Accelerating the construction of livestock powerhouse is an important task for the construction of an agricultural powerhouse and a great modern socialist country. It is of great practical significance to scientifically understand the connotation requirements and theoretical logic of livestock powerhouse construction， grasp the current realistic basis and strategic path of accelerating the construction of livestock powerhouse. Based on the actual development of China’s livestock industry， this study understood the connotation requirements of livestock powerhouse construction in terms of domestic production and supply， international resource utilization， scientific and technological equipment support， feed and forage supply， green cycle development， animal disease prevention and control， and analyzed the realistic results of the current livestock industry development and the shortcomings of livestock powerhouse construction. In order to further lay a solid foundation for the construction of livestock powerhouse， it was recommended to consolidate the foundation of domestic production and supply， improve the efficiency of international resource utilization， enhance the capacity of scientific and technological support， strengthen feed and forage supply， promote green cycle development， and strengthen animal disease prevention and control.
With the development of society and the continuous progress of science and technology， image recognition technology has developed rapidly. As a non-contact and non-destructive information monitoring technology， image recognition technology has been widely used in the field of chicken breeding， which has brought new impetus to the development of modern chicken industry. This paper briefly summarized the image recognition technology， then focused on the application of image recognition technology in chicken behavior recognition， body weight estimation， health monitoring and product classification， and finally summarized the problems and development prospects of image recognition technology in the field of chicken breeding， which was conducive to the efficient， sustainable and healthy development of image recognition technology in the future chicken industry， accelerated the comprehensive combination of artificial intelligence and chicken breeding industry， and provided technical reference basis for promoting the prosperity and development of modern animal husbandry in China.
To reveal the influence of low temperature on the seed-setting rate and physiological characteristics， and alleviating effect of exogenous melatonin （MT） on low temperature stress at the booting stage， 2 different cold tolerance rice （Oryza sativa L.） cultivars Longjing 11 （cold sensitive， LJ11） and Longdao 5 （cold tolerant， LD5） were planted for a pot experiment. They were treated with low temperature （16 ℃） and 100 μmol·L-1 melatonin （MT） spraying respectively at starching stage， and the same amount of water sprayed at outdoor temperature was used as control. The results showed that under low temperature stress， the seed setting rate of LD5 did not change much， the seed setting rate of LJ11 decreased significantly by 5.96%~45.26%. And in the leaves of both LD5 and LJ11， malondialdehyde （MDA） and hydrogen peroxide （H2O2） contents were significantly increased， superoxide dismutase （SOD） and peroxidase （POD） activities significantly increased. At the same time， low temperature stress could also increase the contents of osmotic regulators. The contents of soluble protein， soluble sugar and proline in the leaves both of LD5 and LJ11 were significantly increased， respectively. Foliar spraying of exogenous MT could effectively alleviate the damage of low temperature to rice， and the effect was more obvious on cold-sensitive varieties. It could significantly reduce the contents of MDA and H2O2， and it could significantly increase SOD and POD activities. In addition， the soluble sugar， soluble protein and proline contents of LJ11 significantly increased. Foliar spraying of exogenous MT could also reduce the effect of low temperature on the seed setting rate， and the seed setting rate of LJ11 significantly increased by 3.13%~16.64%. In conclusion， under low temperature stress， MT could induce the increase of antioxidant enzyme activities and osmotic adjustment substances in rice leaves， and effectively scavenge reactive oxygen species， thereby improving the cold resistance of rice.
