Current issue

• 2020 Vol.36 No.35 Published:15 December 2020

  DREB2A Gene Resistant to Osmotic Stress in Rice Germplasms: Genetic Diversity Analysis Tan Jingfa, He Wenchuang, Dong Xilong, Dang Tengfei, Xie Yi, Xi Kun, Sun Yongsheng, Hu Yalin, Jin Deming 2020, 36 (35):  1-13.  DOI: 10.11924/j.issn.1000-6850.casb20191200983 Abstract + ( 387 )   HTML ( 14 )   PDF ( 2255KB )   ( 96 ) The purpose is to analyze the genetic diversity of DREB2A gene in different rice germplasms and to provide molecular tools for genetic improvement of osmotic stress-resistance in rice. Haplotype analysis, phylogenetic tree, genetic distance and codon preference analysis were used to study the functional nucleotide sequence variation and genetic diversity of DREB2A gene in 85 rice germplasms of different types. A total of 55 nucleotide mutation sites were identified, 12 of which were located in the coding region and 43 were located in the non-coding region. Twelve DREB2A alleles were identified, including 3 alleles of African cultivated rice (Oryza glaberrima) with large block variation; and 39 haplotypes were identified according to sequence variations of the DREB2A, of which 33 were new haplotypes; all haplotypes were divided into three groups (Group I, II and III), and Group III was made of 10 haplotypes from African rice; Group III showed greater differences with other two groups according to phylogenetic tree, genetic distance and codon usage preference analysis. Sequence analysis of DREB2A genes in 85 rice germplasms of different types showed that DREB2A alleles in African rice were apparently different to the alleles from other types of germplasms in sequence variation, phylogenetic relationship and codon preference.

  Mutagenesis of Kidney Bean Cultivar A18-1 by EMS and Mutant Library Construction Qin Xiangkai, Feng Guojun, Liu Dajun, Liu Chang, Yang Xiaoxu, Yan Zhishan 2020, 36 (35):  14-21.  DOI: 10.11924/j.issn.1000-6850.casb20191201000 Abstract + ( 315 )   HTML ( 5 )   PDF ( 1631KB )   ( 68 ) Kidney bean (Phaseolus vulgaris L.) as an important economic crop is widely planted. It is characterized by many varieties, obvious phenotypic differences and small genome, and has become an important material for studying the genome function of legume plants. In order to create more mutant materials for improving the varieties and enriching the mutant library, and to accumulate the materials for study genome function of legume plants in the future, dried kidney bean seeds of A18-1 were treated with 0.04 mol/L ethyl methanesulfonate (EMS), 2128 M2 plants were conducted with field phenotype selection during the whole growth period, and 107 mutants were screened, which accounted for 5.03% of the total population. The mutants were constructed with trait variations on leaf, stem, flower, pod, plant type, fertility and maturity. Among them, the number and the type of mutants related to leaf shape and leaf color were the most, accounted for 27.0%. But the number of mutants related to stems, flowers and fertility was equal and the least, taking up 10.3% of total mutants. This experiment could provide new materials for constructing and innovating mutant libraries, and it is of great significance for studying specific relationship between genome function and phenotype as well as genetic breeding.

  The Interaction of Arbuscular Mycorrhizal Fungi, Rhizobia and Phosphate Solubilizing Bacteria: Research Progress Liu Ronglin, Cai Baiyan, Ge Jingping 2020, 36 (35):  22-27.  DOI: 10.11924/j.issn.1000-6850.casb20191200953 Abstract + ( 382 )   HTML ( 3 )   PDF ( 1064KB )   ( 159 ) In the biosphere, cooperation is universal, and a lot of efforts have been made on cooperation research of different species. Researchers have found that Arbuscular mycorrhizal fungi (AMF), rhizobium and phosphate solubilizing bacteria play a positive role in plants and soil. This article mainly reviewed the cooperative symbiotic relationship and interaction of AMF, rhizobium and phosphate solubilizing bacteria, concluded the effects of inoculation with AMF, phosphate solubilizing bacteria and rhizobium on plant growth, soil remediation, and microbial growth, summarized the advantages of double inoculation of these three microorganisms, and further analyzed the interaction of AMF, phosphate solubilizing bacteria and rhizobia, and the effects of inoculation on plant growth and surrounding soil conditions. At last, the main research direction of the interaction of AMF, phosphate solubilizing bacteria and rhizobia were discussed.

