Study on soil phosphorus（P） fraction is an important aspect in probing the mechanisms of soil P accumulation in farmland and mitigating its losing risk to the environment. We used a sequential extraction method to e...Study on soil phosphorus（P） fraction is an important aspect in probing the mechanisms of soil P accumulation in farmland and mitigating its losing risk to the environment. We used a sequential extraction method to evaluate the impacts of long-term fertilization and straw incorporation on inorganic, organic, and residual P（Pi, Po, and Pre） fractions in the plow layer（0–20 cm） of acidic paddy soil in southern China. The experiment comprised of six treatments：（i） no fertilizer control（CK）;（ii） straw incorporation and green manure（SG）;（iii） nitrogen and P fertilizer（NP）;（iv） NP＋SG;（v） NP＋K fertilizer（NPK）; and（vi） NPK＋SG. The results showed that, compared to the initial total soil P content（TSP, 600 mg kg^–1 in 1990）, long-term（20 years） combined continuous P fertilizer and SG significantly increased P accumulation（by 13–20%） while single fertilization（39.3 kg P ha^–1 yr^–1） could maintain soil P status at the most. The average soil P fractions comprised of extractable Pi, Po, and Pre by 51.7, 33.4, and 14.9% in total soil P, respectively. With comparison of no fertilizer addition（CK）, long-term single fertilization significantly（P〈0.05） increased the accumulation of Na HCO3^–, Na OH^–, and HCl^– extractable Pi fractions accounting for two- to three-fold, while SG increased the accumulation of Na HCO3^– and Na OH^– extractable Piand Po accounting for 12–60%. Though the mobilization of Pre fractions was not significant（P〉0.05）, our data indicate that SG may partially substitute for fertilizer P input and minimizing soil P accumulation and subsequent environmental risk in the subtropical paddy soil.展开更多
This study measured the ammonia(NH3)concentration and dry deposition within 100 m around paddy fields(0.6 ha)with double rice cropping in the subtropical hilly area in southern China,with the aims to quantify the dry ...This study measured the ammonia(NH3)concentration and dry deposition within 100 m around paddy fields(0.6 ha)with double rice cropping in the subtropical hilly area in southern China,with the aims to quantify the dry deposition of NH3 around the emission source and to clarify its temporal and spatial variability.The results showed that high NH3 concentrations were found during the 15 d after nitrogen(N)fertilizer application at downwind sites within 100maround the paddy fields,and the NH3 concentrations were 12–62,2.8–7.3,13–38,and 4.9–36μg N m−3 during the 15 d after basal fertilizer application and topdressing in the early rice season and after basal fertilizer application and topdressing in the late rice season,respectively.The NH3 concentrations were relatively low(1.5–-3.8μg N m−3)during other periods of the rice season at the downwind sites,which indicated that N fertilizer application in paddy fields highly affected the NH3 concentration at downwind sites.The NH3 concentrations at the downwind sites decreased significantly with the increase in distance from the paddy fields.The total NH3 dry deposition around 100 m of the paddy fields accounted for approximately 79%and 81%of the emitted NH3 from the paddy fields in the early and late rice seasons,respectively.The results indicate that dry deposition of NH3 around emission sources may be an important way to remove the NH3 volatilized from croplands in this subtropical hilly area.展开更多
Background:Nitrogen(N)saturation theory proposes that an ecosystem might switch from N limitation to carbon(C),phosphorus(P),or other nutrient limitations if it receives continuous N input.Yet,after N limitation is re...Background:Nitrogen(N)saturation theory proposes that an ecosystem might switch from N limitation to carbon(C),phosphorus(P),or other nutrient limitations if it receives continuous N input.Yet,after N limitation is removed,which nutrient is the most limited and whether topography modulates such change is rarely tested at a microbial level.Here,we conducted a two-year N addition experiment under two different topography positions(i.e.a slope and a valley)in a N-saturated subtropical forest.Soil enzyme activity was measured,and ecoenzymatic stoichiometry indexes were calculated as indicators of microbial resource limitation.Results:In the valley,two-year N addition changed the activity of all studied enzymes to various degrees.As a result,microbial C limitation was aggravated in the valley,and consequently microbial decomposition of soil labile organic C increased,but microbial P limitation was alleviated due to the stoichiometry balance.On the slope,however,N addition did not significantly change the activity of the studied enzymes,and did not alter the status of microbial resource limitation.Conclusions:These results indicate that C is a more limited element for microbial growth than P after removing N limitation,but we also highlight that topography can regulate the effect of N deposition on soil microbial resource limitation in subtropical forests.These findings provide useful supplements to the N saturation theory.展开更多
Groundwater quality varies not only in space but also in time. In order to analyze the spatiotemporal variety of ground water quality, the concentration of ammonium nitrogen (NH4N), nitrate nitrogen (NO3N), total nitr...Groundwater quality varies not only in space but also in time. In order to analyze the spatiotemporal variety of ground water quality, the concentration of ammonium nitrogen (NH4N), nitrate nitrogen (NO3N), total nitrogen (TN) and total phosphorus (TP) in very shallow groundwater were investigated in a red-soil catchment in subtropical central China, based on a three-dimensional kriging method. The spatio-temporal analysis demonstrated that NH4N, NO3N and TP presented strong spatio-temporal autocorrelation (with a nugget-to-sill ratio of <25%) and that TN presented a moderate spatio-temporal autocorrelation (with a nugget-to-sill ratio between 25% and 75%). According to the Chinese Groundwater Quality Standards, the ratio of areas contaminated by NH4N, NO3N, TN and TP to the whole catchment was 20.05%, 1.46%, 5.07%, 5.98%, respectively. The 3D delineation of continuously dynamic variation of contaminated area indicated that the catchment’s very shallow groundwater had a moderate contamination by NH4N, slight by TN and TP, and almost non by NO3N. Although the contaminated area was very small, only occurring in small dispersed patches, a close attention should be paid to the shallow groundwater quality because local farmers obtain their domestic drinking water directly from this shallow groundwater without any treatment prior to consuming and the potential health hazard is considerable. The findings from this study highlight the importance of surveillance of the contaminated area over time for decision making to protect public health and maintain sustainable development of the catchment.展开更多
Nitrogen(N)significantly affects rice yield and lodging resistance.Previous studies have primarily investigated the impact of N management on rice lodging in conventional rice monoculture(RM);however,few studies have ...Nitrogen(N)significantly affects rice yield and lodging resistance.Previous studies have primarily investigated the impact of N management on rice lodging in conventional rice monoculture(RM);however,few studies have performed such investigations in rice-crayfish coculture(RC).We hypothesized that RC would increase rice lodging risk and that optimizing N application practices would improve rice lodging resistance without affecting food security.We conducted a two-factor(rice farming mode and N management practice)field experiment from2021 to 2022 to test our hypothesis.The rice farming modes included RM and RC,and the N management practices included no nitrogen fertilizer,conventional N application,and optimized N treatment.The rice yield and lodging resistance characteristics,such as morphology,mechanical and chemical characteristics,anatomic structure,and gene expression levels,were analyzed and compared among the treatments.Under the same N application practice,RC decreased the rice yield by 11.1-24.4% and increased the lodging index by 19.6-45.6% compared with the values yielded in RM.In RC,optimized N application decreased the plant height,panicle neck node height,center of gravity height,bending stress,and lodging index by 4.0-4.8%,5.2-7.8%,0.5-4.5%,5.5-10.5%,and 1.8-19.5%,respectively,compared with those in the conventional N application practice.Furthermore,it increased the culm diameter,culm wall thickness,breaking strength,and non-structural and structural carbohydrate content by 0.8-4.9%,2.2-53.1%,13.5-19.2%,2.2-24.7%,and 31.3-87.2%,respectively.Optimized N application increased sclerenchymal and parenchymal tissue areas of the vascular bundle at the culm wall of the base second internode.Furthermore,optimized N application upregulated genes involved in lignin and cellulose synthesis,thereby promoting lower internodes on the rice stem and enhancing lodging resistance.Optimized N application in RC significantly reduced the lodging index by 1.8-19.5%and stabilized the rice yield(>8,570 kg ha~(-1)on average).This study systematically analyzed and compared the differences in lodging characteristics between RM and RC.The findings will aid in the development of more efficient practices for RC that will reduce N fertilizer application.展开更多
