[Objective]This study aims to explore the photosynthetic physiological response mechanisms of Hosta ventricosa(Salisb.)Stearn under different light conditions and planting densities,in order to provide theoretical and practical guidance for its understory cultivation and landscape application.[Method]Three shading treatments were set:30%-35%transmittance(L1),45%-50%(L2),and 60%-70%(L3),along with three planting densities:10 cm×10 cm(D1),12 cm×12 cm(D2),and 21 cm×21 cm(D3).By analyzing photosynthetic gas exchange parameters,chlorophyll fluorescence,chlorophyll content,osmotic adjustment substances,antioxidant enzyme activities,and morphological indicators of Hosta ventricosa leaves,we investigated the effects of shading,planting density,and their interaction on the growth and photosynthetic adaptation of the plant.[Result](1)In terms of physiological adaptability,H.ventricosa exhibited optimal photosynthetic performance under moderate shading(L2,45%-50%light transmittance),with the net photosynthetic rate reaching 5.55 μmol/(m²·s).It enhanced low-light adaptation and oxidative stress resistance by increasing total chlorophyll content,reducing the chlorophyll a/b ratio(1.91-2.15),and activating the antioxidant enzyme system(e.g.,POD activity reached 388.4 U/g FW).(2)In cultivation mode,moderate density(D2)combined with moderate shading(L2)significantly improved water-use efficiency(up to 8.73 μmol/mmol)and maximized biomass accumulation.(3)Two-factor analysis showed a significant interaction between shading and density,with the combination of moderate shading and moderate density(L2+D2)most effectively promoting the overall optimization of photosynthetic physiological function and morphological development.[Conclusion]The response of H.ventricosa to shading and planting density demonstrates clear physiological plasticity and resource trade-off characteristics.The results indicate that the combination of moderate shading(L2)and moderate density(D2)(L2+D2)can effectively coordinate light distribution within the population,alleviate photoinhibition,enhance antioxidant defense,and improve water-use efficiency.This represents a superior cultivation configuration for achieving both high-quality individual growth and stable population yield.The findings provide direct guidance for the scientific cultivation of H.ventricosa in understory economy,multi-layer landscape construction,and ecological restoration in karst regions.
[Objective]This study aims to investigate the effects of dynamic water temperature changes during overwintering on the growth performance,physiological status,and tissue structure of the red claw crayfish(Cherax quadricarinatus),and to reveal its adaptation mechanisms to low-temperature stress under actual aquaculture conditions,thereby providing a theoretical basis for addressing the bottleneck of low overwintering survival rates that restricts industrial development.[Method]Based on natural water temperature fluctuations,the overwintering process was divided into four stages:pre-overwintering(19.5±2.6)℃,mid-overwintering(13.0±2.2)℃,late-overwintering(15.5±1.3)℃,and post-overwintering(19.5±2.4)℃.Growth indices,digestive enzyme activities,antioxidant capacity,immune parameters,and hepatopancreatic histology of C.quadricarinatus were systematically measured at each stage.[Result](1)The body weight of C.quadricarinatus showed a trend of initial decrease followed by an increase during overwintering:Compared with the pre-overwintering stage,body weight decreased at the mid-overwintering stage but increased significantly thereafter,reaching higher levels in the late and post-overwintering stages(P<0.05).(2)The activities of lipase(LPS),amylase(AMS),and trypsin(TPS)initially decreased at the mid-overwintering stage and then increased in the late and post-overwintering stages(P<0.05).The activities of superoxide dismutase(SOD),catalase(CAT),and glutathione peroxidase(GSH-Px)increased significantly at the mid-overwintering stage(P<0.05),while the total antioxidant capacity(T-AOC)decreased significantly by the post-overwintering stage(P<0.05).Immune indices—lysozyme(LZM),acid phosphatase(ACP),alkaline phosphatase(AKP)—and the expression of the immune-related LZM gene decreased with lowering temperature and were significantly lower than those at the pre-overwintering stage(P<0.05).(3)Histological observation revealed vacuolar damage with dilated in the hepatopancreas during overwintering.[Conclusion]This study preliminarily reveals the dynamic responses of growth,digestion,antioxidant capacity,immunity,and tissue structure in C.quadricarinatus during overwintering under real aquaculture conditions.It delineates the physiological thresholds and structural reversibility characteristics of low-temperature adaptation,providing critical theoretical and data support for formulating precise temperature control and health management strategies during the overwintering period.
[Objective]The study analyzes the impact of agricultural technology training on farmers'fertilizer reduction behaviours and the resulting income effects,aiming to clarify the vital role of agricultural technology training in promoting fertilizer reduction behaviours and to provide a reference for collaborating agricultural green development with farmers'agricultural income.[Method]Based on the data collected from 926 rice farmers in Jiangxi Province,the binary Probit model,propensity score matching and the mediating effect model were applied to investigate the impact and mechanism of agricultural technology training on farmers'chemical fertilizer reduction behaviours.The endogenous switching model was used to systematically assess the income effect of farmers'chemical fertilizer reduction behaviors.[Result]Agricultural technology training significantly promotes farmers'chemical fertilizer reduction behaviours,increasing the adoption probability by an average of 7.7 percentage,and the conclusion remains valid after robustness tests and resolving endogeneity problems.Farmers'environmental cognition and organic fertilizer application behaviours play partial intermediary effects in it.Agricultural technology training has a greater influence on the chemical fertilizer reduction behaviours of elder farmers,highly educated farmers and large-scale farmers,whereas its impact is relatively weaker on younger and small-scale farmers,and statistically insignificant for those with lower education levels.Farmers'chemical fertilizer reduction behaviours increase farmers'agricultural income.In detail,the agricultural income of farmers who actually reduced chemical fertilizer would decrease if they decided against it.[Conclusion]In the future,efforts should be made to improve the content and methods of agricultural technology training to enhance effectiveness,expand science popularization and establish comprehensive supporting policies and services,implement differentiated support for different groups of farmers,and smooth the marketing channels for green agricultural products to promote the development of fertilizer reduction,while increasing their income.
