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- Abstract：As one of the major agricultural countries in the world, the sustainable development of agriculture in China is limited by the shortage of water resources. Improving crop water productivity is one of the most effective measures to ensure food security and alleviate the contradiction between supply and demand of water resources. To reveal the spatio-temporal evolution characteristics of the water productivity(WP)of main grain crops in various provinces of China(Data do not include those of HongKong, Macao and Taiwan regions. The same below), this study calculated the WP of maize and wheat in various provinces of China based on meteorological data and statistical yield, and analyzed the selected meteorological and management factors by using correlation analysis, collinear diagnostic analysis and partial least squares regression analysis, to determine the main factors affecting the WP of maize and wheat. The results showed that: 1)The WP of maize and wheat increased in the range of 1. 19-1. 33 kg/m3 and 0. 90-1. 04 kg/m3 from 2010 to 2019, respectively. In the nine agricultural regions, the high value of maize WP appeared in the Northeast Plain, and the highest value of maize WP was 2. 00 kg/m3 in Jilin Province. The value of wheat WP was high in the middle and lower reaches of the Yangtze River and South China, and the highest value of wheat WP was 1. 91 kg/m3 in Guangdong Province, which was located in South China. 2)According to the results of correlation analysis and partial least squares regression analysis discovered that the main factors affecting the WP of maize were annual evapotranspiration and yield per unit area, and that affecting wheat WP were yield per unit area, fertilizer amount, seeding density, annual mean air temperature, annual mean relative humidity, and total nitrogen, total phosphorus, total potassium, soil bulk density(soil thickness 0-30 cm)and soil organic carbon(0-100 cm)in soil factors. The results of this study have positive reference value for improving the water productivity of maize and wheat in our China.Keywords：Penman-Monteith model;crop water productivity;influencing factor;partial least squares regression analysis41|14|1<HTML><L-PDF> <Meta-XML>Updated：2023-12-22
- Abstract：In order to screen out the high and stable-yield hybrids and ideal testing sites in Northwest China, the AMMI model and GGE biplot were used to analyze the fertility, stability and adaptability of 12 hybrids in 19 testing sites and evaluate the discrimination and representativeness of the testing sites in the regional trial of spring maize in Northwest China in 2022. The results showed that the sources of variation in yield mainly included genotype, environment and genotype-environment interaction, accounting for 4. 39%, 74. 50% and 10. 08% of the total square sum of yield variation, respectively. The AMMI model explained 82. 76% of the genotype-environment interactions. The GGE biplot showed that the 19 testing sites were divided into three ecological region and the seven ideal testing sites of Pingliang and Tianshui in Gansu Province, Bayannur in Inner Mongolia Autonomous Region, Pingluo County in Ningxia Hui Autonomous Region, Yan'an in Shaanxi Province, Changji Prefecture and Kokdala in Xinjiang Uygur Autonomous Region had strong discrimination and representativeness. The high and stable-yield hybrids, ‘DK 2207' and ‘Xiwang 188' were identified by AMMI model and GGE biplot in Northwest China. The AMMI model could fully resolve the genotype-environment interactions and concentrate on evaluating the stability of hybrids, while the GGE biplot had obvious advantages in evaluating the discrimination and representativeness of the testing sites. In summary, the comprehensive application of AMMI model and GGE biplot could improve the reliability of the evaluation of the hybrids and ideal testing sites in the spring maize regional of Northwest China.Keywords：maize;regional trial;AMMI model;GGE biplot;yield analysis35|13|5<HTML><L-PDF> <Meta-XML>Updated：2023-12-22
- Abstract：Three-factor split-zone plot field trial including planting pattern, density and nitrogen fertilization level was used to investigate the regulatory effects of increase planting density on maize yield in relay strip intercropping. The main factor was the planting pattern: Maize relay strip intercropping(A1)and maize monoculture(A2). The sub-factor was the planting density: 60 000(B1)and 75 000 plants/hm2(B2). The sub-sub-factor was the nitrogen fertilization level: 0(C1), 225(C2), 300(C3), 375 kg/hm2(C4). A short-term locational field trial was conducted for two consecutive years to determine and analyze the maize yield, dry matter accumulation, leaf area index and chlorophyll content of maize under the two planting patterns at each period. The results showed that: When the density increased from 60 000 to 75 000 plants/hm2, the maize yield in monoculture and intercropping increased by 5. 36% and 5. 87% respectively, and the maize yield increase in maize relay strip intercropping was 8. 69% higher than that of maize monoculture. Under the two densities, when the application of nitrogen increases to 300 and 375 kg/hm2. The yield was increased by 15. 94% and 14. 28%, respectively, compared to the no nitrogen treatment. The application of nitrogen up to 225 and 300 kg/hm2 of maize monoculture increased yields by 18. 2% and 19. 39%, respectively. The maize yield in intercropping was significantly lower than that of monoculture. However, the yield difference in maize monoculture was reduced when the planting density and N application were increased to 75 000 plants/hm2 and 375 kg/hm2, respectively. The dry matter accumulation of maize in relay strip intercropping increased by 20. 3% and chlorophyll content increased by 42. 6% compared to maize monoculture under 60 000 plants/hm2 and 300 kg/hm2 nitrogen level, which prolonged the active growth period of matter accumulation and increased the growth volume, and were worth to be further exploited for their maize yield potential. In conclusion, the higher maize yield of 8 914. 62 and 9 093. 17 kg/hm2 were obtained at the combination of 60 000 plants/hm2 planting density+300 kg/hm2 nitrogen application and 75 000 plants/hm2 planting density+375 kg/hm2 nitrogen application in maize relay strip intercropping, and there was no significant difference with maize monoculture yield.Keywords：maize;density;nitrogenous fertilizer;relay strip intercropping;yield50|18|9<HTML><L-PDF> <Meta-XML>Updated：2023-12-22