Lodging is a bottleneck problem of restricting the high quality and high yield of rice （Oryza sativa L.） under the rice-crayfish coculture. To study the effect of exogenous melatonin spraying on the lodging characteristics of rice stems under rice-crayfish coculture， ‘Nanjing 5718’ was as the experimental material， and the experiment set two treatments： 200 μmol·L-1 melatonin foliar-spraying at the early stage of jointing （MT） and control treatment （CK）. The morphology index， culm mechanics index， culm chemical composition content， rice yield and the expression levels of key genes for lignin and cellulose biosynthesis under different treatments were determined. The results showed that the rice yield of MT treatment was 9 261 kg·hm-2， which had no significant difference with CK treatment， however， the spikelets per panicle of MT treatment significantly increased than that of CK， while the effective panicles and seed setting rate significantly decreased. Compared with CK treatment， the plant height， panicle length and gravity center height of MT treatment significantly decreased by 13.04%， 14.91% and 22.93%， respectively. The flexural resistance and breaking strength of the second internode significantly increased by 22.39% and 22.34%， and bending moment and lodging index significantly decreased by 20.61% and 35.03%. And the expression levels of key genes for lignin and cellulose biosynthesis including OsCoMT， OsCesA4， OsCesA7 and OsCesA9 genes were upregulated under MT treatment. Correlation analysis showed that the lodging index of MT treatment was extremely significantly positively correlated with plant height， panicle length， and length from breaking point to panicle top， and was significantly negatively correlated with flexural resistance， breaking strength， and bending stress. In conclusion， spraying melatonin could improve the lodging resistance of rice stem under the premise of stable rice production in the rice-crayfish coculture mode， which provided theoretical and practical guidance for the regulation of rice lodging resistance under the rice-crayfish coculture mode.
The stable yield and income of wheat （Triticum aestivum L.） were greatly limited by salt stress. Elucidating the metabolic mechanism of wheat under salt stress will help to further optimize breeding and cultivation， thereby increasing wheat yields in saline-alkali soils. In this study， ultra performance liquid chromatography-tandem mass spectrometer（UPLC-MS/MS） was used to analyze metabolic profiling of wheat roots and leaves treated with salt stress， and to analyze their response mechanism. A total of 759 metabolites differentially accumulated in roots and leaves were identified under normal growth and 24 h salt treatment conditions. In response to salt stress， 207 and 147 metabolites were changed in roots and leaves， respectively， among which 56 were the same differentially accumulated metabolites. Amino acids and their derivatives， flavonoids， organic acids and their derivatives， nucleotides and their derivatives accounted for about 50% of the total differentially accumulated metabolites of wheat roots and leaves in response to salt stress. In addition， lipids accounted for about 20% of the differentially accumulated metabolites of wheat leaves. These differentially accumulated metabolites were mainly involved in metabolic pathways， photosynthesis， carbon fixation and glucose metabolism etc in leaves， and secondary metabolism and amino acid synthesis etc in roots. They were interrelated and constitute a regulatory network of salt stress response， which may improve the adaptability to salt stress in wheat by alleviating osmotic and oxidative stress caused by salt stress.
In order to study the specific regulation effect of dinoconazole compounded with different exogenous substances （amine fresh fat， thidiazuron， prohexadione calcium， and parsamine） on cotton chemical capping and yield enhancement and quality improvement， Xinluzhong 84 was used as test material， and a randomized block design was used. Foliar spraying was carried out before chemical topping （July 5） and during chemical topping （July 15） to determine the plant type， photosynthesis， dry matter accumulation and distribution， yield and quality of cotton. The results showed that there was no significant difference in plant height among the treatments， while the plant width of cotton decreased after chemical capping， but the number of leaves and fruit branches on the main stem increased to a certain extent. The compound treatment of diluconazole could effectively improve the canopy structure of cotton plants. Among them， the leaf area index and canopy opening degree of diconazole compound treatment with thidiazuron were the highest in each period， and the average leaf inclination angle was higher than that in artificial boll stage. The topping control increased by 3.21%. Diluconazole compound treatment could effectively promote leaf photosynthesis， among which the net photosynthetic rate， transpiration rate， stomatal conductance， intercellular CO2 concentration showed the highest performance， which increased by 87.54%， 90.12%， 170.03% and 27.77%， respectively， compared with the manual topping photos. And the total dry matter weight of reproductive organs per plant was also the highest， reaching 62.19 g， an increase of 28.04% compared with the artificial topping control. The optimal combination in this study was the treatment of uniconazole combined with thidiazuron （W2）， the number of bolls per plant was 5.43， the weight per boll was 6.24 g， the yield of seed cotton was 7 330.29 kg·hm-2， and the yield of lint cotton was 3 302.87 kg·hm-2. The highest and the least impact on fiber quality.The results provided theoretical basis and practical reference for the whole process of cotton mechanization in Xinjiang.
