate the plant-microbe-soil continuum, offering crucial insights for precision soil management in intensive tobacco production systems.

The combined application of organic fertilizer and chemical fertilizer can affect plant physiological activities and change the expression of its related genes and metabolites. However, past studies mainly focused on the effects of the combined application of organic and inorganic fertilizers on soil physical and chemical properties, microbial communities, and crop physiological changes, but the response mechanism of plant leaf metabolic cycles to different combined applications of organic fertilizers is not yet completely clear. Therefore, this study employed tobacco as a model crop to investigate the intrinsic regulatory mechanisms of physiological metabolism in tobacco leaves following the combined application of three distinct organic materials with chemical fertilizer and cattle manure. The research first revealed that the composite application of chemical fertilizer, cattle manure, and high-carbon-based compost (CMHC) exerted the most pronounced stimulatory effect on the growth and development of tobacco glandular trichomes. Compared to the control group (CK) treated solely with chemical fertilizer, glandular trichome density increased by 1.56-fold, while α-cembratriene diol and β-cembratriene diol content rose significantly by 146.40% and 2.39-fold respectively. This study employs transcriptomic and metabolomic analyses to reveal for the first time the molecular mechanism by which the combined application of cattle manure with other organic fertilizers enhances tobacco leaf defense capacity. This is achieved by regulating key genes, such as phosphoethanolamine N-methyltransferase and nicotine N-demethylase, in the glycerophospholipid metabolism as well as the tropane, piperidine, and pyridine alkaloid biosynthesis pathways. These regulatory actions promote the synthesis of downstream resistance substances, including N-methyldiethanolamine and nicotine. Notably, in the treatment combining cattle manure with humic acid (CMHC), the upregulation of genes such as glutamate-oxaloacetate transaminase and nicotinate reductase I modulates energy metabolism shifts in the leaves, thereby synergistically promoting leaf growth and the secretion of glandular trichome exudates. In summary, this study systematically elucidates the molecular mechanisms by which the combined application of organic fertilizer regulates tobacco leaf development and metabolite synthesis from an integrated transcriptomic and metabolomic perspective, providing a theoretical basis for green fertilisation and quality improvement in tobacco cultivation.

Investigating the response of tobacco (Nicotiana tabacum L.) roots to different soil bulk densities and their impact on metabolites might improve leaf quality and expand the range of tobacco's applications. In this study, a pot experiment was conducted using flue-cured tobacco as the experimental subjects under natural conditions. Soil bulk density (SBD) was manipulated by incorporating pumice or applying pressure, resulting in five distinct treatments (T1, 0.5 g center dot cm-3; T2, 0.8 g center dot cm-3; T3, 1.1 g center dot cm-3; T4, 1.4 g center dot cm-3; T5, 1.7 g center dot cm-3). The study's main approach was to use non-targeted metabolomics to analyze how the metabolites in tobacco roots are affected by varying soil bulk densities. A total of 14,594 metabolites were identified in root extracts using ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). Differential expression was identified in 281 metabolites across the various soil bulk density treatments. Notably, nicotine was present alongside organic acids and derivatives, amino acids and derivatives, nucleotides and derivatives, sugars/alcohols, amides, and phenolic compounds. Changes in soil bulk density have an important effect on root metabolism. Root metabolites were significantly reduced in soils with SBDs either lower or higher than 1.1 g center dot cm-3. High bulk density of soil caused plant root stress, increasing linoleic acid and alpha-linolenic acid levels, augmenting the ability of plant to withstand stress, and improving the production of defensive substances. These findings indicate that root metabolites can be regulated by adjusting soil bulk density, offering a new strategy to enhance tobacco quality and a unique approach to its multipurpose development as a bioreactor.

This study compared the salt tolerance of two tobacco varieties with different salt tolerances during the germination period-Basma (Oriental tobacco) and K326 (flue-cured tobacco)-under NaCl stress. Basma exhibited higher antioxidant enzyme activity (1.16-3.58 times that of K326), reduced O2-$$ {\mathrm{O}}_2<^>{-} $$ levels by 16.5% during the peak accumulation of reactive oxygen species (ROS) and effectively regulated ion homeostasis by upregulating NtSOS1, reducing Na+ accumulation in aboveground tissues by 21.01-22.90 times and in underground tissues by 12.84-14.15 times compared to K326. Additionally, Basma increased the indole-3-acetic acid (IAA) content in underground tissues by 1.5 times after 72 h of saline stress, a change supported by increased expression of NtPIN4. In summary, Basma demonstrated greater salt tolerance than K326 by increasing antioxidant enzyme activity, regulating ion homeostasis and maintaining IAA balance. These findings suggest that enhancing ROS scavenging, modifying root structure and applying IAA can effectively enhance salt tolerance in tobacco cultivation.

