Abstract:The huge and increasing area of saline-alkali land in China highlights the importance of fully developing and utilizing the resources to ensure arable land availability and maintain national agricultural secu-rity.Cotton is a pioneer crop in saline-alkali land,but there is significant variation in salt tolerance among dif-ferent cotton materials.Therefore,it is crucial to identify and select salt-tolerant cotton materials for planting in saline-alkali land.In this study,58 cotton materials were subjected to salt stress with NaCl solution at 300 mmol/L,and then the germination rate,germination vigor,germination index,plant height,aboveground dry weight and underground dry weight were measured,and their relative values were calculated and analyzed by principal component analysis(PCA)and cluster analysis.The results demonstrated that the 58 materials were divided into five categories including high-salt-resistant category(5 materials),salt-resistant category(11 ma-terials),salt-tolerant category(22 materials),non-salt-tolerant category(16 materials),and salt-sensitive category(4 materials).Furthermore,an optimal regression equation of trait indicators and comprehensive salt tolerance scores,D=-0.775+0.569XGR+0.720XGE+0.404XSW+0.410XRW,was established using stepwise re-gression analysis,so an evaluation method for cotton salt tolerance during germination and seedling stage,which could provide a theoretical foundation for identifying salt-tolerant cotton germplasms.

Abstract:To investigate the mitigation effect of exogenous salicylic acid(SA)on germination inhibition of seed under drought stress,seeds of Polygonatum sibiricum were used as material in the test,and the effects of soaking seeds with 0.01,0.10,1.00 and 2.00 mmol/L SA on seed germination,seedling growth and physi-ological indices under 6％polyethylene glycol(PEG-6000)stress(PG)were studied.The results showed that PG treatment significantly inhibited the seed germination and seedling growth of P.sibiricum showing as the decrease of germination potential,germination index,viability index,as well as seedling bud length,root length and fresh weight.Soaking seed with the suitable concentration of SA that was 0.10 mmol/L significantly improved the germination potential,germination index and vitality index of P.sibiricum seeds under PEG stress,significantly promoted the growth of seedling buds and roots,significantly enhanced the activities of catalase(CAT),superoxide dismutase(SOD)and peroxidase(POD)in buds and roots,significantly reduced the malondialdehyde(MDA)content,and significantly increased the contents of proline and soluble sugar.In conclusion,the treatment of 0.10 mmol/L exogenous SA could significantly reduce the inhibitory effect of PEG stress on germination of P.sibiricum seeds,significantly improve the antioxidant enzyme activities of P.sibiri-cum seedlings to reduce the oxidative damage caused by drought stress,and effectively improve the drought re-sistance of P.sibiricum at seed germination and seedling growth stages.

Abstract:In this experiment,the seedlings of Polygonatum kingianum Coll.et Hemsl.were used as test materials,the salt content was controlled by container salt pouring method,and the NaCl concentration was set as 50,100,150 and 200 mmol/L,respectively.Taking clear water as control(CK),the changes of growth and physiological indicators of P.kingianum seedlings under different NaCl concentrations were studied,and the stress degree was evaluated by correlation analysis,principal component analysis and membership function method,in order to explore the influence of different concentrations of NaCl on seedling growth and physiologi-cal characteristics of P.kingianum.The results showed that the growth and physiological indicators of P.king-ianum seedlings were obviously different under different NaCl treatments.With the increase of NaCl concentra-tion,the agronomic characters of P.kingianum seedlings showed the downward trend;the content of photosyn-thetic pigments in leaves changed significantly,and the contents of chlorophyll a,chlorophyll b and carote-noids decreased under NaCl stress;the malondialdehyde(MDA)content,proline(Pro)content,superoxide dismutase(SOD)activity and relative conductivity of leaves showed the upward trend,while peroxidase(POD)activity and reduced glutathione(GSH)content increased first and then decreased.Principal compo-nent analysis results showed that stem diameter,fibrous root length,fibrous root diameter,chlorophyll con-tent,SOD activity,MDA content and relative conductivity could be used as the evaluation indicators for P.kingianum under NaCl stress.According to the results of comprehensive evaluation,the stress degree of differ-ent NaCl concentrations to P.kingianum seedlings was sorted from higher to lower as 200 mmol/L NaCl,150 mmol/L NaCl,50 mmol/L and 100 mmol/L NaCl.The research results could provide theoretical and scientific bases for high-quality cultivation of P.kingianum.