  He-Ne Laser Mutagenesis Increasing the Fibrinolytic Enzyme Activity of Bacillus subtilis Sun Ying, Wang Haiman, Song Gang, Ge Jingping 2020, 36 (35):  28-36.  DOI: 10.11924/j.issn.1000-6850.casb20191201001 Abstract + ( 396 )   HTML ( 5 )   PDF ( 2168KB )   ( 44 ) The mutant strain HDBF-N7HN5 was obtained by inducing and selecting Bacillus subtilis strain with high fibrinolytic enzyme. He-Ne Laser mutagenesis was conducted in this study with different mutant time. The mutant strains were selected and the activities of fibrinolytic enzyme were detected with different fibrin plates. The results showed that after 45 min with He-Ne Laser mutagenesis, the fibrinolytic enzyme activity of the mutant strain with the highest yield reached 429.89±5.74 IU/mL. The genetic stability analysis of HDBF-N7HN5 indicated that the production of fibrinolytic enzyme was very stable after 10 generation cultivation. The absolute dissolution rate of blood clot treated with crude fibrinolytic solution reached 57.74±0.72%, and the absolute dissolution rate of blood clot treated with 10-fold dilution could also reach 26.89±0.68%. The fibrinolytic enzyme produced by the strain had good thrombolytic effect in vitro. The results of this study not only increase the microbial fibrinolytic activity, but also provide a basis for the industrialization of fibrinolytic produced by this strain.

  An InDel-spot Molecular Marker for the Spotted Trait in Melon: Development and Application Xie Meiting, Liu Li, Hua Deping 2020, 36 (35):  37-41.  DOI: 10.11924/j.issn.1000-6850.casb20191200970 Abstract + ( 300 )   HTML ( 3 )   PDF ( 1398KB )   ( 39 ) The purpose is to improve the selecting efficiency of breeding materials with the spotted and the non-spotted trait in melons. The authors conducted the research with the spotted and non-spotted melons provided in field, and developed the linked InDel-spot molecular marker near the gene controlling the melon spotted trait in chromosome 2. Twenty melons were genotyped with the InDel-spot maker. The results showed that the size of spotted band was about 211 bp, while the non-spotted band was about 219 bp, with 95% of compliance rate. The InDel-spot marker was further used to identify the spotted and non-spotted trait of 2 (F2) and 5 (F3) populations. Among them, the detection accuracy of Qb978 (F2), Qb931 (F3) and Qb932 (F3) was 96.6%, 91.7% and 83.3%, respectively. The results indicate that InDel-spot marker has a great application value in the identification of the spotted and non-spotted trait, which could raise the selecting efficiency of breeding materials and shorten the breeding cycle.

  Hormone Change During Dormancy and Flower Bud Differentiation Process in Lilium oriental × trumpet hybrid ‘ConcaD’Or’ Li Xin, Yang Liuyan, Chen Minmin, Wang Zhen, Xu Junxu, Yang Zhen, Zhang Yongchun 2020, 36 (35):  42-47.  DOI: 10.11924/j.issn.1000-6850.casb20191200950 Abstract + ( 325 )   HTML ( 5 )   PDF ( 2893KB )   ( 50 ) To explore the relationship between hormone change and dormancy and flower bud differentiation of lily, Lilium oriental × trumpet hybrid ‘ConcaD’Or’ was used as material, the stages of dormancy release and flower bud differentiation were identified according to carbohydrate change and microscopic observation, and the changes of hormones were analyzed by HPLC-MS technique. The results showed that the bulb dormancy was released after about 56 days at cold storage of 3℃, and then entered flower bud differentiation process at about 70 days, which was divided into three stages: flower bud differentiation initial stage, floret primordium differentiation stage and flower organ differentiation stage. Before dormancy release, GA3/ABA increased, IAA/ABA and ZR/ABA remained at low level. After dormancy release, GA3/ABA remained rising, IAA/ABA and ZR/ABA increased. At the initial stage of flower bud differentiation, the content of ZR increased, the content of GA3 decreased and ZR/GA3 went up sharply. At the stage of floret primordium differentiation, the content of ZR decreased, the content of GA3 increased and ZR/GA3 went down sharply. At the stage of flower organs differentiation, the contents of ZR and GA3 showed an upward trend and ZR/GA3 remained stable. These results indicated that low level of IAA/ABA and ZR/ABA promoted dormancy maintenance, continuous increase of GA3/ABA promoted dormancy release, the rising of ZR/GA3 promoted the initiation of flower bud differentiation, while its decline promoted the formation of floret primordium. The results will provide references for postharvest storage and flowering regulation of Lilium oriental × trumpet hybrid ‘ConcaD’Or’.