With the development of agriculture, the historic extensive use of chemical fertilizers has increasingly highlighted issues related to soil structure and soil microorganisms. Organic amendments have been proven to be an effective means of improving soil structure and soil microorganisms. Therefore, this study investigated the response mechanisms of soil aggregates, microorganisms, and soil carbon pools to the addition of different organic materials in field trials. In this study, the addition of organic fertilizers significantly altered the nutrient content in the soil. Among them, the high-carbon-based fertilizer (CHB) significantly increased the soil pH, available phosphorus, and available potassium content compared to the control. Additionally, during the early growth stages, CHB treatment significantly enhanced the activities of soil sucrase, urease, catalase, and phosphatase. Compared to the CF group, the treatments of CMO(chemical fertilizer + mushroom residue organic fertilizer), CHB(chemical fertilizer + high carbon base fertilizer) and CBO(chemical fertilizer + bio-organic fertilizer) significantly increased the mechanical stability and the content of water-stable large aggregates (>2 mm) in the soil, and significantly enhanced the organic carbon content in the soil aggregates.Among them, the CMO treatment had the highest content of mechanically stable large aggregates (>2 mm). Compared to the CF group, CHB and CBO treatments significantly altered the microbial community's life history strategy, shifting it toward a K-strategy, with significant positive correlations between K-strategy bacteria and aggregates. Furthermore, the microbial interaction networks under MO and HB treatments showed a clear trend toward increased complexity. SEM analysis revealed that the microbial life history strategy played a dominant role in the changes to soil aggregate structure. These results provide unique insights for further research on organic amendments to regulate soil microorganisms and soil structure.

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Tobacco is a special commercial crop that prefers potassium but not chlorine, and excessive chloride (Cl–) accumulation can cause toxicity. Here, we revealed that the structural characteristics of chloroplasts in tobacco leaves were significantly destroyed under high Cl– salinity, but not mitochondria. Large differences in leaf structure, MDA content, and antioxidant enzyme activities were observed for the treatment with highest chloride accumulation at the 14th day. Moreover, RNA-seq analysis of tobacco leaves exposed to high Cl– salinity revealed global changes in gene transcription levels. A total of 1360 DEGs involved in cell wall, lipid, starch, and secondary metabolism processes were unevenly distributed on chromosomes, and were mainly enriched for starch and sucrose metabolism, phenylpropanoid biosynthesis, ribosome and ribosome biogenesis, protein processing in the endoplasmic reticulum, and plant hormone signal transduction pathways. Overall, our study provides valuable insights for further research on the mechanism underlying Cl– salinity and salt-tolerant tobacco development.

AbstractBiochar and green manure have been widely applied in agricultural production and are important means to achieve sustainable agriculture. However, there is limited research systematically and comprehensively exploring the response of soil microbiota and the changes in soil metabolomics after the addition of two different carbon source amendments to the soil, and the differential mechanisms of soil metabolomics between them remain unclear. In this study, a long-term field experiment (initiated in 2019) was conducted to investigate the effects of biochar and green manure application on soil nutrients and soil functions driven by soil microbes. Compared to the pure fertilizer treatment, biochar increased soil total carbon by 14.54% to 27.04% and soil available potassium by 4.67% to 27.46%. Ryegrass significantly increased soil available phosphorus and organic matter. Under different fertilization regimes, the ecological niches of soil microbes changed significantly. Network analysis revealed that long-term ryegrass returning reduced the complexity of soil microbial networks. Ryegrass and biochar increased dispersal limitation in fungal assemblages (reaching 93.33% and 86.67%, respectively), with biochar particularly enhancing variable selection in bacterial assemblages (accounting for 53.33%). Variation partitioning analysis based on redundancy analysis indicated that humic substances had the highest explanatory power for microbial community variation, with humic substances explaining 38.49% of bacteria and 52.19% of fungi variation. The ryegrass treatment mainly changed the abundance of carbohydrates (CH), amines (AM), c (AH), and lipids (LP), while the BC treatment mainly altered the abundance of organic acids (AC), amines (AM), and carbohydrates (CH). Meanwhile, both treatments significantly reduced the bisphenol A, one of the soil pollutants. Ryegrass incorporation significantly increased the abundance of genes related to soil C, N, P, and S cycling, especially genes involved in carbon decomposition, while biochar significantly enhanced the abundance of nitrogen fixation genes nifH and Hao in soil. Random forest model results indicated that carbohydrates, alcohols, aromatics (AR), and ester (ES) were the main categories of metabolites in soil influenced by differential microbes, and Finegoldia served as a common important metabolic driving species. In summary, this study reveals the processes of soil function, microbial community succession, and metabolism driven by ryegrass and biochar, providing important insights for optimizing soil management and improving soil quality. Graphical Abstract

