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Abstract Grain-filling of rice spikelets (particularly for the later flowering inferior spikelets) is an important characteristic that affects both quality and yield. Rice ratooning technology is used to cultivate a second crop from dormant buds that sprout from stubble left after the first harvest. This study used two rice varieties, the conventional indica rice ‘Jinhui 809’ and the hybrid indica-japonica rice ‘Yongyou 1540’, to assess the impact of rice ratooning on grain-filling. The results indicated that the grain-filling process in inferior spikelets of ratoon season rice (ISR) showed significant improvement compared to inferior spikelets of main crop (late season) rice (ISL). This improvement was evident in the earlier onset of rapid grain-filling, higher seed-setting percentage, and improved grain quality. A label-free quantitative proteomic analysis using mass spectrometry identified 1724 proteins with significant abundance changes, shedding light on the molecular mechanisms behind the improved grain-filling in ISR. The functional analysis of these proteins indicated that ratooning stimulated the metabolic processes of sucrose-starch, trehalose, and hormones in rice inferior spikelets, leading to enhanced enzyme activities related to starch synthesis, elevated concentrations of trehalose-6-phosphate (T6P), indole-3-acetic acid (IAA) and zeatin riboside (ZR) during the active grain-filling phase. This research highlighted the importance of the GF14f protein as a key regulator in the grain-filling process of ISR. It revealed that GF14f transcriptional and protein levels declined more rapidly in ISR compared to ISL during grain-filling. Additionally, the GF14f-RNAi plants specific to the endosperm exhibited improved quality in inferior spikelets. These findings suggest that the enhancement of starch synthesis, increased levels of IAA, ZR, and T6P, along with the rapid decrease in GF14f protein, play a role in enhancing grain-filling in ratoon season rice.

Additive manufacturing (AM) presents promising prospects for the production of laser ceramics, particularly those with composite structures. However, achieving uniform density within these ceramics is a formidable challenge, primarily due to the intrinsic limitations of uneven forces within the mold. This paper introduces the Density Spatiotemporal Evolution (DSE) model, a novel predictive tool designed to map the density distribution in laser ceramics throughout the AM process. The DSE model elucidates that ceramic density increases in proximity to the indenter and mold wall and reveals an oscillatory pattern in particle density during pressing. These insights have been corroborated through experimental measurements and simulation analyses. Leveraging the DSE model and a Simulated Annealing (SA) algorithm, an innovative AM process is proposed. The pressure exerted to each layer of ceramics is gradient distributed, i.e. 18, 18.36, 19.31, 22.08, 33.02 MPa. Preliminary experimental results indicate a significant enhancement in density uniformity, with an improvement of up to 45% in the optimized ceramics. The advancement promises to yield more homogeneous ceramic materials, potentially accelerating the progress of high-energy laser technology.

Abstract The small heat shock proteins (sHSPs) are important components in plant growth and development, and stress response. However, a systematical understanding of the sHSP family is yet to be reported in five diploid Gossypium species. In this study, 34 GlsHSPs, 36 GrsHSPs, 37 GtsHSPs, 37 GasHSPs, and 38 GhesHSPs were identified in Gossypium longicalyx, Gossypium raimondii, Gossypium turneri, Gossypium arboreum, and Gossypium herbaceum, respectively. These sHSP members can be clustered into 10 subfamilies. Different subfamilies had different member numbers, motif distributions, gene structures, gene duplication events, gene loss numbers, and cis‐regulatory elements. Besides, the paleohexaploidization event in cotton ancestor led to expanding the sHSP members and it was also inherited by five diploid Gossypium species. After the cotton ancestor divergence, the sHSP members had the relatively conserved evolution in five diploid Gossypium species. The comprehensive evolutionary history of the sHSP family was revealed in five diploid Gossypium species. Furthermore, several GasHSPs and GhesHSPs were important candidates in plant growth and development, and stress response. These current findings can provide valuable information for the molecular evolution and further functional research of the sHSP family in cotton.

Integrated photonic devices are essential for on-chip optical communication, optical-electronic systems, and quantum information sciences. To develop a high-fidelity interface between photonics in various frequency domains without disturbing their quantum properties, nonlinear frequency conversion, typically steered with the quadratic (χ2) process, should be considered. Furthermore, another degree of freedom in steering the spatial modes during the χ2 process, with unprecedent mode intensity is proposed here by modulating the lithium niobate (LN) waveguide-based inter-mode quasi-phase-matching conditions with both temperature and wavelength parameters. Under high incident light intensities (25 and 27.8 dBm for the pump and the signal lights, respectively), mode conversion at the sum-frequency wavelength with sufficient high output power (−7 – 8 dBm) among the TM01, TM10, and TM00 modes is realized automatically with characterized broad temperature (ΔT ≥ 8 °C) and wavelength windows (Δλ ≥ 1 nm), avoiding the previous efforts in carefully preparing the signal or pump modes. The results prove that high-intensity spatial modes can be prepared at arbitrary transparent wavelength of the χ2 media toward on-chip integration, which facilitates the development of chip-based communication and quantum information systems because spatial correlations can be applied to generate hyperentangled states and provide additional robustness in quantum error correction with the extended Hilbert space.

Abstract Crop roots are colonized by large numbers of microorganisms, collectively known as the root-microbiome, which modulate plant growth, development and contribute to elemental nutrient uptake. In conditions of nitrogen limitation, the over-expressed Calcineurin B-like interacting protein kinase 2 (OsCIPK2) gene with root-specific promoter (RC) has been shown to enhance growth and nitrogen uptake in rice. Analysis of root-associated bacteria through high-throughput sequencing revealed that OsCIPK2 has a significant impact on the diversity of the root microbial community under low nitrogen stress. The quantification of nifH gene expression demonstrated a significant enhancement in nitrogen-fixing capabilities in the roots of RC transgenetic rice. Synthetic microbial communities (SynCom) consisting of six nitrogen-fixing bacterial strains were observed to be enriched in the roots of RC, leading to a substantial improvement in rice growth and nitrogen uptake in nitrogen-deficient soils. Forty and twenty-three metabolites exhibiting differential abundance were identified in the roots and rhizosphere soils of RC transgenic rice compared to wild-type (WT) rice. These findings suggest that OSCIPK2 plays a role in restructuring the microbial community in the roots through the regulation of metabolite synthesis and secretion. Further experiments involving the exogenous addition of citric acid revealed that an optimal concentration of this compound facilitated the growth of nitrogen-fixing bacteria and substantially augmented their population in the soil, highlighting the importance of citric acid in promoting nitrogen fixation under conditions of low nitrogen availability. These findings suggest that OsCIPK2 plays a role in enhancing nitrogen uptake by rice plants from the soil by influencing the assembly of root microbial communities, thereby offering valuable insights for enhancing nitrogen utilization in rice cultivation.

Agronomic measures are the key to promote the sustainable development of ratoon rice by reducing the damage from mechanical crushing to the residual stubble of the main crop, thereby mitigating the impact on axillary bud sprouting and yield formation in ratoon rice. This study used widely recommended conventional rice Jiafuzhan and hybrid rice Yongyou 2640 as the test materials to conduct a four-factor block design field experiment in a greenhouse of the experimental farm of Fujian Agricultural and Forestry University, China from 2018 to 2019. The treatments included fertilization and no fertilization, alternate wetting and drying irrigation and continuous water flooding irrigation, and plots with and without artificial crushing damage on the rice stubble. At the same time, a 13C stable isotope in-situ detection technology was used to fertilize the pot experiment. The results showed significant interactions among varieties, water management, nitrogen application and stubble status. Relative to the long-term water flooding treatment, the treatment with sequential application of nitrogen fertilizer coupled with moderate field drought for root-vigor and tiller promotion before and after harvesting of the main crop, significantly improved the effective tillers from low position nodes. This in turn increased the effective panicles per plant and grains per panicle by reducing the influence of artificial crushing damage on rice stubble and achieving a high yield of the regenerated rice. Furthermore, the partitioning of 13C assimilates to the residual stubble and its axillary buds were significantly improved at the mature stage of the main crop, while the translocation rate to roots and rhizosphere soil was reduced at the later growth stage of ratooning season rice. This was triggered by the metabolism of hormones and polyamines at the stem base regulated by the interaction of water and fertilizer at this time. We therefore suggest that to achieve a high yield of ratoon rice with low stubble height under mechanized harvesting, the timely application of nitrogen fertilizer is fundamental, coupled with moderate field drying for root-vigor preservation and tiller promotion before and after the mechanical harvesting of the main crop.

The isolation and identification of plant growth-promoting endophytic bacteria (PGPEB) from Achyranthes bidentata roots have profound theoretical and practical implications in ecological agriculture, particularly as bio-inoculants to address challenges associated with continuous monoculture. Our research revealed a significant increase in the abundance of these beneficial bacteria in A. bidentata rhizosphere soil under prolonged monoculture conditions, as shown by bioinformatics analysis. Subsequently, we isolated 563 strains of endophytic bacteria from A. bidentata roots. Functional characterization highlighted diverse plant growth-promoting traits among these bacteria, including the secretion of indole-3-acetic acid (IAA) ranging from 68.01 to 73.25 mg/L, phosphorus and potassium solubilization capacities, and antagonistic activity against pathogenic fungi (21.54%−50.81%). Through 16S rDNA sequencing, we identified nine strains exhibiting biocontrol and growth-promoting potential. Introduction of a synthetic microbial consortium (SMC) in pot experiments significantly increased root biomass by 48.19% in A. bidentata and 27.01% in replanted Rehmannia glutinosa. These findings provide innovative insights and strategies for addressing continuous cropping challenges, highlighting the practical promise of PGPEB from A. bidentata in ecological agriculture to overcome replanting obstacles for non-host plants like R. glutinosa, thereby promoting robust growth in medicinal plants.