Chlorophyll is an essential pigment for plant photosynthesis. Drought tolerance affects chlorophyll synthesis， reduces photosynthetic efficiency， and decreases soybean yield. In order to explore the genetic loci of chlorophyll content in soybean under drought stress， drought resistance index （DRI） were calculated by chlorophyll contents under drought and well-watered conditions. Moreover， based on the DRI and re-sequenced genotypes of the soybean natural population （199 accessions） at 20× sequencing depth， the genome-wide association study （GWAS） was performed. The results showed that 237 single nucleotide polymorphisms（SNPs） in 18 loci on the chromosomes 1， 2， 3， 7， 10， 16， 17 and 18 were identified to associate with DRI. Moreover， 181 SNPs （76.37% of the total） were located on chromosome 16， of which 9 SNPs were located in the gene introns， 17 in exons， 21 in upstream or downstream， and 1 in 3’UTR. Based on these， 57 candidate genes flanking the associated SNPs were found， and according to the gene annotation， SNP mutation， and RNA expression， 3 candidate genes， Glyma.16G063600 （F-box protein）， Glyma.10G007000 （AP2-EREBP）， and Glyma.17G143900 （AP2/ERF） were screened out which might be responsible for the drought tolerance in soybean. Above results provided important theoretical foundation for drought tolerance genetic improvement in soybean.
Low temperature is one of the important environmental factors affecting the cultivation of Cyperus esculentus in the agro-pastoral region of northern China. In order to clarify the main identification indexes and screen out the germplasm resources of Cyperus esculentus with strong low temperature tolerance， 18 Cyperus esculentus germplasms from different ecological regions were used to identify and evaluate their low temperature tolerance. The effect of low temperature stress on seedling emergence was studied in 3 consecutive years of late spring chilling. 3， 5， 7 and 9 ℃ were set to simulate the minimum temperature of late spring chilling， and seed germination related indexes and seedling stress resistance physiological indexes were measured to study the cold resistance. The results showed that with the decrease of temperature， germination index， seed vigor index and chlorophyll content in leaves decreased generally， relative membrane permeability increased， the contents of malonaldehyde， soluble sugar and free proline were gradually accumulated， and the activities of superoxide dismutase and peroxidase increased in the mass. Based on field test， laboratory germination test and physiological and biochemical indexes of seedlings， 18 germplasms were classified into 5 categories： strong cold resistance （HLJ105， RY126， BY156 and HLJ106）， cold resistance （RY102 and BY141）， moderate cold resistance （RY114， NM103， XJ101， JL154， LN181 and SX100）， weak cold resistance （HB122 and HN162）， and no cold resistance （QY186， GD187， XY109 and ZYS01）. The results provided basic resources and theoretical basis for the germplasms innovation and cultivars breeding of low temperature resistant Cyperus esculentus.
In order to study the dynamic changes of phenolic substances and antioxidant activities during the development of different pear varieties， the total flavonoids， total phenols， phenolic substances， 1，1-diphenyl-2-picrylhydrazylradical （DPPH） and 2， 2’-azino-bis（3-ethylbenzothiazoline-6-sulfonic acid）（ABTS+） free radical scavenging abilityin the fruits of Kuche Amute， Dangshan pear and Ma pear at different developmental stages wereanalyzed and determined. The results showed that the contents of total flavonoids and total phenols in the three kinds of pear fruits were basically the same during the development process， the content was higher in young fruit stage， and gradually decreased with fruit development. A total of 13 phenolic substances were detected in the three types of pear fruits by high performance liquid chromatography， and the content of arbutin was the highest， with an average of 3 353.43 μg·g-1 DW， accounting for 51.88% of the total components； orthoic acid was the second with an average content of 2 350.29 μg·g-1 DW， accounting for 36.34% of the total components； the content of other phenolic components was low， distributed between 8.09～150.65 μg·g-1 DW， only 0.13%～2.33% of the total phenolic content. The antioxidant activity detection showed that the free radical scavenging power of DPPH and ABTS+ was Dangshan pear > Kuqa Amute > Ma pear. Correlation analysis showed that the total flavonoids， total phenols， arbutin， catechin， chlorogenic acid， epicatechin and other substances in pear fruit had a very significant positive correlation with DPPH free radical scavenging ability （P<0.01）. The results provided the basis for in-depth research and development of natural antioxidant health drugs and functional foods.