[Objective]The effects of soil microbial community diversity on different planting patterns of Carya illinoensis with medicinal plants were investigated to determine appropriate patterns.[Method]High-throughput sequencing was used to analyze,the changes of alpha diversity,beta diversity,community structure and correlations with soil environmental factors of rhizosphere and non-rhizosphere soil microorganisms under Carya illinoensis+Salvia miltiorrhiza,Carya illinoensis+Belamcanda and monoculture planting patterns for 3 years.[Result]There was no significant difference in the ACE,Chao1,Shannon,and Simpson indices of bacteri-al and fungal communities in the rhizosphere and non-rhizosphere soil among Carya illinoensis+Salvia miltior-rhiza,Carya illinoensis+Belamcanda and monoculture,but the interplanting was improved compared with di-versity indices.In the bacterial community,Pseudomonadota and Acidobacteriota were significantly dominant fungal phyla,compared with monoculture,the relative abundance of pseudomonadota was decreased and Acido-bacteriota was increased in interplanting Salvia miltiorrhiza and shoot soil.α-Proteobacteria,β-Proteobacteria,Gp 6 group,Gp 4 group and Thermoleophilia were the significantly dominant groups.Compared with single crop-ping,the relative abundance of α-proteobacteria and β-proteobacteria was reduced in interplanting Salvia milt-iorrhiza and shoot soil,and the relative abundance of Gp 6 group,Gp 4 group and Thermoleophilia was in-creased.The soil bacteria in different cultivation patterns were dominated by Unclassified,Gp6,Gp4 and Gp3.The relative abundance of Gp6 and Gp4 was higher in intercropping Belamcanda chinensis and Salvia miltior-rhiza than in single cropping.In the fungal community,Basidiomycota and Ascomycota were significantly domi-nant bacteria.Compared with single cropping,the relative abundance of interplanting Salvia miltiorrhiza and shoot soil was significantly increased,and Basidiomycota decreased significantly.Agaricomycetes,Sordariomy-cetes,Dothideomyce,Mortierellomycetes and Eurotiomycetes were the significantly dominant groups.Compared with non-intercropping,the relative abundance of Agaricomycetes significantly decreased,while the relative abun-dances of Sordariomycetes,Dothideomycetes,and Mortierellomycetes significantly increased.The soil fungi were dominated by Unclassified,Mortierella and Fusarium.The relative abundance of Mortierella and Fusarium was higher in intercropping Belamcanda chinensis and Salvia miltiorrhiza than in single cropping.pH and sucrase were important environmental factors affecting the soil bacterial communities.[Conclusion]The planting pat-terns of Carya illinoensis+Salvia miltiorrhiza and Carya illinoensis+Belamcanda chinensis significantly affect soil microbial community structure,can improve the soil organic matter content and promote the transformation of soil insoluble phosphorus into effective phosphorus.At the same time,there may be continuous cropping ob-stacles,so crop rotation pattern is recommended.
[Objective]This study aims to provide a theoretical basis for exploring the endangered mechanism and ex situ conservation of Sinomanglietia glauca by systematically comparing the growth and diurnal photosynthetic responses of Sinomanglietia glauca and Schima superba under different light and fertilization treatments.[Method]Seedlings of S.glauca and S.superba were used as experimental materials.Three shading regimes(S0,S1,S2)were established under two fertilization treatments:nitrogen and phosphorus application(N1P1)and no nitrogen and phosphorus application(N0P0),yielding six simulated cultivation treatments.Growth performance and diurnal changes in photosynthetic parameters were then compared between the two species under these treatments.[Result](1)Ground diameter and plant height growth of S.glauca were significantly affected by shading(P<0.001),whereas the effect of fertilization was not significant(P>0.05).In contrast,the growth of S.superba was less affected by shading and fertilization and was even promoted under mild shading.(2)Across all treatments,the diurnal course of net photosynthetic rate(Pn)in both species exhibited a single-peaked pattern,and no midday depression of photosynthesis was observed.Fertilization had no significant effect on Pn in S.glauca(P>0.05).Stomatal conductance(Cond)showed a single-peaked pattern in S.glauca but tended to be bimodal in S.superba.Intercellular CO2 concentration(Ci)generally showed a U-shaped pattern.Transpiration rate(Tr)and water use efficiency(WUE)both showed single-peak patterns in the two species.Light use efficiency(LUE)fluctuated with small amplitude in both species.(3)Under low-light conditions,Pn in S.glauca was constrained by multiple environmental factors,and its adaptability to environmental conditions was significantly lower than that of S.superba,which may help explain its narrow ecological niche.[Conclusion]The growth of S.glauca seedlings is primarily limited by shading,whereas fertilization has little effect.In contrast,S.superba seedlings are less responsive to both shading and fertilization.Compared with S.superba,S.glauca seedlings demand more stringent environmental conditions under various shading levels and exhibit weaker photosynthetic acclimation.Therefore,for ex situ conservation of S.glauca,priority should be given to well-lit sites such as forest gaps,forest edges,and thinned stands,so as to facilitate population conservation and recovery.