Abstract:In this study,YOLOv5s-SCS,a real-time detection algorithm for strawberry maturity was pro-posed based on YOLOv5s.Aiming at the characteristics of large number,small size,covered,overlapping and density of strawberries during detection process,the algorithm optimized the problems of false detection and missing detection for small and dense targets,and significantly improved the detection speed.Firstly,SimOTA matching algorithm was introduced to dynamically assign positive samples of ripe strawberries to improve the recognition ability of ripe strawberries.Secondly,part of C3 module in YOLOv5s neck was replaced with C2f module,which realized the lightweight of model and improved the average detection accuracy.Finally,the Squeeze-and-Excitation(SE)attention mechanism with global receptor field was added to the first C3 module of the YOLOv5s backbone network.The SE mechanism can obtain the importance of each feature channel through automatic learning,and then use the obtained importance to promote features and suppress features which are not important to the task at hand.The experimental results showed that the mean average precision(mAP),accuracy rate,recall rate,model volume and detection speed of the improved algorithm were 98.3％,92.6％,96.6％,13.5 MB and 89.3 frames per second respectively,which were 1.8,1.3 and 2.1 per-centage points higher in mAP,accuracy rate and recall rate respectively compared with the original YOLOv5s,and also 0.32 MB less in model volume and 82.2％higher in detection speed;the time of NMS(non-maximum suppression processing)and image preprocessing was greatly reduced,and the detection speed could meet the real-time detection requirement.Compared with other algorithms,the algorithm had better recognition accuracy and smaller model volume,and had good robustness in complex environment,which provided a solution for developing real-time detection system of strawberry maturity.

Abstract:In order to explore the response characteristics of physical and chemical properties and en-zymes activities of tobacco growing soil to different types of biochar,the random block design was adopted,and three treatments were set,namely,conventional fertilization(CK),conventional fertilization+biochar based fertilizer(T1),and conventional fertilization+hydrochar based fertilizer(T2).The effects of different types of biochar based fertilizers on physicochemical properties and enzymes activities of tobacco growing soil and their correlations were studied.The results showed that compared with CK,T1 treatment significantly in-creased the soil total porosity of 0～20-cm layer by 14.31％and the soil nitrate nitrogen content by 30.32％,and significantly decreased the soil ammonium nitrogen content by 45.71％.Compared with CK,in 0～20-cm and 20～40-cm soil layers,T2 treatment significantly increased soil pH(by 7.74％and 7.57％),total nitro-gen(by 30.85％and 17.69％),nitrate nitrogen(by 30.40％and 24.66％),and decreased C/N(by 25.75％and 21.01％).Compared with CK,the activities of urease and sucrase in 0～20-cm soil layer were significant-ly decreased under T1 and T2 treatments by 19.42％and 29.72％,18.53％and 21.33％,respectively;T1 treatment significantly increased the cellulase activity by 9.72％and 53.95％,respectively.In conclusion,ure-ase and sucrase were the main driving factors of soil physical and chemical properties in 0～20-cm and 20～40-cm soil layers,respectively.