Organic material inputs are recommended to increase soil fertility and crop growth, but organic amendments may also increase carbon (C) emissions. A field experiment was conducted to comprehensively evaluate the effects of different organic amendments on soil respiration and the net ecosystem carbon budget (NECB) in a successive tobacco cultivation system. The experiment included five treatments: no fertilizer (NF), only chemical fertilizer with nitrogen, phosphorus and potassium (NPK), NPK plus ryegrass as green manure (NPKG), NPK plus wheat straw (NPKS) and NPK plus biochar (NPKB). Compared with the NPK treatment, organic amendments significantly improved the leaf yield and quality. The NPKG, NPKS and NPKB treatments significantly increased the cumulative emissions of carbon dioxide (CO2) from microbial respiration (Rh) and total respiration (Rs) during the growing season. Furthermore, the NPKG and NPKS treatments significantly increased the cumulative CO2 efflux from root respiration (Ra) by 25.2 and 21.4 % in 2020 and by 35.2 and 37.7 % in 2021, respectively. The NPKG treatment significantly decreased the mean temperature sensitivity (Q10) of Rh during the growing season in 2021, whereas the NPKB treatment increased the Q10 values of Ra and Rh during the fallow season. The Ra and Rh were positively correlated with root biomass at 0-90 days after transplanting and soil labile C concentrations, respectively. The annual NECB values of the NF and NPK treatments were both negative. However, the NPKG, NPKS and NPKB treatments significantly increased the annual NECB, and the values were 0.37, 0.11 and 0.73 t C ha-1, respectively. Our results indicate that a combination of chemical fertilization, ryegrass incorporation and application of wheat straw or biochar is an effective practice to promote plant growth and soil C sequestration in successively planted tobacco farmland.

Abstract Background Se (selenium) pollution is an emerging environmental concern. Excessive Se induces phytotoxicity. The endogenous H2S (hydrogen sulfide) was involved in plant adaptation to Se stress, but the signaling player of H2S remains unclear. Methods The study was conducted in a hydroponic system with different chemicals added to the treatment solution. Fluorescent tracking was performed to detect endogenous signaling molecules in plant tissues. Physiological changes were determined based on pharmaceutics and histochemical experiments. Gene expression was analyzed using qRT-PCR. The data were summarized using hierarchical cluster and Pearson correlation analysis. Results Se stress inhibited B. rapa growth (e.g. root elongation, shoot height, and seedling fresh weight and dry weight) in both dose- and time-dependent manners, with approximately 50% of root growth inhibition occurred at 20 µM Se. Se stress induced ROS (reactive oxygen species) accumulation and oxidative injury in B. rapa. Se exposure resulted in the upregulation of LCDs (L-cysteine desulfhydrase) and DCDs (D-cysteine desulfhydrase) encoding enzymes for H2S production in B. rapa at early stage of Se exposure, followed by downregulation of these genes at late stage. This was consistent with the change of endogenous H2S in B. rapa. Enhancing endogenous H2S level with NaHS (H2S donor) stimulates endogenous Ca2+ in B. rapa upon Se exposure, accompanied the attenuation of growth inhibition, ROS accumulation, oxidative injury, and cell death. The beneficial effects of H2S on detoxifying Se were blocked by decreasing endogenous Ca2+ level with Ca2+ channel blocker or Ca2+ chelator. Finally, hierarchical cluster combined with correlation analysis revealed that Ca2+ might acted as downstream of H2S to confer Se tolerance in B. rapa. Conclusion Ca2+ was an important player of H2S in the regulation of plant physiological response upon Se stress. Such findings extend our knowledge of the mechanism for Se-induced phytotoxicity. Graphical Abstract