- Abstract：To explore the effects of straw incorporation, reducing nitrogen fertilizer application under the background of increasing temperature on rice production, a total of 3 temperature treatments, normal temperature(NT), moderate temperature(MT, increased by 2 ℃ compared to normal temperature), and extreme high temperature(HT, increased by 5 ℃ compared to normal temperature), were designed 4 different fertilization treatments, conventional fertilization(CF), nitrogen reduction(CDF, reduced by 20% nitrogen fertilizer application compared to conventional treatment), straw incorporation(SF)and straw incorporation coupled with nitrogen reduction(SDF, straw incorporation combined with a 20% reduction in nitrogen fertilizer), were conducted. The physiological characteristics of flag leaves, nutrient uptake, and non-structural carbohydrates(NSC)in stems, sheaths, and grains of ‘Nanjing 9108' at different growth stages were determined. The results showed that: With the temperature increase of 2 and 5 ℃ at the initial heading stage, the SPAD values of flag leaves at the filling stage increased by 37. 77% and 42. 86%, respectively. The net photosynthetic rate of flag leaves under SF treatment decreased by 13. 71% and 5. 88% compared with CF treatment, and the net photosynthetic rate of flag leaves under high temperature reduced nitrogen fertilization treatment was the highest, which was 8. 97% higher than CF treatment. The proportion of nutrient uptake at the panicle to the total nutrient uptake in the shoot was significantly reduced under the high temperature treatment, and the total uptake of nitrogen, phosphorus, and potassium in the shoot of the plant were all reduced by 25. 75%-53. 98%, 53. 29%-64. 82% and 7. 92%-34. 53%, respectively. The total potassium uptake of rice panicles under SF treatment increased by 10. 73% and 6. 82% under MT and HT, respectively, compared with CF treatment. Temperature rise reduced the accumulation of NSCs in rice stem sheaths and their transport to grains. Compared with CF treatment, SF, SDF and CDF all promoted the accumulation of NSCs in grains under room temperature and moderate temperature increase. The NSC content in rice grains of SDF with NT increased by 65. 21% compared to CF; NSC accumulation in SF treatment increased by 26. 04% compared with CF treatment under MT; and it was opposite at high temperature. NSC transport and accumulation were significantly inhibited by SF, SDF and CDF treatment, which were 20. 35%, 18. 57% and 18. 60% lower than CF, respectively. In summary, using straw returning to the field coupled with nitrogen reduction at normal temperature can significantly increase the NSC content in grains, and using straw returning to the field under moderate temperature rise can significantly promote the NSC content in grains by 26. 04% compared to conventional fertilization.Keywords：rice;high temperature;straw returning;reducing nitrogen;physiological characteristic35|11|6<HTML><L-PDF> <Meta-XML>Updated：2023-12-22
- Abstract：The study was to analyze the effect and mechanism of agricultural inorganic fibers(IF)on ryegrass growth under cadmium(Cd)stress. The effects of IF with volume ratios of 1∶19(IF1), 1∶9(IF2)and 3∶17(IF3)on the growth, physiological and biochemical characteristics, soil physicochemical properties and Cd mass fraction of ryegrass on Cd contaminated soil(ω(Cd)=50 mg/kg)were studied by pot experiments. The results showed that: Cd stress significantly inhibited the growth of ryegrass, and the treatment of IF1 could effectively promote the growth of ryegrass, reduce the content of malondialdehyde(MDA)and the production rate of superoxide anion(O·-2)in roots and leaves of ryegrass, improve the mass fraction of soluble protein and antioxidant enzyme activity, increase the mass fraction of available silicon in soil, and increase the Cd mass fraction of ryegrass roots and leaves and the accumulation of Cd in the aboveground part. The growth promotion effect of the treatment of IF2 and IF3 on ryegrass under Cd stress was not obvious, but it can also improve the above physiological and biochemical indexes of ryegrass roots and leaves, and the difference with the treatment of IF1 was not significant; The treatment of IF2 and IF3 could significantly increase the available silicon mass fraction in soil, reduce the soil effective Cd mass fraction, and reduce the Cd mass fraction and Cd accumulation in leaves and roots of ryegrass. This study can provide a basis for opening up a new green way for exogenous substances to improve plant Cd tolerance and strengthen phytoremediation of Cd contaminated soil.Keywords：agricultural inorganic fiber;soil Cd pollution;ryegrass;phytoremediation38|11|1<HTML><L-PDF> <Meta-XML>Updated：2023-12-22
- Abstract：To clarify the contamination level and dietary exposure risk of benzo［a］pyrene in dried jujube dates(Ziziphus jujuba)in China, 100 dried jujube samples were tested in a survey. The concentration distribution of benzo［a］pyrene in dried jujube dates was estimated by the non-parametric bootstrap resampling. Combined with the jujube dates consumption data of two representative Chinese populations(adults and children), dietary exposure of benzo［a］pyrene through eating jujube dates was calculated. Referring to the Joint Expert Committee of FAO/WHO on Food Additives(JECFA)for the point of departure of the carcinogenicity of benzo［a］pyrene the margin of exposure(MOE)was derived for resulting the conclusion of dietary risk of benzo［a］pyrene through consumption of jujube dates. At the same time, for identifying the source of benzo［a］pyrene contamination, an analog of drying process of fresh jujube dates was conducted under laboratory conditions. The results showed that: The mean of benzo［a］pyrene concentration in jujube dates was 2. 00 μg/kg, and the value at 97. 5th percentile was 7. 30 μg/kg. Dietary exposure of benzo［a］pyrene by consumption of jujube dates at mean intake contributed to 0. 000 013 μg/kg bw. d for adults, and 0. 000 054 μg/kg bw. d for children, and at high intake(97. 5th percentile), contributed to 0. 000 152 μg/kg bw. d for adults, and 0. 000 535 μg/kg bw. d for children. MOEs reached 1 851 852-7 692 307 at mean intake, and 186 916-657 895 at 97. 5th percentile intake. This was much higher than the JECFA recommended MOE(>10 000). At the same time, considering the low proportion of jujube dates consumption in total diets(0. 03%-0. 25%), the exposure of benzo［a］pyrene by consumption of jujube dates could be concluded as low concern of dietary risk for health of target populations. Through laboratory simulation of fresh jujube drying experiments, it has been proven that coal fire drying is an important reason for the high concentration of benzo［a］pyrene in jujube.Keywords：Ziziphus jujuba;benzo［a］pyrene;dietary risk assessment;Bootstrap;MOE;uncertainty31|10|0<HTML><L-PDF> <Meta-XML>Updated：2023-12-22