[Objective]To investigate the effects of different planting modes on crop yield,nutrient accumulation,and utilization efficiency of climate resources.[Method]Six cropping patterns were established:maize monocropping,spring maize||spring soybean,potato/spring maize/summer soybean,rapeseed-summer maize||summer soybean,ryegrass-spring maize/summer soybean,and ryegrass-spring maize||spring soybean.A two-year field experiment was conducted to measure yield,nutrient accumulation,and utilization efficiency of light,temperature,and water resources.[Result]The results showed that combined cropping patterns(intercropping,relay intercropping,inter-relay cropping,and rotation)significantly outperformed the monocropping pattern.Specifically,the potato/spring maize/summer soybean pattern had the highest average annual economic yield over two years,increasing by 247.65%compared with maize monocropping.The total accumulation of nitrogen,phosphorus,and potassium under the potato/spring maize/summer soybean and ryegrass-spring maize||spring soybean treatments were significantly higher than those under other treatments.Compared with maize monocropping,the total annual accumulation of nitrogen,phosphorus,and potassium in the potato/spring maize/summer soybean treatment increased by 38%,26%,and 59%,respectively;those in the ryegrass-spring maize||spring soybean treatment increased by 55%,15%,and 40%,respectively.In terms of utilization of light,temperature,and water resources,the potato/spring maize/summer soybean pattern was significantly superior to other treatments,with light energy production efficiency,accumulated temperature production efficiency,and precipitation production efficiency increasing by 72%,17%,and 50%compared with maize monocropping,respectively.[Conclusion]The relay intercropping pattern of potato/spring maize/summer soybean and the cropping pattern of ryegrass-spring maize||spring soybean contribute to high crop yield,efficient nutrient utilization,and full exploitation of climate resources,providing scientific basis and technical support for the screening and promotion of high-efficiency maize-soybean cropping patterns in the middle and lower reaches of the Yangtze River.
[Objective]This study is designed to examine the influence of digital technology application on the service performance of frontline agricultural technology extension staff,while also exploring the mediating role of knowledge network expansion.The overarching goal is to lay a theoretical and empirical groundwork for advancing the informatization and networking of the grassroots agricultural technology extension system.[Method]This study analyzes the impact of digital technology application on the performance of public-interest agricultural extension services by grassroots personnel and its underlying mechanisms,using micro-survey data from 1 506 grassroots agricultural extension workers in Jiangxi Province,along with extended regression models and mediation effect models.[Result]Digital technology application exerts a statistically significant positive effect on the service performance of grassroots agricultural extension personnel at the 1%significance level.Robustness checks employing replace samples and research methodology confirm the validity of these findings.Mechanism analysis indicates that digital technology application improves service delivery performance by expanding knowledge networks formed through agricultural technology dissemination.Heterogeneity results show that compared to full-time agricultural technology extension personnel,digital technology application has a more significant effect on improving the efficiency of extension services for part-time personnel.Compared to agricultural technology extension personnel with agricultural-related majors,digital technology application has a greater effect on improving the extension services for personnel with non-agricultural-related majors.For agricultural technology extension personnel with higher salaries,digital technology application has a greater impact on their extension service provision.[Conclusion]Efforts should be accelerated to improve the conditions for the application of digital technology,strengthen the capabilities and incentive mechanisms of agricultural technology extension personnel,establish a digital agricultural technology extension service system,promote the establishment of a digital service system for agricultural technology extension,and actively explore and advance the digital transformation of government public welfare agricultural technology extension services.
[Objective]The aim is to provide excellent materials for improving the carbon storage of forest stands by screening high carbon sink families of Cyclobalanopsis gilva.[Method]The standard trees of Cyclobalanopsis gilva of different forest ages and diameter classes of 4-14 cm were selected.The aboveground and underground samples were collected by individual felling method and full digging method,respectively.The biomass and organic carbon content were measured,and the biomass and organic carbon models were constructed.The model was used to calculate the biomass and carbon storage of 42 families of 3-year-old Cyclobalanopsis gilva,analyze the genetic variation characteristics of growth and form traits of each family,analyze the genetic variation of biomass and carbon storage of each family,estimate the genetic gain,and screen out the excellent families of Cyclobalanopsis gilva with large biomass and carbon storage gain.[Result](1)There was a significant family×block effect(P<0.01)in the growth and form quality traits of different families of 3-year-old Cyclobalanopsis gilva.The heritability of tree height,ground diameter,crown width and longest lateral branch length was high(0.470-0.518),and the heritability of single plant was relatively low.(2)The optimal fitting model of biomass and organic carbon of Cyclobalanopsis gilva was ln Y=k0+k1ln D+k2ln H+k3ln CW.The fitting accuracy of aboveground part model was better than that of underground part,and the fitting effect of dry biomass and organic carbon model was the best.(3)There were significant or extremely significant family×block effects on biomass and carbon storage of different families of 3-year-old Cyclobalanopsis gilva.The heritability of family was higher than that of single plant.The genetic gains of biomass and carbon storage of living branches were the highest,which were 43.93%and 47.60%,respectively.(4)Based on the comprehensive comparison of family biomass,carbon storage,comprehensive selection index and BLUP breeding value,the top 10%were selected as the selection standard of excellent high-carbon sink families.Fujian JO1,Hunan CB8 and Hunan YS3 were selected as excellent high-carbon sink families.The genetic gains of biomass and carbon storage were 21.27%and 13.60%,respectively,and the realistic gains were 38.96%and 49.98%,respectively.[Conclusion]The heritability of 3-year-old Cyclobalanopsis gilva families is generally high,which is controlled by strong family genetic control.The selected 3 excellent high-carbon sink families of Cyclobalanopsis gilva can be used as excellent material selection for carbon sink afforestation.