明确广元市汉阳镇植烟土壤肥力状况,为该区烟草种植合理布局、平衡施肥和土壤保育提供数据支撑.以广元市汉阳镇植烟土壤为研究对象,采集25个土样,测定土壤pH、基础养分和矿质营养,利用模糊数学综合评价法计算土壤综合肥力得分(IFI).结果表明,该烟区土壤pH、有机质和全氮平均值分别为 6.98、19.13 g/kg和 1.48 g/kg,均处于中等水平,其中 72.00%土壤有机质含量高于15.00 g/kg;土壤有效磷、碱解氮和速效钾平均含量分别为30.41、46.79 和135.72 mg/kg,56%的土壤有效磷含量低于 10 mg/kg,68%土壤速效钾含量低于150 mg/kg,52%土壤IFI处于低水平.该烟区土壤Ca、Fe、Mn、P变异系数分别为39.94%、50.02%、65.79%、49.70%,均属于强变异;土壤Mg、Cu、Zn变异系数分别为31.30%、31.66%、32.71%,均属于中等变异,各指标变异系数表现为Mn＞P＞Ca＞Zn＞Cu＞Mg＞K.该烟区土壤各矿质元素之间大多呈显著或极显著相关,各理化指标间大多呈显著或极显著相关,各矿质元素与基础养分间相关性较差.

[Objective] This study aims to study the effect of acid stress on the seedling growth of different flue-cured tobacco varieties.[Methods] Using Yunyan 116 and Yunyan 87 as test materials, hydroponics was used to explore the effects of different acidity（pH4.0,pH5.0 and pH6.0） on the root system, leaf subcellular structure and physiological and biochemical indexes of flue-cured tobacco seedlings.[Result] Compared with the control（pH 6.0）, the root activity of flue-cured tobacco seedlings decreased, and the root development was slow or even inhibited; chloroplast and mitochondria were damaged to different degrees; MDA content, superoxide dismutase（SOD）activity, peroxidase（POD） activity and catalase（CAT） activity were increased under acid stress conditions. Compared with pH 5.0, the root length, root surface area, root volume and root tip number of flue-cured tobacco seedlings decreased after 6 days of acid treatment at pH value of 4.0; In the cristae, the content of MDA was increased, and the activities of SOD, POD and CAT were decreased. [Conclusion]Acid stress inhibited the root development of flue-cured tobacco seedlings, damaged leaf subcellular structure and antioxidant enzyme system With the decrease of pH, the degree of damage of flue-cured tobacco seedlings increased. Yunyan 116 was more affected by acid stress, while Yunyan 87 showed stronger acid resistance.