Screening, identification and degradation characteristics of one straw degrading actinomycete strain
Abstract：The purpose of this study was to obtain excellent straw degrading actinomycetes and analyze their degradation characteristics. Target strains were screened by enrichment culture method with samples collected from forest soil and straw compost environment. The classification status of degrading strain was determined by observation of culture characteristics, physiological and biochemical identification, and comparative analysis of 16S rDNA sequence. Combined with scanning electron microscope technology, the changes of physical and chemical properties of straw during degradation were analyzed. The effects of culture temperature, initial pH and nitrogen source type on straw degradation were investigated. The dynamic changes of extracellular cellulase activity were measured with natural cellulose as substrate. The results showed that: 1)The strain ZY-2 screened in this study was identified as Streptomyces rochei; 2)The straw degradation rate of Streptomyces rochei ZY-2 could reach 29. 23% within 7 days, and the degradation rates of hemicellulose, cellulose and lignin were 42. 82%, 47. 05% and 13. 63%, respectively; 3)The optimal straw degradation conditions of ZY-2 were as follows: incubation temperature 35-45 ℃, initial pH 6. 0-8. 0, organic nitrogen as nitrogen source; 4)The strain could secrete both endo- and exo-cellulase. Endo-cellulase activity was higher at the early stage of growth and reached the peak(0. 12 U/mL)on the 4th day, while the exo-cellulase activity was higher at the late stage of growth and reached the peak(0. 23 U/mL)on the 6th day. In conclusion, the strain ZY-2 screened in this study is a multi-component lignocellulose degrading actinomycete, which can be used as excellent bacterial resource for the rapid decomposition of straw.Keywords：straw degradation;strain identification;lignocellulose;cellulase38|12|6<HTML><L-PDF> <Meta-XML>Updated：2023-12-22- Abstract：In order to study the yield benefit and soil microbial community of pecan-wheat intercropping system, pecan monoculture(P)and pecan-wheat intercropping(PW)were used as the research objects to compare and analyze the yield benefits under the two modes. Illumina Miseq high-throughput sequencing technology was used to study the diversity, community structure, marker species and co-occurrence network of soil bacteria and fungi, and to explore the relationship between soil chemical properties and microorganisms. The results showed that: 1)The yield of pecan nuts after intercropping was significantly lower than that of monoculture, and its total output value was significantly higher than that of monoculture. 2)Intercropping significantly reduced soil bacterial diversity and fungal richness. 3)Both bacterial and fungal microbial community structure were significantly changed by intercropping. The abundance of Actinobacteria and Basidiomycota increased significantly, and the abundance of Acidobacteria decreased significantly. Micrococcaceae, Xanthobacteraceae, Micromonosporaceae, Sphingomonas, Acidothermus, Gemmatimonas, Pseudarthrobacter, Exophiala and other marker species were enriched in the intercropping soil. 4)The complexity of soil bacterial network in intercropping was higher than that in monoculture, and the complexity of fungal network was lower than that in monoculture. 5)The abundance of bacteria and fungi at the genus level was significantly correlated with soil chemical properties. The changes of bacterial community structure were driven by pH, organic matter, nitrate nitrogen, available phosphorus and total phosphorus, and the changes of fungal community structure were driven by organic matter, nitrate nitrogen, available phosphorus and available potassium. The results of this study are helpful to reveal the underground ecological mechanism of pecan-wheat intercropping system.Keywords：soil microorganisms;pecan;agroforestry;grain and oil safety32|18|6<HTML><L-PDF> <Meta-XML>Updated：2023-12-22
- Abstract：In order to explore the regulation mechanism of gibberellin(GA)and brassinosteroids(BR)on hypocotyl elongation and growth of pumpkin under EOD-FR and their interaction relationship, this study took ‘Japanese cedar' pumpkin as the experimental material. EOD-FR treatment was used to investigate the effects of exogenous GA, BR and GA synthesis inhibitors(PAC)and BR synthesis inhibitors(BRZ)on hypocotyl growth, hormone content and gene relative expression. The interaction and important role of GA and BR in hypocotyl elongation mediated by EOD-FR were discussed. The results showed that: EOD-FR could significantly increase the length of hypocotyls by 39. 8%, the content of endogenous GA and BR, and the expression of GA and BR synthesis and signal transduction genes. The length of hypocotyls supplemented with both GA and BR was significantly longer than that those supplied with BR and GA alone, and PAC and BRZ also had additive effect. BR alleviated 28. 9% of PAC inhibition on hypocotyl, GA alleviated 30. 8% of BRZ inhibition on hypocotyl. BRZ significantly reduced 6. 7% of GA content in hypocotyl, inhibited GA synthesis and expression of signal transduction related genes. PAC significantly reduced 20. 9% of BR content in hypocotyl and also inhibited the expression of genes related to BR synthesis and signal transduction. To sum up, in EOD-FR mediated hypocotyl elongation, GA and BR interacted and coordinated to regulate the hypocotyl length of pumpkin.Keywords：EOD-FR;pumpkin seedling;gibberellin;brassinolide;hypocotyl33|10|0<HTML><L-PDF> <Meta-XML>Updated：2023-12-22