Detecting exogenous gene copy numbers is crucial for examining genetically modified organisms. Traditional methods face a trade-off between feasibility and cost, highlighting the need for a high-precision and low-cost...Detecting exogenous gene copy numbers is crucial for examining genetically modified organisms. Traditional methods face a trade-off between feasibility and cost, highlighting the need for a high-precision and low-cost alternative. In this study, we introduced the RISE method, which is based on Rare Allele Infusion and Sanger Sequencing Estimation, for rice.展开更多
The outbreak of Yantze vole ( Microtus fortis) population in Dongting Lake region is closely related to the evolvement of lake beaches,because the deposition of lake sediments results in the expansion of lake beaches,...The outbreak of Yantze vole ( Microtus fortis) population in Dongting Lake region is closely related to the evolvement of lake beaches,because the deposition of lake sediments results in the expansion of lake beaches,which provides the possibility of the increase of the vole's population. Reclaiming farmland from lake via building cofferdams,eliminating snails by building cofferdams for eradicating schistosomiasis,and over-hunting predators in the region cause the voles becoming a pest after the 1970s. In recent years,the Three Gorges Project and the conversion from farmland into lake have had deep impacts on the environment in the lake region. The dispatching of the down flow rate by the project has induced the expansion of the low and medium level beaches in the lake region,while converting farmland into lake directly has induced the expansion of the lake beaches,both of which have expanded the potential habitats of the vole's population. Therefore,more attention should be paid to the quantitative variation trend of the vole's population in the future.展开更多
Spatial and environmental processes are two ecological processes that have attracted considerable attention in plant community assembly,depending on sampling scale and life history.However,the processes that determine...Spatial and environmental processes are two ecological processes that have attracted considerable attention in plant community assembly,depending on sampling scale and life history.However,the processes that determine community assembly have not been studied in the karst region of southwest China.In this study,a 25-ha(500 m×500 m)monitoring plot within the subtropical climax forest in the karst region was established and canonical correspondence analysis was used to reveal the effects of topography and soil on the spatial patterns of tree community assembly.Our study suggests that spatial processes dominate species composition and the combined effects of spatial and environmental processes play an important role.Overall interpretation rate increases with enlarging the sampling scale.However,the pattern of variation partitioning was similar in different life stages.Environmental variables significantly affected species composition at different sampling sizes and life histories and had a higher interpretation rate of species composition on larger s ampling sizes.Topographic wetness index was the most important variable to explain species composition of the environmental variables.These results suggest that it is necessary to consider the relative importance of environmental and spatial factors on community assembly to better understand,conserve,and manage subtropical karst forests.展开更多
Zinc(Zn) is an essential trace mineral that is required for plant growth and development. A number of protein transporters, which are involved in Zn uptake, translocation and distribution, are finely regulated to main...Zinc(Zn) is an essential trace mineral that is required for plant growth and development. A number of protein transporters, which are involved in Zn uptake, translocation and distribution, are finely regulated to maintain Zn homeostasis in plant. In this study, we functionally characterized an ATP-binding cassette(ABC) transporter gene, OsPDR7, which is involved in Zn homeostasis. Os PDR7 encodes a plasma membrane-localized protein that is expressed mainly in the exodermis and xylem in the rice root.ospdr7 mutants resulted in higher Zn accumulation compared with the wild type. Heterogeneous expression of OsPDR7 in a yeast mutant rescued the Zn-deficiency phenotype, implying transport activity of OsPDR7 to Zn in yeast. However, no ZIP genes except for OsZIP9 showed change in expression profile in the ospdr7 mutants, which suggested that OsPDR7 maintains cellular Zn homeostasis through regulating Os ZIP9 expression. RNA-Seq analysis further revealed a set of differentially expressed genes between the wild type and ospdr7 mutants that allowed us to propose a possible OsPDR7-associated signaling network involving transporters, hormone responsive genes, and transcription factors. Our results revealed a novel transporter involved in the regulation of Zn homeostasis and will pave the way toward a better understanding of the fine-tuning of gene expression in the network of transporter genes.展开更多
Rice is an important dietary source of the toxic mineral cadmium(Cd) for populations in which rice is the main staple food.When grown in agricultural soils that are contaminated with Cd,rice often accumulates excessiv...Rice is an important dietary source of the toxic mineral cadmium(Cd) for populations in which rice is the main staple food.When grown in agricultural soils that are contaminated with Cd,rice often accumulates excessive Cd into the grains,which is a serious threat to agricultural sustainability and human health.To limit Cd accumulation in rice grains,studies on the genetic basis of Cd accumulation in rice have been carried out extensively,and some low-Cd rice varieties have also been developed in recent years.However,the challenges in low-Cd rice breeding still exist because the outcomes of the current genetic improvements for low-Cd rice cannot fully meet the requirements for the development of Cd-safe rice at present.In this review,we outline the progress in understanding the physiological mechanisms and the genetic nature of Cd accumulation in rice and summarize the strategies and outcomes of low-Cd rice breeding over the past decade.By graphing the physiological mechanism of Cd transport in the rice plant,three key steps and some underlying genes are summarized and discussed.Also,two genetic features of the natural variation in rice grain-Cd accumulation,the phenotypic plasticity and subspecies divergence,and the potential genetic explanations for these features are also discussed.Finally,we summarize and discuss current progress and the potential issues in low-Cd rice breeding using different breeding strategies.We hope to propose strategies for future success in the breeding of low-Cd rice varieties over the next decade.展开更多
The subtropical hilly region of China is a region with intensive crop and livestock production,which has resulted in serious N pollution in soil,water and air.This review summarizes the major soil N cycling processes ...The subtropical hilly region of China is a region with intensive crop and livestock production,which has resulted in serious N pollution in soil,water and air.This review summarizes the major soil N cycling processes and their influencing factors in rice paddies and uplands in the subtropical hilly region of China.The major N cycling processes include the N fertilizer application in croplands,atmospheric N deposition,biological N fixation,crop N uptake,ammonia volatilization,N_(2)O/NO emissions,nitrogen runoff and leaching losses.The catchment nutrients management model for N cycle modeling and its case studies in the subtropical hilly region were also introduced.Finally,N management practices for improving N use efficiency in cropland,as well as catchment scales are summarized.展开更多