[Objective]　Leaf chlorophyll content (LCC) of flue-cured Tobacco is an important indicator for characterizing the photosynthesis, nutritional status, and growth of the crop. Tobacco is an important economic crop with leaves as the main harvest object, it is crucial to monitor its LCC. Hyperspectral data can be used for the rapid estimation of LCC in flue-cured tobacco leaves, making it of great significance and application value. The purpose of this study was to efficiently and accurately estimate the LCC of flue-cured tobacco during different growth stages. [Methods]　Zhongyan 100 was chose as the research object, five nitrogen fertilization levels were set. In each plot, three plants were randomly and destructively sampled, resulting in a total of 45 ground samples for each data collection. After transplanting, the reflectance data of the flue-cured tobacco canopy at six growth stages (32, 48, 61, 75, 89, and 109 d ) were collected using a UAV equipped with a Resonon Pika L hyperspectral. Spectral indices for the LCC estimation model of flue-cured tobacco were screened in two ways: (1) based on 18 published vegetation indices sensitive to LCC of crop leaves; (2) based on random combinations of any two bands in the wavelength range of 400‒1000 nm. The Difference Spectral Index (DSI), Ratio Spectral Index (RSI), and Normalized Spectral Index (NDSI) were calculated and plotted against LCC. The correlations between the three spectral indices and leaf LCC were calculated and plotted using contour maps. Five regression models, unary linear regression (ULR), multivariable linear regression (MLR), partial least squares regression (PLSR), support vector regression (SVR), and random forest regression (RFR), were used to estimate the chlorophyll content. A regression estimate model of LCC based on various combinations of spectral indices was eventually constructed by comparing the prediction accuracies of single spectral index models multiple spectral index models at different growth stages. [Results and Discussions] The results showed that the LCC range for six growth stages was 0.52‒2.95 mg/g. The standard deviation and coefficient of variation values demonstrated a high degree of dispersion in LCC, indicating differences in fertility between different treatments at the test site and ensuring the applicability of the estimation model within a certain range. Except for 109 d after transplanting, most vegetation indices were significantly correlated with LCC (p<0.01). Compared with traditional vegetation indices, the newly combined spectral indices significantly improved the correlation with LCC. The sensitive bands at each growth stage were relatively concentrated, and the spectral index combinations got high correlation with LCC were mainly distributed between 780‒ 940 nm and 520‒710 nm. The sensitive bands for the whole growth stages were relatively dispersed, and there was little difference in the position of sensitive band between different spectral indices. For the univariate LCC estimation model, the highest modeling accuracy was achieved using the newly combined Normalized Spectral Index and Red Light Ratio Spectral Index at 75 d after transplanting. The coefficients of determination (R2) and root mean square errors (RMSE) for the modeling and validation sets were 0.822, 0.814, and 0.226, 0.230, respectively. The prediction results of the five resgression models showed that the RFR algorithm based on multivariate data performed best in LCC estimation. The R2 and RMSE of the modeling set using data at 75 d after transplanting were 0.891 and 0.205, while those of the validation set reached 0.919 and 0.146. In addition, the estimation performance of the univariate model based on the whole growth stages dataset was not ideal, with R2 of 0.636 and 0.686, and RMSE of 0.333 and 0.304 for the modeling and validation sets, respectively. However, the estimation accuracy of the model based on multiple spectral parameters was significantly improved in the whole growth stages dataset, with R2 of 0.854 and 0.802, and RMSE of 0.206 and 0.264 for the modeling and validation sets of the LCC-RFR model, respectively. In addition, in the whole growth stages dataset, the estimation accuracy of the LCC-RFR model was better than that of the LCC-MLR, LCC-PLSR, and LCC-SVR models. Compared with the modeling set, R2 increased by 19.06%, 18.62%, and 29.51%, while RMSE decreased by 31.93%, 29.51%, and 28.24%. Compared with the validation set, R2 increased by 8.21%, 12.62%, and 8.17%, while RMSE decreased by 3.76%, 9.33%, and 4.55%. [Conclusions]　The sensitivity of vegetation indices (VIs) to LCC is closely connected to the tobacco growth stage, according to the results this study, which examined the reaction patterns of several spectral indices to LCC in flue-cured tobacco. The sensitivity of VIs to LCC at various growth stages is critical for crop parameter assessment using UAV hyperspectral photography. Five estimation models for LCC in flue-cured tobacco leaves were developed, with the LCC-RFR model demonstrating the greatest accuracy and stability. The RFR model is less prone to overfitting and can efficiently decrease outlier and noise interference. This work could provide theoretical and technological references for LCC estimate and flue-cured tobacco growth monitoring.