  Biochemical Compositions of Wild Tea Germplasm Resources (Camellia taliensis) in Yunnan: Diversity Analysis Yang Shengmei, Jiang Huibing, Duan Zhifen, Li Youyong, Liu Yue, Shang Weiqiong, Liu Benying, Tang Yichun 2020, 36 (35):  48-54.  DOI: 10.11924/j.issn.1000-6850.casb20191200991 Abstract + ( 457 )   HTML ( 4 )   PDF ( 1214KB )   ( 70 ) This study aims to analyze the biochemical composition diversity of wild tea germplasm resources (Camellia taliensis) in Yunnan. The contents of tea polyphenols, amino acids, water extracts, caffeine and catechin from 21 wild tea germplasm resources (Camellia taliensis) in Yunnan were determined, and their biochemical diversity was also evaluated. The results showed that the tea polyphenols content ranged from 18.80% to 25.20%, the amino acids content ranged from 2.00% to 3.90%, the caffeine content ranged from 1.10% to 4.10%, the water extracts content ranged from 45.30% to 52.50%, the total catechin content ranged from 4.37% to 14.17%, the variation coefficient was 3.33%-157.89%, and the average genetic diversity index was 1.77. The cluster analysis of biochemical composition contents divided these 21 resources into 2 groups: the contents of C, EC, non-ester catechin and total catechins in group 1 were relatively low, while the contents of EGCG, ECG, ester catechin and total catechins in group 2 were relatively high. One germplasm with high polyphenols, two germplasms with low caffeine and one germplasm with high amino acids were preliminarily selected from the 21 wild tea germplasm resources, and these excellent resources could be utilized directly or as excellent parent materials for tea breeding.

  Soil Physical and Chemical Properties and Fertility Under Different Land Use Patterns in Daqing Xu Haijun, Yao Qin, Wang Xiaofei, Guan Xiangjun, Sun Yufeng 2020, 36 (35):  55-63.  DOI: 10.11924/j.issn.1000-6850.casb20191000713 Abstract + ( 351 )   HTML ( 6 )   PDF ( 1506KB )   ( 65 ) To understand the variation trend of soil physicochemical properties and fertility under different land use patterns in Daqing, three typical vegetation sampling plots, poplar forest land, meadow land and farmland land, were selected for analyzing the difference of soil physicochemical properties and fertility changes under different vegetation forms. The results showed that: (1) soil available potassium, organic matter and water content in meadow were significantly higher than those in poplar forest and farmland, and soil bulk density in poplar forest was significantly higher than that in meadow and farmland (P<0.05); (2) soil moisture content and available potassium in meadow, farmland and poplar forest showed a decreasing trend, while soil bulk density showed an increasing trend, among them, the physical and chemical properties of poplar forest showed a decreasing trend with the increase of age grade; (3) the comprehensive fertility of meadow (1.94), farmland (1.87) and poplar forest (1.69) belonged to the below-average level and had a decreasing trend successively. It is suggested that more attention should be paid to the adjustment and improvement of soil physical structure in land management.

  Effect of Organic Fertilizer on Soil Characteristics, Yield and Quality of Agricultural Products: Research Progress Yu Yijun, Ma Junwei, Lu Ruohui, Wu Qifeng, Zhu Weifeng, Kong Haimin, Wang Feng 2020, 36 (35):  64-71.  DOI: 10.11924/j.issn.1000-6850.casb2020-0110 Abstract + ( 310 )   HTML ( 4 )   PDF ( 1175KB )   ( 92 ) Applying organic fertilizer is an important means of agricultural production, and it plays a positive and influencing role in the development of green agriculture. In the study, the authors introduced the status quo of organic fertilizer, summarized the effects of organic fertilizer on improving soil fertility, crop yield and quality, and nutrient utilization and pest control, and analyzed the problems in current application of organic fertilizer, such as the impact on the quality of cultivated land and the safety risks of agricultural products, the low efficiency of fertilization, the insufficient diversity of organic fertilizer types and the lagging relevant quality standards. At last, the development directions of organic fertilizer were discussed.