Abstract Background In paddy fields, the noxious weed barnyard grass secretes 2,4-dihydroxy-7-methoxy-2H-1,4-benzoxazin-3(4H)-one (DIMBOA) to interfere with rice growth. Rice is unable to synthesize DIMBOA. Rice cultivars with high or low levels of allelopathy may respond differently to DIMBOA. Results In this study, we found that low concentrations of DIMBOA (≤ 0.06 mM) promoted seedling growth in allelopathic rice PI312777, while DIMBOA (≤ 0.08 mM) had no significant influence on the nonallelopathic rice Lemont. DIMBOA treatment caused changes in the expression of a large number of glutathione S-transferase (GST) proteins, which resulting in enrichment of the glutathione metabolic pathway. This pathway facilitates plant detoxification of heterologous substances. The basal levels of GST activity in Lemont were significantly higher than those in PI312777, while GST activity in PI312777 was slightly induced by increasing DIMBOA concentrations. Overexpression of GST genes (Os09g0367700 and Os01g0949800) in these two cultivars enhanced rice resistance to DIMBOA. Conclusions Taken together, our results indicated that different rice accessions with different levels of allelopathy have variable tolerance to DIMBOA. Lemont had higher GST activity, which helped it tolerate DIMBOA, while PI312777 had lower GST activity that was more inducible. The enhancement of GST expression facilitates rice tolerance to DIMBOA toxins from barnyard grass root exudates.

Continuous improvement of rice breeding methods and consecutive innovation of cultivation technology in China has resulted in a significant increase in the proportion of ratooning rice planting mode. Therefore, ratoon rice has become a prominent rice planting pattern in China. This study reviewed the current situation and prospects regarding ratoon rice's high-yielding formation and physiological mechanisms. We focused on four key aspects: screening and breeding of ratoon rice cultivars, classification, determining suitable stubble height, and water and fertilizer management considerations for rice ratooning. Additionally, we delved into characteristics related to dry matter production and allocation in ratoon rice. This study also explored the regenerative activity and root vigor within the rhizosphere zone while evaluating their relationship with micro-ecological characteristics specific to ratoon rice. We propose the implementation of proper regulation precise over the rhizosphere environment aimed at scaling up sustainable progress in the realm of research, aimed at expanding the utilization of mechanized low-cut stubbles (< 25 cm) for the advancement of the ratoon rice sector. This process is essential for stimulating the availability of vital soil nutrients to promote timely sprouting axillary buds while facilitating tiller growth coordination along with bud elongation, collectively referred to as achieving 'four highs' (high regeneration coefficient, high effective panicle percentage, high harvest index, and high daily yield) alongside 'one low' (low carbon emission) for safe and sustainable development purposes. Furthermore, we have also put forward corresponding policy recommendations in light of the challenges encountered during the development process of the ratoon rice industry.

IntroductionOolong tea, celebrated for its significance in Chinese tea culture, was the subject of investigation in this study.MethodsFive varieties of Minnan oolong tea were sampled, each cultivated under two distinct management approaches: conventional management and natural growth methods. The study aimed to discern variations in sensory attributes, encompassing appearance and liquor color, alongside the analysis of chemical composition.Results and discussionThe results indicated that oolong tea cultivated through conventional manual management generally exhibited qualities in terms of shape and foliage appearance, in contrast to those grown naturally. However, naturally grown oolong tea tended to exhibit more favorable aroma and taste profiles compared to conventionally managed counterparts. Furthermore, the content of water extract, amino acids, polyphenols, caffeine, and other pivotal chemical constituents were typically higher in naturally grown tea varieties compared to conventionally managed ones. Conversely, catechin content was found to be more abundant in traditionally managed bushes than in those grown naturally. These findings emphasize the significance of implementing appropriate natural growth management practices to enhance the quality of Minnan oolong tea and maintain ecological sustainability.

Rice ratooning is a resource-saving and environment-friendly cropping system. It is therefore critical to accelerating the development of ratoon rice production, which has become an important guarantee to stabilize the rice planting area, improve the self-sufficiency rate of rice, and increase farmers' income in Fujian Province. This paper summarized the general rice production trend, the research progress of mechanically harvested ratoon rice technology in variety selection (breeding), fertilizer and water management, and stubble height management. Rice cultivars such as Yongyou 1540, Yongyou 4949, Longliangyouhuazhan, and Y-liangyou 900 were used in farmers' fields in major ratoon rice growing counties such as Pucheng, Jianyang, and Fuqing. The demonstration fields with the application of the ‘3–2–1’ mechanized rice ratooning technology achieved an annual yield of more than 15.00 ​t ​ha−1 for seven consecutive years. In 2021 and 2022, the yield of ratoon crop by the application of the ‘3–2–1’ mechanized rice ratooning technology reached 9.29 and 9.48 ​t ​ha−1, respectively. In this review, the challenges for the sustainable development of mechanized ratoon rice production were also discussed, and the countermeasures and policy interventions for promoting sound ratoon rice system in Fujian were further proposed.

Continuous planting is unavoidable in agricultural production, but continuous planting affects plant growth and physiological characteristics. In this study, we analyzed rhizosphere soil nutrients, physiological characteristics, hormone metabolome changes and their interactions of Casuarina equisetifolia (C. equisetifolia) with the increase of continuous planting number. The results found that C. equisetifolia root was significantly inhibited, the plant height was dwarfed and the biomass was significantly reduced as continuous planting number increased. Secondly, continuous planting caused a decrease in the rhizosphere soil nutrient transformation capacity, and a significant decrease in the total soil nutrient and available nutrient content. Analysis of physiological indexes showed that continuous planting resulted in a decrease in nitrogen, phosphorus, and potassium content, a decrease in the activity of physiological indexes of resistance, and a decrease in photosynthetic capacity of C. equisetifolia leaves. Hormone metabolome analysis showed that continuous planting critically affected the accumulation of five characteristic hormones in C. equisetifolia leaves, in which salicylic acid 2-O-β-glucoside (SAG), 2-oxindole-3-acetic acid (OxIAA), trans-zeatin-O-glucoside (tZOG) and gibberellin A3 (GA3) content decreased significantly while abscisic acid (ABA) content increased significantly. In conclusion, continuous planting lowered the rhizosphere soil nutrient transformation capacity of C. equisetifolia, lowered the soil available nutrient content, inhibited their root growth, and hindered the nutrient uptake and transportation by the root, thus led to the decrease of the nutrient accumulation capacity in the leaves of C. equisetifolia, and the decrease of SAG, OxIAA, and tZOG, GA3 synthesis ability decreased, ABA accumulated in large quantities, C. equisetifolia resistance and photosynthesis ability decreased, and their growth was impeded. This study provides insights for the effective management of continuous planting in the cultivation of C. equisetifolia.

Continuous planting has a severe impact on the growth of Casuarina equisetifolia. In this study, the effects of three different long-term monocultures (one, two and three replanting) on the physicochemical indexes, microbial functional diversity, and soil metabolomics were analyzed in C. equisetifolia rhizosphere soil. The results showed that rhizosphere soil organic matter content, cation exchange capacity, total and available nitrogen, total and available phosphorus, and total and available potassium contents significantly decreased with the increasing number of continuous plantings. The evaluation of microbial functional diversity revealed a reduction in the number of soil microorganisms that rely on carbohydrates for carbon sources and an increase in soil microorganisms that used phenolic acid, carboxylic acid, fatty acid, and amines as carbon sources. Soil metabolomics analysis showed a significant decrease in soil carbohydrate content and a significant accumulation of autotoxic acid, amine, and lipid in the C. equisetifolia rhizosphere soil. Consequently, the growth of C. equisetifolia could hinder total nutrient content and their availability. Thus, valuable insights for managing the cultivation of C. equisetifolia and soil remediation were provided.

Casuarina equisetifolia (C. equisetifolia) is an economically important forest tree species, often cultivated in continuous monoculture as a coastal protection forest. Continuous planting has gradually affected growth and severely restricted the sustainable development of the C. equisetifolia industry. In this study, we analyzed the effects of continuous planting on C. equisetifolia growth and explored the rhizosphere soil microecological mechanism from a metagenomic perspective. The results showed that continuous planting resulted in dwarfing, shorter root length, and reduced C. equisetifolia seedling root system. Metagenomics analysis showed that 10 key characteristic microorganisms, mainly Actinoallomurus, Actinomadura, and Mycobacterium, were responsible for continuously planted C. equisetifolia trees. Quantitative analysis showed that the number of microorganisms in these three genera decreased significantly with the increase of continuous planting. Gene function analysis showed that continuous planting led to the weakening of the environmental information processing-signal transduction ability of soil characteristic microorganisms, and the decrease of C. equisetifolia trees against stress. Reduced capacity for metabolism, genetic information processing-replication and repair resulted in reduced microbial propagation and reduced microbial quantity in the rhizosphere soil of C. equisetifolia trees. Secondly, amino acid metabolism, carbohydrate metabolism, glycan biosynthesis and metabolism, lipid metabolism, metabolism of cofactors and vitamins were all significantly reduced, resulting in a decrease in the ability of the soil to synthesize and metabolize carbon and nitrogen. These reduced capacities further led to reduced soil microbial quantity, microbial carbon and nitrogen, microbial respiration intensity, reduced soil enzyme nutrient cycling and resistance-related enzyme activities, a significant reduction in available nutrient content of rhizosphere soils, a reduction in the ion exchange capacity, and an impediment to C. equisetifolia growth. This study provides an important basis for the management of continuously planted C. equisetifolia plantations.