As important genetic germplasm resources and new potential cells for regenerative medicine， animal stem cells are broadly researched and utilized. In this study， Holstein bovine umbilical cord mesenchymal stem cells （UCMSCs） were isolated and investigated， and their multi-directional differentiation potential etc. biological characteristics were researched.The cells were isolated from 3-month-old fetal umbilical cords of Holstein cows using type Ⅳ collagenase， cultured in vitro. The obtained cells showed a typical “S” shape growth curve， and the population doubling time gradually decreased with the increase of generation.The expression of specific surface marker genes in isolated cells were identified by immunofluorescence and RT-PCR techniques，the results showed that CD29， CD73， CD90 and CD166 expressed， while CD45 didn’t express. After induction of adipogenesis， lipid droplets stained with oil red stain were seen， and adipogenic genes LPL and PPAR-γ both expressed. After induction of osteogenic differentiation， calcium nodules were stained with alizarin red， and osteogenic genes OPN and collagen type Ⅰ gene COL-?Ⅰ expressed； after induction of chondrogenic differentiation， the chondrocytes were stained with Alisin blue， and they expressed chondrogenic key gene transcription factor gene SOX9 and ACAN. In this study， mesenchymal stem cells with good proliferation viability and adipogenic， osteogenic and chondrogenic abilities were successfully isolated from the umbilical cord of Holstein cattle at 3-month-old embryonic， which provided basis for the conservation of animal germplasm resources and regenerative medicine as well as potential cell resources.
In order to rapidly and accurately diagnose and identify nitrogen stress in rice， a field experiment was conducted. Taking the super rice variety ‘Liangyoupei 9’as material， 4 treatments of nitrogen application （0， 210， 300， and 390 kg·hm-2） were set， and images of the first， second， and third leaves at the top of the rice plant were scanned and collected during the spikelet differentiation and the full heading stage. The SE block （squeeze-and-excitation block） module was added to each residual block of the ResNet34 in convolutional neural network （CNN）， and the weight parameters trained on the ImageNet （ImageNet large scale visual recognition challenge） dataset were transferred to the nitrogen nutrition diagnosis model of rice. The feature extraction layer of ResNet34 was kept unchanged， and the pooling layer at the end of the model was replaced with a global average pooling layer. The improved network was used to extract features from rice images and train the optimal weight file. The results showed that the improved network achieved a testing accuracy of 98.13% during the spikelet differentiation stage and 99.46% during the full heading stage of rice. The convergence speed of the model was faster， and the accuracy was improved by more than 7% compared to the original network. Above results showed that it was feasible to add the SE block to the residual block of ResNet34 and use transfer learning to diagnose nitrogen nutrition in rice， which could effectively diagnose and identify the nitrogen nutrition of rice during the spikelet differentiation stage and the full heading stage. Above results provided reference for the diagnosis and identification of nutrient status in crops.
The current cassava planting mainly rely on artificial planting with labor intensity. A small amount of cassava plantation for other fruit and vegetable transplanting converted， the model usually failed to achieve accurate sowing in the process of the operation， resulting in low qualification rate and high seed leakage rate， so the central composite test design theory was used to carry out the optimization test to analyze parameters， and the influence of operating parameters on the qualification rate and seed leakage rate. With the qualification rate and seed leakage rate as the test indexes， the forward speed， crank speed and machine height as the test factors， the three horizontal response surface tests were conducted through the response surface method， and the regression model of each factor， the qualification rate and seed leakage rate were established by Design Expert software to study the influence law of various factors and their interaction on the test index. The field test results showed that the combination of operation parameters was forward speed 0.89~0.94 m?s-1， crank speed 43 r?min-1， and implement height 383 mm， the planting qualification rate was 95.47%， and the seed leakage rate was 2.05%. The relative error with the optimized value of the model was less than 5%， which indicated that the model was reliable. The research results had important guiding significance for improving cassava planting effect， and could also provide reference for the optimization of design and parameter optimization of cassava planting mechanism in the future.