  Effects of Phosphorus Fertilizer on Alfalfa Productivity: A Review Wang Yuanyuan, Zhang Hongxiang, Jin Chengji, Mu Chunsheng 2020, 36 (35):  72-77.  DOI: 10.11924/j.issn.1000-6850.casb20191200951 Abstract + ( 367 )   HTML ( 9 )   PDF ( 1467KB )   ( 67 ) With the development of animal husbandry, higher requirements are raised for the cultivation and production of alfalfa. The effective utilization of phosphate fertilizer is one of the key factors affecting alfalfa productivity. This paper outlined the main symptoms of alfalfa suffering phosphorus deficiency, the effects of phosphorus application levels and methods in different areas on alfalfa productivity, the ways to increase alfalfa productivity by phosphorus application, the mechanism of phosphorus absorption and the interaction effects among phosphorus and other nutrients, as well as water, on alfalfa production. It is suggested to measure soil for fertilization according to local soil physical and chemical properties, especially the available phosphorus content, to establish the climate-soil-fertilization model based on the results, and to study the physiological and molecular mechanisms of phosphorus promoting alfalfa growth. This paper could provide certain information for the development of alfalfa industry.

  Impact of Climate Change on Spring Wheat Growth in Different Climate Types in Northwest China Yang Yang, Ma Yihao, Zhao Hong, Qi Yue, Wang Runyuan, Zhang Kai, Wang Heling 2020, 36 (35):  78-87.  DOI: 10.11924/j.issn.1000-6850.casb2020-0012 Abstract + ( 340 )   HTML ( 9 )   PDF ( 1392KB )   ( 84 ) To study the impacts of observed climate change on crop development and yield could provide more accurate information for assessing the effect of climate change on crop production. In this study, we used ground observation data from five case areas including extreme drought (Dunhuang), arid (Wuwei), semi-arid (Dingxi), semi-humid (Linxia), and humid (Mixian) in northwest China’s 1981(1986)-2017 to analyze the meteorological trends and determine the relationship between spring wheat growth, yield and climatic factors. The results showed that the climate change patterns and their impacts on spring wheat phenology and yield in these stations were diverse both spatially and temporally during the period of 1981-2017. Except the warmer and wetter trends in extreme arid regions, warmer and drier trends were observed in other regions. Correlation analysis showed that spring wheat production in Wuwei, Dingxi and Linxia stations increased in 1981 (1986)-2017, but the change trend was not significant except Wuwei station. The decrease of days ≥30℃ during the wheat growth period in Wuwei station increased the output in Wuwei station in the 37 years, however, the increase of precipitation during the wheat growth period, more grains per panicle and obviously fewer infertile spikelets in Dingxi station increased the output in Dingxi station in the recent 32 years. It is estimated that the global warming trend and change in precipitation pattern will further impact the production and yield of spring wheat in northwest China.

  The Characteristics of Greenhouse Gas Emission from Agriculture in Anhui Xie Liangyu, Yang Shuyun, Zhang Cailin, Yang Wei 2020, 36 (35):  88-91.  DOI: 10.11924/j.issn.1000-6850.casb20191200979 Abstract + ( 349 )   HTML ( 5 )   PDF ( 1247KB )   ( 78 ) As a farming-based province, greenhouse gas emission in Anhui is huge. The study aims on the characteristics of agricultural greenhouse gas emission in Anhui by adopting the methods according to The Provincial Guidelines for Greenhouse Gas Inventory Preparation (Trial). The results showed that in 2005, 2010, 2012 and 2014, the greenhouse gas emission from agricultural sources in Anhui were equivalent to 39.1697 million, 32.4690 million, 31.8270 million and 33.1320 million tons, respectively, with CH4 and N2O accounting for about half of the total emission. Among them, the emission from planting industry was the largest, accounted for about 70%. The emissions from the planting industry were relatively stable, with about 451.1 thousand tons of variation in the four years, accounted for only 1.85% of the 2012 emission from the planting industry. This was due to the fact that the planting industry in Anhui was basically stable in terms of species, scale and yield. The emission of livestock farming in 2005 was significantly higher than that of the other three years due to the change of agricultural production pattern from animal power to mechanization and the decrease of cattle stock. With the increase of the stock of dairy cattle and beef cattle, the emission of breeding industry showed an increasing trend. In general, greenhouse gas emission from agricultural sources in Anhui may increase greatly, and effective measures should be taken to curb the growth trend of livestock industry emission.