[Objective]To determine the antiviral activity of corynoline against porcine epidemic diarrhea virus(PEDV)in vitro and to preliminarily investigate its potential mode of action.[Method]The cytotoxicity of corynoline on African green monkey kidney cells(Vero)and porcine small intestinal epithelial cells(IPEC-J2)was assessed using the cell counting kit-8(CCK-8)assay to determine its safe concentration range.Subsequently,the RT-PCR was employed to evaluate inhibitory effect of corynoline on PEDV replication in both cell types.In vero cells,its dose-dependent antiviral activity was further analyzed using indirect immunofluorescence,Western blotting,and viral titer assays.To elucidate the mechanism of action,a time-course dosing experiment was conducted to evaluate the impact of corynoline on the PEDV life cycle across four stages(adsorption,internalization,replication,and release)using RT-PCR technology.The antiviral efficacy of different administration methods(pretreatment,co-treatment,and post-treatment)was also compared.[Result]Corynoline exhibited no significant cytotoxicity in Vero or IPEC-J2 cells at concentrations below 6.25 μmol/L.Corynoline dose-dependently inhibited PEDV mRNA expression,N protein synthesis,and viral titers.Stage-specific experiments demonstrated the ability of corynoline to interfere with viral adsorption,internalization,and progeny virus release.The pretreated group(dosing prior to infection)exhibited more pronounced antiviral activity.[Conclusion]In vitro,corynoline exerts its anti-PEDV effects through multiple pathways,primarily targeting the stages of viral adsorption,internalization,and release,making it particularly suitable for prophylactic administration.This study systematically elucidates the anti-PEDV activity of corynoline and its mechanisms of action,providing experimental evidence for subsequent mechanism research and drug development.
[Objective]To explore the impact of brassinolide(BR)on the growth,development,and photosynthesis of sesame seedlings under drought stress conditions.[Method]A seedling-stage pot trial was carried out on Poyanghei,a brand of sesame in Jiangxi Province.Two controls were installed:CK(full irrigation,no BR)and T0(drought,water spray).Drought-stressed plants were further supplied with 0.1,0.2,0.4 or 0.8 mg/L BR(giving treatments T1 to T4);After three consecutive days of foliar application,plant height,stem diameter,leaf area,biomass,SPAD value,leaf gas-exchange variables and membrane-lipid peroxidation markers were recorded on days 0,7 and 14 of drought.[Result]The results indicated that,relative to the control group(CK),the growth of sesame seedlings under drought stress significantly increased,with reductions in plant height,stem diameter,leaf area,and above-and below-ground biomass by up to 43.4%,26.6%,46%,60.1%,and 56%,respectively.Additionally,the relative electrical conductivity(REC)and malondialdehyde(MDA)content in the leaves increased significantly by 137.6%and 62.4%,respectively.Meanwhile,the photosynthetic performance of sesame seedling leaves was significantly inhibited under drought stress,with SPAD,net photosynthetic rate(Pn),stomatal conductance(Gs)all significantly reduced compared to the control(CK);intercellular carbon dioxide concentration(Ci)significantly increased Exogenous BR sprays of graded concentrations mitigated drought-induced growth suppression in sesame seedlings,primarily through improvements in leaf gas exchange parameters,enhanced dry matter accumulation in various organs during the seedling stage,and reductions in leaf relative electrical conductivity(REC)and malondialdehyde(MDA)content,thereby mitigating lipid peroxidation damage to the seedlings.Compared to T0,the T3 treatment significantly increased Pn,Gs,and SPAD values by up to 38.6%,64.6%,and 26%,respectively,while reducing MDA and REC by up to 23.8%and 45.1%,respectively.[Conclusion]Exogenous application of BR can alleviate the inhibitory effects of drought stress on sesame seedlings,maintain normal growth,development,and metabolism,with the best alleviation achieved at a BR concentration of 0.4 mg/L.