Abstract Free-living bacterial community and abundance have been investigated extensively under different soil management practices. However, little is known about their nitrogen (N) fixation abilities, and how their contributions to N budgets impact plant growth, yield, and carbon (C) and N cycling enzymes in a long-term consecutive sugarcane monoculture farming system, under contrasting amendments, along different soil horizons. Here, nifH gene amplicon was used to investigate diazotrophs bacterial community and abundance by leveraging high-throughput sequencing (HTS). Moreover, edaphic factors in three soil depths (0–20, 20–40, and 40–60 cm) under control (CK), organic matter (OM), biochar (BC), and filter mud (FM) amended soils were investigated. Our analysis revealed that β-glucosidase activity, acid phosphatase activity, ammonium (NH4 +-N), nitrate (NO3 –N), total carbon (TC), total nitrogen (TN), and available potassium (AK) were considerably high in 0–20 cm in all the treatments. We also detected a significantly high proportion of Proteobacteria and Geobacter in the entire sample, including Anabaena and Enterobacter in 0–20 cm soil depth under the BC and FM amended soils, which we believed were worthy of promoting edaphic factors and sugarcane traits. This phenomenon was further reinforced by network analysis, where diazotrophs bacteria belonging to Proteobacteria exhibited strong and positive associations soil electrical conductivity (EC), soil organic matter content (SOM) available phosphorus (AP), TN, followed by NH4+-N and NO3 –N, a pattern that was further validated by Mantel test and Pearson’s correlation coefficients analyses. Furthermore, some potential N-fixing bacteria, including Burkholderia, Azotobacter, Anabaena, and Enterobacter exhibited a strong and positive association with sugarcane agronomic traits, namely, sugarcane stalk, ratoon weight, and chlorophyll content. Taken together, our findings are likely to broaden our understanding of free-living bacteria N-fixation abilities, and how their contributions to key soil nutrients such as N budgets impact plant growth and yield, including C and N cycling enzymes in a long-term consecutive sugarcane monoculture farming system, under contrasting amendments, along different soil horizons.

Human actions have led to consistent and profound alterations in land use, which in turn have had a notable effect on the services provided by ecosystems. In this research, the Google Earth Engine (GEE) was initially employed to perform a supervised classification of Landsat satellite images from 2000 to 2020, which allowed us to obtain land-use data for Putian City, China. Next, the geo-informatic Tupu model and the revised valuation model were used to explore the spatial attributes and ecological effects of land-use changes (LUCs). Subsequently, EEH (eco-economic harmony), ESTD (ecosystem services tradeoffs and synergies degree index), and ESDA (exploratory spatial data analysis) methods were employed to further analyze the coordination level, trade-offs, synergies, and spatial patterns of ecological-economic system development. The findings revealed that: (1) The land-use composition in Putian City was predominantly cultivated land and forest land, with other types of land intermixed. Concurrently, there was an ongoing trend of expansion in urban areas. (2) ESV in Putian City exhibited an upward trend, increasing from 15.4 billion CNY to 23.1 billion CNY from 2000 to 2020. (3) ESV exhibited an imbalance in spatial distribution, with high-high agglomeration areas concentrated in the central part of Putian City and the coastal region of Hanjiang District, while low-low agglomeration areas were prevalent in Xianyou County in the southwest, Xiuyu District along the coast, and Licheng District in the urban center. (4) Synergistic relationships among ESs predominated, though the trade-off relationship showed a tendency to expand. (5) The ecological environment and economic progress in Putian City collectively faced a region of potential risk. The findings of this study are intended to serve as a guide for improving the distribution of land resources and for developing strategies that ensure the sustainable development of the region’s socio-economic framework.

Exploring the mechanisms and processes of land-use transitions (LUTs) and their impact on ecosystem services can effectively elucidate the intricate interactions between human and natural systems, which is pivotal for advancing the sustainable development of regional economies and enhancing ecological environments. However, the existing literature lacks comprehensive analysis regarding the spatial and temporal evolution of LUTs, with insufficient integration of the “spatial pattern” and “time process”. Moreover, traditional assessments of the ecosystem services value (ESV) often overlook their negative costs. To address these gaps, this study first utilized the Google Earth Engine (GEE) cloud platform and employed the random forest algorithm to conduct supervised classification on Landsat remote-sensing images from the years 2000, 2010, and 2020 within the research area, thereby obtaining land-use data for three distinct periods. And then, we investigated the geographic features of LUTs and their ecological effects in the Ningde City of China from 2000 to 2020. The geo-informatic Tupu model and a newly revised method of benefit transfer were primarily employed for this purpose. The findings indicate the following: (1) Over the study period, the land-use structure of Ningde City predominantly comprised cultivated land and forest land, with continuous decreases in both types and a concurrent increase in built-up land. (2) Significant disparities exist in the spatial distribution of Tupu units, notably with “forest land → cultivated land” and “cultivated land → built-up land” as crucial units influencing ESV changes. (3) The ESV in Ningde City decreased from CNY 1105.54 × 108 to CNY 1020.47 × 108 over 2000–2020, while the ecosystem dis-services value exhibited an opposing trend, rising from CNY 12.68 × 108 to CNY 20.39 × 108. (4) The net ESV in Ningde City showed a decline over the same period, indicating a certain vulnerability in the city’s ecological system structure. This study aims to enhance our understanding of the influence of land-use patterns on ESV, offering valuable insights for regional ecological–environment management and land-use policy formulation, thereby fostering sustainable development in ecological, environmental, and socio-economic dimensions. Furthermore, the results serve as a reference for evaluating net ecosystem services value in other countries/regions.

IntroductionThe utilization of biochar (BC) as a soil amendment in agriculture has gained significant traction among many farmers and researchers, primarily due to its eco-friendly role in boosting crop output. However, the performance of specific metabolites (e.g., zeatin, melatonin, sucrose, and phenyllactic acid) in the various tissues of sugarcane plant (leaf, stem, and root) and rhizosphere soil-deemed plant growth and stress regulators in a long-term BC-amended field remains poorly understood. Additionally, literature on the shift in soil attributes and crop growth triggered by the strong response of these bioactive compounds to longterm BC utilization remains undocumented.MethodsMetabolome integrated with highthroughput sequencing analyses were conducted to identify and quantify the performance of plant growth and stress-regulating metabolites in a long-term BC-amended field. Additionally, we investigated how the response of these compounds to BC-treated soil influences crop traits and soil biochemical properties.ResultsWe also identified and quantified the performance of pathogenic bacteria and unraveled the association between these compounds and potential plant growth-promoting bacteria. The BC-supplemented soil significantly boosted the crop traits, including brix, sucrose content, and chlorophyll, as well as soil nutrients, such as soil total nitrogen (TN), ammonium (NH4+-N), and nitrate (NO3--N). We also noticed that metabolite-deemed plant growth and stress regulators, including melatonin and phenyllactic acid, were enriched considerably in the stem and root tissues of the BC-amended soil. Zeatin in the leaf, stem, and root tissues exhibited the same trend, followed by sucrose in the leaf tissue of the BC-treated soil, implying that the strong response of these compounds to BC utilization contributed to the promotion of crop traits and soil quality. Pathogenic bacteria belonging to Proteobacteria and Acidobacteria were suppressed under the BC-supplemented soil, especially in the root tissue and rhizosphere soil, whereas plant growth-regulating bacteria, mainly Bradyrhizobium, responded strongly and positively to several metabolites.DiscussionOur finding provides valuable information for agronomists, farmers, and environmentalists to make informed decisions about crop production, land use, and soil management practices. Proper soil assessment and understanding of the interaction between the attributes of soil, BC, and metabolites are essential for promoting sustainable agriculture practices and land conservation.

IntroductionOrganic soil amendments such as filter mud (FM) and biochar (BC) can potentially influence the abundance and composition of metabolites. However, our current understanding of the stimulatory effects of FM and BC’s long-term impact on stress-regulating metabolites, such as abscisic acid (ABA), jasmonic acid (JA), melatonin, and phenyllactic acid (PLA), and these substrates regulatory effects on disease-causing bacteria in sugarcane ratooning field, which is susceptible to nutrients depletion, diseases, etc., remain poorly understood. Additionally, little is known about how the long-term interaction of these substrates and compounds influences sugarcane ratooning soil enzyme activities, nutrient cycling, and crop growth performance.MethodsTo answer these questions, we adopted metabolomics tools combined with high-throughput sequencing to explore the stimulatory effects of the long-term addition of FM and BC on metabolites (e.g., PLA and abscisic aldehyde) and quantify these substrates’ regulatory effects on disease-causing bacteria, soil enzyme activities, nutrient cycling, and crop growth performance.ResultsThe result revealed that ratoon crop weight, stem diameter, sugar content, as well as soil physico-chemical properties, including soil nitrate (NH3+-N), organic matter (OM), total nitrogen (TN), total carbon (TC), and β-glucosidase, marked a significant increase under the BC and FM-amended soils. Whereas soil available potassium (AK), NO3–N, cellulase activity, and phosphatase peaked under the BC-amended soil, primarily due to the enduring effects of these substrates and metabolites. Furthermore, BC and FM-amended soils enriched specific stress-regulating metabolites, including JA, melatonin, abscisic aldehyde, etc. The sustained effects of both BC and FM-amended soils suppressed disease-causing bacteria, eventually promoting ratooning soil growth conditions. A number of key bioactive compounds had distinct associations with several beneficial bacteria and soil physico-chemical properties.DiscussionThis study proves that long-term BC and FM application is one of the eco-friendly strategies to promote ratoon crop growth and soil quality through the enrichment of stress-regulating metabolites and the suppression of disease-causing bacteria.