Abstract:To clarify the effects of different plant type and planting density on peanut yield and select the suitable planting density and plant type,the peanut cultivar of"Qinghua 7"was used as material in the test.Split-plot design was used with three planting densities of 210 thousand(D1),180 thousand(D2)and 150 thousand(D3)plants per hectare for the main plots,and four plant type shaping treatments of non-pressing ring(T0),pressing ring of 50 mm in diameter(T1),pressing ring of 75 mm in diameter(T2),and pressing ring of 100 mm in diameter(T3)at the early blooming and pegging stage for the subplots.Two years of field experiment were conducted and the effects of plant type and planting density on growth characteristics and yield of peanut were studied.The results showed that increasing density promoted the vegetative growth and significantly increased leaf area coefficient of peanut,while inhibited the reproductive growth and decreased the net photosynthetic rate and chlorophyll content of peanut functional leaves.Shaping plant type by pressing ring inhibited the vegetative growth of peanut,decreased the net photosynthetic rate and chlorophyll content of peanut functional leaves,while promoted the reproductive growth.Shaping plant type by pressing ring played vital roles in coordinating vegetative growth and reproductive growth,and increased the storage capacity.Under the planting density of 210 thousand plants per hectare,the treatment of pressing ring of 50 mm in diameter(D1T1)had the highest peanut yield,while under the planting densities of 180 thousand and 150 thousand plants per hectare,the highest yield occurred under the treatment of pressing ring of 100 mm in diameter(D2T3 and D3T3).This conclusion could provide a theoretical basis for the selection of high-yield peanut plant types under different planting densities.

Abstract:In order to determine the effects of salt stress,drought stress and their combination on growth and photosynthetic characteristics of different soybean(Glycine max L.)varieties(lines),7 soybean varieties(lines)were used as materials,and the pot experiment was conducted by setting four treatments including control(CK,normal water supply,75％of maximum field water capacity),salt stress(S,0.44％of soil salt content),drought stress(D,35％of maximum field water capacity)and salt-drought combined stress(S+D,35％of maximum field water capacity,0.44％of soil salt content).The effects of different treatments on 31 in-dicators of soybean seedlings such as growth parameters,photosynthetic characteristics,chlorophyll content,chlorophyll fluorescence parameters and root configuration were studied.The results showed that compared with CK,the digital biomass,leaf area,normalized vegetation index,leaf chlorophyll content,and some chloro-phyll fluorescence parameters including Fm,Fv/Fm,Fv/Fo,ΦPS Ⅱ,ETR and NPQ of soybean seedlings were significantly reduced under S and S+D treatments,especially under S+D treatment.Drought stress signif-icantly increased the leaf angle value and leaf projection area of soybean seedlings.The three stress treatments significantly reduced total root length,root surface area,root volume,root tip number,root bifurcation num-ber,cross number,photosynthetic rate,stomatal conductance,intercellular CO2 concentration and transpira-tion rate of soybean seedlings,and most of these indicators decreased to a significant level,but the reduction range under drought stress treatment was smaller than that under salt stress and their combination.In conclu-sion,the effects of salt and drought combined stress on soybean seedling growth were the most obvious,fol-lowed by salt stress and drought stress in order.According to the results of principal component analysis and membership function comprehensive evaluation,21C49 was a salt-tolerant line,Mengdou 46 was a variety re-sistant to drought stress and salt-drought combined stress,Heike 68 was a salt-sensitive and drought-sensitive variety,and Longken 330 was a variety sensitive to salt-drought combined stress.

Abstract:Crop pests and diseases pose a significant threat to global agricultural production,often lead-ing to substantial economic losses.The application of machine vision and machine learning methods for crop pest and disease monitoring not only enhances detection efficiency,but also facilitates timely preventive meas-ures to reduce losses.Convolutional neural network(CNN),as a prominent deep learning technique,has been widely used in computer vision for image and object recognition,and also has achieved promising a-chieves in crop disease and pest detection.This paper outlined the key aspects and development history of CNN-based techniques for crop disease and pest detection,reviewed the major research directions and ad-vancements in this area,summarized the main issues in current research,and proposed corresponding solu-tions.The aim of this paper was to provide a theoretical basis for CNN application in agriculture and to offer technical supports for the intelligent management of agricultural production.