- Abstract：In order to accurately grasp the research progress of H5 subtype of avian influenza, based on 393 articless in the CNKI literature database and 1 560 articles in the Web of Science(WOS)literature database as research samples, in the study, the country of publication, number of documents, high-frequency cited documents, high-frequency keywords, main published authors and institutions, etc. were analyzed. The results show that: 1)Internationally, China and the United States have more researches in this field, with the number of publications accounting for 56. 80%; The number of literature is closely related to the severity of the avian influenza epidemic. Compared with the CNKI literature sample, the WOS literature sample has more advantages in terms of the number of literature and the citation frequency of highly cited literature, and the cooperation among the issuing institutions and the issuing authors in the WOS literature sample is closer. 2)The high-frequency cited literature and high-frequency keywords reflect the research hotspots in this field to a certain extent, mainly including the transmission and evolution of H5 subtype avian influenza virus caused by wild birds; the epidemiology, pathogenesis and immunotherapy of H5 subtype avian influenza; the development of new vaccines such as recombinant vaccines, inactivated vaccines and chimeric hemagglutinin vaccines; and preventive and control measures for outbreaks of H5 subtype avian influenza. This study concluded that long-term surveillance and prediction of the epidemic, rapid virus detection technology and development of novel vaccines are still hot spots for research in the future, providing reference values for workers in the field of H5 subtype avian influenza.Keywords：avian influenza subtype H5;CNKI;Web of Science;visualization analysis36|10|1<HTML><L-PDF> <Meta-XML>Updated：2023-12-22
- Abstract：In order to investigate the effects of different concentrate to forage ratios diets on the growth performance and serum biochemical indexes of Angus cattle-yaks in short-term confinement, in the study, thirty healthy Angus cattle-yak of Angus × Datong yak with similar age(four months old)and weight(114. 97±28. 33 kg)were selected and divided into three groups, with 10 replicates per treatment group and 1 cow per replicate. The dietary concentrate to the coarse ratio of each experimental group was 30∶70(Group C30), 45∶55(Group C45), and 60∶40(Group C60), with a pre-feeding period of 10 days and a regular feeding period of 90 days. The results showed as follows: 1)Compared with the C30 group of Angus cattle-yaks, the average daily gain(ADG)and chest girth in the C45 and C60 groups were significantly increased(P<0. 05)throughout the experiment, while the feed to weight ratio(F/G)was significantly decreased(P<0. 05). During the test 1-30 d the dry matter intake(DMI)was significantly reduced in the C45 and C60 groups(P<0. 05), while it was significantly increased in the 61-90 d(P<0. 05). The ADG was significantly increased in the C45 and C60 groups in the 1-30 d, and in the C60 group in the 61-90 d(P<0. 05). During the test 1-30 d and 61-90 d, the F/G was significantly reduced in the C45 and C60 groups(P<0. 05). 2)Compared with the C30 group, the serum glucose, total protein, albumin, globulin, and free fatty acids of Angus cattle-yaks in the C45 and C60 groups was significantly increased(P<0. 05). In conclusion, it can increase average daily gain, but also reduce feed to gain ratio, and it also can improve serum biochemical indexes of Angus cattle-yaks with high-concentrate diets, but too much concentrate doesn't give higher yields, so the optimal ratio of concentrate to roughage for short-term fattening of Angus cattle-yaks is suggested to be 45∶55. The finding provides a theoretical and practical basis for scientific feeding to improve the production performance and short-term fattening of Angus cattle-yaks.Keywords：concentrate to forage ratio;angus cattle-yaks;growth performance;serum biochemical indexes33|10|2<HTML><L-PDF> <Meta-XML>Updated：2023-12-22
- Abstract：In order to further explore the molecular regulation mechanism affecting sheep fertility, the ovarian transcriptome data of 16 high-breed sheep with many lambs and low-breed sheep with single lambs were analyzed. The WGCNA and eGWAS were used to construct ovine ovarian weighted gene co-expression network and expression-based genome-wide association, DESeq2 was used for differential gene analysis, and EWSS was used to mine the highly differentiated reproductive genes. The results showed that: 1)26 747 genes were expressed in ovarian tissues of high-breeding sheep and low-breeding sheep; 2)17 908 highly variable genes were clustered into 9 co-expressed gene modules; 3)Among the 884 differentially expressed genes, the up-regulated expression genes of high-prolificacy sheep were more than those of low-prolificacy sheep; 4)A total of 28 727 high-quality SNPs were obtained, and 232 highly variable SNPs were screened; 5)Twelve highly differentiated genes(FGD4、LHFPL2、PPIL6、MILR1、PPP1R9B、NUP62、POU2F3、PHLDB1、SH3PXD2B、XPC、DAXX and MXRA5)affecting sheep fecundity were screened by multiple methods. In summary, this study revealed the expression pattern of sheep ovarian genes and multi-dimensional screening of sheep fertility difference genes, and finally found 12 key genes that may regulate sheep reproduction, providing theoretical basis and data support for sheep reproduction research.Keywords：sheep;litter size;reproduction;reproductive genes32|11|4<HTML><L-PDF> <Meta-XML>Updated：2023-12-22