Combined application of organic fertilizer is an effective measure to improve the productivity and ecological effect of newly added soil.However,the effect of organic fertilizer application in newly added orchard soil...Combined application of organic fertilizer is an effective measure to improve the productivity and ecological effect of newly added soil.However,the effect of organic fertilizer application in newly added orchard soil is not clear.In this project,the soil of newly built peach orchard in the Longquan Mountain of Chengdu was applied with 45 t/hm 2 of organic fertilizer.After 9 months of planting 6 varieties of honey peach(Wanhujing,Baifeng,Zhongtao 13,Huangjinmitao 1,Zhongpan 101,Zhongpan 104),the locally well developed peach orchard was taken as the control.The physical and chemical properties of soil from four topography(top slope,middle slope,lower slope and flat land)of newly built peach orchard were analyzed,and the effect of organic fertilizer on soil was evaluated.The results showed that combined application of organic fertilizer had different effects on soils from orchards with different varieties of peach and from different terrain parts of the same peach variety.Specifically,it had the best effect on soil improvement in Baifeng(local variety),Zhongpan 101 and Zhongpan 104(introduced varieties).Meanwhile,the best effect of soil improvement was found on top slope.Cluster analysis divided newly built peach orchards,uncultivated soil,and locally well developed peach orchard into four groups,indicating that the selected amount of organic fertilizer application in this study has improved the soil of peach orchards to some extent,but it was still necessary to increase the application amount.It was better for 54 t/hm 2 amount of organic fertilization on the part of top and middle slope,and 60 t/hm 2 on the lower slope and flat land.The comprehensive ecological benefit assessment of organic fertilizer should be conducted based on long-term monitoring of peach orchard ecological environment,fruit tree growth,fruit yield and quality,which would provide scientific basis for peach orchard production and management.展开更多
A two-chamber microbial fuel cell(MFC)with algal-film cathode was constructed.It showed good electric-generating performance with three electric-generating stages:start-up,development,and stable.An average output volt...A two-chamber microbial fuel cell(MFC)with algal-film cathode was constructed.It showed good electric-generating performance with three electric-generating stages:start-up,development,and stable.An average output voltage reached~0.412 V during the stable period.A maximum power density during continuous operation was 19.76 mW/m^(2).Bacterial samples were collected from the anode in the three stages(A1,A2,and A3),and their community structure and diversity were analyzed using Illumina MiSeq high-throughput sequencing technology.A total of 4238 operational taxonomic units were identified based on the number of taxa.At the phylum level,Proteobacteria and Bacteroidetes played a dominant role in the three stages and increased significantly during electricity generation.Compared with A1,the relative abundances of Proteobacteria in A2 and A3 increased by 23.30%and 32.06%,respectively,whereas those of Bacteroidetes in A2 and A3 increased by 5.56%and 14.50%,respectively.At the genus level,there were differences in the composition of bacterial communities among the three stages.Acinetobacter and Chlorobium became the dominant genera in A2,replacing Nitrospira and norank_f__Saprospiraceae in A1,and Sphingobacterium and Ochrobactrum became the dominant genera in A3.According to the sample cluster and principal component analyses,A1 was clustered into one class,and A2 and A3 were clustered into a second class.This work revealed bacterial community succession at the anode of an algal-film cathode MFC during the electricity generation process,which provides a theoretical basis for the subsequent promotion of electricity generation by algal-film cathode MFCs.展开更多
Background： The protein/energy ratio is important for the production performance and utilization of available feed resources by animals. Increased protein consumption by mammals leads to elevated feed costs and incre...Background： The protein/energy ratio is important for the production performance and utilization of available feed resources by animals. Increased protein consumption by mammals leads to elevated feed costs and increased nitrogen release into the environment. This study aimed to evaluate the effects of dietary protein/energy ratio on the growth performance, carcass traits, meat quality, and plasma metabolites of pigs of different genotypes. Methods： Bama mini-pigs and Landrace pigs were randomly assigned to two dietary treatment groups （Chinese conventional diet with low protein/energy ratio or National Research Council diet with high protein/energy ratio; n = 24 per treatment） in a 2 x 2 factorial arrangement. Blood and muscle samples were collected at the end of the nursery, growing, and finishing phases. Results： We observed significant interactions （P 〈 0.05） between breed and diet for total fat percentage, intramuscular fat （IMF） content, protein content in biceps femoris （BF） muscle, and plasma urea nitrogen （UN） concentration in the nursery phase; for average daily gain （ADG）, average daily feed intake （ADFI）, dry matter, IMF content in psoas major （PM） muscle, and plasma total protein and albumin concentrations in the growing phase; and for drip loss and plasma UN concentration in the finishing phase. Breed influenced （P 〈 0.05） growth performance, carcass traits, and meat quality, but not plasma metabolites. Throughout the trial, Landrace pigs showed significantly higher （P 〈 0.0_5） ADG, ADFI, dressing percentage, lean mass rate, and loin-eye area than did Bama mini-pigs, but significantly lower （P 〈 0.0.5） feed/gain ratio, fat percentage, backfat thickness, and IMF content. Dietary protein/energy ratio influenced the pH value, chemical composition of BF and PM muscles, and plasma activities of glutamic-pyruvic transaminase and gamma-glutamyl transpeptidase, and plasma concentration of UN. Conclusions： Compared with Landrace pigs, Bama mini-pigs showed slower growth and lower carcass performance, but had better meat quality. Moreover, unlike Landrace pigs, the dietary protein/energy ratio did not affect the growth performance of Bama mini-pigs. These results suggest that, in swine production, low dietary protein/energy ratio may be useful for reducing feed costs and minimizing the adverse effects of ammonia release into the environment.展开更多
We investigated the size distribution of water-stable aggregates and the soil carbon, nitrogen and phosphorus concentration over aggregate size fractions based on a long-term （1990-2006） fertilization experiment in ...We investigated the size distribution of water-stable aggregates and the soil carbon, nitrogen and phosphorus concentration over aggregate size fractions based on a long-term （1990-2006） fertilization experiment in a reddish paddy soil. The results showed that the largest water-stable aggregate （WSA） （〉5 mm） and the smallest WSA （〈0.25 mm） took up the first largest proportion （38.3%） and the second largest proportion （23.3%）, respectively. Application of organic materials increased the proportion of the large WSA （〉2 mm） and decreased the proportion of the small WSA （〈1 ram）, resulting in an increase in the mean weight diameter of WSA, whereas application of chemical fertilizer had little effect. Application of organic materials, especially combined with chemical fertilizers, increased total carbon, nitrogen and phosphorus concentrations in all sizes of WSA, and total carbon, nitrogen and phosphorus were prone to concentrate in the large WSA. Further more, application of organic materials improved the supply effectiveness of available phosphorus, whereas had little influence on the labile carbon in WSA. Application of chemical fertilizers improved concentrations of total and available phosphorus in all sizes of WSA, whereas had little influence on total carbon and nitrogen contents. Economical fertilization model maintained the soil fertility when compared with full dose of chemical fertilizers, indicating that using organic materials could reduce chemical fertilizers by about one third.展开更多
Land cover type is critical for soil organic carbon （SOC） stocks in territorial ecosystems. However, impacts of land cover on SOC stocks in a karst landscape are not fully understood due to discontinuous soil distri...Land cover type is critical for soil organic carbon （SOC） stocks in territorial ecosystems. However, impacts of land cover on SOC stocks in a karst landscape are not fully understood due to discontinuous soil distribution. In this study, considering soil distribution, SOC content and density were investigated along positive successional stages （cropland, plantation, grassland, scrubland, secondary forest, and primary forest） to determine the effects of land cover type on SOC stocks in a subtropical karst area. The proportion of continuous soil on the ground surface under different land cover types ranged between 0.0% and 79.8%. As land cover types changed across the positive successional stages, SOC content in both the 0-20 cm and 20-50 cm soil layers increased significantly. SOC density （SOCD） within O-lOO cm soil depth ranged from 1.45 to 8.72 kg m^-2, and increased from secondary forest to primary forest, plantation, grassland, scrubland, and cropland, due to discontinuous soil distribution. Discontinuous soil distribution had a negative effect on 8OC stocks, highlighting the necessity for accurate determination of soil distribution in karst areas. Generally, ecological restoration had positive impacts on SOC accumulation in karst areas, but this is a slow process. In the short term, the conversion of croplandto grassland was found to be the most efficient way for SOC sequestration.展开更多