Abstract:Root rot caused by Fusarium fungi is very serious in cucumber growing areas in Tianjin.In this study,the healthy soil samples were collected from cucumber planting fields in 4 districts of Tianjin,and biocontrol strains for this disease were isolated by plate face-off method.Their antibacterial activity and syner-gistic effect were evaluated through mixing sterile filtrate and pot tests,and they were identified by morphologi-cal,physicochemical and molecular biological analyses.The results showed that 8 strains were isolated with good inhibition effect on Fusariumoxy sporum and F.solani,among them,the strains BL-29 and BL-40 showed more than 50％inhibition rate on the two pathogens.After compatibility tests,it was found that the strains BL-01,BL-09 and BL-21 had better compatibility,and their composite sterile filtrate had the inhibition rate on the two pathogens more than 68.5％and 71.6％respectively,which were significantly higher than those of the sterile filtrate from individual strain.The results of pot experiments showed that the composite suspension of the 3 strains had 67.6％of prevention effect on cucumber root rot disease,which was significantly higher than the suspension of individual strain(P＜0.05).The strains BL-09 and BL-21 were identified as Bacillus velezensis,and the strain BL-21 was as B.halotolerans through identification.The multi-component combina-tion of biocontrol bacteria had the potential of effective disease control.

Abstract:The increase of greenhouse gases is the main cause of global warming,which has become a serious challenge to human society.Biochar as porous carbon-rich substance produced by high-temperature py-rolysis under anaerobic or oxygen-limited conditions plays important roles in improving soil fertility,increasing soil carbon sequestration potential and reducing greenhouse gas emissions due to their special physical and chemical properties.In this paper,the effects of biochar application in wetland especially paddy fields on soil carbon sequestration and greenhouse gas(CO2,CH4,N2O)emissions were reviewed.The results were as fol-lows:(1)The carbon sequestration and emission reduction capacity of wetland soil was affected by many fac-tors such as wetland type,soil type,and preparation temperature and addition amount of biochar.(2)The ap-plication of biochar in wetland could significantly increase soil pH value,reduce soil bulk density,increase soil organic carbon content,and improve soil carbon sequestration capacity.(3)Adding different types of bio-char into wetland could reduce soil CO2 emission,promote or inhibit CH4 emission,and inhibit N2O emission.(4)The promotion or inhibition effects of biochar on CH4 and N2O emission in paddy fields were affected by factors such as raw materials and addition amount of biochar.After searching and reading the literatures,it was found that there were fewer studies on the effects of adding biochar in wetland ecosystem on greenhouse gas e-missions.Therefore,it is necessary to further enrich the researches on the effects of different wetland types and raw materials,characteristics and application amount of biochar on soil carbon sequestration and emission re-duction.

Abstract:Soil conditioner application and grass planting in acidified orchards are effective measures to improve soil quality and enhance fruit yield and quality.The 2-year field experiment was conducted in acidified Qiuyue pear orchards in the Jiaodong Peninsula by setting four treatments including farmer accustomed fertili-zation(CK),farmer accustomed fertilization+1 500 kg/hm2 silicon-calcium-potassium-magnesium fertilizer(soil conditioner)(T1),farmer accustomed fertilization+grass planting(T2),and farmer accustomed fertili-zation+soil conditioner+grass planting(T3).Their effects on soil quality,and fruit yield and quality of Qi-uyue pear in the acidified orchard were studied.The results showed that the application of soil conditioner and grass planting significantly improved the soil environment in acidified pear orchards.Compared with CK,the soil pH value in 0～20-cm layer increased by 0.60,0.56 and 0.81 units,and the soil organic matter content increased by 12.34％,12.94％and 26.65％in T1,T2 and T3 treatments,respectively;the activity of soil en-zymes such as urease,peroxidase,β-glucosidase and phosphatase were also increased.The application of soil conditioner or grass planting had no significant effect on Qiuyue pear fruit yield,but significantly improved the fruit quality.T3 treatment had significant effects on fruit yield and quality,and soil quality.Compared with CK,T3 treatment increased the fruit yield by 12.15％and 7.22％in 2022 and 2023,respectively,and signifi-cantly increased soluble sugar and vitamin C contents in Qiuyue pear fruits.In conclusion,the application of soil conditioner combined with grass planting in acidified orchards could significantly increase the fruit yield and quality of Qiuyue pear,and significantly improve the soil quality.