- Abstract：To explore the effects of sperm motility and testis and epididymal tissues on gene expression in Hyline Brown breeder roosters, eight Hyland Brown breeding roosters with significantly different sperm motility(four with high motility and four with low motility)were selected and their testis and epididymal tissues were collected for transcriptome sequencing after slaughter. The differentially expressed genes between different sperm motility groups and different tissues were screened using the two-factor module of DESeq2, and functional enrichment analysis was performed. The results showed that: 1)112 differentially expressed genes were found between the high and low sperm motility groups in the two tissues; 32 genes were highly expressed in the high sperm motility group and 80 genes were highly expressed in the low sperm motility group. The differentially expressed genes were significantly enriched in cytokine-cytokine receptor interaction, intestinal immune network for IgA production, and glycerolipid metabolism, among which CTRP3, TDRD5, KATNAL2, SOCS3 and CSF3 may be important genes regulating sperm motility in chickens. 2)9 212 differentially expressed genes were identified between testis and epididymis tissues. The number of genes that were highly expressed in testis tissues was 5 206 and 4 006 genes were highly expressed in epididymal tissues. The testis-specific highly expressed genes were significantly enriched in eight pathways including cell cycle, nucleocytoplasmic transport, oocyte meiosis and glycerophospholipid metabolism ect, with differentially expressed genes such as YTHDC2, MEIG1, GTSF1, JAM3 and SFMBT1 playing an important role in spermatogenesis. Genes highly expressed in epididymal tissues were involved in signalling pathways such as MAPK signalling pathway, tight junctions, glutathione metabolism, etc. ACE and MMEL1 were the key genes that played a role in the epididymis. In summary, it was shown that different tissues and sperm motility have an effect on the expression of genes related to reproduction in breeding roosters, laying the foundation for further investigation into the molecular regulatory mechanisms affecting breeding performance in breeding roosters.Keywords：breeding cock;RNA-seq;testis;epididymis;sperm motility31|10|1<HTML><L-PDF> <Meta-XML>Updated：2023-12-22
- Abstract：In order to discover new Tanacetum cinerariifolium like pesticide degradation genes and achieve heterologous and efficient expression in E. coli, the strain Raoultella ornithinolytica with wide degradation spectrum and high degradation rate screened by our research group in the early stage was taken as the research object, and its pyrethroid pesticide degradation enzyme gene BioH was cloned and expressed in E. coli. Through genome annotation, protein annotation and pathway annotation of the whole sequence of R. ornithinolysis, and sequence comparison with existing pyrethroid pesticide degradation genes, potential genes with pyrethroid pesticide degradation function were screened; Using the genomic DNA of R. ornithinolytica as used as a template, and specific primers were designed according to the functional gene sequence for PCR amplification; The target fragment was recovered and connected to the pMD19-T vector, and positive clones were screened and identified; After the target fragment was digested and recovered, it was connected with the pET32a(+)expression vector and transformed into E. coli BL21(DE3). The correct recombinant strain was induced to express by IPTG, and the protein expression was analyzed by SDS-PAGE. The results showed that the BioH gene was obtained by screening, which has the function of hydrolase, and also has the conserved pentapeptide motif-GXSXG in the sequence of other pyrethroid pesticide degradation genes. After PCR amplification, a band with the size of 783 bp was obtained. Positive clones were obtained by recombinant technology. PCR amplification, enzyme digestion and DNA sequencing were verified. The recombinant bacteria obtained about 43 ku(including 6×His tag)is a recombinant protein with molecular weight, which exists in the form of inclusion body. In this experiment, BioH gene was screened and cloned, and the prokaryotic expression vector was successfully constructed and expressed in E. coli BL21(DE3).Keywords：Raoulia ornithinolysis;pyrethroid pesticide;degrading gene;gene cloning;prokaryotic expression34|14|1<HTML><L-PDF> <Meta-XML>Updated：2023-12-22
- Abstract：The geometrical morphological characteristics of shelterbelt are complex and relatively flexible. The deformation and vibration will occur under the wind load, and the aerodynamic effects of shelterbelt are quite complex. How to simulate the windbreak effect of shelterbelt under the actual wind field as realistically as possible in the wind tunnels is particularly important. In view of this, this study summarizes the pertinent literature published at home and abroad, and reviews the progress research of windbreak effects of shrub and tree shelterbelt from the aspects of model design, approaching flow simulation and testing technology in the wind-tunnel simulation tests. The results show that: The determination of geometric scale of shelterbelt model should consider the size of shelterbelt and wind tunnel section, and the blockage ratio should be generally smaller than 5%; Considering that the deformation and vibration of trees under wind load will further affect the surrounding flow field, the dynamic similarity should be paid special attention to in addition to geometric similarity in model design; On the basis of mean wind speed, the consideration of statistical characteristics of fluctuating wind speed should be strengthened in the approaching flow simulation and wind speed measurement in the wind tunnel testing of shelterbelt; When the balance is used to determine the aerodynamic coefficients of shelterbelt, the sampling frequency should be determined according to the frequency of the model itself, so as to avoid the result distortion caused by the two frequencies being too close.Keywords：shelterbelt;wind tunnel test;similarity condition;model design;approaching flow simulation;testing technology41|13|3<HTML><L-PDF> <Meta-XML>Updated：2023-12-22