[Objective]This study explores the rootstock-scion effect on the response to potassium deficiency in grafted Camellia oleifera seedlings from the perspectives of anatomical structure,potassium nutrient accumulation,and water potential,providing theoretical guidance for regulating potassium absorption and utilization in oil tea as well as for selecting and using rootstocks.[Method]Two potassium treatments were designed:potassium application(K1:6 mmol/L)and potassium deficiency(K0:0 mmol/L).Potted experiments were carried out using five one-year-old grafted Camellia oleifera seedlings with either the same rootstock and different scions or the same scion and different rootstocks(Gan 8/Gan Wu 2,Gan Wu 1/Gan Wu 2,Gan Wu 2/Gan Wu 2,Gan Wu 2/Gan 8,Gan Wu 2/Gan Wu 1)as experimental materials.Regular sampling was conducted to observe and measure stem and leaf anatomical structure,potassium content,and water potential,in order to analyze the response differences of grafted Camellia oleifera with different rootstocks or scions to potassium deficiency.[Result](1)The response of tissue thickness in the leaves of tea-oil seedlings during the seedling stage to potassium deficiency is not only related to the scion variety but also affected by the rootstock variety.For Gan 8,whether used as a rootstock or scion,the tissues of the grafted seedlings'leaves are thicker when no potassium is applied,whereas for Gan Wu 1,the tissues are thicker under potassium application.The anatomical structure of the stem responds to potassium deficiency more closely depending on the scion variety.Potassium deficiency promotes an increase in stem and pith diameter in Gan 8 scion combinations,with diameters in November being 11.29%and 47.70%larger than those under the K1 treatment,whereas in the other two scion combinations,the diameters under potassium deficiency are significantly smaller than with potassium application.(2)Potassium deficiency overall affects the accumulation of potassium nutrients in the stems and leaves of grafted seedlings.The effect on leaf potassium content is determined by the scion variety and is not related to the rootstock variety.In Gan 8 and Gan Wu 1 scion combinations,leaf potassium content under K0 treatment is significantly reduced by 37.8%and 30.7%compared to K1 treatment,while in Gan Wu 2 scion combination,the difference between K0 and K1 treatments is not significant.The effect of potassium deficiency on stem potassium content is related not only to the scion but also varies with different rootstocks.Under potassium deficiency,the stem potassium content in May for Gan Wu 1 rootstock and scion combinations decreased significantly by 36.9%and 40.7%compared to K1,whereas for Gan 8 and Gan Wu 2 used as either rootstock or scion,stem potassium content during the seedling stage was not significantly affected.(3)Potassium deficiency enhances the predawn water potential in all combinations of tea-oil seedlings,while its effect on midday water potential is smaller;the scion variety is the key factor determining the water response of tea-oil seedlings.Gan 8 scion combinations are more sensitive to potassium deficiency,with predawn water potential in May and November being significantly higher than K1,increasing by 67.86%and 45.82%,respectively;differences in rootstock varieties have relatively smaller effects on water potential responses to potassium deficiency.[Conclusion]The response of grafted Camellia oleifera seedlings to potassium deficiency during the seedling stage shows both rootstock and scion effects.The response of leaf anatomical structure and stem potassium content to potassium deficiency is jointly influenced by the scion and rootstock,whereas the response of leaf potassium content,stem anatomical structure,and water physiology(water potential)is mainly dominated by the scion variety.It is recommended that nutrient management of tea-oil plants should consider the differences in scion variety characteristics while also paying attention to the influence of the grafted rootstock varieties.
[Objective]There are some differences in the response of rice to drought stress with different growth stages.The study can provide theoretical basis for scientific irrigation and drought resistance and yield reduction of rice.[Method]A field plot experiment was conducted under rain-sheltered conditions,with normal irrigation as the control.Four drought levels of light drought(W1),moderate drought(W2),severe drought(W3)and extreme drought(W4)were set up at tillering stage(P1)and heading and flowering stage(P2),respectively.The plant height,tillering dynamics,chlorophyll content,yield and its composition,water consumption and water use efficiency were measured.[Result]The increase of drought degree inhibited the morphological development of rice.The average reduction of plant height and tiller number under drought treatment at tillering stage was 2.0 and 4.1 percentage points higher than that under drought treatment at heading and flowering stage,respectively.The SPAD values of leaves at tillering stage and heading and flowering stage decreased with the increase of drought grade,which decreased 11.5%-24.2%and 6.5%-21.8%respectively compared with CK.The effect of drought stress on rice yield was different at tillering stage and heading and flowering stage.When the drought at tillering stage continued to moderate drought level,the yield decreased gradually(8.4%-32.2%),while different levels of drought at heading and flowering stage led to a gradual decrease in yield(9.9%-40.1%).The yield reduction factor of drought stress at tillering stage was the decrease of effective panicles and grain number per panicle,while the heading and flowering stage was the significant decrease of 1000-grain weight and seed setting rate.The water consumption at tillering stage and heading and flowering stage decreased 6.8%-20.1%and 6.3%-17.8%respectively with the increase of drought grade,while the water use efficiency showed growth period differentiation.The average decrease of drought treatment at tillering stage was not significant(2.5%),and the average decrease at heading and flowering stage was 14%.[Conclusion]Drought at tillering stage affects yield formation by inhibiting tillering and panicle differentiation,while drought at heading and flowering stage causes a synergistic decrease in yield and water use efficiency by inhibiting grain filling.Therefore,systematically revealing the differential effects of continuous drought stress on the growth and water use of rice at key growth stages has practical guiding value for improving rice drought defense ability and ensuring food security.
[Objective]To determine the taxonomic status of Streptomyces AX-1 and its control effect against Geotrichum candidum on nectarines.[Method]The status was determined by observing the cultural,physiological and biochemical characteristics of strain AX-1 on various media including ISP2,ISP3,ISP4,ISP5,ISP6,ISP7,and PDA,combined with 16S rDNA sequence analysis.The antagonistic activity of AX-1 against G.candidum was determined using the dual culture assay,with the inhibition rate calculated accordingly.The fermentation filtrate of AX-1 was prepared and subjected to different dilution treatments;its effect on the colony diameter of the pathogen was measured by the mycelial growth rate method,and the inhibition rate was computed.Morphological changes of the pathogen's mycelia after treatment with the fermentation filtrate were observed under an optical microscope.The inhibitory effect of the fermentation filtrate on the spore germination of G.candidum was assessed by the spore germination method.Finally,the control efficacy of the fermentation filtrate at different dilutions against lesion expansion on nectarine fruits was evaluated using the in vitro fruit inoculation method.[Result]Based on morphological observation,physiological and biochemical analysis,and molecular identification,strain AX-1 was identified as Streptomyces albidoflavus.Its aerial hyphae were white,and its spores were elliptical.This strain could utilize various carbon sources such as mannitol,glucose,xylose,arabinose,and lactose,as well as nitrogen sources including glycine and KNO₃.In the dual culture assay,the inhibition rate of AX-1 against G.candidum reached 67.08%.The fermentation filtrate significantly inhibited the mycelial growth of the pathogen,and the inhibitory effect was enhanced with the decrease of dilution ratio;after 5 days of treatment with the 10-fold diluted filtrate,the inhibition rate reached 67.24%.Microscopic observation showed that after treatment with the fermentation filtrate,the pathogen mycelia exhibited malformations such as uneven thickness,swelling and thickening,and reduced branching.The fermentation filtrate significantly inhibited spore germination;the germination rate of spores treated with the 10-fold diluted filtrate was only 17.33%,with an inhibition rate of 80%.The in vitro control efficacy test indicated that the fermentation filtrate of AX-1 could effectively inhibit lesion expansion on nectarine fruits,and the 10-fold diluted filtrate showed the best control effect,reaching 66.81%.[Conclusion]Strain AX-1 is identified as Streptomyces albidoflavus.Its fermentation filtrate exerts significant antagonistic activity against Geotrichum candidum by suppressing mycelial growth and spore germination.Given its vitro control efficacy,Streptomyces albidoflavus AX-1 holds considerable potential for development as a biocontrol agent against postharvest diseases.