  Characteristics of Climate Change in Typical Karst Plateau Lake: A Case Study of Caohai in Guizhou Mao Tianxu, Zhao Qingxia 2020, 36 (35):  92-98.  DOI: 10.11924/j.issn.1000-6850.casb20191200941 Abstract + ( 627 )   HTML ( 7 )   PDF ( 1617KB )   ( 57 ) Caohai is the largest natural freshwater lake in Guizhou Province as a typical representative of the lakes in the Karst Plateau. In this study, monthly temperature and precipitation data from 1951 to 2016 of Weining were collected and accumulated anomalies analysis, Mann-Kendall test, Sen’s slope estimation method and wavelet analysis were used to reveal the characteristics of the regional climate change. The results showed that the climate of Caohai has developed into a warmer and drier trend from 1951 to 2016, the annual mean temperature increased significantly at the rate of 0.14℃/10 a, the increase rate in different seasons followed the order of autumn > winter > summer > spring, the annual precipitation declined obviously at the rate of 21.46 mm/10 a, the order in different seasons was autumn > summer > spring > winter. The temperature of Caohai showed a downward trend in the 1950s to 1970s and then continued to rise from the point of decadal variability, the beginning of warming in summer and winter was earlier than the beginning of warming in spring and autumn. The abrupt change of annual mean temperature occurred in 2002 to 2003, which were inconsistent in different seasons, and the abrupt change of annual and seasonal precipitation occurred around 1983. The Morlet wavelet analysis showed that the annual average temperature of Caohai had three evident characteristic time scales, with 29, 14 and 6 years, while four evident characteristic time scales in precipitation with 30, 20, 9 and 4 years. These results could provide a scientific basis for ecological and environmental protection and sustainable development of Caohai, and also provide data support for formulating strategies addressing global warming for the lake region on the Karst Plateau.

  Effects of Climate Change on Aboveground Biomass in Hulunbeir Grassland Wang Haimei, , Liu Hao, Xiao Fang 2020, 36 (35):  99-105.  DOI: 10.11924/j.issn.1000-6850.casb20191200984 Abstract + ( 485 )   HTML ( 7 )   PDF ( 1484KB )   ( 64 ) Based on the main meteorological data such as temperature, pressure, humidity, wind and the measured data of aboveground biomass in the growing season, the effects of climate change and types of climatic year on the formation of forage yield were analyzed. The results showed that: (1) the precipitation of Erguna and Ewenck meteorological station fluctuated without obvious trend; (2) the mean annual temperature of the two meteorological stations increased significantly, with the trend of 0.348℃/10 a and 0.444℃/10 a, respectively, the rate of temperature increase was obviously higher than that in northeast China during the same period, and the rate of temperature increase in Ewenck was higher than that in Qinghai-Tibet area where the temperature increase was the fastest; (3) the potential evapotranspiration of Erguna and Ewenck fluctuated and increased; (4) the wet index degree of the two meteorological stations showed a significant fluctuation and decreasing trend, and the climate showed a more obvious drying trend; (5) the moisture condition affected the formation of grassland biomass in the two meteorological stations, and the formation of aboveground biomass was significantly inhibited in drought year. There was a linear regression relationship between the aboveground biomass and the moisture index of the month and the previous month.

  Herbicide Ingredients in Fermentation Broth of One Strain of Fungi: Analysis Zhang Qi, Zhang Qingxu, Pang Xiaomin, Wang Haibin, Ye Jianghua, Jia Xiaoli, He Haibin 2020, 36 (35):  106-112.  DOI: 10.11924/j.issn.1000-6850.casb20200200088 Abstract + ( 396 )   HTML ( 4 )   PDF ( 1513KB )   ( 44 ) To identify the herbicidal potential and constituents of microorganisms from Eucalyptus rhizosphere, a strain of fungi from the rhizosphere soil of Eucalyptus was used as material. The herbicidal activity of the strain fermentation broth was identified by bioassay, and the components of fermentation broth were further verified by GC-MS. The results showed that the fermentation broth of the strain at different concentrations had significant inhibition on the root length, plant height and dry weight of barnyard grass. The inhibition rate of the fermentation broth on the root length of barnyard grass was the highest (7.55%) under 50 times of diluted solution. The highest inhibition rate of barnyard grass height and dry weight was 56.53% and 25.46% by undiluted fermentation broth, respectively. GC-MS results showed that a total of 86 substances were detected, of which the largest proportion of compounds was nitrogen compounds accounting for 59.10%, followed by carboxylic acids and esters accounting for 19.26%. The bioassay results showed that o-coumaric acid, citral and piperine could inhibit the root length and plant height of lettuce at low concentrations. These results indicated that the strain could produce a variety of allelochemical analogues compounds, which made the strain fermentation broth have a strong weed-inhibition, and a great potential to be developed as a microbial herbicide.