- Abstract：In order to explore the impact of uncertainty of forestry carbon sequestration project management on the investment threshold of investors under the goal of carbon peaking and carbon neutrality, this study takes four typical cases of forestry carbon sequestration projects in Zhejiang Province, Fujian Province, Guangdong Province and Hubei Province as research objects. Focusing on the uncertainty of carbon price and technological progress in forestry carbon sink project management, this study uses the real option investment decision theory and solution method to build a threshold evaluation model for investors to carry out forestry carbon sink project investment under double uncertainty conditions. And then, the impact and difference of the uncertainty of carbon price and technological progress on the investment threshold of investors are investigated, and the impact of other economic parameters on the investment threshold of investors under the condition of double uncertainty is revealed. The results show that: 1)There are obvious differences in the investment threshold of different types of forestry carbon sequestration projects, showing that the carbon sequestration projects of management forestry are significantly lower than those of afforestation forestry. Specifically, the Phyllostachys pubescens afforestation carbon sequestration project, Phyllostachys pubescens management carbon sequestration project, Chinese fir afforestation carbon sequestration project and Chinese fir management carbon sequestration project from high to low are 645. 90, 415. 09, 160. 28 and 135. 89 yuan/t respectively, which indicates that from the perspective of economics, it may be more feasible for investors to invest in management forestry carbon sequestration projects. 2)Carbon price volatility has a significant positive impact on the investment threshold of different types of forestry carbon sequestration projects; However, the technological progress of forestry carbon sequestration projects will reduce the investment threshold of different types of forestry carbon sequestration projects. If the probability of technological progress increasing to a certain extent, the investors will choose the immediate investment strategy. 3)Under the dual uncertainty of carbon price and technology, labor price and fertilizer price have a positive impact on the investment threshold of different types of forestry carbon sequestration projects; contrarily, the prices of wood, bamboo and bamboo shoots have a significant negative impact on the investment threshold. Finally, based on the above research results, this study puts forward some countermeasures and suggestions from various angles to promote investors to invest in forestry carbon sink project investment. This study provides a scientific basis for decision making to achieve China's carbon peak carbon neutral target.Keywords：“double carbon” background;forestry carbon sequestration project;investment threshold;influence mechanism37|12|8<HTML><L-PDF> <Meta-XML>Updated：2023-12-22
- Abstract：To explore the spatial differences and convergence characteristics of agricultural high-quality development(AHD)in agro-ecological zones, an evaluation index system is constructed for AHD based on the data of China's 31 provinces, egions and municipalities(except Hong Kong, Macao and Taiwan regions)from 2005—2019. The entropy-value-assignment method is applied to measure the AHD level. The magnitude and source of the AHD differences in the agro-ecological zoning are revealed with Dagum's Gini coefficient, and the AHD convergence characteristics are probed in depth. The results show that: On the whole, the AHD level is gradually increased in the study period, but there are decreasing gradient differences among regions; There are significant regional differences in AHD in agro-ecological zones with the overall differences showing a "U" trend primarily due to inter-regional differences; There is no obvious convergence and absolute convergence but a more significant conditional convergence in AHD. Therefore, it is necessary to continue to promote the structural reform of the agricultural supply side and realize the regional coordination in the AHD improvement.Keywords：agro-ecological zoning;high-quality agricultural development;regional differences;convergence31|10|5<HTML><L-PDF> <Meta-XML>Updated：2023-12-22
- Abstract：To study the historical origin and development of rural settlement and fully understand the basic law of the existence and continuity of rural settlements, the evolution of rural settlement in Hebei Province in prehistoric and ancient times in terms of quantity and spatial distribution were analyzed with the help of the data from ancient sites and traditional villages and the methods of the Nearest Neighbor Index and the Kernel Density Estimation. The results showed that: 1)The site selection of rural settlements in prehistoric times was mainly related to the changes in agricultural production conditions under the influence of natural factors. Humans mainly lived in the north of Hebei Province in the Paleolithic Age. With the emergence of agriculture in the Neolithic Age, rural settlements gradually formed, and showed the characteristics of increasing numbers, lacking in plains and developing southward. 2)The rapid changes in the number of rural settlements in ancient times were mainly related to social factors such as wars and disasters. For example, the Ming dynasty adopted the method of migration from Shanxi Province to restore the post-war population. 3)Historically, rural settlements showed obvious agglomeration in space. The agglomeration regions included the southwest of Zhangjiakou City, the west of Shijiazhuang City, and the west of Xingtai City and Handan City. Agricultural production conditions had always been the leading factor affecting the spatial distribution of rural settlements. Therefore, as the basic condition for the existence and continuity of rural settlements and the most important cornerstone for the formation of rural economy and society, agriculture should be considered in the regulation of rural settlements in the future. This study can provide theoretical and practical references for scientifically and reasonably defining ancient villages and protecting their historical and cultural heritage in village planning.Keywords：rural settlement;historical origin;historical evolution;historical motivation;Hebei Province30|15|2<HTML><L-PDF> <Meta-XML>Updated：2023-12-22