[Objective]The purpose of this experiment is to compare the efficiency of imidacloprid mineralization by electro-Fenton system under pure oxygen and air aeration respectively,and explore the enhancement mechanism of pure oxygen aeration in the electro-Fenton system.[Method]The electro-Fenton system was constructed using a ring-shaped graphite felt cathode and a BDD plate anode.Under the conditions of initial pH of 3,Fe2+dosage of 0.5 mmol/L,and current density of 1 mA/cm2(based on the effective area of the graphite felt),pure oxygen and air were continuously bubbled into the reactor at a flow rate of 1.2 L/min.The TOC removal performance of the electro-Fenton process under pure oxygen and air aeration was determined,along with the concentration variations of H2O2 and iron ions of various valences,and the biodegradability(BOD5/COD ratio)of treated solution.The mineralization current efficiency and energy consumption of the system were also calculated.[Result]Compared with air aeration,using pure oxygen aeration could increase the TOC removal efficiency of the electro-Fenton system from 57.11％to 70.45％,enhance the mineralization current efficiency from 135.61％to 173.32％,and reduce the energy consumption from 39.86 kWh/kg TOC to 31.00 kWh/kg TOC.Pure oxygen aeration significantly enhanced the cathodic in-situ H2O2 production capacity,with the maximum H2O2 concentration reaching 4.31 mmol/L,which was 2.12 times that under air aeration during the same period.The maximum current efficiency for H2O2 production reached 54.78％,which was 1.37 times that under air aeration during the same period.The Fe2+/Fe3+ratio in the electro-Fenton system gradually decreased with reaction time,dropping to 4.35 and 2.86 after 120 min under air and pure oxygen aeration,respectively,with the ratio being consistently lower under pure oxygen condition.The TOC removal efficiency of the pure oxygen aeration system exhibited a trend of first increasing and then decreasing with the increase of iron dosage,and 0.1 mmol/L was identified as the optimal dosage achieving the best balance between hydroxyl radical generation and quenching in this system.Under their respective optimal iron dosages,after treating the imidacloprid solution for 2 h,the BOD5/COD ratios of the effluents from the air and pure oxygen aeration systems were 0.065 and 0.234,respectively,indicating that pure oxygen aeration was more effective to improve the biodegradability of the solution.[Conclusion]Although the Fe2+/Fe3+ratio is lower under pure oxygen aeration,which is unfavorable for Fenton reaction,the positive effect brought by the significant increase in H2O2 concentration plays a dominant role.Therefore,the pure oxygen aeration electro-Fenton system exhibits superior TOC removal performance and biodegradability improvement compared to the air aeration electro-Fenton system.
[Objective]To lay the foundation for the automative operation of ridge cabbage harvesting,and to address the issues such as severe shading of the ridge furrows by mature cabbage leaves and significant deviations in traditional navigation line fitting algorithms,research on ridge furrow identification and navigation line fitting was conducted.[Method]Firstly,furrow data with different degrees of occlusion were collected,and a cabbage furrow dataset was created using data augmentation,and the dataset was classified into three categories:slightly occluded(Low),heavily occluded(Middle),and severely occluded(High)through the Grid Method statistics.Then,machine vision algorithms were used to conduct image preprocessing and image segmentation on slightly occluded,heavily occluded and severely occluded furrows to obtain the position information of the furrows.Subsequently,the furrow information was initially denoised through algorithms in mathematical morphology,and further denoised through the contour function(FindContours)to simultaneously obtain the boundary coordinate information of the furrows.Subsequently,the boundary of the furrow was utilized to extract the point clouds in the furrow as the reference points for navigation line fitting.Finally,a comparative test of Random Sample Consensus(RANSAC)algorithm,Ordinary Least Squares(OLS)method and Huber loss function navigation line fitting was carried out.[Result]The results show that the RANSAC algorithm performs better.The navigation line fitting experiment was conducted by improving the RANSAC algorithm in combination with the Trimmed Mean.The test results indicate that when the original image is used as the processing object,compared with the traditional algorithm,the improved RANSAC algorithm significantly improves the fitting accuracy of minor and severe occlusions.They increased by 5.7 and 8.4 percentage points respectively.When the data-enhanced image was taken as the processing object,it was found that the improved algorithm is generally superior to the traditional algorithm.However,the processing method of brightness enhancement had the greatest interference on the fitting effect.Compared with the original image,the fitting accuracy was reduced by up to 9.9 percentage points.The influence of geometric transformation and Gaussian blur on the fitting effect is second,and the influence of brightness reduction is the least.[Conclusion]The test results prove that the improved RANSAC algorithm can effectively enhance the fitting accuracy of navigation lines and has high robustness.
