China is a major soybean consumer and importer. Promoting the revitalization of the soybean industry and strengthening the technological innovation of the soybean seed industry have great significances for ensuring China’s food and safety. Based on the data of China’s soybean planting area， export， and import volume since 2016 and relevant research advances， this paper analyzed the situation challenges faced by China’s soybean industry， such as large rigid demand and long-term dependence on imports， low average yield level and limited planting area， and potential risks faced by imports that would exist for a long time and are not easy to share. This paper briefly described the scientific and technological innovation results of China’s soybean seed industry during the “13^th Five-Year” Plan period， and systematically analyzed the problems faced by the scientific and technological innovation of China’s soybean seed industry， such as low research level of germplasm resources， insufficient original scientific and technological innovation ability， imperfect commercial breeding system， lagging intellectual property protection system. It also put forward countermeasures and suggestions to promote the scientific and technological innovation and development of China’s soybean seed industry， in order to promote China’s soybean seed industry technology self-reliance development.

Rice semi-dwarf mutants play important roles in plant type improvement and high-yield breeding. Previously， a semi-dwarf mutant named d534 was obtained by mutagenesis from the indica rice cv. Wushan Simiao （R534）. The phenotype， genetic module and GA₃ sensitivity of d534 were analyzed in this study. Field observations found that， compared with the wild type R534， d534 delayed to head for 7 d and plant height decreased 29.22 cm（by 26.86%）. The panicle and the first internode from top 1^st to 5^th internode were significantly shortened by 71.27%， 68.75%， 70.18%， 85.17%， 77.86% and 71.18% compared with wild type in the length， indicating that the target gene of d534 would control the elongation of panicle and all internodes. Genetic analysis revealed that the phenotypes of dwarfism and late-heading were both controlled by the same recessive nuclear gene. The determination of endogenous GA₃ content showed that the GA₃ in the stem of d534 seedlings was 0.17 ng·g^-1， which was 60.47% lower than that of R534， indicating that the phenotype of dwarfism in d534 was related to the lack of endogenous GA₃. After treated with 25 and 50 mg·L^-1 GA₃ for 5 d on d534 seedlings， the plant height was 71.76% and 74.98% higher than that of untreated group （0 mg·L^-1 GA₃）. Meanwhile， such a height was more than that of untreated R534 seedlings， indicating that exogenous GA₃ would rescue the plant height of d534. qRT-PCR analysis showed that the expression levels of OsGA20ox2 and OsGA3ox2 genes in d534 stem and leaf were significantly down-regulated compared with R534， indicating that the insufficient synthesis of endogenous GA₃ in d534 might be related to the down-regulation of OsGA20ox2 and OsGA3ox2 gene expression levels. This study confirmed that d534 was a semi-dwarf mutant with shortened internodes and insufficient endogenous GA₃. It provided basis for revealing the biological mechanism underlying the semi-dwarfism in d534.

GRAS gene family is a kind of transcription factor widely distributed in plants， which plays an important role in plant growth and development， biological and abiotic stress， light signal， hormone signal response and other processes. The physicochemical properties， chromosome localization， phylogeny and cis-acting elements of GRAS gene family in maize were analyzed. The results showed that a total of 49 ZmGRAS genes were identified in the whole genome of maize， which were unevenly distributed on chromosomes 1 to 10， and the physicochemical properties of the encoded proteins were very different， which might play a role in different microenvironments. Phylogenetic analysis classified GRAS proteins into 8 subfamilies， which might play important roles in regulating growth and development and stress response. The promoter regions of GRAS genes in maize contained variety of cis-acting elements such as hormone response， light response and stress response， which might be involved in important response such as hormone and stress. Collinear analysis showed that genes with collinear relationships might be the result of replication of chromosome segments， and belonged to the same subfamily with similar structure and function. The identification and analysis of GRAS gene family in maize provided the basis for further research on the function of GRAS genes and their response mechanisms to stress in maize.