Endoplasmic reticulum is the main site of protein folding and post-translational modification in eukaryotic cells. It also participates in the regulation of Ca2+ and lipid storage and synthesis， and has important physiological functions. Herpesviruses is a class of enveloped DNA viruses. The synthesis and processing of its surface glycosylated envelope proteins depends on the endoplasmic reticulum. During virus replication， a large number of synthesized glycosylated envelope proteins are excessive in the endoplasmic reticulum. Accumulation causes endoplasmic reticulum stress （ERS）， which in turn leads to unfolded protein response （UPR）. Some herpesviruses may have evolved mechanisms to regulate the UPR to create an optimal egoistic environment for the replication process. When they replicate in host cells， they will cause related endoplasmic reticulum UPR signaling cascades， such as cell damage， inflammation， apoptosis， etc. In this paper， the mechanism of endoplasmic reticulum stress/unfolded protein response （ERS/UPR） response to viruses was reviewed， and the molecular mechanism and related signaling pathways of ERS caused by herpes simplex virus type Ⅰ， pseudorabies virus， marek virus， duck enteritis virus and other herpes viruses were expounded， which provided theoretical basis for the research and development of herpes virus-related vaccines and drug targets.
In order to master the drug resistance and drug resistance gene carried by Enterococcus faecalis from different animal sources in Zhaosu， Yili， Xinjiang， a total of 1 120 samples from cloacal swabs （chicken）， nasal swabs and anal swabs （sheep， cattle） were collected from free-range farmers in Zhaosu， Yili， Xinjiang. Enterococcus faecalis was isolated from swabs. Drug susceptibility of Enterococcus faecalis were tested by agar dilution method， and the related resistance genes were detected by PCR method. The results showed a total of 263 strains of Enterococcus faecalis were isolated and identified with an isolation rate of 23.5%. The resistance of different animal-derived Enterococcus faecalis from high to low was sheep， chicken and cattle sources. The resistances of Enterococcus faecalis from sheep were more than 75.0% to erythromycin， tetracycline， florfenicol and doxycycline， which was significantly higher than chicken-derived and cattle-derived Enterococcus faecalis； the resistance rates of Enterococcus faecalis from chicken were 0~50.0%； the resistance rates of Enterococcus faecalis from cattle were lower than 21.1%； all Enterococcus faecalis were fully sensitive to ampicillin and vancomycin. The detection rates of efflux pump gene emeA in Enterococcus faecalis from different sources were all higher than 80.0%. The detection rates of ermB， fexA， optrA， tet（M） and aph（3’）-Ⅲgenes from sheep were more than 70.0%， which were basically the same as drug resistance situation. The genesof cfr， ermC and poxtA were not detected. Different animal-derived Enterococcus faecalis showed different degrees of resistance to antibiotics， and the drug-resistant genotypes were basically the same as the drug-resistant phenotype. It was recommended to strengthen the regular detection of drug resistance and drug resistance genes of animal-derived Enterococcus faecalis，and arranged rational drug administration for different animals according to the prevalence of drug resistance and drug resistance genes.
To investigate the effects of sea rice cultivation on microbial community of coastal saline soil and its relationship with environmental factors， the soils with 0.2% and 0.6% salt concentration were as materials， in which sea rice was grown as treatment groups （S1 and S2） and no plant as control groups（CK1 and CK2）. The chemical properties， nutrient content and microbial community structure of soil under different treatments were determined. The results showed that， after planting sea rice， the contents of humus， available phosphorus and available potassium significant increased， which peaked at 19.26 g·kg-1， 40.61 mg·kg-1， 98.33 mg·kg-1 and 17.42 g·kg-1， 34.79 mg·kg-1， 88.69 mg·kg-1 under S1 and S2 treatments in the heading stage， respectively. At the same time， the contents of alkali-hydrolytic nitrogen， ammonium nitrogen and nitrate nitrogen of soil significantly increased after planting sea rice， and the contents were the highest at heading stage. Compared with the control group， the microbial biomass carbon （MBC）， microbial biomass nitrogen （MBN） and microbial respiratory activity （MR） under treatment groups increased significantly， which increased 190.42%， 234.13% and 93.33% in S1 treatment， 195.33%， 184.26% and 108.14% in S2 treatment， respectively. At the same time， the planting sea rice had significant effects on the diversity of coastal saline soil microbial community structure. The relative abundances of dominant microfloras under S1 treatment were significantly higher than those under S2 treatment. Under S1 treatment， the relative abundances of Burkholderiacea， Chitinophagacea， Methylophilacea， Pyrinomonadaceae， Sphingomonadaceae， Blastocatellaceae increased significantly by 75.63%， 4.01%， 54.67%， 65.03%， 99.11%， 49.93%， 119.75%， respectively. Under S2 treatment， the relative abundances of Burkholderiacea， Methylophilacea， Blastocatellaceae， Nitrosomonadaceae increased significantly by 29.83%， 28.17%， 148.84%， 44.81%， respectively. Correlation analysis showed that pH of soil was extremely significant positively correlated with the relative abundance of Burkholderiaceae and Methylophilaceae， while the contents of Humus， the soil alkali-hydrolytic nitrogen， ammonium nitrogen， nitrate nitrogen were extremely significant positively correlated with the relative abundance of Pyrinomonadaceae and Blastocatellaceae.
