Sustained organic amendments utilization enhances ratoon crop growth and soil quality by enriching beneficial metabolites and suppressing pathogenic bacteria

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

Plant growth and stress-regulating metabolite response to biochar utilization boost crop traits and soil health

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

Filtered mud improves sugarcane growth and modifies the functional abundance and structure of soil microbial populations

Background Exploring high-quality organic amendments has been a focus of sustainable agriculture. Filtered mud (FM), a sugar factory waste derived from sugarcane stems, could be an alternative organic amendment for sugarcane production. However, the effects of its application proportions on soil fertility, nutrient cycling, structure of soil bacterial and fungal communities, and the growth of sugarcane in clay-loam soils remain unexplored. Methods Three application proportions of FM: (FM1-(FM: Soil at 1:4), FM2-(FM: Soil at 2:3), and FM3-(FM: Soil at 3:2)) were evaluated on sugarcane growth and soil nutrient cycling. High throughput sequencing was also employed to explore soil microbial dynamics. Results We observed that FM generally increased the soil’s nutritional properties while improving NO3− retention compared to the control, resulting in increased growth parameters of sugarcane. Specifically, FM1 increased the concentration of NH4+−N, the N fraction preferably taken up by sugarcane, which was associated with an increase in the plant height, and more improved growth properties, among other treatments. An increase in the proportion of FM also increased the activity of soil nutrient cycling enzymes; urease, phosphatase, and β-glucosidase. High throughput sequencing revealed that FM reduced the diversity of soil bacteria while having insignificant effects on fungal diversity. Although increasing FM rates reduced the relative abundance of the phyla Proteobacteria, its class members, the Gammaproteobacteria and Betaproteobacteria containing some N-cycling related genera, were stimulated. Also, FM stimulated the abundance of beneficial and lignocellulose degrading organisms. These included the bacterial phyla Actinobacteria, Bacteroidetes, Acidobacteria, Chloroflexi, and the fungal phylum Ascomycota. The distribution of the soil microbial community under FM rates was regulated by the changes in soil pH and the availability of soil nutrients. Since FM1 showed more promise in improving the growth properties of sugarcane, it could be more economical and sustainable for sugarcane production in clay-loam soils

Liming Positively Modulates Microbial Community Composition and Function of Sugarcane Fields

Liming combined with an optimum quantity of inorganic fertilizer, as a soil amendment in intensive agriculture, is a viable agricultural practice in terms of improving soil nutrient status and productivity, as well as mitigating soil degradation. The chief benefits of this strategy are fundamentally dependent on soil microbial function. However, we have limited knowledge about lime’s effects on soil microbiomes and their functions, nor on its comprehensive influence on soil nutrient status and the productivity of sugarcane plantations. This study compares the impacts of lime application (1-year lime (L1), 2-year lime (L2), and no lime (CK) on microbial communities, their functions, soil nutrient status, and crop yield in a sugarcane cropping system. We employed Illumina sequencing and functional analysis (PICRUSt and FUNGuild) to decipher microbial communities and functions. In comparison with CK, lime application (L1 and L2) mitigated soil acidity, increased the level of base cations (Ca2+ and Mg2+), and improved soil nutrient status (especially through N and P) as well as soil microbial functions associated with nutrient cycling and that are beneficial to plants, thereby improving plant agronomic parameters and yield. Liming (L1 and L2) increased species richness and stimulated an abundance of Acidobacteria and Chloroflexi compared to CK. In comparison with CK, the two functional categories related to metabolism (amino acid and carbohydrate) increased in the L1 field, whereas cofactors and vitamin metabolites increased in the L2 field. Turning to fungi, compared to CK, liming enriched symbiotrophs (endophytes, ectomycorrhizae, and arbuscular mycorrhizae) and led to a reduction of saprotrophs (Zygomycota and wood saprotrophs) and pathotrophs. The observed benefits of liming were, in turn, ultimately reflected in improved sugarcane agronomic performance, such as increased stalk height and weight in the sugarcane planting system. However, the increase in the above-mentioned parameters was more prominent in the L2 field compared to the L1 field, suggesting consecutive liming could be a practical approach in terms of sustainable production of sugarcane

Integrating the Soil Microbiota and Metabolome Reveals the Mechanism through Which Controlled Release Fertilizer Affects Sugarcane Growth

Root−soil underground interactions mediated by soil microorganisms and metabolites are crucial for fertilizer utilization efficiency and crop growth regulation. This study employed a combined approach of soil microbial community profiling and non-targeted metabolomics to investigate the patterns of root-associated microbial aggregation and the mechanisms associated with metabolites under varying controlled-release fertilizer (CRF) application rates. The experimental treatments included five field application rates of CRF (D1: 675 kg/ha; D15: 1012.5 kg/ha; D2: 1350 kg/ha; D25: 1687.5 kg/ha; and D3: 2025 kg/ha) along with traditional fertilizer as a control (CK: 1687.5 kg/ha). The results indicated that the growth of sugarcane in the field was significantly influenced by the CRF application rate (p Leotiomycetes, Cercospora, Anaeromyxobacter, isoleucyl-proline, and methylmalonic acid. Redundancy analysis unveiled soil pH, soil organic carbon, and available nitrogen as the primary drivers of microbial communities, while the metabolic profiles were notably influenced by the available potassium and phosphorus. The correlation heatmaps illustrated potential microbial−metabolite regulatory mechanisms under CRF application conditions. These findings underscore the significant potential of CRF in sugarcane field production, laying a theoretical foundation for sustainable development in the sugarcane industry