Abstract:In order to determine the effects of foliar application of melatonin(MT)on cadmium(Cd)accumulation and stress resistance of tobacco seedlings under different nitrogen levels,the experiment was con-ducted by using hydroponic method and setting sodium nitrate(NaNO3)levels as 0.1,5 and 10 mmol/L,MT concentration as 100 µmol/L,and Cd concentration as 20 µmol/L.The biomass,physiological characteristics and Cd accumulation and transport of tobacco seedlings under Cd stress and different nitrate nitrogen levels were analyzed after foliar application of MT.The expression differences of Cd transport-related genes(NtIRT1,NtNRAMP1,NtNRAMP3,NtHMA2 and NtHMA3)were also detected and analyzed.The results showed that there were significant differences in the relieving ability of MT on Cd stress under different nitrate nitrogen lev-els.Compared with the normal nitrogen supply level(5 mmol/L),high nitrogen treatment(10 mmol/L)could promote the growth of tobacco seedlings,and spraying MT could further effectively increase the tobacco seedlingbiomass,the superoxide dismutase(SOD),peroxidase(POD),catalase(CAT)and ascorbate perox-idase(APX)activities and the ascorbic acid(AsA)and reduced glutathione(GSH)contents,but reduce the malonaldehyde(MDA)content;while under low nitrogen treatment(0.1mmol/L),spraying MT signifi-cantly decreased the SOD,POD and APX activities and the AsA and GSH contents,and significantly in-creased the MDA content.The Cd absorption capacity of tobacco seedlings was the strongest at high nitrogen level.MT application could decrease the expression level of NtIRT1,NtNRAMP1,NtHMA2 and NtHMA3 in the root of tobacco seedlings,and the decrease of NtNRAMP1 and NtHMA2 reached the significant level,so as to inhibit the Cd absorption.The absorption capacity of Cd was the weakest at low nitrogen level,and the miti-gation capacity to Cd was weak after MT application;the expression of NtIRT1,NtNRAMP1 and NtHMA3 were up-regulated,and the increase of NtNRAMP1 and NtHMA3 reached a significant level,so as to improve the transport capacity of Cd.In conclusion,nitrate nitrogen playedthe significant role in promoting exogenous MT to alleviate the influence of Cd stress on growth and development of tobacco seedlings and cadmium accumula-tion.With the increase of nitrogen level,MT application could significantly change the physiological character-istics of tobacco,reduce the absorption and accumulation of Cd,and improve the tolerance of tobacco seed-lings to Cd stress.

Abstract:High temperature during grain filling stage can lead to the decline of rice quality,and the grain quality varies with variety and spikelet position.In this study,four indica rice varieties were used as the research objects,and the split-plot design was adopted with two sowing date treatments(S1 and S2)in the main plot and four indica rice varieties(V1,V2,V3,V4)in the subplot,to study the effects of different tem-perature at filling stage on quality of rice grain at different grain positions caused by staged sowing under field conditions.The results showed that high temperature at filling stage under S1 sowing date reduced the whole rice rate,dissipation value and peak time,and increased the chalky grain rate,globin content,peak viscosi-ty,disintegration value and gelatinization temperature of the four rice varieties.Under the suitable temperature condition at grain filling stage of S2 treatment,the rice milling rate and whole rice milling rate of grains from the upper part of panicle in each variety were significantly higher than those from the lower part.Under the high temperature condition at grain filling stage of S1 treatment,the chalky grain rate,chalkines,peak viscosi-ty and disintegration value of grains from the upper part of panicle in each variety were higher than those from the lower part,and most of which were different significantly,but the dissipation value and peak time were significantly lower than those from the lower part.There was no significant correlation between gluten content,rice milling rate and characteristic values of RVA spectrum.The correlations between chalky grain rate,chalk-iness,albumin,globulin and each characteristic value of RVA spectrum were reverse with that between amy-lose and each characteristic value of RVA spectrum,indicating that the contents of amylose and protein com-ponents directly affected the gelatinization characteristics and eating quality of rice.In summary,high tempera-ture at filling stage of S1 treatment reduced the rice milling rate and increased the characteristics such as chalk-iness rate,peak viscosity and gelatinization temperature,which had significant effects on the upper,middle and lower grains,and the effect was more obvious on the grain quality of upper panicle.