To improve nutrient management and promote natural leaf ripening of flue-cured tobacco in tobacco-rice rotation area， a field experiment was designed and 4 fertilization treatments including T1 （chemical fertilizer applied in both rice season and flue-cured tobacco season）， T2 （chemical fertilizer + rapeseed cake fertilizer in flue-cured tobacco season， chemical fertilizer in rice season）， T3 （chemical fertilizer applied in flue-cured tobacco season， chemical fertilizer + rapeseed cake fertilizer applied in rice season） and T4 （chemical fertilizer + rapeseed fertilizer applied in both rice season and flue-cured tobacco season） were set in both rice and flue-cured tobacco season. The effects of organic fertilizer application on photosynthesis， fluorescence characteristics and activities of key enzymes in carbon and nitrogen metabolism of tobacco plants were studied. The results showed that all the indexes of tobacco plant applying rapeseed cake fertilizer were better than those applied chemical fertilizer in both seasons， and the physiological effects of tobacco plant treated with cake fertilizer in the current tobacco season were better than those in the rice season， and the physiological effect of tobacco plant treated with cake fertilizer in both tobacco and rice seasons was the best. Compared with T2， T3 and T1， the total chlorophyll content in T4 treatment increased by 15.0%， 26.6% and 45.3%， and the net photosynthetic rate in T4 treatment increased by 13.3%， 36.1% and 66.0%， respectively. The combined application of chemical and cake fertilizer in both tobacco and rice seasons could significantly increase the photosynthetic rate， promote the transformation of photosynthetic products and maintain the nitrogen metabolism level， ensure the smooth progress of various metabolic processes in tobacco plant at the late growth stage， and be more conducive to the normal mature of tobacco leaves in the field， improve tobacco curing characteristics， and promote the formation of high quality tobacco leaves， increase the income of tobacco farmers.
To Explore the effect of straw decompostition agents on the changes of physicochemical parameters and microbial communities in the decomposition of rice straw， 2 treatments were set up in the experiment： straw decompostition agent（JF） and no inoculation（CK）. Changes of the physicochemical parameters and microbial communities composition were measured and analyzed. The results showed that straw decompostition agent had insignificant effects on decomposition rate， pH， total organic carbon， total nitrogen and the ratio of C/N， but the content of total P increased by 8.4% and the ratio of C/P decreased by 9.1%， significantly. At the phylum level， Proteobacteria， Firmicutes， Bacteroidetes and Actinobacteria were the dominant bacteria communities， Basidiomycota， Ascomycota and Unclassified fungi were the dominant fungus communities. The abundances of Proteobacteria and Actinobacteria at 0~8 and 8~28 d in JF were higher than those in CK， respectively. Basidiomycota， Ascomycota and Unclassified fungi were the dominant fungus communities in the temperature rising， cooling off and maturity stage， and their abundances in JF were higher than those in CK. At the genus level， the dominant bacteria communities included Bacillus， Pseudoxanthomonas， Escherichia-Shigella， Cronobacter， Cellvibrio and Paenibacillus，the dominant fungus communities included Coprinopsis， Aspergillus， Wallemia， Melanocarpus and Thermomyces. The abundances of Escherichia-Shigella and Cronobacter in JF were 0.3%~4.5% and 1.3%~3.1% higher in the temperature rising stage than those in CK， respectively. The abundance of Wallemia in JF was 3.9%~4.5% higher in the temperature rising stage than that in CK. The abundances of Melanocarpus and Thermomyces in JF were 39.2% and 39.1% higher on the 8th day than those in CK， respectively. The canonical correlation analysis （CCA） showed that total nitrogen and available phosphorus were the most important environmental indicators affecting bacteria and fungus communities. To sum up， the straw decompostition agent affected the decomposing of rice straw by increasing the maturity indexes of part of the rice straw and increasing the abundances of some functional microbial communities， which provided theoretical and scientific basis for improving the utilization rate of rice straw returning to the field.