Responses of roots and rhizosphere of female papaya to the exogenous application of GA3

Abstract Exogenous GAs have an indeterminate effect on root development. Our current study used female papaya to reveal how the roots and rhizosphere respond to the exogenous application of GA3 by investigating the transcriptome profile in roots, metabolic profile and microbial community in both roots and rhizosphere of GA3-treated and control female papaya. The results demonstrated that exogenous GA3 treatment enhanced female papaya lateral root development, which gave plants physical advantages of water and nutrient uptake. In addition, it was likely that GA3 spraying in papaya shoot apices increased the level of auxin, which was transported to roots by CpPIN1, where auxin upregulated CpLBD16 and repressed CpBP to promote the lateral root initiation and development. In papaya roots, corresponding transporters (CpTMT3, CpNRT1:2, CpPHT1;4, CpINT2, CpCOPT2, CpABCB11, CpNIP4;1) were upregulated and excretion transporters were downregulated such as CpNAXT1 for water and nutrients uptake with exogenous GA3 application. Moreover, in GA3-treated papaya roots, CpALS3 and CpMYB62 were downregulated, indicating a stronger abiotic resistance to aluminum toxic and phosphate starvation. On the other hand, BRs and JAs, which involve in defense responses, were enriched in the roots and rhizosphere of GA3-treated papayas. The upregulation of the two hormones might result in the reduction of pathogens in roots and rhizosphere such as Colletotrichum and Verticillium. GA3-treated female papaya increased the abundance of beneficial bacteria species including Mycobacterium, Mitsuaria, and Actinophytocola, but decreased that of the genera Candidatus and Bryobacter for that it required less nitrate. Overall, the roots and rhizosphere of female papaya positively respond to exogenous application of GA3 to promote development and stress tolerance. Treatment of female papaya with GA3 might result in the promotion of lateral root formation and development by upregulating CpLBD16 and downregulating CpBP. GA3-treated papaya roots exhibited feedback control of brassinolide and jasmonate signaling in root development and defense. These findings revealed complex response to a growth hormone treatment in papaya roots and rhizosphere and will lead to investigations on the impact of other plant hormones on belowground development in papaya

Metagenomic Analysis Exploring Taxonomic and Functional Diversity of Soil Microbial Communities in Sugarcane Fields Applied with Organic Fertilizer

Organic fertilizers are critically important to soil fertility, microbial communities, and sustainable agricultural strategies. We compared the effect of two fertilizer groups (organic+chemical fertilizer: OM, chemical fertilizer: CK) on sugarcane growth, by observing the difference in microbial communities and functions, soil nutrient status, and agronomic characters of sugarcane. The results showed that the sugar content and yield of sugarcane increased significantly under organic fertilizer treatment. We believe that the increased soil nutrient status and soil microorganisms are the reasons for this phenomenon. In addition, redundancy analysis (RDA) shows that the soil nutrient condition has a major impact on the soil microbial community. In comparison with CK, the species richness of Acidobacteria, Proteobacteria, Chloroflexi, and Gemmatimonadetes as well as the functional abundance of nucleotide metabolism and energy metabolism increased significantly in the OM field. Moreover, compared with CK, genes related to the absorption and biosynthesis of sulfate were more prominent in OM. Therefore, consecutive organic fertilizer application could be an effective method in reference to sustainable production of sugarcane

The regulatory effects of Pseudostellaria heterophylla polysaccharide on immune function and gut flora in immunosuppressed mice

Abstract Polysaccharide (PF40) has been recognized as a main bioactive substances in Pseudostellaria heterophylla (Miq.). The current study explored the potential protective effects of PF40 on immune system in mice with cyclophosphamide‐induced immunosuppression. The mice were intragastric administered PF40 at the dosage of 100, 200 or 400 mg/kg once daily for 30 days, On the 24th and 25th day, the additional intraperitoneal injection of PF40 (50 mg/kg) were administered. The results showed that PF40 enhanced the cell‐mediated immunity via improvements in macrophage phagocytosis, splenocyte proliferation, NK cell activity and delayed type hypersensitivity. Equally, it improves humoral immunity through promoting the formation of serum hemolysin. Moreover, PF40 maintain the immune balance of splenic lymphocytes and altered the intestinal physiological status in Cyp‐induced mice. PF40 regulates the intestinal microbiota by restoring the relative abundance of Odoribacter and Mucispirillum and reducing the relative abundance of Sporosarcina, Yaniella, and Jeotgalicoccus in Cyp‐intervened mice. The findings suggested that PF40 might be a promising natural functional foods for reducing chemotherapy‐induced immunosuppression

Sugarcane Rhizosphere Bacteria Community Migration Correlates with Growth Stages and Soil Nutrient

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

Effects of the configurations with different organic and inorganic fertilizers on grain yield and its related physiological traits of the main and its ratoon rice crops

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