In order to explore the response ability of upland cotton to drought under different water stress and screen the key drought-resistant indexes and the excellent drought-resistant germplasm resources，30 upland cotton core germplasms were selected as experimental materials， and compared with normal irrigation treatment during the whole growth period， 2 water stress treatments， one water after sowing and one water at the flowering bollboll stage respectively， and 2 water stress treatments at the flowering bollboll stage were set up. The corresponding indexes were measured at bud stage， boll stage and boll opening stage by descriptive statistical analysis， difference analysis， principal component analysis and correlation analysis， the drought resistance of materials was evaluated by using drought resistance comprehensive evaluation value （D）. The results showed that drought stress had different effects on the growth and development of different cotton materials，the D value of the treatment of watering one water after sowing and one water at flowering and boll stage was more discrete （0.285~0.774） ， which could more clearly distinguish between different varieties of drought resistance. Using D value， 30 materials could be divided into 4 types： Type Ⅰ included 6 cotton varieties such as ‘Zhongmiansuo 41’‘ Xinluzao 7’ etc. and showed high drought resistance； Type Ⅱ included 11 cotton varieties such as ‘Jinmian 46’‘Xinluzao 31’etc. and showed middle drought resistance； Type Ⅲ included 5 cotton varieties such as‘Zhongmiansuo 17’‘Lu 1138’etc. and showed drought sensitive； Type Ⅳ included 8 cotton varieties such as‘ Xinluzhong 8’‘Jiumian 8’ etc. and showed high sensitive to drought. The first node number of fruit branch， number of fruit branch， plant height， grain yield and lint percentage were sensitive to drought， which could be used as the key indexes for drought resistance evaluation of cotton. Above results could provide basis for cotton drought-resistant.

In order to further improve germplasm and breed new screw pepper， 60 screw pepper germplasm materials through many years of selfing and homozygosity by the pepper team of Horticulture of College， Shanxi Agricultural University were as materials. The main agronomic traits were investigated and then the hereditary diversity， correlation analyais， principal component analysis （PCA） and clustering analysis were conducted. The results showed that the 11 agronomic traits had different degrees of variation， the coefficient of variation varied from 10.52% to 58.07%， with an average of 32.04%. The coefficient of variation of the fruit number per plant was the highest （58.07%）， and the coefficient of variation of the longitudinal diameter of fruit was the lowest （10.52%）. The correlation analysis showed that there were extremely significant positive correlations between plant height and plant span， between transverse diameter of fruit and pulp thickness， weight per fruit， between weight per fruit and ventricular number， pulp thickness， and there were significant positive correlations between transverse diameter of fruit and ventricular number. There were extremely significant negative correlations between longitudinal diameter of fruit and ventricular number， between fruits number per plant and pulp thickness， transverse diameter of fruit， weight per fruit， and there were significant negative correlations between fruits number per plant and ventricular number. Based on 11 agronomic traits， the principal component analysis got 4 principal components whose cumulative contribution rate was 70.628%； the cluster analysis divided 60 germplasms into 5 categories by Euclidean distance 5. Above results provided a basis for the utilization of germplasm resources and the breeding of screw pepper varieties suitable for market demand.

The variation and correlation of leaf traits can reflect the resource utilization and adaptive survival strategies of plants. In order to explore the traits and variation rules of the leaves of Sophora japonica of different ages， taking the leaves of Sophora japonica of different ages in Liaocheng city as the research object， 13 indicators including the leaf area （LA）， leaf fresh weight （FW）， leaf dry weight （DW）， leaf length （LL）， leaf width （LW）， petiole length （PL）， leaf thickness （LT）， rachis length （RL）， leaf shape index （LI）， specific leaf area （SLA）， leaf dry matter content （LDMC） ， leaf tissue density （LTD）， and specific leaf weight （SLW） were measured， and one-way analysis of variance and coefficient variation analysis were used to explore the characteristics of leaf traits at different tree ages. Principal component analysis and correlation analysis were used to study the adaptation rules of Sophora japonica leaves at different tree ages. The results showed that the DW， LL and PL of reserve resources were significantly higher than those of other tree ages （P<0.01）. The total coefficient variations of 13 leaf traits of Sophora japonica were from 8.57% to 81.48%； among leaf traits of different tree ages， the coefficient variation of the reserve resource LTD was the largest which was 92.86%， and the coefficient variation of the secondary ancient tree LDMC was the smallest which was 5.84%. LA， FW， DW， LL and LW were extremely significantly positively correlated with each other （P<0.01）； SLA was significantly negatively correlated with FW， DW， LTD and SLW （P<0.01）， and positively correlated with LT（P<0.01）； LDMC was significantly positively correlated with FW， DW， LTD and SLW （P< 0.01）. The leaf traits of reserve resources had the characteristics of high LDMC and SLW， low SLA， and belong to the survival strategy of “quick investment-income type”； the secondary ancient trees and the first grade ancient trees showed high SLA， low LDMC and SLW leaf character combinations， and adopted a “slow investment-benefit” and “conservative” strategy. Above results provided a scientific basis for the formulation of maintenance and management strategies for different age classes of Sophora japonica.