【Objective】The present paper aimed to study the impact of organic and inorganic combined application on the organic carbon composition, carbon bank management index and organic carbon functional group of tobacco planting soil in Wuxi county, so as to provide reference for improving the quality of tobacco planting soil and reasonable fertilization.【Method】Four treatments were set up under the condition of constant nitrogen input in field experiment: chemical fertilizer（CF）, chemical fertilizer with mushroom slag organic fertilizer（CMO）, chemical fertilizer with high carbon-based fertilizer（CHB）, and chemical fertilizer with biological organic fertilizer（CBO）.The effect of organic and inorganic application on soil carbon reservoir was studied by measuring total organic carbon and active carbon functional group structure using Fourier infrared spectrometry（FTIR）.【Result】（i） Compared with single organic fertilizer, the soil supplemented with organic fertilizer was slightly increased, and there was no significant difference between the treatments, significantly increased the output value on flue-cured tobacco leaf;（ii） The DOC, MBC content of the soil active carbon bank treated with organic fertilizer was significantly higher than that of single chemical fertilizer treatment.Among them, CMO treatment showed the largest increase in soil DOC content, thus being 67.13%, 12.84%, and 28.54% higher than CF, CHB, CBO, respectively.CBO treatment showed the most increase in soil MBC content, with soil MBC content increasing 42.32% compared to CF and CHB treatment showing 11.43% higher soil EOC compared to CF;（iii）Among the three organic fertilizers, the DOC distribution of DOC, CMO, CBO, EOC, and the carbon bank management index of CHB treatment was significantly greater than CF and CMO;（iv） The structure difference of each treated organic carbon functional group was small, which mainly included phenols, aromatic hydrocarbons, olefins and mesamides.The relative peak area at 1634 cm -1 was associated significantly positively with soil MBC content, and that at 468 cm -1 was associated significantly negatively with soil TOC content.【Conclusion】Compared with single organic fertilizer, soil organic residue organic fertilizer significantly improved soil DOC and MBC content and high carbon-based fertilizer significantly improved soil EOC content and carbon bank management index.Short-term organic and inorganic distribution had little impact on organic carbon functional groups.However, the peaks at 1634 and 468 cm -1 were significantly associated with the soil TOC and MBC content.At the same time, organic-inorganic fertilizer significantly increased the yield and output value of flue-cured tobacco.

The widespread and continuous cultivation of tobacco has led to soil degradation and reduced crop yields and quality. Green manure is an essential organic fertilizer that alleviates obstacles to continuous cultivation. However, the plant–soil microecological effects of green manure on flue-cured tobacco cultivation remain unclear. Thus, a positioning trail including two treatments, chemical fertilizer application only (treatment NPK) and chemical fertilizer application with turning ryegrass (treatment NPKG) was conducted, and the effect of ryegrass returning on the soil physicochemical properties, soil microbiome, crop yield, and quality of flue-cured tobacco in continuous cropping soil were investigated. Results showed that returning ryegrass to the field increased the thickness of soil humus layer from 13 cm to 15 cm, reduced the humus layer soil bulk density to 1.29 cm3/g. Ryegrass tilled and returned to the field increased soil organic matter content by 6.89–7.92%, increased rhizosphere soil available phosphorus content by 2.22–17.96%, and converted the soil non-exchangeable potassium into potassium that was available for plant absorption and utilization. Ryegrass tilling and returning to the field increased the potassium content of middle leaves of flue-cured tobacco by 7.69–10.07%, the increased potassium content in flue-cured tobacco was accompanied by increased total sugar, reducing sugar, and the ratio of reducing sugar to nicotine, which facilitated the harmonization of the chemical composition of cured tobacco leaves. Moreover, the increased number of markedly improved operational taxonomic units enhanced the complexity of the soil bacterial community and its compactness after ryegrass tillage and their return to the field. The available potassium, available phosphorus, total potassium content, pH, and sampling period of the rhizosphere soil had considerable effects on the rhizosphere microbial. Ryegrass tilling and returning to the field changed the soil microbiome, which increased the abundance of bulk soil Proteobacteria, rhizosphere soil Fibrobacterota, and microbes with anti-pathogen activity (Lysobacteria, Sphingomonas, Chaetomium, and Minimedusa); and reduced the abundance of pathogenic fungi Neocosmospore genus in the soil. In brief, ryegrass returned to the field, improved soil microecology and restored soil nutrients, and established a new dynamic balance of soil ecology, thereby improving the quality of cultivated land and the quality of flue-cured tobacco.