  Wood Vinegar Application in Agricultural Diseases, Pests and Weeds Control: A Review Liu Runyu, Ye Lefu, Wang Xue, Yu Huiling, Fu Xue 2020, 36 (35):  113-118.  DOI: 10.11924/j.issn.1000-6850.casb2020-0132 Abstract + ( 1003 )   HTML ( 23 )   PDF ( 1160KB )   ( 143 ) To develop the application value of wood vinegar as high quality biological pesticide, this paper summarized the application cases of wood vinegar made from different types of raw material in the control of bacterial and fungal diseases, viral diseases, root knot nematodes, arthropod pests and weeds. The effects of wood vinegar on the control of the diseases, weeds and pests were reviewed. Under the appropriate concentration, it could effectively inhibit fungi, bacteria and root knot nematodes. As an adjuvant, it also could be used to control plant viral diseases. It had the repellent effect on pests. When the concentration was high, the direct poisonous effect was also obvious. For some weed species in crop fields, wood vinegar had the potential to be developed as a biological herbicide. This paper briefly introduced the mechanism of wood vinegar on harmful organisms, and pointed out that wood vinegar, as a biological pesticide, had the characteristics of wide source of raw materials, wide spectrum of killing pests, environmentally friendly and not easy to lead to the development of resistance and so on. As a biological pesticide, wood vinegar has a great application value, and the wood vinegar products should be fractionated and purified to achieve the comprehensive goal of mechanism research and product standardization in the future.

  Optimization and Improvement of Sectrophotometry Method to Determine Cation Exchange Capacity in Soil Yang Lili, Li Fei, Chen Yu, Zhao Bing, Xiao Rong, Hou Bingbing, Zhou Wangqiong 2020, 36 (35):  119-122.  DOI: 10.11924/j.issn.1000-6850.casb20191200995 Abstract + ( 298 )   HTML ( 6 )   PDF ( 1192KB )   ( 50 ) To improve the detection accuracy and efficiency of the cation exchange capacity in soil, and in view of the shortcomings of the national standard method, the authors optimized the experimental steps such as blank test, extraction and centrifugation under the same principle. The accuracy, precision and stability of the new method were analyzed through comparative experiments, parallel experiments and condition experiments. The results showed that the blank test was redefined by experiments, and the extraction time in the national standard method was optimized from 60 min to 30 min, as well as the centrifugation time was optimized from 10 min to 20 min, which greatly shortening the test time of a sample. Under these conditions, four different types of the certified reference materials of national soil were tested, and it was found that the measured values of cation exchange capacity were in agreement with the standard values of the certified reference materials of soil. This method possesses the advantages of high efficiency, excellent accuracy, precision, and simple operation, and is suitable for the determination of cation exchange capacity in large quantities of soil samples.

  Antibacterial and Antioxidant Effects of Ultrasound Extract of Glycyrrhiza uralensis Li Wenfen, Sun Ruige, Wang Bo 2020, 36 (35):  123-126.  DOI: 10.11924/j.issn.1000-6850.casb20191200967 Abstract + ( 399 )   HTML ( 6 )   PDF ( 1266KB )   ( 76 ) To find a safe food preservative, this study explored the antibacterial and antioxidant effects of Glycyrrhiza ultrasonic extract. Experiments with Escherichia coli and Bacillus subtilis were made to determine the radius of bacteriostatic circle by agar diffusion method. Antioxidant activity (DPPH scavenging ability and anti-O-phenylene three phenol self-oxidation) of each sample were investigated. Under the effect of Glycyrrhiza extract, the inhibition circle radius of E. coli reached 1.01 ± 0.08 cm, and the inhibition circle radius of B. subtilis reached 0.96 ± 0.03 cm after 18 hours of culture. Also, the free radical scavenging ability to DPPH was 93.1%, which was significantly higher than that of the control group (0.1mg/ml vitamin C). The highest anti-O-phenylene three phenol self-oxidation effect was 87.57%. In general, the extract of Glycyrrhiza uralensis has good antibacterial effect on the above two kinds of bacteria, and has certain antioxidant effect on DPPH and O-phenylene three phenol.