To further investigate the physiological response mechanisms of jujube to mixed saline-alkali stress， the experiment was conducted to simulate soil salinity stress by different concentrations of NaCl and NaHCO₃ at full fruit period of Junzao， including 0， 60， 120， 180， 240 and 300 mmol·L^-1. The changes of microstructure， ultrastructure， photosynthesis and fluorescence parameters of Junzao leaves under different stress levels were analyzed. The results showed that， with the increase of salt concentration， the leaf thickness， cuticle thickness， epidermal thickness and fenestrated tissue thickness of jujube showed a trend of increasing and then decreasing， and the thickness of spongy tissue and cell structure laxity gradually decreased. When salt concentrations was higher than 180 mmol·L^-1， the number of osmiophilic particles in chloroplasts increased significantly， their size became larger， and the structure of stromal lamellae was loosened. Meanwhile， with the increase of stress level， net photosynthetic rate， stomatal conductance and transpiration rate gradually decreased， intercellular CO₂ concentration increased， which indicated photosynthetic limitation was dominated by non-stomatal factors. Under high level treatments of 240 and 300 mmol·L^-1， F₀ significantly increased， while F_m， F_v/F_m， F_v/F₀ significantly decreased， ABS/RC， TR_o/RC and DI_o/RC showed an overall trend of first decrease and then increase， and ET_o/RC showed a continuous decreasing trend. In conclusion， higher saline-alkali stress could cause significant changes in the ultrastructure of Junzao leaves， inhibite the photosynthetic capacity， increase the size and number of osmiophilic vesicles， and appear the starch grains， which provided a theoretical basis for the in-depth study of the salt tolerance mechanism of jujube.

In order to study the difference of meat quality and the expression characteristics of meat quality-related genes in Tibetan sheep at different altitudes， the meat quality and nutritional components of longissimus dorsi， triceps brachii and biceps femoris of Tibetan sheep at altitude 2 500， 3 500 and 4 500 m were determined， and the expression levels of meat-related genes （H-FABP， LPL， MC4R and CAST） were determined and their correlations were analyzed. The results showed that the Tibetan sheep meat of low altitude had lower shearing force， lower water loss rate， higher tenderness and better taste， especially longissimus dorsi was better than the other 2 parts. The Tibetan sheep meat of high altitude had higher cooked meat rate and higher meat yield. The contents of mineral and crude protein in high altitude Tibetan sheep meat were higher， while the low altitude Tibetan sheep meat was more succulent. Compared with the two leg muscles， the longissimus dorsi had better taste. The expression levels of genes related to meat quality were differences among different altitudes. Among them， H-FABP had the highest expression levels in different muscles at mid-altitude， and LPL， MC4R and CAST had the highest expression levels in biceps femoris of Tibetan sheep at low altitude， and was higher in the longissimus dorsi of Tibetan sheep at middle and high altitude. The correlation analysis showed that the expression levels of H-FABP， LPL， MC4R and CAST genes were significantly correlated with cooked meat rate， shear stress， water loss rate， ash， crude fat， crude protein and dry matter in Tibetan sheep. It showed that the meat quality and nutritional components of Tibetan sheep at different altitudes were different， and the expression levels of meat-related genes in different parts were also different， which affected the meat quality of Tibetan sheep. Above results provided basis for meat selection and genetic improvement of Tibetan sheep at different altitudes.

The effect of pesticide application is closely related to the pesticide spraying process. The modeling and simulation of pesticide spraying process can solve the difficulties in field experimental research caused by the difference of plant growth cycle， the different occurrence of pests and diseases， and the uncontrollable natural field environments. According to the resistance， resurgence， residue （3R）/efficacy， efficiency， eco-environment （3E）/method， model， measurement （3M） of the pesticide applications， the modeling and simulation researches on the pesticide spraying process， such as atomization， transportation and deposition， were summarized and analyzed. The semi-physical simulation system of pesticide spraying was put forward and analyzed based on the development of simulation technology. Finally， several research suggestions were proposed to promote research on innovative precision pesticide spraying technology and R&D of high-quality plant protection machinery， such as establishing atomization model for carrying out the atomization mechanism of new nozzles， the multi-phase flow field simulation of mass pesticide droplets， the spraying target customization and target recognition model， the comprehensive pesticide droplet drift model， and the coupling between plant growth model and pesticide spraying system.