- Abstract：To address the problem that the consumption behavior of green agricultural products has multivariate nonlinear interaction characteristics, and it is difficult for traditional statistical methods to accurately predict consumption behavior, a generalized regression neural network model based on improved fruit fly algorithm for consumer behavior prediction is proposed. Firstly, to address the problem of single fruit fly flight caused by uneven fruit fly swarm search, the study proposes a uniform fruit fly swarm search mechanism, i. e. , sector fruit fly optimization algorithm to speed up the search ability and efficiency. Secondly, to address the problem of the smoothing factor of generalized regression neural network is susceptible to human selection, an improved fruit fly algorithm is proposed to optimize the selection of generalized regression neural network parameters to automate the selection of parameters and improve the prediction ability of the model. The proposed model is applied to predict the consumption behavior of green agricultural products. The results showed that: Compared with the generalized regression neural network model, the genetic algorithm optimized the generalized regression neural network, and the particle swarm algorithm optimized the generalized regression neural network, fruit fly algorithm optimized the generalized regression neural network and improved fruit fly algorithm optimized the generalized regression neural network models decrease 4. 45%, 1. 89%, 4. 54% and 5. 03%, respectively. Above results indicated that the genetic algorithm, particle swarm algorithm, fruit fly algorithm and improved fruit fly algorithm could optimize the smoothing factor of the generalized regression neural network model and improve the prediction accuracy of the model. From the three evaluation indexes of mean absolute error, mean square error, and root mean square error, the improved fruit fly algorithm optimized the generalized regression neural network model displaied higher prediction accuracy than those of the other six single prediction models. The results demonstrate the effectiveness of the improved fruit fly algorithm optimized the generalized regression neural network model in predicting green agricultural products consumption behavior, which can provide decision support for suppliers to adjust production plans and corporate marketing activities.Keywords：improved fruit fly algorithm;generalized regression neural network;consumption behavior;prediction;green agricultural products32|10|0<HTML><L-PDF> <Meta-XML>Updated：2023-12-22
- Abstract：Based on the survey data of farmers in the areas of kiwifruit in Shaanxi Province, this study uses PSM to construct counterfactual hypotheses. The effect of agricultural science and technology service on farmers' adoption of green production technology is examined, and the moderating effect mechanism of incentive measure is explored. The results show that: Agricultural science and technology service has a significant and stable promoting effect on farmers' adoption of green production technology, and the degree of farmers' adoption of green production technology by participating households is 12. 39% higher than that of non-participating households. From the perspective of the difference of supply entities, the various supply entities of agricultural science and technology services promote the adoption of green production technology by farmers in descending order of government departments, business entities, and agricultural universities. The impact of agricultural science and technology service on farmers' adoption of green production technology lies in the heterogeneity of green production technologies and group heterogeneity. The incentive measure has a positive moderating effect on the impact of agricultural science and technology service on the adoption of green production technology by farmers, and the moderating effects are social incentives, market incentives, and government incentives in order.Keywords：agricultural science and technology service;green production technology adoption;propensity score matching model;incentive measure;farmer35|10|1<HTML><L-PDF> <Meta-XML>Updated：2023-12-22
- Abstract：To promote the high-quality development of conservation tillage, based on the field survey data of 2 127 grain growers in 14 provinces, this study used Logit model, Shapley-value decomposition and multivariate Probit model to investigate the key influencing factors of conservation tillage technology adoption behavior and its differentiated performance. The results show that: The age, education level and risk preference of decision makers, whether received agricultural training and membership of agricultural cooperative can significantly promote the adoption of conservation tillage technology. Nevertheless, land fragmentation is one of the main obstacles hindering the adoption of conservation tillage technology. An inverted U-shaped relationship is discovered between land scale and the adoption of conservation tillage technology. Among the explanatory factors, the contribution of individual characteristics, management characteristics and family characteristics to the difference of technology adoption decision-making gradually decreases. Among different types of agricultural business, the education level, whether received agricultural training and the number of migrant workers are the common key factors, while age, land scale, degree of land fragmentation and whether land has been adjusted are the group difference factors. Among different levels of part-time, the education level and land scale are the common key factors, and age, whether received agricultural training, degree of land fragmentation and whether land has been adjusted are the group differences. In addition, when farmers choose a number of conservation tillage sub-technologies, there is a significant complementary relationship between the sub-technologies' adoption decisions. Therefore, on the one hand, we should combine the resource endowment and actual production demand of different types of farmers to selectively formulate the extension scheme of conservation tillage technology. On the other hand, it is necessary to optimize supporting measures and reduce barriers to technology adoption.Keywords：conservation tillage;technology adoption;farmers' behavior;Shapley-value decomposition;sustainable utilization of cultivated land29|10|6<HTML><L-PDF> <Meta-XML>Updated：2023-12-22