[Objective]Large-scale farmers,as the core subjects of grain production and management,play a crucial role in ensuring grain production capacity through their behavior regarding double-cropping rice planting.Although existing government support has an incentive effect,the mechanism and heterogeneous impacts of different dimensions of government support have not yet been fully clarified,and further research is urgently needed.[Method]Based on survey data from Jiangxi Province in 2024,this study employs double-hurdle model to empirically analyze and verify the impact of government support on large-scale farmers'double-cropping rice planting behavior from technical training,fund subsidies,and high-standard farmland construction.[Result]Funding subsidies have a positive effect on the double-cropping rice planting behavior of large-scale farmers at the 1％significance level.Technical training and high-standard farmland construction positively influence large-scale farmers'decisions to adopt double-cropping rice planting at the 5％and 1％levels,respectively,but show no significant impact on the intensity of double-cropping rice planting.Meanwhile,the effects of government support on farmers'planting behavior vary across different levels of farmers'part-time farming,participation in industrial organizations,and village economic development.[Conclusion]To stabilize the double-cropping rice production of large-scale farmers,we propose optimizing the subsidy mechanism for double-cropping rice planting,establishing a precise technical training system,strengthening the quality improvement and long-term management mechanism of high-standard farmland construction,improving the benefit linkage mechanism of socialized service organizations,and collaboratively incentivizing the double-cropping rice planting behavior of large-scale farmers.
[Objective]This study aims to explore the absorption and accumulation of selenium(Se)from soil and foliar fertilizers in different citrus varieties,to clarify the distribution patterns of Se within various citrus organs and tissues after foliar application,to screen suitable selenium foliar fertilizers for citrus production,and to provide a theoretical foundation for the standardized production of selenium-enriched citrus fruits.[Method]The relationship between fruit selenium content and soil selenium content was investigated across five major commercially cultivated citrus varieties in Jiangxi Province.Soil and fruit samples were collected and analyzed for total selenium concentration.Furthermore,16 citrus varieties were treated with foliar applications of three selenium fertilizers:nano-Se,yeast-derived organic Se(Se-yeast),and sodium selenite(Na₂SeO₃).The differences in fruit selenium content among cultivars and fertilizer types were systematically compared.Cluster analysis was employed to classify the varieties based on their ability to accumulate selenium in fruit.Finally,the Se content in different tissues and organs(including leaves,stems,roots,peel,and pulp)was quantitatively analyzed after nano-Se application to elucidate its distribution pattern in citrus.[Result]Among 17 orchards of the five major varieties,10 had Se-rich soil(Se>0.4 mg/kg).However,none of the citrus fruits from these orchards reached the fruit selenium-enriched standard(Se>10 µg/kg),indicating a limited capacity for natural selenium uptake from soil.In contrast,foliar application of all three kinds of Se fertilizers significantly increased fruit Se content in all 16 tested cultivars to attain the Se-enriched standard,with considerable variation among varieties.The cultivar'Cuipi'kumquat exhibited substantially higher fruit Se levels than all others.Among the remaining cultivars,'Orah'tangor exhibited the highest selenium content after nano-selenium application,'Miguang'mandarin showed the highest after Se-yeast application,and'Harumi'recorded the highest after sodium selenite application.Cluster analysis indicated that pomelo varieties,'Eureka'lemon,'Nanfeng'mandarin,and satsuma mandarin consistently demonstrated weak capacity for Se absorption and accumulation across all three type fertilizers.Conversely,'Harumi'tangor demonstrated a strong capacity for all three type fertilizers.'Xinyu'tangerine was highly efficient in absorbing nano-Se and yeast-derived organic Se;'Orah'and'Kanpei'tangor were highly efficient for nano-Se and sodium selenite;and'Miguang'mandarin and'Ehime 28'tangor showed strong absorption and enrichment capabilities for yeast-derived organic Se and nano-Se.Following foliar application,Se content was highest in leaves,followed by stems,peel,and roots,and was lowest in the pulp.[Conclusion]Citrus exhibits a limited capacity to absorb Se from soil.Different citrus varieties show significant variation in their absorption of various foliar Se fertilizers,necessitating the selection of appropriate foliar fertilizers based on specific varietal characteristics.Nano-Se fertilizer can be recommended as the primary choice for Se-enriched citrus production.Alternatively,yeast-derived organic Se fertilizer can be prioritized for Satsuma mandarin,'Ehime 28'tangor,'Newhall'navel orange,'Jinsha'pummelo,'Nova'tangelo,and'Cuipi'kumquat.After foliar application,Se is primarily absorbed and metabolized by the leaves,then transported along a concentration gradient to accumulate in the stems,roots,peel,and pulp.These results establish a theoretical and practical foundation for developing Se-enriched citrus production technologies.
