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Oats (Avena sativa L.) are a staple grain and forage crop with substantial market demand. In China, they are the second most-imported forage grass, only after alfalfa (Medicago sativa L.). Enhancing the salt tolerance of oats to facilitate their cultivation in saline areas can thereby increase forage yield and promote the utilization of saline land, which constitutes an important reserve land resource in China. This study aimed to identify the bacterial strain Bacillus sp. LrM2 (hereafter referred to as strain LrM2) to determine its precise species-level classification and evaluate its effects on oat photosynthesis and growth under salt stress through indoor pot experiments. The results indicated that strain LrM2, capable of urease production and citrate utilization, was identified as Bacillus mojavensis. The strain LrM2 had a positive effect on shoot and root growth of oats under 100 mM NaCl stress conditions. Strain LrM2 inoculation modulated osmotic stress in oats under 100 mM NaCl stress by significantly increasing soluble sugar and decreasing proline content in leaves. It inhibited Na+ uptake and promoted K+ absorption in the roots, thereby reducing Na+ translocation to the leaves and mitigating ionic toxicity. Inoculation with strain LrM2 significantly increased photosynthetic pigment content (chlorophyll a, carotenoids), improved gas exchange parameters (stomatal conductance, transpiration rate, net rate of photosynthesis), enhanced PSII photochemical efficiency (maximum quantum yield, coefficient of photochemical quenching, actual photosynthetic efficiency of PSII, electron transfer rate), and reduced the quantum yield of non-regulated energy dissipation. These improvements, coupled with increased relative water content and instantaneous water use efficiency, thereby collectively enhanced the overall photosynthetic performance. In conclusion, strain LrM2 represents a promising bio-resource for mitigating salt stress and promoting growth in oats, with direct applications for developing novel biofertilizers and sustainable agricultural strategies.

As the polyploidy progenitor of modern sugarcane, Saccharum spontaneum is considered to be a valuable resistance source to various biotic and abiotic stresses. However, little has been reported on the mechanism of drought tolerance in S. spontaneum . Herein, the physiological changes of S. spontaneum GXS87-16 at three water-deficit levels (mild, moderate, and severe) and after re-watering during the elongation stage were investigated. RNA sequencing was utilized for global transcriptome profiling of GXS87-16 under severe drought and re-watered conditions. There were significant alterations in the physiological parameters of GXS87-16 in response to drought stress and then recovered differently after re-watering. A total of 1569 differentially expressed genes (DEGs) associated with water stress and re-watering were identified. Notably, the majority of the DEGs were induced by stress. GO functional annotations and KEGG pathway analysis assigned the DEGs to 47 GO categories and 93 pathway categories. The pathway categories were involved in various processes, such as RNA transport, mRNA surveillance, plant hormone signal transduction, and plant-pathogen interaction. The reliability of the RNA-seq results was confirmed by qRT-PCR. This study shed light on the regulatory processes of drought tolerance in S. spontaneum and identifies useful genes for genetic improvement of drought tolerance in sugarcane.

Allelopathy plays a major role in agricultural production, influencing plant protection, crop yield, and crop rotation systems. This study investigated the effects of root exudates on 3105c alfalfa (Medicago sativa) seeds and seedlings to identify crops with strong and weak allelopathic potential. The results revealed that corn (Zea mays L.) (T1) exhibited the strongest allelopathic effects, whereas soybean (Glycine max (Linn.) Merr.) (T10) exhibited the weakest effects. T1 promoted seed germination by increasing radicle length and the simple vitality index. Both T1 and T10 promoted 3105c seedling growth and enhanced antioxidant capacity, albeit through different mechanisms. T1 primarily increased antioxidant capacity by elevating ascorbate and dehydroascorbate levels while reducing malondialdehyde content. In contrast, T10 enhanced antioxidant capacity by increasing soluble sugar and protein levels via hydroxyl free radical inhibition. These findings demonstrate that the allelopathic properties of corn effectively promote alfalfa growth by enhancing seed germination and improving physiological stress resistance.