  Competitive Advantage of Characteristic Freshwater Fish Industry of China Yuan Yuan, Yuan Yongming, Dai Yunyun, He Yanhui, Gong Yunchong 2020, 36 (35):  127-133.  DOI: 10.11924/j.issn.1000-6850.casb2020-0008 Abstract + ( 469 )   HTML ( 6 )   PDF ( 1243KB )   ( 72 ) To analyze the competitive advantage of China’s characteristic freshwater fish industry, this paper carries out an analysis in 31 provinces and regions based on Michael Porter's diamond model. This paper also constructed the competitiveness evaluation index system of characteristic freshwater fish industry, mainly focused on four main export species of Oreochromis niloticus, Anguillas, Ictalurus punctatus and Acipenser sturio, so as to explore the competitive advantage and international competitiveness of the industry. The results show that: (1) China’s characteristic freshwater fish industry has obvious resource endowment advantages in production competitiveness factors, in terms of market demand factors, the consumption of characteristic freshwater fish is increasing day by day; in terms of related industries, market structure and competition, the technical content and economic added value of processed products of characteristic freshwater fish needs to be improved, the industrialized application of specialized feed for characteristic freshwater fish is not enough, and the number of large-scale enterprises needs to be increased; in terms of opportunities and government policies, a green and healthy ecological breeding system has been gradually established; (2) the resource endowment coefficient of characteristic freshwater fish is always above 1.0, which has obvious advantages of resource endowment; the international market share of China’s characteristic freshwater fish is 73.22%, the trade competitiveness index is close to 1; the revealed comparative advantage coefficients of tilapia and eel are both greater than 6, indicating that China’s characteristic freshwater fish products have obvious competitive advantages in the domestic and foreign markets.

  Analysis of Physical and Chemical Properties of Sludge-based Biochar at Different Pyrolysis Temperatures Ma Tao 2020, 36 (35):  134-138.  DOI: 10.11924/j.issn.1000-6850.casb2020-0157 Abstract + ( 383 )   HTML ( 6 )   PDF ( 1279KB )   ( 69 ) To study the effect of pyrolysis temperature on the basic physical and chemical properties of sludge-based biochar, so as to provide a theoretical basis for the safe, reasonable and efficient disposal of sludge, dried sludge was pyrolyzed at 200, 300, 500 and 700 ℃ (SBC200、SBC300、SBC500、SBC700), respectively, and the basic physical and chemical properties of sludge-based biochar were determined. The results showed that the surface particle structure of the biochar prepared at different temperatures was not damaged. The pore size was in the range of 10-50 μm. The surface of SBC200 was smooth, the most probable pore size and the median pore size were the largest, which were 20.1 μm and 14.8 μm, respectively. The surface of the SBC700 was rough, with the largest specific surface area of 5.98 m2/g. With the increase of pyrolysis temperature, the yield, water content, conductivity, volatile matter and cation exchange capacity of sludge-based biochar decreased significantly. The total carbon, oxygen, total nitrogen, hydrogen content, available phosphorus and ammonium nitrogen decreased gradually. The pH and ash content of sludge-based biochar increased significantly with the increase of pyrolysis temperature. The preparation of biochar is an effective way to dispose sludge safely. The sludge-based biochar prepared at low temperature has great potential to improve soil fertility, while the biochar prepared at high temperature has great potential to improve the pH of acid soil.