- Abstract：In response to the current situation where China's grain harvester technology is unable to fully to meet the needs of new agricultural operators and the international competitiveness of agricultural products is limited, patent measurement method is adopted in this study. Two analytical perspectives, quality and quantity, are taken into account, and three dimensions of technology competition hotspots analysis are integrated with innovation subject analysis and competition pattern analysis. Research on the competitive situation of different countries and their micro innovation entities in the field of grain harvesters are conducted. The results indicate that: 1)The technology of grain harvesters is in a mature stage, and the competition hotspots of technology research and development has shifted in the development process; 2)Compared to the centralized innovation pattern centered around enterprises in other countries, China tends to rely more on universities and research institutions, and its patent application force is relatively scattered. At the same time, China's main patent application force lacks output quality; 3)As a key layout area for other patent application countries, China has very few external layout patents; 4)The micro innovation entities in different countries show a central tendency in the layout of technology priorities, and there are extensive technological links. Overall, in order to develop grain harvester technology, China should pay attention to the shift of competition hotspots, accelerate the construction of an innovative pattern centered on enterprises, and take measures to ensure the quality of technological output and enhance its own technological influence.Keywords：grain harvester;technological competition situation;patent measurement;competition pattern29|17|2<HTML><L-PDF> <Meta-XML>Updated：2023-12-22
- Abstract：In order to promote the scientific and technological innovation capacity of China's seed industry, this study uses panel data of 31 provinces(municipalities and autonomous regions)from 1999 to 2020(The data do not include those of Hongkong, Macao and Taiwan. The same below. ), and divides the scientific and technological innovation of crop breeding into basic research, applied research and experimental development stages based on the innovation chain perspective. Moreover, the social network analysis method is used to analyze the development characteristics of cross-regional industry-academia-research cooperation, the Dagum Gini coefficient is used to analyze the regional differences of scientific and technological innovation in crop breeding, and the β convergence model is applied to test the influence of cross-regional industry-academia-research cooperation on the convergence of scientific and technological innovation in crop breeding in this study. The results are as follows: 1)The efficiency of the transfer of innovation resources in the cooperation decreases although cross-regional industry-university-research cooperation illustrates a growing trend. 2)The regional differences in crop breeding science and technology innovation are large, but the gaps are gradually narrowing, and the innovation differences mainly originate from inter-regional. In addition, relative to the experimental development phase, the regional differences are larger and the differences are narrowing more slowly in basic and applied research. 3)There is convergent development characteristics of crop breeding science and technology innovation, and cross-regional industry-academia-research cooperation has accelerated the convergence. At the national level, cross-regional industry-academia-research cooperation has the strongest contribution to the convergence of innovation in basic research, and the smallest to that in applied research. Focusing on different regions, it is found that the cross-regional industry-academia-research cooperation has promoted innovation convergence in the eastern, central, and western regions, and has contributed more to the growth of innovation in the central and western regions than to the eastern region. In terms of different periods, the facilitation of cross-regional industry-academia-research cooperation on the convergence of crop breeding scientific and technological innovation is weakened due to the reduced efficiency of innovation resource transfer in the cooperation. Therefore, the government should not only actively promote cross-regional industry-academia-research cooperation, but also guide the accelerated flow and sharing of innovation resources in order to strengthen the role of cross-regional industry-academia-research cooperation in promoting breeding science and technology innovation convergence.Keywords：scientific and technological innovation in crop breeding;cross-regional industry-academia-research cooperation;social network analysis;innovation chain;convergence30|12|0<HTML><L-PDF> <Meta-XML>Updated：2023-12-22
- Abstract：In order to improve the business performance of listed agricultural and forestry enterprises in China, based on the data of listed agricultural and forestry enterprises in China from 2011 to 2020, the panel data regression model and the second-order least squares method are adopted to empirically analyze the impact of digital level on the business performance of listed agricultural and forestry enterprises. The research results show that: The digitalization level has a significant upward effect on the operating performance of listed agricultural and forestry enterprises, but it also has a certain heterogeneity in its empirical results, among which, the improvement effect on the operating performance of listed agricultural and forestry enterprises in the eastern region and small scale is significant. After the robustness test, the above empirical results are still valid. In addition, the path test results of the impact of digital level on the operating performance of listed agricultural and forestry enterprises show that it is mainly through optimizing internal governance and reducing operating costs to promote the improvement of enterprise performance. Therefore, the listed agricultural and forestry enterprises should give priority to the optimization of their internal management level and the reduction of their operating costs when making digital management decisions and the relevant functional departments of the government when formulating the digital management policy system for agricultural and forestry enterprises. The government should adopt a digital development strategy that is suitable for the local area, increase research and development investment, implement digital security policies, create a good market environment for listed agricultural and forestry enterprises, and promote the improvement of their business performance.Keywords：digital economy;digitalization level;agricultural and forestry listed enterprises;business performance36|11|1<HTML><L-PDF> <Meta-XML>Updated：2023-12-22