Abstract:Drones,characterized by high mobility,flexibility and work efficiency,have become an inte-gral part of China's agricultural machinery and equipment,achieving remarkable application results in areas such as agricultural monitoring and farming operations.Equipped with various earth observation sensors such as visible-light and spectral cameras,LiDAR and thermal imagers,drones can rapidly,efficiently and accurately acquire remote sensing data of crops and soil.By integrating machine learning and artificial intelligence algo-rithms,they enable precise analysis of field area and yield estimation,pest and disease monitoring and early warning,soil quality assessment,and so on.Additionally,drones can be fitted with spraying and seeding sys-tems to perform efficient agricultural tasks such as crop protection and sowing.To better promote the applica-tion and development of agricultural drone technology in China,this paper provided a brief introduction to drone types,path planning,onboard sensors,and specialized farming payloads,and summarized the research progress and application status of drone technology in China's agricultural monitoring(including crop planting area and yield estimation,pest and disease monitoring and early warning,soil quality assessment,and crop phenotyping research)and farming operations(crop protection,fertilization,seeding,and harvesting).Fur-thermore,the current limitations of agricultural drone technology application in China were analyzed and its fu-ture development directions were prospected,aiming to provide a scientific reference for advancing the applica-tion of drones in China's agricultural production.

Abstract:In order to explore the effects of tillage measures and straw returning methods on soil physico-chemical characteristics and corn yield,a two-year field positioning experiment was conducted by setting five treatments including rotary tillage with no straw returning(CK),rotary tillage with crushed straw returning(RTS),rotary tillage with straw biochar returning(RTB),deep tillage with crushed straw returning(DPS),and deep tillage with straw biochar returning(DPB).The effects of the five treatments on soil physical struc-ture,nutrient content,enzyme activity and corn yield were studied.The results showed that compared with CK,all the tillage and straw returning treatments could improve soil structure,and increase soil nutrient con-tent,enzyme activity and corn yield.The proportion of 0.25～1 mm particle size aggregates under RTB and DPB treatments significantly increased by 5.44％and 6.16％compared to CK,while that of 1～2 mm particle size aggregates under DPB and DPS treatments significantly increased by 9.59％and 7.74％,respectively.The proportion of＞2 mm particle size aggregates under DPB treatment significantly increased by 5.48％compared to CK.The R＞0.25 value of soil aggregates under DPS and DPB treatments significantly increased by 5.25％and 5.35％compared to CK,respectively.The mean weight diameter(MWD)value of RTB and DPB treatments significantly increased by 6.67％and 11.11％compared to CK,respectively.The organic matter,available phosphorus and available potassium contents in soil treated by RTB and DPB significantly increased by 8.34％,7.75％and 9.48％,and 10.06％,5.33％,and 6.32％,respectively compared to CK.The DPB treat-ment significantly increased the activities of soil urease,sucrose,catalase and alkaline phosphatase compared to CK.The corn yield under different treatments showed DPB＞RTB＞DPS＞RTS＞CK(in 2023).Correlation a-nalysis results showed that there were very significant positive correlations between corn yield and soil porosity and urease activity,but a very significant negative correlation between corn yield and soil bulk density,indi-cating that corn yield was greatly influenced by soil structure and enzymes activities.In summary,compared with CK,different tillage measures and straw returning methods could improve soil structure,soil quality and corn yield,and the treatment of deep tillage with straw biochar returning performed relatively well.