  Biomass Energy in Bulk Curing Barn: Application Status and Development Direction Wang Hang, Wen Zhiqiang, He Zhenfeng, Qiu Miaowen, Zhang Minjian 2020, 36 (35):  139-142.  DOI: 10.11924/j.issn.1000-6850.casb20191200993 Abstract + ( 405 )   HTML ( 6 )   PDF ( 1009KB )   ( 111 ) The aim is to study the biomass energy with strong economic benefit and practicability in tobacco curing. This study summarized the application status of gas, liquid and solid biomass energy that were often used in bulk curing barn. The effects of three biomass energy sources on the quality of tobacco leaf roasting and the technological maturity of energy conversion equipment were summed up. Based on the above, the advantages and limitations of the three biomass energy sources in bulk curing barn were analyzed, and the results showed that solid biomass pellet fuel was the optimal in the application of bulk curing barn. It is proposed that strengthening the research of raw material formula, improving the technology of pellet fuel burner, and integrating the agricultural internet of things technology are the research directions to achieve accurate baking.

  The Satisfaction of Reclamation Farmers on the Policy of Linking the Increase and Decrease of Urban and Rural Construction Land: An Investigation of the Ethnic Minority Areas in the Southeast of Chongqing Zeng Deheng, Yang Jiao, Chen Chunjiang 2020, 36 (35):  143-149.  DOI: 10.11924/j.issn.1000-6850.casb20191100882 Abstract + ( 268 )   HTML ( 5 )   PDF ( 1195KB )   ( 55 ) Linking the increase and decrease of urban and rural construction land is an important policy to optimize the structure of urban and rural land and carry out poverty alleviation, reclamation is a key part of the policy, and the satisfaction of reclamation farmers is a significant indicator to measure the effectiveness of the policy. This paper firstly sorted out the policies and procedures of the reclamation stage in Chongqing, and combined with the field investigation of the poverty-stricken townships in the ethnic minority areas in the southeast of Chongqing, constructed the reclamation farmers' satisfaction index system, evaluated and analyzed the satisfaction differences before and after the change of the policy implementation rules by the fuzzy comprehensive evaluation method. The results show that after the policy adjustment, the satisfaction of reclamation farmers to "economic compensation" and "environmental improvement" has been greatly improved, but there is still room for improvement in "policy promotion", "reclamation implementation", "government service" and "legal guarantee". Finally, from the satisfaction of reclamation farmers, this paper puts forward some suggestions on how to improve the policy of linking increase and decrease of urban and rural construction land in terms of compensation and guarantee of rights and interests.

  Research Progress on Agricultural Green Prevention and Control Technology Extension in China Song Ying, Hu Baogui 2020, 36 (35):  150-155.  DOI: 10.11924/j.issn.1000-6850.casb20200100016 Abstract + ( 468 )   HTML ( 2 )   PDF ( 1240KB )   ( 88 ) The purpose is to sort out the green prevention and control technologies currently used in China’s agricultural production, and to lay a theoretical foundation for the development of green prevention and control technologies in China. The CNKI was used as the original document source, and the advanced search “theme” = “green prevention and control”, “Including”=“technology promotion”, the time was from 2010 to 2019, the relevant information of 344 documents was obtained by literature research analysis. The problems existing in the application and promotion of green prevention and control technology in China’s agricultural production at this stage were summarized, and the corresponding solutions for the existing problems were proposed. The results show that by analyzing the number and distribution of published articles, it could be seen that China’s green prevention and control technologies are in the continuous development stage, and more researchers are exploring this field in depth. Among the technologies, biological control technology and physical control technology have strong applicability, and could be rapidly promoted and widely used in various regions of China.

  Research on Spatial Distribution Optimization of Rural Land Use in Heilongjiang Based on Sansheng Space——Taking Yongxing Town of Mingshui County as an example Sun Lina, Dong Aijing, Gong Yue 2020, 36 (35):  156-164.  DOI: 10.11924/j.issn.1000-6850.casb20190600262 Abstract + ( 639 )   HTML ( 10 )   PDF ( 2064KB )   ( 82 ) Under the background of rural revitalization strategy, the study on the layout optimization of rural land use space in Heilongjiang Province from the perspective of Sansheng Space is conducive to promoting the ecological and livable beautiful rural construction. This paper takes Yongxing Town, Mingshui County, Heilongjiang Province as the research area, combines the actual situation of Yongxing Town in Mingshui County and the information collected to construct the classification system of Sansheng Space in Yongxing, using GIS spatial geography analysis method. And the landscape index method analyzes the current situation of Sansheng Space in Yongxing, and proposes the optimization strategy of land use spatial layout, in order to provide reference for the layout optimization of rural land use space in other areas of Heilongjiang Province.