The most common damage to ramie tramet cultivation is stem loading. Traditional monitoring methods have drawbacks such as being time-consuming and inefficient. A method for obtaining ramie lodging information was investigated by unmanned aerial vehicles （UAV） in this study. Firstly， the canopy orthophoto and digital surface model （DSM） of ramie were created using Pix4D Mapper software. Then， the spectral， textural， and shape features of the canopy were extracted from the DSM， along with the canopy height index. Finally， a combination of 3 machine learning algorithms was used to createa classification model for normal and lodging canopies. The results showed that the DSM-based extracted plant height information could effectively replace the actual measured plant height in the field， with a model R² of 0.899. The spectral， textural， shape， and height characteristics of fallen and normal ramets differed. The support vector machine and decision tree models outperformed the other learning algorithms， achieving 99% accuracy and efficiently identifying normal/lodging ramie plots. Above results provided technical assistance for accurate and rapid assessment of crop lodging.

The applicable range of contact parameters between existing soil and touching soil component materials is relatively narrow， making it difficult to simulate operating conditions under high moisture content. In order to explore the adhesion of various materials to soil with different moisture contents and more accurately solve the adhesion problem between touching soil components and soil， this article took southern stubble soil planting rice as the object， and used the "Hertz Mindlin with JKR Cohesion" model in EDEM to calibrate the contact parameters of soil with different moisture contents and 45# steel， ultra-high molecular weight polyethylene（UHMWPE）， polytetrafluoroethylene （PTFE）. On the basis of previous tests， Box-Behnken four factor and three level tests were designed with impact restitution coefficient， static friction coefficient， rolling friction coefficient and JKR as test factors and soil rolling distance as test indicators. Finally， the regression model was optimized， and the optimal parameters of collision coefficient of restitution， static friction coefficient， rolling friction coefficient and JKR of soil with 21%， 26%， 31% （±1%） moisture content and 45# steel， UHMWPE， PTFE were obtained. The maximum relative error between the simulated rolling distance and the measured rolling distance was 3.46%， indicating that the calibrated parameters were accurate and reliable， and provided reference for the design of touching soil components in reducing adhesion and detachment.

Minirhizotron technique can directly monitor the dynamic growth and development of plant roots and be used to obtain clear root images. However， because of the complex soil environment， uneven particle size and large number of fine roots， it easily causes discontinuity of the divided roots and mistakes the soil background as the root. To solve the above problems， the CP-DeepLabv3+ algorithm was proposed to segment image. The coordinate attention mechanism （CA） was introduced to effectively segment the target location information and made the edge of the target more continuous. Strip pooling （SP） branch was added to ASPP feature extraction module to avoid unnecessary connections between distant locations and improve the accuracy of image segmentation. CP-DeepLabv3+ algorithm was applied to test maize root dataset. The results showed that the mean intersection-over-union （MIoU） value was 82.95%， the mean pixel accuracy （MPA） value was 92.47%， which was 3.69% and 4.44% higher than the original DeepLabv3+ model， respectively. This algorithm could effectively segment maize root and has practical significance for feature extraction.

To identify the pathogen which seriously caused fruit blotch disease in melo， the melon fruit samples suspected bacterial fruit blotch disease were collected from Dongfang city， Hainan province. Pathogen was isolated and purified from samples， and the pathogenicity of bacterium strains was confirmed according to Koch’s postulate. The identification of the pathogenic strains was carried out according to the colony morphology， physiological and biochemical analysis and 16S rDNA sequences analysis. The results showed that the isolated bacterium with similar cultural characteristics was obtained from all diseased samples， which the separation rate of bacteria was 100%. All of tested strains showed pathogenic to melon fruits. Strains were identified as Gram-negative bacterium， which colony morphology， physiology and biochemistry shared similarly with that of Acidovorax citrull. BLAST analysis showed that the 16S rDNA sequences had 100% homology with that of A. citrulli， and the phylogenetic analysis showed the pathogen was A. citrulli. Above results determined the pathogen of melon fruit blotch，which provided a basis for effective prevention and control of this disease.