Soybean-maize belt composite planting is one of the important cultivation patterns to improve crop yield and to ensure food security. In order to explore the application effect of plastic film mulching on soybean-maize belt composite planting， poly propylene carbonate（PPC）based biodegradable permeable mulching film treatment （T1）， polyethylene（PE）ordinary permeable mulching film treatment （T2） and no mulching treatment （T3） were set，and soybean monoculture mode PE common permeable mulching film treatment （CK1） and maize monoculture mode no mulching treatment （CK2） were as control，the economic effects of different planting modes under different mulching films were studied. The results showed that the total biodegradable permeable mulching film could significantly increase the system yield under the belt composite planting mode （T1）， which was 29.56% higher than that under PE common permeable mulching film （T2）， 44.23% higher than that without plastic mulching film （T3）， and 121.67% higher than that under PE common permeable mulching film （CK1）， and 38.92% higher than that maize monoculture （CK2） without mulching film. There was no significant difference in yield per unit between T2， T3 and CK2， while CK1 showed a significant low yield per unit. T1 treatment significantly increased farmland income， with the output value per unit area was 36 271 yuan·hm-2. The degradation degree of the whole biodegradable permeable mulching film reached 85.1% after 130 d of the combined planting mode of soybean and maize， which effectively alleviated the white pollution of farmland. Based on this， the permeable plastic film mulching with full biodegradation could be used as a technical approach to solve the problems of difficulty in weed control， climate drought and white pollution of farmland in the extension and application of soybean and maize strip composite planting technology.
In order to quantify the effect of biochar application on soil pH and provide theoretical basis for biochar application in soil improvement and fertility cultivation， based on the electronic databases CNKI， Wanfang and Web of Science， 413 biochar on soil pH case studies based on the keywords “Biochar”， “Biochar”， “soil pH” and “soil pH” were collected from 59 published literatures. Meta-analysis was implied to quantify the effect degree of soil conditions， biochar characteristics and biochar application amount on soil pH. The results showed that， compared with no biochar application， biochar application could significantly increase soil pH by 8.70%. In the strongly acidic soil （4.5<pH≤5.5） and extremely acidic soil （pH≤4.5）， the increase rate were the highest， which were 15.17% and 9.68%， respectively. Different biochar could significantly increase soil pH， and showed the trend as straw biochar （10.04%） > shell residue biochar （7.02%） > wood biochar （6.61%）. The biochar prepared at ≤400 ℃ had the best promotion effect of 15.26% under different pyrolysis temperatures， while， the increasing effect decreased with the increase of pyrolysis temperature， such as the pyrolysis temperature was between 400~700 ℃. The increasing effect was higher in 3 months， then the increase gradually slowed down.These results indicated that in strongly acidic soil （4.5<pH≤5.5）， straw pyrolysis biochar at low temperature （≤400 ℃） was preferred to be applied， which could better improve soil pH and provide scientific basis for the promotion and application of biochar in the future.
To study the effect of planting density on the growth traits， physiological characters， yield and nutritional quality of Fritillaria hupehensis， and then screen the optimal planting densities， 4 planting densities were set up for the experiment. The results showed that with the increase of density， the plant height， chlorophyll content， catalase activity， superoxide dismutase activity， peroxidase activity and soluble protein content of Fritillaria hupehensis increased first and then decreased. When the plant-row spacing was 10 cm×15 cm （PD3）， the above indexes reached the maximum value， while the superoxide anion free radical content and malondialdehyde content were the minimum. With the increase of planting density， the yield of Fritillaria hupehensis increased. When the row spacing was 5 cm×10 cm （PD1）， the yield （11 975.3 kg·hm-2） of Fritillaria hupehensis was the largest. The yield increment increased first and then decreased， with the increasing of density. When the row spacing was 10 cm×15 cm （PD3）， the yield increment （5 081.0 kg·hm-2） and peiminine content （0.297%） of Fritillaria hupehensis were the largest. In conclusion， reasonably dense planting could significantly increase the yield and nutritional quality of Fritillaria hupehensis （P<0.05）， and the plant-row spacing of 10 cm×15 cm was the optimal planting density of Fritillaria hupehensis， which would provide theoretical basis for the high-yield and nutritional quality cultivation of Fritillaria hupehensis.