Background Rhizome is vital for carbon and nitrogen metabolism of the whole plant. However, the effect of carbon and nitrogen in the rhizome on rhizome expansion remains unclear. Results Three wild Kentucky bluegrass ( Poa pratensis L.) germplasms with different rhizome expansion capacity (strong expansion capacity, ‘YZ’; medium expansion capacity, ‘WY’; and weak expansion capacity, ‘AD’) were planted in the field and the rhizomes number, tiller number, rhizome dry weight, physiological indicators and enzyme activity associated carbon and nitrogen metabolisms were measured. Liquid chromatography coupled to mass spectrometry (LC-MS) was utilized to analyze the metabolomic of the rhizomes. The results showed that the rhizome and tiller numbers of the YZ were 3.26 and 2.69-fold of that of the AD, respectively. The aboveground dry weight of the YZ was the greatest among all three germplasms. Contents of soluble sugar, starch, sucrose, NO 3 − -N, and free amino acid were significantly higher in rhizomes of the YZ than those of the WY and AD ( P  < 0.05). The activities of glutamine synthetase (GS), glutamate dehydrogenase (GDH) and sucrose phosphate synthase (SPS) of the YZ were the highest among all three germplasm, with values of 17.73 A·g − 1  h − 1 , 5.96 µmol·g − 1  min − 1 , and 11.35 mg·g − 1  h − 1 , respectively. Metabolomics analyses revealed that a total of 28 differentially expressed metabolites (DEMs) were up-regulated, and 25 DEMs were down-regulated in both comparison groups (AD vs. YZ group and WY vs. YZ group). Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis demonstrated that metabolites related to histidine metabolism, tyrosine metabolism, tryptophan metabolism, and phenylalanine metabolism were associated with rhizomes carbon and nitrogen metabolism. Conclusions Overall, the results suggest that soluble sugar, starch, sucrose, NO 3 − -N, and free amino acid in rhizome are important to and promote rhizome expansion in Kentucky bluegrass, while tryptamine, 3-methylhistidine, 3-indoleacetonitrile, indole, and histamine may be key metabolites in promoting carbon and nitrogen metabolism of rhizome.

Livestock manure is a major source of environmental pollution and greenhouse gas emissions if improperly managed. Aerobic composting represents a sustainable approach to manure recycling that can stabilize organic matter, mitigate carbon loss, and recover nutrients for agricultural use. In this study, sheep manure was mixed with sawdust to optimize the carbon-to-nitrogen (C/N) ratio and enhance aeration, and the mixture was subjected to aerobic composting with a cellulose-degrading microbial inoculant. To rigorously evaluate the biological effects, a control treated with sterilized inoculant was included to eliminate nutrient inputs from the carrier matrix. The inoculant significantly improved composting performance by extending the thermophilic phase by five days and reducing the C/N ratio to 19.8 on day 32, thereby shortening the composting cycle. Moreover, microbial inoculation enhanced nutrient retention, resulting in a 20.14% increase in total nutrient content, while the germination index (GI) reached 89.75%, indicating high compost maturity and reduced phytotoxicity. Microbial community analysis revealed that cellulose-degrading inoculants significantly altered microbial richness and diversity and accelerated community succession. Redundancy analysis (RDA) and hierarchical partitioning analysis showed that total organic carbon (TOC) and GI were the main environmental drivers of bacterial community dynamics, whereas pH and GI primarily regulated fungal community succession. These findings suggest a strong link between compost maturity and microbial community restructuring. This study demonstrates that cellulose-degrading microbial inoculation accelerates the composting of sheep manure, enhances organic matter degradation, and improves fertilizer efficiency while reducing the phytotoxicity of the final product.

Water stress causes considerable yield losses in sugarcane. To investigate differentially expressed genes under water stress, a pot experiment was performed with the sugarcane variety GT21 at three water-deficit levels (mild, moderate and severe) during the elongation stage and gene expression was analyzed using microarray technology. Physiological parameters of sugarcane showed significant alterations in response to drought stress. Based on the expression profile of 15,593 sugarcane genes, 1,501 (9.6%) genes were differentially expressed under different water-level treatments; 821 genes were upregulated and 680 genes were downregulated. A gene similarity analysis showed that approximately 62.6% of the differentially expressed genes shared homology with functional proteins. In a Gene Ontology (GO) analysis, 901 differentially expressed genes were assigned to 36 GO categories. Moreover, 325 differentially expressed genes were classified into 101 pathway categories involved in various processes, such as the biosynthesis of secondary metabolites, ribosomes, carbon metabolism, etc. In addition, some unannotated genes were detected; these may provide a basis for studies of water-deficit tolerance. The reliability of the observed expression patterns was confirmed by RT-PCR. The results of this study may help identify useful genes for improving drought tolerance in sugarcane.

High‐frequency vibration in piping systems poses a significant risk of fatigue failure. While applying high‐damping alloy layers is an effective mitigation strategy, optimizing their layout is crucial. However, the localized application of damping materials induces significant nonproportional damping, a phenomenon presenting a major challenge for dynamic topology optimization, as conventional methods are either inaccurate or computationally prohibitive. This study overcomes this challenge by introducing a novel topology optimization framework that accurately and efficiently handles nonproportional damping effects. The core of the framework is the integration of an iterative modal superposition method for dynamic analysis, enabling its effective use within an optimization loop. This methodology was applied to optimize an M2052 Mn–Cu damping layer on a steel pipe to suppress shell vibration in the 1200–1400 Hz band. Numerical results show that the proposed method yields a physically rational layout in high modal strain energy regions, unlike the simplified proportional damping assumption. Experimental validation confirmed the method’s effectiveness: the optimized design, using 70% less material, achieved peak acceleration reductions (up to 84.32%) comparable to a fully covered configuration, highlighting its significant engineering value.