In karst regions,the spatial heterogeneity of soil mineral oxides and environmental variables is still not clear.We investigated the spatial heterogeneity of SiO2,Al2O3,Fe2O3,CaO,MgO,P2O5,K2O,and MnO contents in the s...In karst regions,the spatial heterogeneity of soil mineral oxides and environmental variables is still not clear.We investigated the spatial heterogeneity of SiO2,Al2O3,Fe2O3,CaO,MgO,P2O5,K2O,and MnO contents in the soils of slope land,plantation forest,secondary forest,and primary forest,as well as their relationships with environmental variables in a karst region of Southwest China.Geostatistics,principal component analysis(PCA),and canonical correlation analysis(CCA)were applied to analyze the field data.The results show that SiO2was the predominant mineral in the soils(45.02%–67.33%),followed by Al2O3and Fe2O3.Most soil mineral oxide components had a strong spatial dependence,except for CaO,MgO,and P2O5in the plantation forest,MgO and P2O5in the secondary forest,and CaO in the slope land.Dimensionality reduction in PCA was not appropriate due to the strong spatial heterogeneity in the ecosystems.Soil mineral oxide components,the main factors in all ecosystems,had greater influences on vegetation than those of conventional soil properties.There were close relationships between soil mineral oxide components and vegetation,topography,and conventional soil properties.Mineral oxide components affected species diversity,organic matter and nitrogen levels.展开更多
Background: Pregnancy is associated with important changes in gut microbiota composition. Dietary factors may affect the diversity, composition, and metabolic activity of the intestinal microbiota. Among amino acids, ...Background: Pregnancy is associated with important changes in gut microbiota composition. Dietary factors may affect the diversity, composition, and metabolic activity of the intestinal microbiota. Among amino acids, proline is known to play important roles in protein metabolism and structure, cell differentiation, conceptus growth and development, and gut microbiota re-equilibration in case of dysbiosis.Results: Dietary supplementation with 1% proline decreased(P < 0.05) the amounts of Klebsiella pneumoniae,Peptostreptococcus productus, Pseudomonas, and Veillonella spp. in distal colonic contents than that in the control group. The colonic contents of Butyrivibrio fibrisolvens, Bifidobacterium sp., Clostridium coccoides, Clostridium coccoides-Eubacterium rectale, Clostridium leptum subgroup, Escherichia coli, Faecalibacterium prausnitzii,Fusobacterium prausnitzii, and Prevotella increased(P < 0.05) on d 70 of pregnancy as compared with those on d 45 of pregnancy. The colonic concentrations of acetate, total straight-chain fatty acid, and total short-chain fatty acids(SCFA) in the proline-supplemented group were lower(P < 0.05), and butyrate level(P = 0.06) decreased as compared with the control group. Almost all of the SCFA displayed higher(P < 0.05) concentrations in proximal colonic contents on d 70 of pregnancy than those on d 45 of pregnancy. The concentrations of 1,7-heptyl diamine(P = 0.09) and phenylethylamine(P < 0.05) in proximal colonic contents were higher, while those of spermidine(P = 0.05) and total bioamine(P = 0.06) tended to be lower in the proline-supplemented group than those in the control group. The concentrations of spermidine, spermine, and total bioamine in colonic contents were higher(P < 0.05) on d 70 of pregnancy than those measured on d 45 of pregnancy. In contrast, the concentration of phenylethylamine was lower(P < 0.05) on d 70 than on d 45 of pregnancy.(Continued on next page)(Continued from previous page)Conclusion: These findings indicate that L-proline supplementation modifies both the colonic microbiota composition and the luminal concentrations of several bacterial metabolites. Furthermore, our data show that both the microbiota composition and the concentrations of bacterial metabolites are evolving in the course of pregnancy. These results are discussed in terms of possible implication in terms of luminal environment and consequences for gut physiology and health.展开更多
The application of straw and biochar is widely practiced for the improvement of soil fertility.However,its impact on microbial functional profiles,particularly with regard to paddy soils,is not well understood.The aim...The application of straw and biochar is widely practiced for the improvement of soil fertility.However,its impact on microbial functional profiles,particularly with regard to paddy soils,is not well understood.The aim of this study was to investigate the diversity of microbial carbon use patterns in paddy soils amended with straw or straw-derived biochar in a 3-year field experiment in fallow soil and at various development stages of a rice crop(i.e.,tillering and blooming).We applied the community level physiological profiling approach,with 15 substrates(sugars,carboxylic and amino acids,and phenolic acid).In general,straw application resulted in the greatest microbial functional diversity owing to the greater number of available C sources than in control or biochar plots.Biochar amendment promoted the use of α-ketoglutaric acid,the mineralization of which was higher than that of any other substrate.Principal component analyses indicated that microbial functional diversity in the biochar-amended soil was separated from those of the straw-amended and control soils.Redundancy analyses revealed that soil organic carbon content was the most important factor regulating the pattern of microbial carbon utilization.Rhizodeposition and nutrient uptake by rice plants modulated microbial functions in paddy soils and stimulated the microbial use of N-rich substances,such as amino acids.Thus,our results demonstrated that the functional diversity of microorganisms in organic amended paddy soils is affected by both physicochemical properties of amendment and plant growth stage.展开更多
Dissolved organic nitrogen （DON） represents a significant pool of soluble nitrogen （N） in soil ecosystems. Soil samples under three different horticultural management practices were collected from the Xiaxiyang Or...Dissolved organic nitrogen （DON） represents a significant pool of soluble nitrogen （N） in soil ecosystems. Soil samples under three different horticultural management practices were collected from the Xiaxiyang Organic Vegetable and Fruit Farm, Shanghai, China, to investigate the dynamics of N speciation during 2 months of aerobic incubation, to compare the effects of different soils on the mineralization of ^14C-labeled amino acids and peptides, and to determine which of the pathways in the decomposition and subsequent ammonification and nitrification of organic N represented a significant blockage in soil N supply. The dynamics of N speciation was found to be significantly affected by mineralization and immobilization. DON, total free amino acids, and NH^＋-N were maintained at very low levels and did not accumulate, whereas NO3^--N gradually accumulated in these soils. The conversion of insoluble organic N to low-molecular-weight （LMW） DON represented a main constraint to N supply, while conversions of LMW DON to NH4^＋-N and NH4^＋-N to NO3^--N did not. Free amino acids and peptides were rapidly mineralized in the soils by the microbial community and consequently did not accumulate in soil. Turnover rates of the additional amino acids and peptides were soil-dependent and generally followed the order of organic soil 〉 transitional soil 〉 conventional soil. The turnover of high-molecular-weight DON was very slow and represented the major DON loss. Further studies are needed to investigate the pathways and bottlenecks of organic N degradation.展开更多
基金supported by the Knowledge Innovation Program of the Chinese Academy of Sciences(KZCX2-YW-T07)the National Natural Science Foundation of China (41171396)
文摘Study on soil phosphorus（P） fraction is an important aspect in probing the mechanisms of soil P accumulation in farmland and mitigating its losing risk to the environment. We used a sequential extraction method to evaluate the impacts of long-term fertilization and straw incorporation on inorganic, organic, and residual P（Pi, Po, and Pre） fractions in the plow layer（0–20 cm） of acidic paddy soil in southern China. The experiment comprised of six treatments：（i） no fertilizer control（CK）;（ii） straw incorporation and green manure（SG）;（iii） nitrogen and P fertilizer（NP）;（iv） NP＋SG;（v） NP＋K fertilizer（NPK）; and（vi） NPK＋SG. The results showed that, compared to the initial total soil P content（TSP, 600 mg kg^–1 in 1990）, long-term（20 years） combined continuous P fertilizer and SG significantly increased P accumulation（by 13–20%） while single fertilization（39.3 kg P ha^–1 yr^–1） could maintain soil P status at the most. The average soil P fractions comprised of extractable Pi, Po, and Pre by 51.7, 33.4, and 14.9% in total soil P, respectively. With comparison of no fertilizer addition（CK）, long-term single fertilization significantly（P〈0.05） increased the accumulation of Na HCO3^–, Na OH^–, and HCl^– extractable Pi fractions accounting for two- to three-fold, while SG increased the accumulation of Na HCO3^– and Na OH^– extractable Piand Po accounting for 12–60%. Though the mobilization of Pre fractions was not significant（P〉0.05）, our data indicate that SG may partially substitute for fertilizer P input and minimizing soil P accumulation and subsequent environmental risk in the subtropical paddy soil.