The determination for properly combined application rate of organic and inorganic fertilizers is the key to coordinating soil nutrient supplies and rice growth demands, thereby obtaining improved economic and ecological returns in rice ratooning. A complete randomized block design (RCBD) trial with different configurations of organic and inorganic nitrogen fertilizers was conducted to determine the optimal substitution rate of organic nitrogen for inorganic nitrogen and its effect on the related physiological attributes and yield performance of the main and ratoon rice crops in 2018−2019. The results showed that 30% organic and 70% inorganic nitrogen in the mixture fertilizer (GM2) could produce the best effect on root activity, nitrogen nutrient uptake and its utilization, as well as the dry matter accumulation and its partitioning. This in turn resulted in improved productive panicles and harvest index, and hence increased grain yield by 10.36% and 15.48% in GM2 regime relative to that in CF treatment. Moreover, the uptake and utilization efficiency, agronomic utilization efficiency and partial productivity of nitrogen fertilizer were 44.37%, 23.82 kg/kg and 48.97 kg/kg, respectively under the optimal GM2 treatment, which were much higher than those in CF treatment by 12.66%, 5.05% and 13.4%, respectively. The results suggested that properly combined application of organic and chemical nitrogen fertilizer could improve soil nutrient supply to guarantee an efficient plant growth and rational dry matter allocation, thereby increasing the harvest index and grain yield in rice ratooning.

Studies have shed light on the impact of the co-application of inorganic fertilizer and biochar on soil fertility, health, and crop growth performance and yield. However, insufficient literature exists regarding the appropriate nitrogen reduction ratio for enhancing soil quality and maximizing crop nitrogen utilization following the application of biochar in a continuous tobacco-rice rotation field. Here, we explored nitrogen absorption and utilization patterns of tobacco crops, as well as the response characteristics of functional genes related to soil nitrogen cycling subjected to the interaction of reduced nitrogen utilization ratios following biochar application in a long-term tobacco-rice rotation field. The results showed that the treatments with 10% (T2) and 20% (T3) nitrogen reduction combined with biochar (30 t∙ha−1) promoted nitrogen utilization efficiency and nitrogen harvest index of tobacco plants. In the second year of the experiment, T2 and T3 significantly increased the nitrogen harvest index by 3.85% and 5.78% compared with the conventional nitrogen application treatment (T1), respectively. We believe that the increase in abundance of nitrification, nitrogen fixation, and ammonification genes, including nxrA, nifH, and UreC in the rhizosphere soil, precipitate the high nitrogen absorption and utilization efficiency in the biochar combined with nitrogen reduction treatments, respectively. This suggests that biochar application at a rate of 30 t·ha−1, nitrogen fertilizer usage can be reduced by 10% and 20% to achieve optimal and sustainable tobacco production.

Abstract Background As one of the vital crops globally, sugarcane (Saccharum officinarum L.) has been one of model crops for conducting metabolome research. Although many studies have focused on understanding bioactive components in specific sugarcane tissues, crucial questions have been left unanswered about the response of metabolites to niche differentiation such as different sugarcane tissues (leaf, stem and root), and soil regions (rhizosphere and bulk) under silicon (Si) amended soils. Here, nontargeted metabolite profiling method was leveraged to assess the similarities and differences in the abundance and community composition of metabolites in the different sugarcane and soil compartments. Identify the compartment-specific expression patterns of metabolites, and their association with cane agronomic traits and edaphic factors. We also investigated the response of sugarcane agronomic traits and edaphic factors to Si amended soil. Results We found that Si fertilizer exhibited the advantages of overwhelmingly promoting the height and theoretical production of cane, and profoundly increased soil Si content by 24.8 and 27.0%, while soil available potassium (AK) was enhanced by 3.07 and 2.67 folds in the bulk and rhizosphere soils, respectively. It was also noticed that available phosphorus (AP) in the rhizosphere soil tremendously increased by 105.5%. We detected 339 metabolites in 30 samples using LC–MS/MS analyses, 161 of which were classified and annotated, including organooxygen compounds (19.9%), carboxylic acids and derivatives (15.5%), fatty acyls (15.5%), flavonoids (4.4%), phenols (4.4%), and benzene and substituted derivatives (3.7%). In addition, the total percentages covered by these core metabolites in each compartment ranged from 94.0% (bulk soil) to 93.4% (rhizosphere soil), followed by 87.4% (leaf), 81.0% (root) and 80.5% (stem), suggesting that these bioactive compounds may have migrated from the belowground tissues and gradually filtered in various aboveground niches of the plant. We also observed that the variations and enrichment of metabolites abundance and community were compartment-specific. Furthermore, some key bioactive compounds were markedly associated with plant growth parameters and soil edaphic. Conclusion Taken together, we hypothesized that Si utilization can exhibit the advantage of enhancing edaphic factors and cane agronomic traits, and variations in metabolites community are tissue-specific.

Radix pseudostellariae is one of the well-known genuine medicinal herbs in Fujian province, China. However, the continuous cropping obstacles with respect to R. pseudostellariae have seriously affected the sustainable utilization of medicinal resources and the development of related industrial systems. The occurrence of continuous cropping obstacles is a comprehensive effect of multiple deteriorating biological and abiotic factors in the rhizosphere soil. Therefore, intensive ecological methods have been the key to abating such obstacles. In this study, four treatments were set up, i.e., fallow (RP-F), fallow + bacterial fertilizer (RP-F-BF), rice-paddy-upland rotation (RP-R), and rice-paddy-upland rotation + bacterial fertilizer (RP-R-BF), during the interval between two plantings of R. pseudostellariae, with a newly planted (NP) treatment as the control. The results show that the yield of R. pseudostellariae under the RP-F treatment decreased by 46.25% compared to the NP treatment. Compared with the RP-F treatment, the yields of the RP-F-BF, RP-R, and RP-R-BF treatments significantly increased by 14.11%, 27.79%, and 62.51%, respectively. The medicinal quality of R. pseudostellariae treated with RP-R-BF was superior to that achieved with the other treatments, with the total saponin and polysaccharide contents increasing by 8.54% and 27.23%, respectively, compared to the RP-F treatment. The ecological intensive treatment of RP-R-BF significantly increased the soil pH, content of organic matter, abundance of beneficial microbial populations, and soil enzyme activity, thus remediating the deteriorating environment of continuous cropping soil. On this basis, the ecological intensive treatment RP-R-BF significantly increased the activity of protective enzymes and the expression levels of genes related to disease and stress resistance in leaves and root tubers. Redundancy and Pearson correlation analyses indicated that rice-paddy-upland rotation improved the soil structure, promoted the growth of eutrophic r-strategy bacterial communities, enhanced compound oxidation and reduction, broke the relationship between the deteriorating environment and harmful biological factors, and eventually weakened the intensity of harmful factors. The subsequent application of bacterial fertilizer improved the beneficial biological and abiotic factors, activated various ecological functions of the soil, enhanced the ecological relationship between various biological and abiotic factors, and reduced the stress intensity of R. pseudostellariae, thereby improving its disease and stress resistance, and ultimately reflecting the recovery of yield and quality. The results indirectly prove that the intensive ecological amelioration of the soil environment was the main factor for the yield recovery of R. pseudostellariae under continuous cropping.