Background Drought limits crop growth and is an important issue in commercial sugarcane ( Saccharum officinarum ) production. Drought tolerance in sugarcane induced by endophytic nitrogen-fixing bacteria is a complex biological process that ranges from altered gene expression and cellular metabolism to changes in growth and productivity. Results In this study, changes in physiological features and transcriptome related to drought tolerance in sugarcane conferred by the Burkholderia endophytic nitrogen-fixing bacterial strain GXS16 were investigated. Sugarcane samples inoculated with GXS16 exhibited significantly higher leaf relative water content than those without GXS16 inoculation during the drought stages. Sugarcane treated with GXS16 had lower levels of H 2 O 2 and higher levels of abscisic acid than sugarcane not treated with GXS16 in the non-watering groups. Transcriptomic analysis of sugarcane roots identified multiple differentially expressed genes between adjacent stages under different treatments. Moreover, both trend and weighted correlation network analyses revealed that carotenoid biosynthesis, terpenoid backbone biosynthesis, starch and sucrose metabolism, and plant hormone signal transduction strongly contributed to the drought-tolerant phenotype of sugarcane induced by GXS16 treatment. Accordingly, a gene regulatory network including four differentially regulated genes from carotenoid biosynthesis ( crtB , crtZ , ZEP and CYP707A ) and three genes from terpenoid backbone biosynthesis ( dxs , dxr , and PCME ) was constructed. Conclusions This study provides insights into the molecular mechanisms underlying the application of GXS16 treatment to enhance drought tolerance in sugarcane, which will lay the foundation for crop development and improve productivity.

This paper presents an experimental investigation on the stress–strain behavior and the damage mechanism of polypropylene fiber reinforced concrete (PFRC) under monotonic and cyclic compression. Fifty-four specimens for different fiber volume fractions and aspect ratios were tested. Acoustic emission (AE) technique was used to monitor the damage progression. The damage mechanism of concrete was analyzed based on the AE parametric analysis. The results show that the incorporation of polypropylene fiber (PF) has a positive effect on the monotonic and cyclic behaviors of concrete, especially for the post-cracking branch. The toughness and ultimate strain are enhanced and the performance degradation in terms of elastic stiffness and strength is alleviated by the addition of PF. However, PF has little influences on the plastic strain, and the damage process of concrete is mainly driven by the envelope strain. The effect of fiber volume fraction on the cyclic behavior of concrete shows more pronounced than that of aspect ratio. In addition, it is found from AE results that the damage, closely related to AE events, has a quick evolution just after the peak stress, with the AE hits having a concentrated release. The total amount of AE hits increases with increasing fiber volume fraction due to fiber pullout and sliding, while the concrete with fiber aspect ratio of 280 reaches the largest amount. Meanwhile, as substantiated by AE, the failure of PFRC shows an obvious shear mode, with shear cracks dominating the damage progression. Finally, a damage elasto-plastic model is developed to predict the monotonic and cyclic responses of PFRC and the prediction yields a fairly close estimation with experimental results.

Background Sugarcane growth and yield are complex biological processes influenced by endophytic nitrogen-fixing bacteria, for which the molecular mechanisms involved are largely unknown. In this study, integrated metabolomic and RNA-seq were conducted to investigate the interaction between an endophytic bacterial strain, Burkholderia GXS16, and sugarcane tissue culture seedlings. Results During treatment, the colonization of GXS16 in sugarcane roots were determined, along with the enhanced activities of various antioxidant enzymes. Accordingly, 161, 113, and 37 differentially accumulated metabolites (DAMs) were found in the pairwise comparisons of adjacent stages. In addition, transcriptomic analyses obtained 1,371 (IN-vs-CN), 1,457 (KN-vs-IN), and 365 (LN-vs-KN) differentially expressed genes (DEGs), which were mainly involved in the pathways of glutathione metabolism and carbon metabolism. We then assessed the pattern of metabolite accumulation and gene expression in sugarcane during GXS16 colonization. The results showed that both DAMs and DGEs in the upregulated expression profiles were involved in the flavonoid biosynthesis pathway. Overall, p-coumaroyl-CoA in sugarcane roots transferred into homoeriodictyol chalcone and 5-deoxyleucopelargonidin due to the upregulation of the expression of genes shikimate O-hydroxycinnamoyltransferase (HCT), chalcone synthase (CHS), and phlorizin synthase (PGT1). Conclusions This study provides insights into the gene regulatory mechanisms involved in the interaction between GXS16 and sugarcane roots, which will facilitate future applications of endophytic nitrogen-fixing bacteria to promote crop growth.