In order to study the effect of ginseng rust rot on ginseng quality and soil related factors， the rust rot infested ginseng， healthy ginseng and its rhizosphere soil were used as materials to detect soil physicochemical properties and soil enzyme activities.The contents of phenolic acid and saponin in ginseng root and rhizosphere soil were determined by high performance liquid chromatography（HPLC）， and the number of pathogenic bacteria in soil was determined by molecular means. The results showed that ginseng root saponin content decreased by 50.1%~72.5% with rust rot increase； the soil and root secretion of the kinds of allelochemicals， content was closely related to the degree of ginseng disease， part of the saponins class matter content increased， the highest increased by 7.5 times， and the frequency increased；succinic acid， cinnamic acid content was significantly higher than healthy plants， compared with the healthy plant， and it increased 3.69 and 2.39 times， respectively. The determination of soil factors showed that except catalase activity increased with the aggravation of the disease， the other soil quality indexes decreased with the aggravation of the disease， among which the reduction of available phosphorus was as high as 55.0%， and the content of soil quality decreased at the initial onset of the disease， it could characterize the occurrence of ginseng rust rot. According to the correlation analysis， the gray correlation degree between the number of pathogenic bacteria and soil factors was 0.362 5~0.497 5， and the gray correlation degree between the number of pathogenic bacteria and allelochemicals was 0.182 5~0.619 9. Above results indicated that the quality of ginseng would be affected directly or indirectly after the disease of ginseng. Therefore， improving the soil environment， regulating the soil ecological balance and reducing the incidence of ginseng disease were one of the ways to improve the quality of ginseng.

In order to investigate the characteristics of nitrogen and phosphorus emission in a small ecological agriculture watershed， the small eco-agricultural Fendong watershed of Changhu Reservoir in Dazhan town， Yingde City， Guangdong province， was chosen as the research region，the content and diffuse pollution characteristics of nitrogen and phosphorus， the identification of the critical source area， and the effects of eco-agriculture on reduction of nitrogen and phosphorus emission were studied by means of field observations and laboratory measurements. The results showed that the water pollution was low at the watershed scale， most of the water quality were not worse than level Ⅲ. Total nitrogen （TN） and total phosphorus （TP） were the main pollution loads in the watershed， and the dissolved nitrogen was the main nitrogen composition （>50%）. The critical source areas included soil erosion， goose farms， residential areas， and pig farms. The total loads of TN and TP were 345.22 and 69.47 kg during the study period， respectively. The pollution load intensity into the river was low， and the inflow coefficients of TN and TP were 0.16 and 0.63， respectively. Above results indicated the effect of nitrogen and phosphorus emission reduction in the small ecological agriculture watershed was remarkable， and the absorption capacity of nitrogen and phosphorus was strong， which made the nitrogen and phosphorus pollution load low and the water quality good， so ecological agriculture should be worth popularized and widely applied.

In order to study the influence of microbial agents on the dynamic changes among relevant physicochemical indicators in the process of composting leafy vegetable waste， leafy vegetable waste was used as the main material and corn straw as the auxiliary material， and 4 exogenous microbial agents， VT-1000， Qunlin fermenting bacteria， Reactor special strain 001 and SUKAAgre-C3009/C， were added for fermentation， with no added bacteria agent as control， and the relevant indicators were measured and analyzed for comprehensive comparison. The results showed that at 24 d of fermentation， all the piles reached complete decomposition， and the seed germination index（GI）of the treatment with the addition of bacterium was significantly higher than that of the treatment without the addition of bacterium， among which the pile with the addition of VT-1000 microbial agents had the highest GI of 113%. The piles with added bacterium could all warm up to above 60 ℃ at 2 d， and could maintain a high temperature period （≥50 ℃） for 6~8 d， 3~5 d more than without added bacterium， of which the highest temperature was 69.9 ℃ with the addition of VT-1000 microbial agents， and the high temperature lasted for 8 d， effectively solving the problem of high water content of leafy vegetables affecting the quality of compost. Combining the nutrient contents of each treatment showed that the organic matter degradation rate and total nitrogen content were the highest with the addition of VT-1000 bacterial agent， which were 21.0% and 25.8 g·kg^-1， respectively. The application of self-made organic fertilizer with added VT-1000 microbial agents could significantly increase soil organic matter and total nutrient content， effectively improve soil physical and chemical properties， and the cost of self-made organic fertilizer was the lowest， which only about 1/10 of the other 2 fertilizers. Above results showed that the addition of microbial agent could promote compost maturation， increase the temperature of the pile， prolong the duration of the high temperature period， and improve the quality of compost. On the whole， the addition of VT-1000 microbial agents had the best effect.