Reducing greenhouse gas emissions while improving productivity is the core of sustainable agriculture development. In recent years, rice ratooning has developed rapidly in China and other Asian countries, becoming an effective measure to increase rice production and reduce greenhouse gas emissions in these regions. However, the lower yield of ratooning rice caused by the application of a single nitrogen fertilizer in the ratooning season has become one of the main reasons limiting the further development of rice ratooning. The combined application of nitrogen and phosphorus plays a crucial role in increasing crop yield and reducing greenhouse gas emissions. The effects of combined nitrogen and phosphorus application on ratooning rice remain unclear. Therefore, this paper aimed to investigate the effect of combined nitrogen and phosphorus application on ratooning rice. Two hybrid rice varieties, ‘Luyou 1831’ and ‘Yongyou 1540’, were used as experimental materials. A control treatment of nitrogen-only fertilization (187.50 kg·ha−1 N) was set, and six treatments were established by reducing nitrogen fertilizer by 10% (N1) and 20% (N2), and applying three levels of phosphorus fertilizer: N1P1 (168.75 kg·ha−1 N; 13.50 kg·ha−1 P), N1P2 (168.75 kg·ha−1 N; 27.00 kg·ha−1 P), N1P3 (168.75 kg·ha−1 N; 40.50 kg·ha−1 P), N2P1 (150.00 kg·ha−1 N; 13.50 kg·ha−1 P), N2P2 (150.00 kg·ha−1 N; 27.00 kg·ha−1 P), and N2P3 (150.00 kg·ha−1 N; 40.50 kg·ha−1 P). The effects of reduced nitrogen and increased phosphorus treatments in ratooning rice on the yield, the greenhouse gas emissions, and the community structure of rhizosphere soil microbes were examined. The results showed that the yield of ratooning rice in different treatments followed the sequence N1P2 > N1P1 > N1P3 > N2P3 > N2P2 > N2P1 > N. Specifically, under the N1P2 treatment, the average two-year yields of ‘Luyou 1831’ and ‘Yongyou 1540’ reached 8520.55 kg·ha−1 and 9184.90 kg·ha−1, respectively, representing increases of 74.30% and 25.79% compared to the N treatment. Different nitrogen and phosphorus application combinations also reduced methane emissions during the ratooning season. Appropriately combined nitrogen and phosphorus application reduced the relative contribution of stochastic processes in microbial community assembly, broadened the niche breadth of microbial communities, enhanced the abundance of functional genes related to methane-oxidizing bacteria and soil ammonia-oxidizing bacteria in the rhizosphere, and decreased the abundance of functional genes related to methanogenic and denitrifying bacteria, thereby reducing greenhouse gas emissions in the ratooning season. The carbon footprint of ratooning rice for ‘Luyou 1831’ and ‘Yongyou 1540’ decreased by 25.82% and 38.99%, respectively, under the N1P2 treatment compared to the N treatment. This study offered a new fertilization pattern for the green sustainable development of rice ratooning.

Monovalent cation proton antiporters (CPAs) play crucial roles in ion and pH homeostasis, which is essential for plant development and environmental adaptation, including salt tolerance. Here, 68 CPA genes were identified in soybean, phylogenetically dividing into 11 Na+/H+ exchangers (NHXs), 12 K+ efflux antiporters (KEAs), and 45 cation/H+ exchangers (CHXs). The GmCPA genes are unevenly distributed across the 20 chromosomes and might expand largely due to segmental duplication in soybean. The GmCPA family underwent purifying selection rather than neutral or positive selections. The cis-element analysis and the publicly available transcriptome data indicated that GmCPAs are involved in development and various environmental adaptations, especially for salt tolerance. Based on the RNA-seq data, twelve of the chosen GmCPA genes were confirmed for their differentially expression under salt or osmotic stresses using qRT-PCR. Among them, GmCHX20a was selected due to its high induction under salt stress for the exploration of its biological function on salt responses by ectopic expressing in Arabidopsis. The results suggest that the overexpression of GmCHX20a increases the sensitivity to salt stress by altering the redox system. Overall, this study provides comprehensive insights into the CPA family in soybean and has the potential to supply new candidate genes to develop salt-tolerant soybean varieties.

Crop perennialization has garnered global attention recently due to its role in sustainable agriculture. However, there is still a lack of detailed information regarding perennial rice’s regenerative characteristics and physiological mechanisms in crop ratooning systems with different rice stubble heights. In addition, the response of phytohormones to varying stubble heights and how this response influences the regenerative characteristics of ratoon rice remains poorly documented. Here, we explored the regenerative characteristics and physiological mechanisms of an annual hybrid rice, AR2640, and a perennial rice, PR25, subjected to different stubble heights (5, 10, and 15 cm). The response of phytohormones to varying stubble heights and how this response influences the regenerative characteristics of ratoon rice were also investigated. The results show that PR25 overwintered successfully and produced the highest yield, especially in the second ratoon season, mainly due to its extended growth duration, higher number of mother stems, tillers at the basal nodes, higher number of effective panicles, and heavier grain weight when subjected to lower stubble heights. Further analysis revealed that PR25 exhibited a higher regeneration rate from the lower-position nodes in the stem with lower stubble heights. this was primarily due to the higher contents of phytohormones, especially auxin (IAA) and gibberellin (GA3) at an early stage and abscisic acid (ABA) at a later stage after harvesting of the main crop. Our findings reveal how ratoon rice enhances performance based on different stubble heights, which provides valuable insights and serves as crucial references for delving deeper into cultivating high-yielding perennial rice.

Abstract The application of biochar and plant‐growth‐promoting bacteria (PGPBs) in biocontrol soil‐borne pathogens has garnered worldwide interest recently. However, how agricultural replanting disease is alleviated by a combination of biochar and PGPBs treatment (SYBB) remains largely unexplored. In this study, we investigated the beneficial effects of single biochar addition and the combination of biochar and PGPBs on alleviating replanting disease by altering the rhizosphere microbiome and metabolites. Our field experiment showed that the SYBB treatment had a better alleviating effect on replanting disease than the single biochar addition. The study indicated the dominant effect of deterministic processes on the bacterial community and of stochastic processes on the fungal community under biochar and PGPBs treatment. The combination of biochar and PGPBs tended to convert the stochastic processes of fungal community assembly into deterministic processes. We found SYBB treatment increased the abundance of potentially beneficial Pseudomonas, Lysobacter, Gemmatimonadetes and Nitrospira, and decreasing the abundance of potentially pathogenic Fusarium, Talaromyces and Fusarium oxysporum. Moreover, the SYBB treatment increased the abundances of carbohydrates, fatty acids and plant hormones, and decreased the abundances of amino acids in the rhizosphere soil. Co‐occurrence network analysis indicated that SYBB treatment increased the connections within the microbial communities and drove the alteration of co‐occurrence network among the microbial communities and metabolites, which increased positive correlations in bacteria‐metabolite networks and decreased positive correlations in fungi‐metabolite networks. Spearman correlation analysis showed the abundances of beneficial Streptomyces, Pseudomonas and Lysobacter were significantly and positively correlated to the metabolites most increased under SYBB treatment. The combination of biochar and PGPBs alleviated replanting disease by mediating the change of rhizosphere soil metabolites, and stimulating the proliferation of indigenous and beneficial soil microbes. The research results are intended to provide the basis for new strategies for green and sustainable remediation of soil‐borne pathogens.

We firstly propose the integration of heterogeneous Tm:YAG and Ho:YAP crystals into a single bulk structure for a compact, diode-pumped passively Q-switched (PQS) Ho laser. Efficient 2129 nm laser, with maximum CW power of 6.67 W was obtained from the Tm:YAG/Ho:YAP gain medium, with slope efficiency of 38.3% and optical conversion efficiency of 27.4% by considering the incident diode power at 785 nm. Modulated by a Cr:ZnSe saturable absorber inside a hybrid cavity, characteristic self-pulsing of the integrated Ho laser can be suppressed for a stable PQS process, where average output power of 743 mW at 2053.3 nm was obtained with shortest pulse duration of 123 ns at 14.2 kHz. As the maximum thermal stress of 48.2 MPa is far below the fracture limits of each integrated section (∼160 MPa), higher laser power can be expected. The results pave the way to explore the integration of other existing Tm-doped and Ho-doped hosts for an accessible 2.1 μm source.

BackgroundRatoon rice cropping has been shown to provide new insights into overcoming the current challenges of rice production in southern China. However, the potential mechanisms impacting yield and grain quality under rice ratooning remain unclear.MethodsIn this study, changes in yield performance and distinct improvements in grain chalkiness in ratoon rice were thoroughly investigated, using physiological, molecular and transcriptomic analysis.ResultsRice ratooning induced an extensive carbon reserve remobilization in combination with an impact on grain filling, starch biosynthesis, and ultimately, an optimization in starch composition and structure in the endosperm. Furthermore, these variations were shown to be associated with a protein-coding gene: GF14f (encoding GF14f isoform of 14-3-3 proteins) and such gene negatively impacts oxidative and environmental resistance in ratoon rice.ConclusionOur findings suggested that this genetic regulation by GF14f gene was the main cause leading to changes in rice yield and grain chalkiness improvement of ratoon rice, irrespective of seasonal or environmental effects. A further significance was to see how yield performance and grain quality of ratoon rice were able to be achieved at higher levels via suppression of GF14f.

BackgroundPlant growth-promoting bacteria (PGPB) represents a common biological fertilizer with remarkable effect in improving crop production and environmental friendliness.MethodsIn the present work, we presented a detailed characterization of plant morphology and physiology, metabolism, and pharmacological activity of A. roxburghii between Burkholderia ambifaria LK-P4 inoculation and un-inoculation (CK) treatment by routine analytical techniques (include microscopy and enzymatic activity assays and so on) coupled with metabolomics approaches.ResultsMorphological and physiological results showedthat the P4 bacteria could significantly increase plant stomatal density, freshweight, survival rate,and the content of total flavonoids in leaves but reducethe amount of free amino acid. Furthermore, metabolite data showed that fatty acids (linoleic acid, linolenic acid, stearic acid) and active substance (kyotorphin and piceatannol) were specifically up-regulated in P4 inoculation. It was also demonstrated that the differential metabolites were involved in citrate cycle, glyoxylate and dicarboxylate metabolism, and biosynthesis of unsaturated fatty acids pathway. In addition, pharmacological efficacy found that A. roxburghii under P4 inoculation can significantly decrease (p < 0.05) blood glucose levels and protect the organs of mice with similar effect of Glibenclamide tablets.ConlusionOverall, it can be seen that the exogenous P4 bacteria can promote the growth and increase content of special metabolites in A. roxburghii. This study provided theoretical basis and supported for the high-yield and high-quality bionic cultivation of A. roxburghii.