Abstract:Cyperus esculentus L.is both an herb oil crop and an applied cash crop for grain,oil,feed and fertilizer with high comprehensive utilization value,furthermore,it has the characteristics of drought re-sistance and salt and alkali tolerance.Identifying the molecular regulation mechanism of alkali resistance of C.esculentus could lay a foundation for its molecular breeding.In this study,the seedlings of C.esculentus were subjected to 100 mmol/L mixed alkali(NaHCO3 and Na2CO3 at 2:1 of mole ratio)stress treatment,and were sampled at 0,3,6,9 and 12 days after treatment.Physiological indicators such as contents of malondialde-hyde(MDA),soluble protein(SP)and proline(Pro),and activities of superoxide dismutase(SOD),per-oxidase(POD)and catalase(CAT)were determined,and transcriptome analysis was performed.The results showed that under alkali stress,SOD and CAT activities increased rapidly in the earlier 6 days and then de-creased gently;POD activity increased rapidly first and then decreased rapidly after 6 days of stress;MDA content increased gradually first and increased rapidly after 6 days;both Pro and SP contents showed gradual upward trends,and the former increased rapidly,while the latter increased relatively slowly.Transcriptome a-nalysis showed that 5 842 differentially expressed genes(DEGs)were identified at 6 days of alkali stress,a-mong which,3 136 genes up-regulated and 2 706 genes down-regulated.GO and KEGG enrichment analysis showed that the DEGs were significantly enriched at the processes of plant hormone signal transduction,starch and sucrose metabolism and so on.In addition,the results of real-time fluorescence quantitative PCR(qRT-PCR)analysis were roughly the same as those of transcriptome analysis,which confirmed the validity of the RNA-seq data.The above results provided important information for further understanding the response mecha-nism of C.esculentus seedlings to alkali stress.

Abstract:Continuous cropping seriously affected the growth of peanut plants,resulting in decreased yield and quality.Intercropping,as a combined planting mode,is a safe,effective and ecological method to alleviate continuous cropping obstacles.In order to further investigate the effects of maize-peanut intercropping on rhizosphere microecological environment and yield of peanut,the fields of continuous cropping peanut for 10 years in Juxian County of Shandong Province were selected,'Huayu 22'and'Zhengdan 958'were used as experimental materials,and the intercropping mode of maize and peanut at 3∶4 was set with continuous cropping peanut as control.The effects of maize-peanut intercropping on nitrogen,phosphorus,potassium and organic matter contents and microbial community structure in rhizosphere soil,and pod yield of peanuts were studied.The effects of maize root exudes and maize rhizosphere microorganisms on the growth and rhizosphere microbial community structure of continuous cropping peanut were investigated through laboratory simulation experiments.The results of field experiment showed that compared with continuous cropping peanut,maize-peanut intercropping significantly increased the contents of orgnic matter,alkali hydrolytic nitrogen,available phosphorus and available potassium,significantly increased the abundance of Actinospica,Granulicella,Bry-obacter and Chujaibacter while significantly decreased the abundance of Bradyrhizobium and Mesorhizobium in the rhizosphere soil of peanut.The 100-pod weight of intercropped peanut increased significantly by 41.8%,the rotten pod number per plant decreased significantly by 66.7%,and the pod yield increased significantly by 32.2%.The results of laboratory simulation experiments showed that adding maize root exudate and rhizosphere microorganism could increase the abundance of Actinospica in rhizosphere soil and significantly promote root growth of continuous cropping peanut;Maize root exudate treatment significantly increased the peanut above-ground dry weight by 24.1%,while the root length and root surface area increased only by 7.2%and 5.4%.Maize rhizosphere microorganism treatment increased the peanut above-ground dry weight by 4.7%and in-creased the root length and root surface area by 50.5%and 47.4%,respectively.In conclusion,maize-peanut intercropping could improve the availability of soil nutrients and the structure of microbial community in peanut rhizosphere,reduce rotten pod number and thus increase peanut yield.Maize root exudates and maize rhizo-sphere soil microorganism in maize-peanut intercropping system played an important role in improving the soil ecological environment of continuous cropping peanut,and were one of the main factors to alleviate the obsta-cles of continuous cropping peanut.

Abstract:Low temperature often produces irreversible damage to sorghum seedlings.In order to clarify the alleviating effect of exogenous melatonin(MT)pretreatment on sorghum seedlings under low temperature,the experiment on the ecophysiological effects of different MT concentrations on sorghum seedlings under low-temperature stress was conducted firstly in order to screen out the optimum MT concentration,and then four treatments of ambient temperature control(CK),ambient temperature+melatonin(CK+MT),low-tempera-ture control(LT)and low temperature+melatonin(LT+MT)were set to study the alleviating effect of MT pretreatment on cold damage to sorghum seedlings.The results showed that 200 μmol/L MT pretreatment had the best effect on alleviating cold damage to sorghum seedlings through promoting the synthesis of photosynthet-ic pigments,increasing the activity of antioxidant enzymes,enhancing the stability of cell membranes,in-creasing the content of osmotic substances,and improving the efficiency of AsA-GSH cycle,so as to promote the growth of plants.In addition,the content of indoleacetic acid,indolebutyric acid,gibberellin A1,gibber-ellin A7 and abscisic acid were mostly significantly increased,and that of indolecarboxylic acid,gibberellin A3,jasmonic acid and dihydrojasmonic acid were significantly decreased in the sorghum seedlings under exog-enous MT pretreatment.The results of this study might provide a reference for the use of MT to alleviate cold damage to sorghum seedlings.