In order to study the effects of silicon， calcium， potassium and magnesium fertilizer and different cultivation densities on the characteristics， material accumulation and yield formation of hybrid rice,‘Jingliangyou 534 ’was used as the test variety. The split plot design was used in the experiment. 2 fertilizer treatments were set up in the main area : no silicon, calcium, potassium and magnesium fertilizer and increasing silicon, calcium, potassium and magnesium fertilizer （G）. 4 transplanting densities were set up in sub-area: 19.3×10⁴（M1）, 16.0×10⁴（M2）, 13.0×10⁴（M3） and 10.0×10⁴ plants·hm^-2（M4）. Through 2 consecutive years of field positioning experiments, the rice yield and composition factors, dry matter accumulation, tillering dynamics and panicle structure were investigated, and the effects of increasing silicon, calcium, potassium and magnesium fertilizer and density treatments on rice growth and yield were analyzed. The results showed that silicon, calcium, potassium and magnesium fertilizer and transplanting density jointly affected rice yield. Under the same nitrogen application rate and silicon, calcium, potassium and magnesium fertilizer, the increase of transplanting density could significantly increase the effective panicle, population dry matter production and tiller number of rice, and increase rice yield. Compared with M1, M3 and M4 treatments, the effective panicle under M2 treatment increased by 5.83%, 13.69% and 12.50% on average in 2 years. At the same density, application of silicon, calcium, potassium and magnesium fertilizer could significantly increase the effective panicle, increase the accumulation of dry matter in rice, and significantly improve the leaf area index of rice in the later stage of growth. The average yield increased by 8.30%~12.56% in 2 years compared with no application of silicon, calcium, potassium and magnesium fertilizer. Combining the interaction effect of silicon, calcium, potassium and magnesium fertilizer and transplanting density, under the conditions of this experiment, when the pure nitrogen application rate was 150 kg·hm^-2, the application of silicon, calcium, potassium and magnesium fertilizer was 300 kg·hm^-2, and the transplanting density was 16.0×10⁴ plants·hm^-2, ‘Jingliangyou 534’ had the largest dry matter production and yield. The results could provide reference for high-yield and high-efficiency rice cultivation in Sichuan.

Winter wheat is an important ration crop in the Loess Plateau and the yield is greatly affected by rainfall and other factors，in order to study the effect of precipitation on water consumption and yield of winter wheat，the long-term observation data of winter wheat Zhenyuan experimental site of the Gansu academy of agricultural sciences in recent 40 years were collected. The variation trend of winter wheat yield and water consumption with precipitation was illustrated. The results showed that the yield of winter wheat on the loess plateau increased at a rate of 51.2 kg·hm^-2 every year in the past 40 years， but the persistence coefficient was only 0.43. The yield greatly increased with the rise of precipitation from mid-October to mid-November， the first ten days of mid-March， the first ten days of May， and the last ten days of May. The satisfaction rate of precipitation in the whole growth period was 64.4%， but was only 52.7% in the dry year， while at jointing-filling stage was the lowest among different growth stages. The average water consumption during the growth period of winter wheat was 361.3 mm， which showed a downward trend in the past 40 years. The water consumption from sowing to rejuvenation accounted for 34.3% of the total in the whole growth period. In dry years and median water years， the precipitation satisfaction rates were 36.9% at the seedling emergence-jointing stage and 42.2% at jointing-filling stage，respectively. At these 2 stages， precipitation had a significant impact on the yield of winter wheat. According to the yield correlation of winter wheat， the order from high to low was water consumption > panicles > grains per ear > soil moisture before sowing > precipitation during growth period >annual precipitation. Winter wheat yield in the loess plateau area had been poorly stable in recent 40 years due to a large proportion of water consumption from sowing to the regreening stage and insufficient precipitation at this time， affected the tillering and spike formation and water use efficiency of winter wheat. Above results indicated that ensuring the precipitation satisfaction rate of winter wheat in the key growth period and the efficient accumulation of precipitation in the fallow period was an important guarantee for stable and high yield of winter wheat，which were of great significance to the sustainable development of winter wheat industry.