Abstract Background The asynchronous filling between superior spikelets (SS) and inferior spikelets (IS) in rice has become a research hotspot. The stagnant development and poor grain filling of IS limit yields and the formation of good quality rice. A large number of studies on this phenomenon have been carried out from the genome, transcriptome and proteome level, indicating that asynchronous filling of SS and IS filling is a complex, but orderly physiological and biochemical process involving changes of a large number of genes, protein expression and modification. However, the analysis of metabolomics differences between SS and IS is rarely reported currently. Results This study utilized untargeted metabolomics and identified 162 metabolites in rice spikelets. Among them, 17 differential metabolites associated with unsynchronized grain filling between SS and IS, 27 metabolites were related to the stagnant development of IS and 35 metabolites related to the lower maximum grain-filling rate of IS compared with the SS. We found that soluble sugars were an important metabolite during grain filling for SS and IS. Absolute quantification was used to further analyze the dynamic changes of 4 types of soluble sugars (sucrose, fructose, glucose, and trehalose) between SS and IS. The results showed that sucrose and trehalose were closely associated with the dynamic characteristics of grain filling between SS and IS. The application of exogenous sugar showed that trehalose functioned as a key sugar signal during grain filling of IS. Trehalose regulated the expression of genes related to sucrose conversion and starch synthesis, thereby promoting the conversion of sucrose to starch. The difference in the spatiotemporal expression of TPS-2 and TPP-1 between SS and IS was an important reason that led to the asynchronous change in the trehalose content between SS and IS. Conclusions The results from this study are helpful for understanding the difference in grain filling between SS and IS at the metabolite level. In addition, the present results can also provide a theoretical basis for the next step of using metabolites to regulate the filling of IS.

BackgroundThe consecutive monoculture of Rehmannia glutinosa leads to a serious decrease in its production and quality. Previous studies have demonstrated that intercropping altered species diversity and rhizosphere microbial diversity. However, it remained unknown whether the impaired growth of monocultured plants could be restored by enhanced belowground interspecific interactions.MethodIn the present research, a continuous cropping facilitator Achyranthes bidentata was intercropped with R. glutinosa under pot conditions, and three different types of root barrier treatments were set, including that complete belowground interaction (N), partial belowground interaction (S), and no belowground interspecies interaction (M), with the aims to investigate belowground interaction and the underlying mechanism of alleviated replanting disease of R. glutinosa by intercropping with A. bidentata.ResultsThe results showed that the land equivalent ratio (LER) of the two years was 1.17, and the system productivity index (SPI) increased by 16.92 % under S treatment, whereas no significant difference was found in N and M regimes. In the rhizosphere soil, intercropping systems had significantly increased the contents of sugars and malic acid in the soil of R. glutinosa, together with the content of organic matter and the invertase and urease activities. Meanwhile, intercropping increased the community diversity of fungi and bacteria, and the relative abundance of potential beneficial bacteria, such as Bacillus, Nitrospira, and Sphingomonas, despite the pathogenic Fusarium oxysporum was still the dominant genus in the rhizospheric soil of R. glutinosa under various treatments. The results of antagonism experiments and exogenous addition of specific bacteria showed that Bacillus spp. isolated from rhizosphere soil had a significant antagonistic effect on the pathogen of R. glutinosa.ConlusionTaken together, our study indicated that the R. glutinosa//A. bidentata intercropping systems alleviate the consecutive monoculture problem of R. glutinosa by recruiting beneficial bacteria. The studies we have conducted have a positive effect on sustainable agricultural development.

The microbiomes of plant are potential determinants of plant growth, productivity, and health. They provide plants with a plethora of functional capacities, namely, phytopathogens suppression, access to low-abundance nutrients, and resistance to environmental stressors. However, a comprehensive insight into the structural compositions of the bacterial abundance, diversity, richness, and function colonizing various microenvironments of plants, and specifically their association with bioactive compounds and soil edaphic factors under silicon (Si) amendment remains largely inconclusive. Here, high-throughput sequencing technology and nontargeted metabolite profiling method were adopted to test the hypotheses regarding microbiome niche abundance, diversity, richness, function, and their association with bioactive compounds and soil edaphic factors within different ecological niches (leaf, stem, root, rhizosphere, and bulk soils) under Si amendment during cane growth were we addressed. Our results demonstrated that Si correspondingly increased sugarcane theoretical production and yield, and remarkably enhanced soil nutrient status, especially Si, AP, and AK. It was also observed that bacterial diversity demonstrated tissue-dependent distribution patterns, with the bulk soil, rhizosphere soil, and root endosphere revealing the highest amount of bacterial diversity compared with the stem and leaf tissues. Moreover, Si exhibited the advantage of considerably promoting bacterial abundance in the various plant compartments. Co-occurrence interactions demonstrated that Si application has the potential to increase bacterial diversity maintenance, coexistence, and plant–soil systems bacteria connections, thereby increasing the functional diversity in the various plant tissues, which, in turn, could trigger positive growth effects in plants. Network analysis further revealed that metabolite profiles exhibited a strong association with bacterial community structures. It was also revealed that Si content had a considerable positive association with bacterial structures. Our findings suggest that the dynamic changes in microbe’s community composition in different plant and soil compartments were compartment-specific. Our study provides comprehensive empirical evidence of the significance of Si in agriculture and illuminated on differential metabolite profiles and soil microbe’s relationship.

Light is an important environmental factor. Plants adapt to their light environment by developing the optimal phenotypes. Light-mediated hypocotyl growth is an ideal phenotype for studying how plants respond to light. Thus far, many signaling components in light-mediated hypocotyl growth have been reported. Here, we focused on identifying the transcription factors (TFs) involved in blue light-mediated hypocotyl growth. We analyzed the blue-light-mediated hypocotyl lengths of Arabidopsis TF–overexpressing lines and identified three NF–YC proteins, NF–YC7, NF–YC5, and NF–YC8 (NF–YCs being the short name), as the negative regulators in blue light-inhibited hypocotyl elongation. NF–YC–overexpressing lines developed longer hypocotyls than those of the wild type under blue light, while the deficient mutants nf–yc5nf–yc7 and nf–yc7nf–yc8 failed to exhibit hypocotyl elongation under blue light. NF–YCs physically interacted with CRY2 (cryptochrome 2) and PIF4/5 (phytochrome interacting factor 4 or 5), while the NF–YCs–PIF4/5 interactions were repressed by CRY2. Moreover, the overexpression of CRY2 or deficiency of PIF4/5 repressed NF–YC7–induced hypocotyl elongation under blue light. Further investigation revealed that NF–YC7 may increase CRY2 degradation and regulate PIF4/5 activities under blue light. Taken together, this study will provide new insight into the mechanism of how blue light inhibits hypocotyl elongation.

The expansion of tea plantations has caused changes in land use structure, which, in turn, has affected the regional habitat quality. Exploring the characteristics of changes in land use structure and habitat quality under different development scenarios is important for the formulation of regional land planning policies and the guarantee of ecological security. This study quantified the habitat quality of the study area from 2010 to 2020 based on the InVEST habitat quality module and explored the land use distribution patterns and habitat quality change characteristics under different scenarios in combination with the PLUS model. The results show that, from 2010 to 2020, the area of tea plantations expanded by 153.0126 km2, and the mean value of habitat quality increased from 0.6502 to 0.6919; in different development scenarios, the area of tea plantations was from large to small in the order of scenario 1 (871.2468), scenario 3 (599.4531) and scenario 2 (518.5440), and the mean value of habitat quality was from high to low in the order of scenario 1 (0.7385), scenario 2 (0.7162) and scenario 3 (0.6919). This study mainly explored the structural changes of land use and habitat quality evolution characteristics under different development scenarios in the study area, and the results of the study can provide a reference basis for rational land development and utilization and habitat conservation in the large-scale tea plantation area.

Schematic of the dynamic process of the laser-induced plasma assisted ablation. The process consists of laser heating, plasma generation, absorption enhancement and material removal.

Basic helix–loop–helix (bHLH)/HLH transcription factors are involved in various aspects of the growth and development of plants. Here, we identified four HLH genes, PePRE1-4, in moso bamboo plants that are homologous to Arabidopsis PRE genes. In bamboo seedlings, PePRE1/3 were found to be highly expressed in the internode and lamina joint by using quantitative RT-PCR analysis. In the elongating internode of bamboo shoots, PePRE genes are expressed at higher levels in the basal segment than in the mature top segment. Overexpression of PePREs (PePREs-OX) in Arabidopsis showed longer petioles and hypocotyls, as well as earlier flowering. PePRE1 overexpression restored the phenotype due to the deficiency of AtPRE genes caused by artificial micro-RNA. PePRE1-OX plants showed hypersensitivity to propiconazole treatment compared with the wild type. In addition, PePRE1/3 but not PePRE2/4 proteins accumulated as punctate structures in the cytosol, which was disrupted by the vesicle recycling inhibitor brefeldin A (BFA). PePRE genes have a positive function in the internode elongation of moso bamboo shoots, and overexpression of PePREs genes promotes flowering and growth in Arabidopsis. Our findings provided new insights about the fast-growing mechanism of bamboo shoots and the application of PRE genes from bamboo.