Abstract:In order to screen efficient antagonistic strains against Fusarium root rot,some strains were i-solated from the rhizosphere soil of healthy tomato,and then the taxonomic status and antagonism of the key antagonistic bacteria were identified and evaluated based on morphological,physiological and biochemical characteristics and 16S rRNA gene sequence.Their biocontrol effects were also determined by pot and field in situ cultivation experiments.The results showed that 93 strains were obtained from the rhizosphere soil of healthy tomato in the facility disease area,and 7 strains with bacteriostatic effect were obtained by using Fu-sarium oxysporum as the target bacterium.Through qualitative and quantitative detection,it was found that the strain MS06 had the strongest antagonistic effect,and had the characteristics of nutrient activation,IAA secre-tion,siderophore production,cellulose and protein degradation.Based on morphological and 16S rRNA phylo-genetic analyses,MS06 strain was identified as Bacillus velezensis.The fermentation broth of B.velezensis MS06 was applied to pot and field experiments,it was found that the incidence rate of tomato Fusarium root rot were 0 and 4.87％,the disease indexes were 0 and 1.87,and the relative control efficiency were 100.00％and 80.21％,respectively.It was speculated that its antibacterial mechanism was to made the F.oxysporum lose infection ability through dissolving cell wall and mycelium by secreting chitinase and cellulase,so as to inhibit the growth of pathogenbacteria.In summary,B.velezensis MS06 had excellent biocontrol function,and the field application of its solid agent had good control effect on tomato Fusarium root rot,which might be used as a candidate strain resource for tomato probiotic antagonistic agent.

Abstract:Saline-alkali stress(SA)is a kind of common abiotic stress in nature that can inhibit the ab-sorption of water and nutrients by plants,induce plant cells to produce a large number of reactive oxygen spe-cies(ROS),and inhibit plant growth and biomass accumulation.As an active molecule with various regulatory abilities,melatonin(MT)plays the important role in regulating seed germination and plant growth and devel-opment under stresses.In this study,the soybean varieties HH49(with saline-alkali tolerance)and HN95(with saline-alkali sensitivity)were used as experimental materials,and their seedlings were cultured in sa-line-alkali soil(pH=8.78)to V1 stage by potted method.Foliar application of exogenous 300 µmol·L-1 MT was conducted to clarify the effects of MT treatment on chlorophyll metabolism and photosynthetic capacity of soybean leaves under SA.The results showed that compared with the control(CK),SA increased the contents of superoxide anion(O2·-)and hydrogen peroxide(H2O2)in soybean seedling leaves,regulated the expres-sion levels of genes related to chlorophyll(Chl)synthesis and decomposition in soybean seedling leaves,de-creased chlorophyll content and photosynthesis and fluorescence parameters,affected the accumulation and metabolism of carbohydrates,and inhibited plant growth.Exogenous MT treatment significantly increased the activity of antioxidant enzymes in leaves,decreased the ROS accumulation,up-regulated the expression levels of GmGSA2,GmGUN4,GmPORB and GmCHLG genes related to chlorophyll synthesis,down-regulated the ex-pression levels of GmHCAR,GmPPH,GmPAO and GmRCCR genes related to chlorophyll decomposition,in-creased the content of chlorophyll in leaves,improved the photosynthetic capacity of plants,promoted the ac-cumulation and metabolism of soluble sugar,sucrose and starch,and so promoted plant growth of soybean.The results of this study could provide a theoretical basis for breeding saline-tolerant soybean varieties and develo-ping saline-alkali tolerant tillage measures.