基金This research was supported by the National Natural Science Foundation of China[grant number 41771336],the National Key Research and Development Program of China[grant number 2016YFD0201204]the Youth Innovation Promotion Association of the Chinese Academy of Sciences[grant number 2017418].
文摘This study measured the ammonia(NH3)concentration and dry deposition within 100 m around paddy fields(0.6 ha)with double rice cropping in the subtropical hilly area in southern China,with the aims to quantify the dry deposition of NH3 around the emission source and to clarify its temporal and spatial variability.The results showed that high NH3 concentrations were found during the 15 d after nitrogen(N)fertilizer application at downwind sites within 100maround the paddy fields,and the NH3 concentrations were 12–62,2.8–7.3,13–38,and 4.9–36μg N m−3 during the 15 d after basal fertilizer application and topdressing in the early rice season and after basal fertilizer application and topdressing in the late rice season,respectively.The NH3 concentrations were relatively low(1.5–-3.8μg N m−3)during other periods of the rice season at the downwind sites,which indicated that N fertilizer application in paddy fields highly affected the NH3 concentration at downwind sites.The NH3 concentrations at the downwind sites decreased significantly with the increase in distance from the paddy fields.The total NH3 dry deposition around 100 m of the paddy fields accounted for approximately 79%and 81%of the emitted NH3 from the paddy fields in the early and late rice seasons,respectively.The results indicate that dry deposition of NH3 around emission sources may be an important way to remove the NH3 volatilized from croplands in this subtropical hilly area.
基金funded by the Strategic Priority Research Program of Chinese Academy of Sciences(XDA13010302)the National Natural Science Foundation of China(Nos.31872691,41877094,and 31760153)+1 种基金Guangxi Bagui Scholarship Program to Dejun LiNational High-Level Talents Special Support Program to Dejun Li.
文摘Background:Nitrogen(N)saturation theory proposes that an ecosystem might switch from N limitation to carbon(C),phosphorus(P),or other nutrient limitations if it receives continuous N input.Yet,after N limitation is removed,which nutrient is the most limited and whether topography modulates such change is rarely tested at a microbial level.Here,we conducted a two-year N addition experiment under two different topography positions(i.e.a slope and a valley)in a N-saturated subtropical forest.Soil enzyme activity was measured,and ecoenzymatic stoichiometry indexes were calculated as indicators of microbial resource limitation.Results:In the valley,two-year N addition changed the activity of all studied enzymes to various degrees.As a result,microbial C limitation was aggravated in the valley,and consequently microbial decomposition of soil labile organic C increased,but microbial P limitation was alleviated due to the stoichiometry balance.On the slope,however,N addition did not significantly change the activity of the studied enzymes,and did not alter the status of microbial resource limitation.Conclusions:These results indicate that C is a more limited element for microbial growth than P after removing N limitation,but we also highlight that topography can regulate the effect of N deposition on soil microbial resource limitation in subtropical forests.These findings provide useful supplements to the N saturation theory.
文摘Groundwater quality varies not only in space but also in time. In order to analyze the spatiotemporal variety of ground water quality, the concentration of ammonium nitrogen (NH4N), nitrate nitrogen (NO3N), total nitrogen (TN) and total phosphorus (TP) in very shallow groundwater were investigated in a red-soil catchment in subtropical central China, based on a three-dimensional kriging method. The spatio-temporal analysis demonstrated that NH4N, NO3N and TP presented strong spatio-temporal autocorrelation (with a nugget-to-sill ratio of <25%) and that TN presented a moderate spatio-temporal autocorrelation (with a nugget-to-sill ratio between 25% and 75%). According to the Chinese Groundwater Quality Standards, the ratio of areas contaminated by NH4N, NO3N, TN and TP to the whole catchment was 20.05%, 1.46%, 5.07%, 5.98%, respectively. The 3D delineation of continuously dynamic variation of contaminated area indicated that the catchment’s very shallow groundwater had a moderate contamination by NH4N, slight by TN and TP, and almost non by NO3N. Although the contaminated area was very small, only occurring in small dispersed patches, a close attention should be paid to the shallow groundwater quality because local farmers obtain their domestic drinking water directly from this shallow groundwater without any treatment prior to consuming and the potential health hazard is considerable. The findings from this study highlight the importance of surveillance of the contaminated area over time for decision making to protect public health and maintain sustainable development of the catchment.
基金supported by the National Natural Science Foundation of China(32301961)the Natural Science Foundation of Jiangsu Province,China(BK20210791)+3 种基金the General Project of Philosophy and Social Science Research in Colleges and Universities in Jiangsu Province,China(2023SJYB2057)the Priority Academic Program Development of Jiangsu Higher Education Institutions,China(PAPD)the Qinglan Project of Yangzhou University,Chinathe Lv Yang Jin Feng Talent Plan of Yangzhou City,China(YZLYJF2020PHD100)。
文摘Nitrogen(N)significantly affects rice yield and lodging resistance.Previous studies have primarily investigated the impact of N management on rice lodging in conventional rice monoculture(RM);however,few studies have performed such investigations in rice-crayfish coculture(RC).We hypothesized that RC would increase rice lodging risk and that optimizing N application practices would improve rice lodging resistance without affecting food security.We conducted a two-factor(rice farming mode and N management practice)field experiment from2021 to 2022 to test our hypothesis.The rice farming modes included RM and RC,and the N management practices included no nitrogen fertilizer,conventional N application,and optimized N treatment.The rice yield and lodging resistance characteristics,such as morphology,mechanical and chemical characteristics,anatomic structure,and gene expression levels,were analyzed and compared among the treatments.Under the same N application practice,RC decreased the rice yield by 11.1-24.4% and increased the lodging index by 19.6-45.6% compared with the values yielded in RM.In RC,optimized N application decreased the plant height,panicle neck node height,center of gravity height,bending stress,and lodging index by 4.0-4.8%,5.2-7.8%,0.5-4.5%,5.5-10.5%,and 1.8-19.5%,respectively,compared with those in the conventional N application practice.Furthermore,it increased the culm diameter,culm wall thickness,breaking strength,and non-structural and structural carbohydrate content by 0.8-4.9%,2.2-53.1%,13.5-19.2%,2.2-24.7%,and 31.3-87.2%,respectively.Optimized N application increased sclerenchymal and parenchymal tissue areas of the vascular bundle at the culm wall of the base second internode.Furthermore,optimized N application upregulated genes involved in lignin and cellulose synthesis,thereby promoting lower internodes on the rice stem and enhancing lodging resistance.Optimized N application in RC significantly reduced the lodging index by 1.8-19.5%and stabilized the rice yield(>8,570 kg ha~(-1)on average).This study systematically analyzed and compared the differences in lodging characteristics between RM and RC.The findings will aid in the development of more efficient practices for RC that will reduce N fertilizer application.