Understanding the normal variation of the sugarcane rhizosphere fungal community throughout its life cycle is essential for the development of agricultural practices for fungal and ecological health associated with the microbiota. Therefore, we performed high-throughput sequencing of 18S rDNA of soil samples using the Illumina sequencing platform for correlation analysis of rhizosphere fungal community time series, covering information from 84 samples in four growth periods. The results revealed that the sugarcane rhizosphere fungi possessed the maximum fungal richness in Tillering. Rhizosphere fungi were closely associated with sugarcane growth, including Ascomycota, Basidiomycota, and Chytridiomycota, which showed high abundance in a stage-specific manner. Through the Manhattan plots, 10 fungal genera showed a decreasing trend throughout the sugarcane growth, and two fungal genera were significantly enriched at three stages of sugarcane growth (p < 0.05) including Pseudallescheria (Microascales, Microascaceae) and Nectriaceae (Hypocreales, Nectriaceae). In addition, soil pH, soil temperature, total nitrogen, and total potassium were critical drivers of fungal community structure at different stages of sugarcane growth. We also found that sugarcane disease status showed a significant and strong negative effect on selected soil properties by using structural equation modeling (SEM), suggesting that poor soil increases the likelihood of sugarcane disease. In addition, the assembly of sugarcane rhizosphere fungal community structure was mainly influenced by stochastic factors, but after the sugarcane root system became stable (Maturity), the stochastic contribution rate decreased to the lowest value. Our work provides a more extensive and solid basis for the biological control of sugarcane potential fungal diseases.

Abstract Background Soybean (Glycine max) is an important oil provider and ecosystem participant. The protein phosphatase 2C (PP2C) plays important roles in key biological processes. Molecular evolution and functional analysis of the PP2C family in soybean are yet to be reported. Results The present study identified 134 GmPP2Cs with 10 subfamilies in soybean. Duplication events were prominent in the GmPP2C family, and all duplicated gene pairs were involved in the segmental duplication events. The legume-common duplication event and soybean-specific tetraploid have primarily led to expanding GmPP2C members in soybean. Sub-functionalization was the main evolutionary fate of duplicated GmPP2C members. Meanwhile, massive genes were lost in the GmPP2C family, especially from the F subfamily. Compared with other genes, the evolutionary rates were slower in the GmPP2C family. The PP2C members from the H subfamily resembled their ancestral genes. In addition, some GmPP2Cs were identified as the putative key regulator that could control plant growth and development. Conclusions A total of 134 GmPP2Cs were identified in soybean, and their expansion, molecular evolution and putative functions were comprehensively analyzed. Our findings provided the detailed information on the evolutionary history of the GmPP2C family, and the candidate genes can be used in soybean breeding.

Abstract Background Identification of the allelopathy-interrelated metabolites from the allelopathic rice rhizosphere is crucial to understand the allelopathic mechanism of rice, which in turn can promote its applications to farming. In this study, the metabolites from the rhizosphere soil of five different rice lines, including allelopathic rice accession PI312777 (PI) and non-allelopathic rice accession Lemont (Le) as well as their genetic derivatives (e.g., phenylalanine ammonia-lyase (PAL) gene overexpression transgenic lines of PI and Le, namely, PO and LO respectively, and PAL RNA interference line of PI, namely, PR) were identified and comparatively analyzed to explore the positive compounds that are involved in the process of rice allelopathy. Results The results showed that 21 non-polar compounds and 21 polar compounds differed in content in the rhizosphere soil of PI and Le, which include several volatile fatty acids and long-chain fatty acids. The relative contents of fatty acids also differed between PAL overexpressing or RNA interference (RNAi)-silenced line and their wild-type respectively. Acetic acid content also differed among groups, i.e., it is higher in the high allelopathic potential rice. Further analysis showed that different metabolites from the ADS8 resin-extracted phase were more abundant than that those from the ADS21 resin-extracted phase, suggesting that the allelochemicals in root exudates of allelopathic rice are mainly non-polar substances. KEGG annotation of these differential metabolites revealed that these compounds were related to nutrient metabolism, secondary metabolite synthesis, signaling substance synthesis, and toxin degradation. Conclusions Rice allelochemicals deposited in the ADS8 resin-extracted phase were more abundant than those in the ADS21 resin-extracted phase. Allelochemicals in root exudates of allelopathic rice are mainly non-polar substances, and long-chain fatty acids are considered as allelopathy interrelated metabolites.

Abstract Background Rice is a chilling-sensitive crop that would suffer serious damage from low temperatures. Overexpression of the Lsi1 gene (Lsi1-OX) in rice enhances its chilling tolerance. This study revealed that a serine hydroxymethyltransferase (OsSHMT) mainly localised in the endoplasmic reticulum (ER) is involved in increasing tolerance to chilling. Results A higher transcription level of OsSHMT was detected in Lsi1-OX rice than in the wild type. Histone H1 and nucleic acid binding protein were found to bind to the promoter region of OsSHMT and regulate its expression, and the transcription levels of these proteins were also up-regulated in the Lsi1-OX rice. Moreover, OsSHMT interacts with ATP synthase subunit α, heat shock protein Hsp70, mitochondrial substrate carrier family protein, ascorbate peroxidase 1 and ATP synthase subunit β. Lsi1-encoded protein OsNIP2;1 also interacts with ATP synthase subunit β, and the coordination of these proteins appears to function in reducing reactive oxygen species, as the H2O2 content of transgenic OsSHMT Arabidopsis thaliana was lower than that of the non-transgenic line under chilling treatment. Conclusions Our results indicate that ER-localised OsSHMT plays a role in scavenging H2O2 to enhance the chilling tolerance of Lsi1-OX rice and that ATP synthase subunit β is an intermediate junction between OsNIP2;1 and OsSHMT.

We demonstrate a direct diode-pumped passively Q-switched (PQS) Tm/Ho composite laser with a developed compact hybrid cavity, where the lasing wavelengths were changeable from Ho laser to Tm laser via decreasing initial transmittance of the crystalline Cr:ZnSe saturable absorbers (SAs) from 95%, 92%, to 89%. Using a common 808 nm diode laser as the pump source, maximum average output power of 390 mW, maximum pulse energy of 39 uJ, and the shortest pulse with a full width at half maximum of 22 ns were obtained at lasing wavelengths of 2122 nm, 2090 nm, and 2011 nm respectively, where these peak wavelengths remained stable during the PQS processes with different SAs.

Q-switched and polarized Ho lasers are the ideal driving source for mid-infrared radiation via optical parametric oscillation. Although intra-cavity pumping is an efficient way to achieve the Ho laser oscillation at 2.1 μm, which also facilitates the direct use of common diodes in a compact structure, it was demonstrated to be not suitable for Q-switching due to the saturable effect of the Ho-doped gain medium. Here, we report a RbTiOPO4 Q-switched intra-cavity pumped laser via integrating the Tm-doped and Ho-doped gain medium into a composite structure and decoupling the Tm laser from the Ho laser before it was modulated by the RbTiOPO4 crystal. The shortest pulse of 41 ns at repetition frequency of 1 kHz was obtained with a peak power of 7.5 kW. By competing with the intensified self-pulsing, the maximum pulse repetition frequency was found to reach 7 kHz, which was half the driving frequency of the electro-optical modulator. The results pave the way for achieving regular pulses from the intra-cavity pumping mechanism, which facilities a compact, accessible and robust pulse source at 2.1 μm.

Sugarcane–legume intercropping systems can effectively control pests and diseases as well as improve the fertility and health of farmland soil. However, little is known about the response of bacterial abundance, diversity, and community composition in the rhizosphere and non-rhizosphere soils under the sugarcane–peanut farming system. A field experiment was conducted with two treatments: sugarcane monoculture and sugarcane–peanut intercropping to examine the response of sugarcane parameters and edaphic factors. We also deciphered bacterial abundance, diversity, and community composition in the root endosphere, rhizosphere, and bulk soil by leveraging Illumina sequencing to conduct the molecular characterization of the 16S rRNA gene and nitrogenase (nifH) gene. We observed that sugarcane–peanut intercropping exhibited the advantages of tremendously increasing cane stalk height, stalk weight, and millable stalk number/20 m, and edaphic factors, namely, pH (1.13 and 1.93), and available phosphorus exhibited a fourfold and sixfold increase (4.66 and 6.56), particularly in the rhizosphere and bulk soils, respectively. Our result also showed that the sugarcane–peanut intercropping system significantly increased the bacterial richness of the 16S rRNA gene sequencing data by 13.80 and 9.28% in the bulk soil and rhizosphere soil relative to those in the monocropping sugarcane system, respectively. At the same time, sugarcane intercropping with peanuts significantly increased the Shannon diversity of nitrogen-fixing bacteria in the sugarcane rhizosphere soil. Moreover, most edaphic factors exhibited a positive regularity effect on bacterial community composition under the intercropping system. A linear discriminant analysis with effect size analysis of the 16S rRNA sequencing data revealed that bacteria in the root endosphere of the intercropped cane proliferated profoundly, primarily occupied by Devosia, Rhizobiales, Myxococcales, Allorhizobium-Neorhizobium-Pararhizobium-Rhizobium, Bradyrhizobium, and Sphingomonas. In conclusion, our findings demonstrated that sugarcane–peanut intercropping can enhance edaphic factors, sugarcane parameters, and bacterial abundance and diversity without causing adverse impacts on crop production and soil.