In order to explore the characteristics of carbon sink function restoration of ecosystems in the process of highway construction in grassland areas，taking the road ecosystem in Xilingol typical grassland area as the research object，the characteristics of carbon sink function among 4 typical disturbance modes （roller compaction，embankment，cutting and borrow site） of road ecosystem in typical grassland area under different vegetation restoration years （1，5 and 15 a） were compared based on field measurements and space instead of time method. The results showed that， with the increase of restoration years，the vegetation community characteristics indicators increased significantly under different disturbance methods. Vegetation organic carbon content，soil organic carbon content and restoration period showed positive correlation，and showed restoration 15 a > restoration 5 a > restoration 1 a. The maximum value occurred when the restoration period was 15 a and the embankment vegetation carbon content was 143.65 g·kg-1 and the embankment soil carbon content was 14.33 g·kg-1. Under different restoration years，the order of organic carbon content in the four disturbed plots from high to low was embankment > cutting > fetch ground > rolling. The organic carbon content of the road embankment was higher than the other three samples at all three restoration years， and exceeded the native control by 21.6% at restoration 15 a. The results were of great significance for road ecosystem restoration and carbon sequestration function evaluation.
In order to explore the structural changes of forest land after selective cutting and provide a basis for the restoration of important species such as Larix sibirica， 2 different types of communities of natural forest in Berqin area in Altai mountain were took as materials. The important value method and diameter class distribution method were used to study the species composition， diameter class structure in the arbor layer， the composition， number and height characteristics of renewed seedlings after the Larix sibirica had been felled. The investigated of the plot showed that Larix sibirica was the dominant species in 2 communities before felling. The important value of Picea obovata in height thinning （ZT） was 65.30， which was absolutely dominant， and the imporatnt value of Larix sibirica in height thinning （HT） ranking first with 56.70 in community Ⅰ. Abies sibirica had the largest important value for 61.05 in community Ⅱ after 30 years selective felling. With the increased of cutting intensity， the diameter distribution of trees shifted to a larger diameter class， small-diameter grades accounted for 77.80% in LT and the number of large-diameter trees accounted for 64.80% in HT. The regeneration characteristics of different community types were different after selective felling. Picea obovata seedlings accounted for 61.00% of light thinning and 77.00% of height thinning for community Ⅰ， with the increased of cutting intensity， Larix sibirica seedlings significantly increased. The seedling height level of light thinning was concentrated in <30 cm， while it was mainly concentrated in 30~60 cm for height thinning. Abies sibirica seedlings accounted for the vast majority for 92.00% but Picea obovata seedlings accounted for merely in community Ⅱ. Generally speaking， after selective felling， the regeneration ability of Abies sibirica and Picea obovata were stronger than that of Larix sibirica， and gradually replaced Larix sibirica as the predominant species； the higher the intensity of selective cutting， the better effects of natural regeneration of Larix sibirica. It was suggested that sufficient light conditions might be needed for natural regeneration.
Aquaponics is an innovative compound production system composed of recirculating aquaculture and hydroponic cultivation， which has the characteristics of high resource utilization rate， no chemical fertilizers and antibiotics， low consumption， high efficiency and sustainability. It is considered as a modern agricultural farming system of ecological protection. Although aquaponics system has developed rapidly in recent years and has been widely promoted and applied， it still lacks systematic cognition and holistic analysis. This paper summarized the technological development of aquaponics system， the main research contents， research progress and development trend at home and abroad. Combined with the development status of aquaponics system， it was predicted that the future aquaponics system construction would tend to be decoupled and ecological， the layout would move toward urbanization and three-dimensional， the large-scale intelligent and commercial implementation would be carried out， and the trend would be diversified and integrated innovation. Meanwhile， relevant improvement suggestions were put forward， which aimed to provide scientific ideas for the efficient construction and sustainable development of aquaponics complex system.
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