基金supported by the Natural Science Foundation of Hunan Province for Distinguished Young Scholars, China (Grant No.2021JJ10041)the Biological Breeding-National Science and Technology Major Project, China (Grant No.2023ZD04072)the Hainan Yazhou Bay Seed Laboratory and National Seed Group, China (Grant Nos.B23CQ15HP and B23YQ1517)。
文摘Detecting exogenous gene copy numbers is crucial for examining genetically modified organisms. Traditional methods face a trade-off between feasibility and cost, highlighting the need for a high-precision and low-cost alternative. In this study, we introduced the RISE method, which is based on Rare Allele Infusion and Sanger Sequencing Estimation, for rice.
基金Supported by the National Natural Science Foundation(30870402,31170396)Key Knowledge Innovation Project of Chinese Academy of Sciences(KSCX-EW-N-05)
文摘The outbreak of Yantze vole ( Microtus fortis) population in Dongting Lake region is closely related to the evolvement of lake beaches,because the deposition of lake sediments results in the expansion of lake beaches,which provides the possibility of the increase of the vole's population. Reclaiming farmland from lake via building cofferdams,eliminating snails by building cofferdams for eradicating schistosomiasis,and over-hunting predators in the region cause the voles becoming a pest after the 1970s. In recent years,the Three Gorges Project and the conversion from farmland into lake have had deep impacts on the environment in the lake region. The dispatching of the down flow rate by the project has induced the expansion of the low and medium level beaches in the lake region,while converting farmland into lake directly has induced the expansion of the lake beaches,both of which have expanded the potential habitats of the vole's population. Therefore,more attention should be paid to the quantitative variation trend of the vole's population in the future.
基金supported by the National Natural Science Foundation of China (42071073,31971487)Youth Innovation Promotion Association of the Chinese Academy of Sciences (2021366)+2 种基金Guangxi Key Research and Development Program (AB17129009)the Hechi Distinguished Expert Program to Fuping Zengthe Guangxi Bagui Scholarship Program to Dejun Li。
文摘Spatial and environmental processes are two ecological processes that have attracted considerable attention in plant community assembly,depending on sampling scale and life history.However,the processes that determine community assembly have not been studied in the karst region of southwest China.In this study,a 25-ha(500 m×500 m)monitoring plot within the subtropical climax forest in the karst region was established and canonical correspondence analysis was used to reveal the effects of topography and soil on the spatial patterns of tree community assembly.Our study suggests that spatial processes dominate species composition and the combined effects of spatial and environmental processes play an important role.Overall interpretation rate increases with enlarging the sampling scale.However,the pattern of variation partitioning was similar in different life stages.Environmental variables significantly affected species composition at different sampling sizes and life histories and had a higher interpretation rate of species composition on larger s ampling sizes.Topographic wetness index was the most important variable to explain species composition of the environmental variables.These results suggest that it is necessary to consider the relative importance of environmental and spatial factors on community assembly to better understand,conserve,and manage subtropical karst forests.
基金jointly supported by the Key Research and Development Plan of Jiangsu Province,China (Grant No. BE2020318-2)the National Natural Science Foundation of China (Grant No. U19A2026)。
文摘Zinc(Zn) is an essential trace mineral that is required for plant growth and development. A number of protein transporters, which are involved in Zn uptake, translocation and distribution, are finely regulated to maintain Zn homeostasis in plant. In this study, we functionally characterized an ATP-binding cassette(ABC) transporter gene, OsPDR7, which is involved in Zn homeostasis. Os PDR7 encodes a plasma membrane-localized protein that is expressed mainly in the exodermis and xylem in the rice root.ospdr7 mutants resulted in higher Zn accumulation compared with the wild type. Heterogeneous expression of OsPDR7 in a yeast mutant rescued the Zn-deficiency phenotype, implying transport activity of OsPDR7 to Zn in yeast. However, no ZIP genes except for OsZIP9 showed change in expression profile in the ospdr7 mutants, which suggested that OsPDR7 maintains cellular Zn homeostasis through regulating Os ZIP9 expression. RNA-Seq analysis further revealed a set of differentially expressed genes between the wild type and ospdr7 mutants that allowed us to propose a possible OsPDR7-associated signaling network involving transporters, hormone responsive genes, and transcription factors. Our results revealed a novel transporter involved in the regulation of Zn homeostasis and will pave the way toward a better understanding of the fine-tuning of gene expression in the network of transporter genes.
基金supported by the National Natural Science Foundation of China (U19A2026 and 31972490)。
文摘Rice is an important dietary source of the toxic mineral cadmium(Cd) for populations in which rice is the main staple food.When grown in agricultural soils that are contaminated with Cd,rice often accumulates excessive Cd into the grains,which is a serious threat to agricultural sustainability and human health.To limit Cd accumulation in rice grains,studies on the genetic basis of Cd accumulation in rice have been carried out extensively,and some low-Cd rice varieties have also been developed in recent years.However,the challenges in low-Cd rice breeding still exist because the outcomes of the current genetic improvements for low-Cd rice cannot fully meet the requirements for the development of Cd-safe rice at present.In this review,we outline the progress in understanding the physiological mechanisms and the genetic nature of Cd accumulation in rice and summarize the strategies and outcomes of low-Cd rice breeding over the past decade.By graphing the physiological mechanism of Cd transport in the rice plant,three key steps and some underlying genes are summarized and discussed.Also,two genetic features of the natural variation in rice grain-Cd accumulation,the phenotypic plasticity and subspecies divergence,and the potential genetic explanations for these features are also discussed.Finally,we summarize and discuss current progress and the potential issues in low-Cd rice breeding using different breeding strategies.We hope to propose strategies for future success in the breeding of low-Cd rice varieties over the next decade.
基金supported by the National Natural Science Foundation of China(41771336,41471267,4211101081,42161144002)Youth Innovation Promotion Association of the Chinese Academy of Sciences(Y2021102)+1 种基金Key Research and Development Program of Hunan Province(2020NK2011)Chinese Academy of Science and Technology Service Network Initiative Project(KFJ-STSQYZD-2021-22-002).
文摘The subtropical hilly region of China is a region with intensive crop and livestock production,which has resulted in serious N pollution in soil,water and air.This review summarizes the major soil N cycling processes and their influencing factors in rice paddies and uplands in the subtropical hilly region of China.The major N cycling processes include the N fertilizer application in croplands,atmospheric N deposition,biological N fixation,crop N uptake,ammonia volatilization,N_(2)O/NO emissions,nitrogen runoff and leaching losses.The catchment nutrients management model for N cycle modeling and its case studies in the subtropical hilly region were also introduced.Finally,N management practices for improving N use efficiency in cropland,as well as catchment scales are summarized.
基金Supported by the Research Project of China Railway 23 rd Bureau Group Co.,Ltd.(LQST-03-GCB-2022-02)the National Natural Science Foundation of China(42277245).