Plants and rhizosphere bacterial microbiota have intimate relationships. As neighbors of the plant root system, rhizosphere microorganisms have a crucial impact on plant growth and health. In this study, we sampled rhizosphere soil of sugarcane in May (seedling), July (tillering), September (elongation) and November (maturity), respectively. We employ 16S rRNA amplicon sequencing to investigate seasonal variations in rhizosphere bacteria community structure and abundance, as well as their association with soil edaphic factors. The results demonstrate that soil pH, total nitrogen (TN) and available nitrogen (AN) decrease substantially with time. Rhizosphere bacteria diversity (Shannon) and the total enriched OTUs are also significantly higher in July relative to other months. Bacteria OTUs and functional composition exhibit a strong and significant correlation with soil temperature (Tem), suggesting that Tem was the potential determinant controlling rhizosphere bacteria diversity, enriched OTUs as well as functional composition. Redundancy analysis (RDA) point toward soil total potassium (TK), pH, TN, Tem and AN as principal determinant altering shifting bacteria community structure. Variation partitioning analysis (VPA) analysis further validate that a substantial proportion of variation (70.79%) detected in the rhizosphere bacteria community structure was attributed to edaphic factors. Mfuzz analysis classified the bacterial genera into four distinct clusters, with cluster two exhibiting a distinct and dramatic increase in July, predominantly occupied by Allocatelliglobosispora. The stochastic forest model found the key characteristic bacterial populations that can distinguish the four key growth periods of sugarcane. It may help us to answer some pending questions about the interaction of rhizosphere microorganisms with plants in the future.

Improving chilling tolerance at the seedling stage in rice is essential for agricultural research. We combined a physiological analysis with transcriptomics in a variety Dular subjected to chilling followed by recovery at normal temperature to better understand the chilling tolerance mechanisms of rice. Chilling inhibited the synthesis of chlorophyll and non-structural carbohydrate (NSC) and disrupted the ion balance of the plant, resulting in the impaired function of rice leaves. The recovery treatment can effectively reverse the chilling-related injury. Transcriptome results displayed that 21,970 genes were identified at three different temperatures, and 11,732 genes were differentially expressed. According to KEGG analysis, functional categories for differentially expressed genes (DEGs) mainly included ribosome (8.72%), photosynthesis–antenna proteins (7.38%), phenylpropanoid biosynthesis (11.41%), and linoleic acid metabolism (10.07%). The subcellular localization demonstrated that most proteins were located in the chloroplasts (29.30%), cytosol (10.19%), and nucleus (10.19%). We proposed that some genes involved in photosynthesis, ribosome, phenylpropanoid biosynthesis, and linoleic acid metabolism may play key roles in enhancing rice adaptation to chilling stress and their recovery capacity. These findings provide a foundation for future research into rice chilling tolerance mechanisms.

The complex composition and interaction of root-associated microbes are critical to plant health and performance. In this study, we presented a detailed characterization of three rhizocompartment (rhizosphere, rhizoplane, and root) microbiomes of Achyranthes bidentata under different years of consecutive monoculture by deep sequencing in order to determine keystone microorganisms via co-occurrence network analysis. The network analysis showed that multiple consecutive monoculture (MCM, represented 5Y and 10Y) soils generated some distinct beneficial bacterial taxa such as Bacillus, Fictibacillus, Bradyrhizobium, Shinella, and Herbaspirillum. For fungi, Mortierella substituted for Fusarium in occupying an important position in different rhizocompartments under A. bidentate monoculture. Quantitative PCR analysis confirmed a significant increase in Bacillus, Pseudomonas, and Burkholderia spp. The results of the inoculation assay showed that addition of beneficial bacteria Bacillus subtilis 74 and Bacillus halodurans 75 significantly increased the root length and fresh weight of A. bidentata. Furthermore, three types of phytosterones, as the main allochemicals, were identified both in the rhizosphere soil and in culture medium under sterile conditions by LC-MS/MS. When looking at in vitro interactions, it was found that phytosterones displayed a positive interaction with dominant beneficial species (Bacillus amyloliquefaciens 4 and B. halodurans 75) and had a negative effect on the presence of the pathogenic fungi Fusarium solani and Fusarium oxysporum. Overall, this study demonstrated that consecutive monoculture of A. bidentata can alter the bacterial and fungal community by secreting root exudates, leading to recruitment of beneficial microbes and replacement of plant-specific pathogenic fungi with plant beneficial fungi.

The continuous cropping of plants can result in the disruption of the soil microbial community and caused significant declines in yields. However, there are few reports on the effects of continuous cropping of sugarcane on the microbial community structure and functional pathway. In the current study, we analyzed the structural and functional changes of microbial community structure in the rhizospheric soil of sugarcane in different continuous cropping years using Illumina Miseq high-throughput sequencing and metagenomics analysis. We collected rhizosphere soils from fields of no continuous cropping history (NCC), 10 years of continuous cropping (CC10), and 30 years of continuous cropping (CC30) periods in the Fujian province. The results demonstrated that continuous sugarcane cropping resulted in significant changes in the physicochemical properties of soil and the composition of soil bacterial and fungal communities. With the continuous cropping, the crop yield dramatically declined from NCC to CC30. Besides, the redundancy analysis (RDA) of the dominant bacterial and fungal phyla and soil physicochemical properties revealed that the structures of the bacterial and fungal communities were mainly driven by pH and TS. Analysis of potential functional pathways during the continuous cropping suggests that different KEGG pathways were enriched in different continuous cropping periods. The significant reduction of bacteria associated with rhizospheric soil nitrogen and sulfur cycling functions and enrichment of pathogenic bacteria may be responsible for the reduction of effective nitrogen and total sulfur content in rhizospheric soil of continuous sugarcane as well as the reduction of sugarcane yield and sugar content. Additionally, genes related to nitrogen and sulfur cycling were identified in our study, and the decreased abundance of nitrogen translocation genes and AprAB and DsrAB in the dissimilatory sulfate reduction pathway could be the cause of declined biomass. The findings of this study may provide a theoretical basis for uncovering the mechanism of obstacles in continuous sugarcane cropping and provide better guidance for sustainable development of the sugarcane.

Under consecutive monoculture, the abundance of pathogenic fungi, such as Fusarium oxysporum in the rhizosphere of Radix pseudostellariae, negatively affects the yield and quality of the plant. Therefore, it is pertinent to explore the role of antagonistic fungi for the management of fungal pathogens such as F. oxysporum. Our PCR-denatured gradient gel electrophoresis (DGGE) results revealed that the diversity of Trichoderma spp. was significantly declined due to extended monoculture. Similarly, quantitative PCR analysis showed a decline in Trichoderma spp., whereas a significant increase was observed in F. oxysporum. Furthermore, seven Trichoderma isolates from the R. pseudostellariae rhizosphere were identified and evaluated in vitro for their potentiality to antagonize F. oxysporum. The highest and lowest percentage of inhibition (PI) observed among these isolates were 47.91 and 16.67%, respectively. In in vivo assays, the R. pseudostellariae treated with four Trichoderma isolates, having PI > 30%, was used to evaluate the biocontrol efficiency against F. oxysporum in which T. harzianum ZC51 enhanced the growth of the plant without displaying any disease symptoms. Furthermore, the expression of eight defense-related genes of R. pseudostellariae in response to a combination of F. oxysporum and T. harzianum ZC51 treatment was checked, and most of these defense genes were found to be upregulated. In conclusion, this study reveals that the extended monoculture of R. pseudostellariae could alter the Trichoderma communities in the plant rhizosphere leading to relatively low level of antagonistic microorganisms. However, T. harzianum ZC51 could inhibit the pathogenic F. oxysporum and induce the expression of R. pseudostellariae defense genes. Hence, T. harzianum ZC51 improves the plant resistance and reduces the growth inhibitory effect of consecutive monoculture problem.

The growth and productivity of Casuarina equisetifolia is negatively impacted by planting sickness under long-term monoculture regimes. In this study, Illumina MiSeq sequencing targeting nifH genes was used to assess variations in the rhizospheric soil diazotrophic community under long-term monoculture rotations. Principal component analysis and unweighted pair-group method with arithmetic means (UPGMA) clustering demonstrated distinct differences in diazotrophic community structure between uncultivated soil (CK), the first rotation plantation (FCP), the second rotation plantation (SCP), and the third rotation plantation (TCP). Taxonomic analysis showed that the phyla Proteobacteria increased while Verrucomicrobia decreased under the consecutive monoculture (SCP and TCP). The relative abundance of Paraburkholderia, Rhodopseudomonas, Bradyrhizobium, Geobacter, Pseudodesulfovibrio, and Frankia increased significantly while Burkholderia, Rubrivivax, and Chlorobaculum declined significantly at the genus level under consecutive monoculture (SCP and TCP). Redundancy analysis (RDA) showed that Burkholderia, Rubrivivax, and Chlorobaculum were positively correlated with total nitrogen and available nitrogen. In conclusion, continuous C. equisetifolia monoculture could change the structure of diazotrophic microbes in the rhizosphere, resulting in the imbalance of the diazotrophic bacteria population, which might be a crucial factor related to replanting disease in this cultivated tree species.