In order to explore the effects of rotation of flue-cured tobacco and different crops on soil quality control of long-term continuous cropping， 4 rotation treatments were set， including barley and flue-cured tobacco （YCDM）， garlic and flue-cured tobacco （YCDS）， rape and flue-cured tobacco （YCYC）， and broad bean and flue-cured tobacco （YCCD）， and the tobacco planting plots with continuous cropping for more than 10 years was used as control （CK）. The physicochemical properties， enzyme activities and microbial community structures of soils under different rotation treatments were analyzed. Based on correlation analysis and redundancy analysis， the relationship between soil physicochemical properties， enzyme activities and microbial community structure was analyzed. The results showed that， compared with CK， soil bulk density decreased by 26.58%~30.29% and total porosity increased by 21.13%~48.26%. Compared with CK， soil pH， available nitrogen （AN）， available phosphorus （AP） and available potassium （AK） contents under the YCCD treatment significantly increased by 11.84%， 30.57%， 6.42% and 41.1%， respectively. Compared with CK， the activities of catalase （CAT）， invertase （INV）， urease （URE） and acid phosphatase （ACP） increased by 16.81%~42.35%， 38.09%~51.48%， 7.69%~64.29% and 5.82%~76.33%， respectively. The YCCD mode had the most significant improvement effect. The results of high-throughput sequencing showed that the OTUs of bacteria under rotation treatments was significantly higher than that of CK. The α-diversity showed that the richness and diversity of bacterial communities were significantly different among different rotation treatments. The richness of fungal communities was significantly different， but the diversity was not. The results of β-diversity analysis showed that the differences of soil fungal communities among different rotation treatments were small， and the differences of soil bacterial communities were large. Among them， YCCD treatment had the largest difference in bacterial and fungal communities compared with CK. At the phylum level， the YCCD treatment increased the relative abundance of Acidobacteria and Actinobacteria， while decreased the relative abundance of Ascomycota. Correlation analysis and redundancy analysis showed that URE， AN， AK and pH were the key factors affecting soil microbial community structure. In conclusion， reasonable rotation of flue-cured tobacco and other crops could improve soil available nutrient content and soil enzyme activity， and then regulate soil microbial community structure， which could reduce the obstacles of continuous cropping of flue-cured tobacco， and finally achieve the goal of stable yield and increase of flue-cured tobacco.

To investigate the pollution characteristics and risk of heavy metals in soil of Jinggang honey pomelo orchards， 18 representative soil samples were collected from Jinggang pomelo orchards in 4 main production areas of Ji’an City， Jiangxi Province. Soil physicochemical properties and heavy metals （Cd， Pb， As， Hg and Cr） content were determined. The pollution levels of soil heavy metals were evaluated by single factor pollution index， geoaccumulation index and Nemero comprehensive pollution index. The potential ecological risks of soil heavy metals were discussed in potential ecological risk index （RI）. The results showed that soil acidification was serious， the fertility was in the middle and lower levels， and the available nitrogen was lack in the study area. The average contents of Cd， Pb， As， Hg and Cr were 0.23， 63.81， 13.95， 0.10 and 167.28 mg·kg^-1 in 0 to 20 cm soil， which were 2.30， 1.99， 1.35， 1.25 and 3.49 times of the background values， respectively. The average contents of Cd， Pb， As， Hg and Cr were 0.26， 62.40， 13.51， 0.10 and 167.87 mg·kg^-1 in 20 to 40 cm soil， which were 2.60， 1.94， 1.31， 1.25 and 3.50 times of the background values， respectively. There was no significant difference in heavy metal content at different depths. Single factor and geoaccumulation index analysis showed that the accumulation of Cr， Pb and Cd in the soil of the study area was serious， and 11.11% of Cd was seriously polluted. With the standard value as the reference， the soil heavy metal pollution in the study area was mainly mild pollution， belonging to low ecological hazard degree. With the background value as the reference， the soil heavy metal pollution in the study area was mainly moderate and serious， belonging to medorate and strong hazard degrees. The correlation analysis showed that Cr had good homology with Pb and As. Redundancy analysis showed that soil pH and organic matter were the main environmental factors affecting the change of heavy metals in soil of pomelo orchards in Jinggang. Overall， the heavy metal pollution of soil in the study area was light， but there were some orchards exceeding the standard and the accumulation of Cd， Cr and Pb in soil. Fruit farmers and relevant departments should pay more attention and take effective measures to prevent their ecological risks.