文摘Combined application of organic fertilizer is an effective measure to improve the productivity and ecological effect of newly added soil.However,the effect of organic fertilizer application in newly added orchard soil is not clear.In this project,the soil of newly built peach orchard in the Longquan Mountain of Chengdu was applied with 45 t/hm 2 of organic fertilizer.After 9 months of planting 6 varieties of honey peach(Wanhujing,Baifeng,Zhongtao 13,Huangjinmitao 1,Zhongpan 101,Zhongpan 104),the locally well developed peach orchard was taken as the control.The physical and chemical properties of soil from four topography(top slope,middle slope,lower slope and flat land)of newly built peach orchard were analyzed,and the effect of organic fertilizer on soil was evaluated.The results showed that combined application of organic fertilizer had different effects on soils from orchards with different varieties of peach and from different terrain parts of the same peach variety.Specifically,it had the best effect on soil improvement in Baifeng(local variety),Zhongpan 101 and Zhongpan 104(introduced varieties).Meanwhile,the best effect of soil improvement was found on top slope.Cluster analysis divided newly built peach orchards,uncultivated soil,and locally well developed peach orchard into four groups,indicating that the selected amount of organic fertilizer application in this study has improved the soil of peach orchards to some extent,but it was still necessary to increase the application amount.It was better for 54 t/hm 2 amount of organic fertilization on the part of top and middle slope,and 60 t/hm 2 on the lower slope and flat land.The comprehensive ecological benefit assessment of organic fertilizer should be conducted based on long-term monitoring of peach orchard ecological environment,fruit tree growth,fruit yield and quality,which would provide scientific basis for peach orchard production and management.
基金supported by the Natural Science Foundation of Hunan Province(2022JJ60097 and 2022JJ60094)the Research Project of Education Department of Hunan Province(22C1420).
文摘A two-chamber microbial fuel cell(MFC)with algal-film cathode was constructed.It showed good electric-generating performance with three electric-generating stages:start-up,development,and stable.An average output voltage reached~0.412 V during the stable period.A maximum power density during continuous operation was 19.76 mW/m^(2).Bacterial samples were collected from the anode in the three stages(A1,A2,and A3),and their community structure and diversity were analyzed using Illumina MiSeq high-throughput sequencing technology.A total of 4238 operational taxonomic units were identified based on the number of taxa.At the phylum level,Proteobacteria and Bacteroidetes played a dominant role in the three stages and increased significantly during electricity generation.Compared with A1,the relative abundances of Proteobacteria in A2 and A3 increased by 23.30%and 32.06%,respectively,whereas those of Bacteroidetes in A2 and A3 increased by 5.56%and 14.50%,respectively.At the genus level,there were differences in the composition of bacterial communities among the three stages.Acinetobacter and Chlorobium became the dominant genera in A2,replacing Nitrospira and norank_f__Saprospiraceae in A1,and Sphingobacterium and Ochrobactrum became the dominant genera in A3.According to the sample cluster and principal component analyses,A1 was clustered into one class,and A2 and A3 were clustered into a second class.This work revealed bacterial community succession at the anode of an algal-film cathode MFC during the electricity generation process,which provides a theoretical basis for the subsequent promotion of electricity generation by algal-film cathode MFCs.
基金supported by the National Basic Research Program of China(No.2012CB124704 and 2013CB127305)KC.Wong Education Foundation,Hong Kong
文摘Background： The protein/energy ratio is important for the production performance and utilization of available feed resources by animals. Increased protein consumption by mammals leads to elevated feed costs and increased nitrogen release into the environment. This study aimed to evaluate the effects of dietary protein/energy ratio on the growth performance, carcass traits, meat quality, and plasma metabolites of pigs of different genotypes. Methods： Bama mini-pigs and Landrace pigs were randomly assigned to two dietary treatment groups （Chinese conventional diet with low protein/energy ratio or National Research Council diet with high protein/energy ratio; n = 24 per treatment） in a 2 x 2 factorial arrangement. Blood and muscle samples were collected at the end of the nursery, growing, and finishing phases. Results： We observed significant interactions （P 〈 0.05） between breed and diet for total fat percentage, intramuscular fat （IMF） content, protein content in biceps femoris （BF） muscle, and plasma urea nitrogen （UN） concentration in the nursery phase; for average daily gain （ADG）, average daily feed intake （ADFI）, dry matter, IMF content in psoas major （PM） muscle, and plasma total protein and albumin concentrations in the growing phase; and for drip loss and plasma UN concentration in the finishing phase. Breed influenced （P 〈 0.05） growth performance, carcass traits, and meat quality, but not plasma metabolites. Throughout the trial, Landrace pigs showed significantly higher （P 〈 0.0_5） ADG, ADFI, dressing percentage, lean mass rate, and loin-eye area than did Bama mini-pigs, but significantly lower （P 〈 0.0.5） feed/gain ratio, fat percentage, backfat thickness, and IMF content. Dietary protein/energy ratio influenced the pH value, chemical composition of BF and PM muscles, and plasma activities of glutamic-pyruvic transaminase and gamma-glutamyl transpeptidase, and plasma concentration of UN. Conclusions： Compared with Landrace pigs, Bama mini-pigs showed slower growth and lower carcass performance, but had better meat quality. Moreover, unlike Landrace pigs, the dietary protein/energy ratio did not affect the growth performance of Bama mini-pigs. These results suggest that, in swine production, low dietary protein/energy ratio may be useful for reducing feed costs and minimizing the adverse effects of ammonia release into the environment.
基金funded by the Knowledge Innovativation Program of the Chinese Academy of Sciences (KZCX2-YW-423)the National Basic Research Program of China (2005CB121106)
文摘We investigated the size distribution of water-stable aggregates and the soil carbon, nitrogen and phosphorus concentration over aggregate size fractions based on a long-term （1990-2006） fertilization experiment in a reddish paddy soil. The results showed that the largest water-stable aggregate （WSA） （〉5 mm） and the smallest WSA （〈0.25 mm） took up the first largest proportion （38.3%） and the second largest proportion （23.3%）, respectively. Application of organic materials increased the proportion of the large WSA （〉2 mm） and decreased the proportion of the small WSA （〈1 ram）, resulting in an increase in the mean weight diameter of WSA, whereas application of chemical fertilizer had little effect. Application of organic materials, especially combined with chemical fertilizers, increased total carbon, nitrogen and phosphorus concentrations in all sizes of WSA, and total carbon, nitrogen and phosphorus were prone to concentrate in the large WSA. Further more, application of organic materials improved the supply effectiveness of available phosphorus, whereas had little influence on the labile carbon in WSA. Application of chemical fertilizers improved concentrations of total and available phosphorus in all sizes of WSA, whereas had little influence on total carbon and nitrogen contents. Economical fertilization model maintained the soil fertility when compared with full dose of chemical fertilizers, indicating that using organic materials could reduce chemical fertilizers by about one third.
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences (Grant No. XDA05070403)the National Natural Science Foundation of China (Grant Nos. 41171246, 41301273)the National Science-technology Support Plan Projects (Grant No. 2012BAD05B03-6)
文摘Land cover type is critical for soil organic carbon （SOC） stocks in territorial ecosystems. However, impacts of land cover on SOC stocks in a karst landscape are not fully understood due to discontinuous soil distribution. In this study, considering soil distribution, SOC content and density were investigated along positive successional stages （cropland, plantation, grassland, scrubland, secondary forest, and primary forest） to determine the effects of land cover type on SOC stocks in a subtropical karst area. The proportion of continuous soil on the ground surface under different land cover types ranged between 0.0% and 79.8%. As land cover types changed across the positive successional stages, SOC content in both the 0-20 cm and 20-50 cm soil layers increased significantly. SOC density （SOCD） within O-lOO cm soil depth ranged from 1.45 to 8.72 kg m^-2, and increased from secondary forest to primary forest, plantation, grassland, scrubland, and cropland, due to discontinuous soil distribution. Discontinuous soil distribution had a negative effect on 8OC stocks, highlighting the necessity for accurate determination of soil distribution in karst areas. Generally, ecological restoration had positive impacts on SOC accumulation in karst areas, but this is a slow process. In the short term, the conversion of croplandto grassland was found to be the most efficient way for SOC sequestration.