[Objective]To analyze the variation patterns and genetic parameters of seed and cone traits in the hybrid progeny of Chenshan red-heart Chinese cunninghamia and Chinese cunninghamia,providing a theoretical reference for parental selection in its hybrid breeding and the establishment of multi-clone seed orchards.[Method]With four superior clones from the 1.5-generation seed orchard of Chenshan red-heart Chinese fir and two superior clones from Chinese fir provenance seed orchard at the national base in Baiyunshan Forest Farm,Qingyuan District,Ji'an City,Jiangxi Province as parents,controlled pollination was conducted according to a 6×6 complete diallel cross design.Measurements and analyses were conducted on four cone traits(cone length,cone width,cone volume,fresh cone weight)and two seed quality traits(thousand-seed weight,germination rate)for the 36 hybrid combinations.[Result]Cone traits of Chinese fir are primarily influenced by the maternal parent and the interaction between the paternal and maternal parents,while thousand-seed weight and germination rate are jointly affected by the paternal parent,maternal parent,and their interaction.The results showed that extremely significant differences(P<0.001)existed among the 36 hybrid combinations for cone length,cone width,cone volume,fresh cone weight,thousand-seed weight,and germination rate.Extremely significant differences(P<0.001)were also observed in the general combining ability(GCA),specific combining ability(SCA),and reciprocal effect(REC)for each trait.Cone traits in the hybrid combinations were predominantly controlled by additive gene effects,supplemented by non-additive gene effects.In contrast,two seed quality traits were primarily governed by non-additive gene effects,with additive gene effects playing a supplementary role.The GCA for cone traits was higher in Chinese cunninghamia than in Chenshan Red-heart Chinese cunninghamia,while the GCA for germination rate was generally greater in Chenshan Red-heart Chinese cunninghamia compared to Chinese cunninghamia.Based on the general combining ability for germination rate,clones H43 and H16 of Chenshan Red-hearted Chinese cunninghamia were selected as superior clones.Based on the GCA,SCA,and REC effect values for seed and cone traits in the hybrid progeny,combinations H43×R4,H43×H21,and H21×H48 were identified as superior hybrid combinations.[Conclusion]Significant differences were observed in the seed and cone traits among different cross combinations of Chinese cunninghamia in the complete diallel mating design.While self-pollination does not significantly affect the cone traits of Chinesecunninghamia,it leads to a severe decline in germination rate.There are considerable differences in the GCA of different seed and cone traits in Chinese cunninghamia.In the selection of breeding parents for Chinese cunninghamia,it is essential to prioritize hybrid combinations that demonstrate outstanding seed germination rates to improve the germination rate of the offspring.
[Objective]This study aims to investigate the effects of intercropping with soybean on the microbial community structure in the rhizosphere soil of cassava,and to clarify the regulatory effects of different intercropping row spacings on microbial diversity and composition.[Method]A field experiment was conducted with cassava monoculture(C)and cassava/soybean intercropping at row spacings of 30 cm,40 cm,and 50 cm(denoted as IS30,IS40,and IS50,respectively).Cassava rhizosphere soil samples were collected,and bacterial and fungal communities were analyzed using high-throughput sequencing.[Result]The results showed that intercropping significantly reduced the richness of soil bacterial communities(ACE and Chao1 indices),but had no significant effect on diversity indices(Shannon and Simpson).In contrast,both the richness and diversity of fungal communities were significantly increased under the IS30 treatment.Principal component analysis(PCA)revealed clear separation between intercropping and monoculture treatments in both bacterial and fungal community structures,with the IS40 treatment having the greatest impact on bacteria and IS₃₀ on fungi.At the phylum level,intercropping increased the relative abundance of Proteobacteria and Firmicutes,while decreasing that of Acidobacteriota and Bacteroidota.At the genus level,beneficial taxa such as Burkholderia-Caballeronia-Paraburkholderia and Acidothermus were significantly enriched in intercropped soils.The relative abundance of pathogenic fungi such as Fusarium in the IS₃₀ treatment was 32.69%,significantly lower than the 50.52%observed in monoculture,representing a reduction of 35.29%.[Conclusion]These findings indicate that cassava/soybean intercropping can regulate rhizosphere microbial community structure by enhancing beneficial microorganisms,suppressing pathogens,and optimizing the soil microecological environment,with the 30 cm row spacing being the most effective.This study provides a microbiological ecological basis for optimizing cassava-soybean intercropping systems and promoting sustainable agricultural practices.
[Objective]Pseudomonas aeruginosa(P.aeruginosa)is a common multidrug-resistant opportunistic pathogen that poses a significant threat to public health and human well-being.Consequently,developing novel fungicides targeting multidrug-resistant bacteria has become an urgent need for controlling pathogenic contamination.[Method]In this study,P.aeruginosa was used as the host bacterium to isolate lytic phages from sewage,characterized their biological properties,analyzed their complete genomes,and determined their combined effects with antibiotics on inhibiting and eradicating biofilms.[Result]A lytic phage vB_PaS_JXAU_S1 of multidrug-resistant P.aeruginosa was successfully isolated.It belongs to the Siphoviridae family.Its optimal multiplicity of infection was 0.01,the latent period was 20 min,and the burst size was 110 PFU/cell.The phage exhibited good thermal and pH stability.The whole genome size of vB_PaS_JXAU_S1 comprises 42 685 bp and encodes 58 open reading frames.vB_PaS_JXAU_S1 showed synergistic effects(FICI≤0.5)when combined with ciprofloxacin,imipenem,and meropenem.Specifically,when combined with meropenem(1/8 MIC),the inhibition rate of biofilm formation within 24 h was 87.37%,and the eradication rate of mature biofilms(72 h)is 63.15%.[Conclusion]This study successfully isolated and identified a lytic P.aeruginosa phage,designated as vB_PaS_JXAU_S1.Its combination with antibiotics exhibits synergistic effects against P.aeruginosa biofilms,providing new insights and methodologies for developing phage-based biocontrol agents to combat contamination by multidrug-resistant pathogens.