In order to study the physiochemical properties and microbial community structure in rhizosphere soil of Dracocephalum tanguticum， the microbial communities in rhizosphere soil from Gongbujiangda （GB）， Kanuo （KR） and Luolong （LL） in Tibet were as materials. The microbial community in rhizosphere soil of D. tanguticum was analyzed by illumine high-throughput sequencing， and the physiochemical properties were determined and their correlation with core microbial communities were studied. The results showed that there were significant differences among different regions in the physiochemical properties. A total of 3 900 bacterial OTUs and 1 990 fungal OTUs were obtained in rhizosphere soil of D. tanguticum from 3 regions. The microbial diversity index in the rhizosphere soil of D. tanguticum grown in different regions was significant difference. Actinobacteria was the dominant bacterial phyla in all samples of D. tanguticum. Basidiomycota was the dominant fungal phyla in GB sample， Ascomycota was the dominant fungal phyla in KR and LL samples. The dominant genus was difference among different samples. Principal component analysis showed that the compositions of bacterial and fungal community were different among different samples. The analysis of core microbial communities showed that there were 257 core bacterial genera and 102 fungal genera. The correlation analysis showed that the changes of microbial community in rhizosphere soil were correlated with the physiochemical properties， and the contents of total potassium， available potassium， total phosphorus， total nitrogen and available nitrogen were the key determinants affecting the composition of microbial community in rhizosphere soil of D. tanguticum. Overall， the microbial community structure in rhizosphere soil of D. tanguticum grown in the different regions were significant differences， and the microbial community structure of rhizosphere soil was strongly linked to the physiochemical properties of rhizosphere soil. Above results provided theoretical bases for artificial cultivation and screening beneficial microorganisms of D. tanguticum.

In order to prepare a highly effective antibacterial agent， chitosan（CS） was used as raw material to prepare 6-carboxyl chitosan（C-COS） by laccase /2，2，6，6-tetramethylpiperidine-1-oxyl radical （TEMPO） system， and then the silver-carried oxidized chitosan （C-COS-Ag） was prepared by reaction with silver nitrate. The antibacterial activity of C-COS-Ag was studied. The results showed that the antibacterial effect of C-COS-Ag was significantly improved compared with CS. Its inhibitory zone diameters against Escherichia coli and Staphylococcus aureus were （22.75±1.50） and （13.75±2.50） mm， respectively， with a minimum inhibitory concentration of 6.10 μg·mL^-1。The bacterial growth curve test confirmed that C-COS-Ag could significantly reduce the growth rate of Escherichia coli and Staphylococcus aureus； the penetration test of cell contents showed that C-COS-Ag could destroy the cell membrane and cell wall morphology of bacteria， resulting in the exudation of nucleic acids， proteins and other macromolecules， the increase of alkaline phosphatase activity， the decrease of β-galactosidase activity， the obstruction of galactose synthesis pathway， and the normal metabolism of bacteria were affected. Above results provided a theoretical basis for the application of C-COS-Ag.

In order to screen walnut leaf extracts with strong potency and mosquito repellent effects， ultrasound-assisted hydrodistillation was applied to extract ‘J. regia Wen185’ ‘C. cathayensis’ ‘J. nigra’ and ‘J. regia Shisheng’ leaf volatile oil. With the extraction rate of volatile oil from walnut leaves as the index，orthogonal experiments were conducted on the basis of single-factor experiments to derive the best extraction conditions of volatile oil from walnut leaves， and combined with the mosquito repellent test， the best repellent content of 4 walnut leaf extracts were screened with the repellent rate as the index. It was shown that the best extraction conditions for the extraction of volatile oil from ‘J. nigra’ leaves by ultrasound-assisted water distillation were 8 h， 10 min of ultrasound time， and 1∶10 （g·mL^-1） solid-liquid ratio. Under these conditions， the extraction rate of volatile oil of walnut leaves was 0.475%. Using anhydrous ethanol as the solvent， the mosquito repellent rate of the solutions of four kinds of walnut leaf volatile oil extract solutions were measured under dilution of 10%， 20%， 30% and 40%. The mosquito repellent effect time of ‘J. nigra’ leaf volatile oil extract solution could reach 20 min at 30% content， and when the repellent rate was 85.18%， the repellent effect was the best. Vaporized oil extract solution of ‘J. nigra’ leaves had good mosquito repellent effect and had the potential to be developed as a plant-derived repellent， which was worthy of further promotion and application.