基金Under the auspices of Chinese Academy Sciences Action Plan for the Development of Western China(No.KZCX2-XB3-10)Major State Basic Research Development Program of China(No.2011BAC09B02)+2 种基金Strategic Priority Research Program-Climate Change:Carbon Budget and Related Issues'of Chinese Academy of Sciences(No.XDA05070404,XDA05050205)National Natural Science Foundation of China(No.31070425,31000224,U1033004)Guangxi Provincial Program of Distinguished Expert in China
文摘In karst regions,the spatial heterogeneity of soil mineral oxides and environmental variables is still not clear.We investigated the spatial heterogeneity of SiO2,Al2O3,Fe2O3,CaO,MgO,P2O5,K2O,and MnO contents in the soils of slope land,plantation forest,secondary forest,and primary forest,as well as their relationships with environmental variables in a karst region of Southwest China.Geostatistics,principal component analysis(PCA),and canonical correlation analysis(CCA)were applied to analyze the field data.The results show that SiO2was the predominant mineral in the soils(45.02%–67.33%),followed by Al2O3and Fe2O3.Most soil mineral oxide components had a strong spatial dependence,except for CaO,MgO,and P2O5in the plantation forest,MgO and P2O5in the secondary forest,and CaO in the slope land.Dimensionality reduction in PCA was not appropriate due to the strong spatial heterogeneity in the ecosystems.Soil mineral oxide components,the main factors in all ecosystems,had greater influences on vegetation than those of conventional soil properties.There were close relationships between soil mineral oxide components and vegetation,topography,and conventional soil properties.Mineral oxide components affected species diversity,organic matter and nitrogen levels.
基金jointly supported by grants from the National Nature Science Foundation of China(31572421 and 31270044)National Key R&D Program(2017YFD0500503)“Western Light”key program for Talent Cultivation from Chinese Academy of Sciences,and Chinese Academy of Sciences Visiting Professorship for Senior International Scientists(F.Blachier,2013T2S0014)
文摘Background: Pregnancy is associated with important changes in gut microbiota composition. Dietary factors may affect the diversity, composition, and metabolic activity of the intestinal microbiota. Among amino acids, proline is known to play important roles in protein metabolism and structure, cell differentiation, conceptus growth and development, and gut microbiota re-equilibration in case of dysbiosis.Results: Dietary supplementation with 1% proline decreased(P < 0.05) the amounts of Klebsiella pneumoniae,Peptostreptococcus productus, Pseudomonas, and Veillonella spp. in distal colonic contents than that in the control group. The colonic contents of Butyrivibrio fibrisolvens, Bifidobacterium sp., Clostridium coccoides, Clostridium coccoides-Eubacterium rectale, Clostridium leptum subgroup, Escherichia coli, Faecalibacterium prausnitzii,Fusobacterium prausnitzii, and Prevotella increased(P < 0.05) on d 70 of pregnancy as compared with those on d 45 of pregnancy. The colonic concentrations of acetate, total straight-chain fatty acid, and total short-chain fatty acids(SCFA) in the proline-supplemented group were lower(P < 0.05), and butyrate level(P = 0.06) decreased as compared with the control group. Almost all of the SCFA displayed higher(P < 0.05) concentrations in proximal colonic contents on d 70 of pregnancy than those on d 45 of pregnancy. The concentrations of 1,7-heptyl diamine(P = 0.09) and phenylethylamine(P < 0.05) in proximal colonic contents were higher, while those of spermidine(P = 0.05) and total bioamine(P = 0.06) tended to be lower in the proline-supplemented group than those in the control group. The concentrations of spermidine, spermine, and total bioamine in colonic contents were higher(P < 0.05) on d 70 of pregnancy than those measured on d 45 of pregnancy. In contrast, the concentration of phenylethylamine was lower(P < 0.05) on d 70 than on d 45 of pregnancy.(Continued on next page)(Continued from previous page)Conclusion: These findings indicate that L-proline supplementation modifies both the colonic microbiota composition and the luminal concentrations of several bacterial metabolites. Furthermore, our data show that both the microbiota composition and the concentrations of bacterial metabolites are evolving in the course of pregnancy. These results are discussed in terms of possible implication in terms of luminal environment and consequences for gut physiology and health.
基金financially supported by the National Key Research and Development Program of China(2016YFE0101100)the National Natural Science Foundation of China(41771334,41771337 and 31470629)+2 种基金the Youth Innovation Team Project of the Institute of Subtropical Agriculture,Chinese Academy of Sciences(2017QNCXTD_GTD)the Chinese Academy of Sciences Instrument Function Development Project,the Government Program of Competitive Growth of Kazan Federal University and by the “RUDN University program5–100”
文摘The application of straw and biochar is widely practiced for the improvement of soil fertility.However,its impact on microbial functional profiles,particularly with regard to paddy soils,is not well understood.The aim of this study was to investigate the diversity of microbial carbon use patterns in paddy soils amended with straw or straw-derived biochar in a 3-year field experiment in fallow soil and at various development stages of a rice crop(i.e.,tillering and blooming).We applied the community level physiological profiling approach,with 15 substrates(sugars,carboxylic and amino acids,and phenolic acid).In general,straw application resulted in the greatest microbial functional diversity owing to the greater number of available C sources than in control or biochar plots.Biochar amendment promoted the use of α-ketoglutaric acid,the mineralization of which was higher than that of any other substrate.Principal component analyses indicated that microbial functional diversity in the biochar-amended soil was separated from those of the straw-amended and control soils.Redundancy analyses revealed that soil organic carbon content was the most important factor regulating the pattern of microbial carbon utilization.Rhizodeposition and nutrient uptake by rice plants modulated microbial functions in paddy soils and stimulated the microbial use of N-rich substances,such as amino acids.Thus,our results demonstrated that the functional diversity of microorganisms in organic amended paddy soils is affected by both physicochemical properties of amendment and plant growth stage.
基金Project supported by the National High Technology Research and Development Program (863 program) of China(No. 2006AA10A311)the National Natural Science Foundation of China (No. 40901124)the Shanghai Leading Aca-demic Discipline Program,China (No. B209)
文摘Dissolved organic nitrogen （DON） represents a significant pool of soluble nitrogen （N） in soil ecosystems. Soil samples under three different horticultural management practices were collected from the Xiaxiyang Organic Vegetable and Fruit Farm, Shanghai, China, to investigate the dynamics of N speciation during 2 months of aerobic incubation, to compare the effects of different soils on the mineralization of ^14C-labeled amino acids and peptides, and to determine which of the pathways in the decomposition and subsequent ammonification and nitrification of organic N represented a significant blockage in soil N supply. The dynamics of N speciation was found to be significantly affected by mineralization and immobilization. DON, total free amino acids, and NH^＋-N were maintained at very low levels and did not accumulate, whereas NO3^--N gradually accumulated in these soils. The conversion of insoluble organic N to low-molecular-weight （LMW） DON represented a main constraint to N supply, while conversions of LMW DON to NH4^＋-N and NH4^＋-N to NO3^--N did not. Free amino acids and peptides were rapidly mineralized in the soils by the microbial community and consequently did not accumulate in soil. Turnover rates of the additional amino acids and peptides were soil-dependent and generally followed the order of organic soil 〉 transitional soil 〉 conventional soil. The turnover of high-molecular-weight DON was very slow and represented the major DON loss. Further studies are needed to investigate the pathways and bottlenecks of organic N degradation.