In order to offer a theoretical foundation for the creation of scientific fertilization plans for tobacco planting in this study, descriptive statistics, the correlation coefficient approach, and fuzzy comprehensive evaluation method were used to examine 418 soil samples from tobacco-planted fields in Sichuan Huidong,Henan Luoyang and southern Anhui. The results showed that, the pH of tobacco-planted soils in Huidong ranged from 5.36 to 8.66, and 77.88% of the samples soil pH above 7.50. The organic matter content was generally low.The 67% of soil had the content of alkali-hydrolyzable nitrogen in samples was below 90mg/kg. The content of total nitrogen was moderate, and the contents of available phosphorus and potassium were rich. The pH of tobacco-planted soils in Luoyang was alkalescence, and the contents of organic matter and alkali-hydrolyzable nitrogen were deficient, more than 70% of the soil were at the level of “deficiency” or below. The contents of total nitrogen and available phosphorus were moderate, with coefficient variation of available phosphorus was79.38%. The available potassium content was rich. In the tobacco-planted soils of southern Anhui, the pH and contents of organic matter and total nitrogen were moderate. Moreover, the content of alkali-hydrolyzable nitrogen was high, and the contents of available potassium was deficient, with 82.82% of the soil samples below150mg/kg. The content of available phosphorus was rich but heterogeneity was strong. There were significant differences（P ＜ 0.05） in the comprehensive fertility index（IFI） of tobacco-planted soils in the three ecological regions, southern Anhui（0.69） ＞ Huidong（0.52） ＞ Luoyang（0.43）. Among them, 75.76% of the soil IFI in southern Anhui tobacco area was above grade II, the proportion of grade II and grade III in Huidong tobacco area was 31.73% and 46.15%, respectively, while nearly 50% of the soil in Luoyang tobacco area was grade IV. The alkaline fertilizer should be reduced, and the soil pH should be adjusted by soil amelioration in the tobaccoplanted areas of Huidong and Luoyang, increasing soil organic matter and available nitrogen content. Potassium fertilizer should be appropriately increased to meet the needs of tobacco growth and development in southern Anhui.

AbstractBackground In the context of increasing global soil salinization, reducing the damage caused by soil salinity and improving the salt tolerance of crops has become an urgent issue in modern agriculture. However, few studies have reported on the different salt tolerance performances of different varieties of tobacco crops under salinity stress due to the gradual evolution of geographical separation. Results The aim of this study was to investigate the different performances of Basma (Spice tobacco) and K326(Flue-cured tobacco) under NaCl stress in order to find a more effective method to improve salt tolerance in tobacco. In this study, Basma and K326 were treated with a 150 mM NaCl solution, and a blank control treatment was included. Physiological indicators such as root length growth, antioxidant enzyme activity, ion concentration, hormone content, and related gene expression were measured. In the plate medium, the root length growth of K326 under NaCl stress treatment was only 60% of that of Basma, which had higher salt tolerance. The reasons for this difference mainly concentrated on three aspects. Firstly, in Basma, the accumulation of reactive oxygen species caused by salt stress is scavenged by increasing the activity of antioxidant enzymes, and the damage to the plasma membrane is decreased. Secondly, the ion toxicity caused by salt stress is relieved by increasing the expression of theSOS1gene in the roots, which can balance the intracellular osmotic pressure and maintain ion balance. Lastly, the expression ofPIN4, a key gene in growth hormone transport, is upregulated to obtain antigravity transport of growth hormone and increase IAA content in roots, promoting root growth. Conclusion In this study, it was found that oriental tobacco Basma demonstrated greater resistance to salt stress compared to flue-cured tobacco K326. This was primarily observed in the root growth and activity, as well as in significant differences in physiological indexes such as active oxygen accumulation, ion distribution regionalization, and hormone content distribution. The experimental results suggest that Basma achieves strong salt tolerance through three main mechanisms: increasing the activity of antioxidant enzymes to eliminate ROS accumulation, expressingSOS1to adapt to ion regionalization under salt stress, regulating sodium-potassium ratio, and increasing the expression of IAA polar transporter genePIN4to maintain a balance of IAA content.

选取邓州烟区2018—2021年烤烟种植规模、气候、经济性状等因素,并在2021年抽取邓州5个主要植烟乡镇17户职业烟农为研究对象,对邓州市近年烤烟种植整体情况进行调查,分析了影响邓州地区烤烟经济效益的主要生产因素.结果表明,邓州地区光热雨水充足,适合烟草生长的生态条件.该地区主要存在烟草生产防灾体系不完善、烟农雇用人工困难且人工成本逐年增长、部分烟农对烟草施肥不合理等影响烤烟生产发展的因素.为了进一步优化邓州烤烟生产技术,应加强烟农防灾意识教育,成熟期防止采收过晚,加强多雨田间下烤烟烘烤技术能力;烟站主动与当地雇工协会开展协商合作;烟农应提高种植素养,对烟田采取因地施肥等措施,通过增加烤烟产值,减少烤烟生产成本来提高烤烟经济效益,维持邓州烟草生产稳步发展.