Current issue

• 2021 Vol.37 No.5 Published:15 February 2021

  Effects of Direct-seeding Methods and Seeding Rate Combinations on Population Development and Yield Components of Rice Zhang Jianjun, Liu Hong, Jiang Xiaoping, Li Chunyuan, Huang Qinglin, Zhang Xiaoxia 2021, 37 (5):  1-7.  DOI: 10.11924/j.issn.1000-6850.casb2020-0073 Abstract + ( 528 )   HTML ( 4 )   PDF ( 1282KB )   ( 82 ) To optimize population development and yield components of direct-seeding rice, explore potential productivity of new varieties and study high quality and high efficiency cultivation technology of rice direct-seeding, a field comparison experiment was conducted using the split plot design. The main plot was two direct-seeding methods, including wet direct-seeding and dry direct-seeding, the subplot was five seeding rates. The effects of direct-seeding methods and seeding rate combinations were studied on population development and yield components of rice. The results showed that dry direct-seeding could improve seedling emergence. For ‘Huashengzaoxiang’ and ‘Zhongzao35’, the effective panicles at the seeding rate of 45~75 kg/hm 2 were significantly improved and the peak seedlings were extremely improved with the increase of the seeding rate, but the tillering ability and spike rate in wet direct-seeding was better than that of dry direct-seeding under the same seeding rate. For ‘Huashengzaoxiang’ and ‘Zhongzao35’, the actual yield at the seeding rate of 45~75 kg/hm 2increased with the increase of seeding rate under the 2 kinds of direct-seeding, but wet direct-seeding was more useful to increase the actual yield because the yield increase was mainly associated with the significant increase of the effective panicles under wet direct-seeding, and the effect of full grain number per panicle and 1000-grain weight was not obvious.

  The Photosynthesis Mechanism of Tolerant and Sensitive Maize Germplasm Resources Under Salt Tolerance at Seedling Stage Wang Mingquan, Fu Lixin, Li Guoliang, Hu Guanghui, Ren Honglei, Hu Shaoxin, Yang Jianfei, Liu Chang, Gong Shichen 2021, 37 (5):  8-14.  DOI: 10.11924/j.issn.1000-6850.casb2020-0047 Abstract + ( 604 )   HTML ( 19 )   PDF ( 1387KB )   ( 70 ) The increasing level of soil salinization has gradually become a major environmental factor affecting plant growth and restricting grain yield. In the study, salt tolerant inbred line B46 and salt sensitive inbred line NC236 were selected as experimental materials to analyze the variation of the photosynthesis under salt tolerance at seedling stage. Under low concentration (55 mmol/L NaCl) salt stress, the content of chlorophyll in maize inbred lines increased. The content of chlorophyll in the leaves of B46 increased significantly compared with that of NC236. With the increase of NaCl concentration, the content of chlorophyll in the two maize inbred lines presented a downward trend, and the content decrease of B46 was less than that of NC236. The amplitude change of the maximum photochemical efficiency (Fv/Fm), the potential photochemical efficiency (Fv/Fo), the photochemical quenching coefficient (qP) and the initial fluorescence (Fo) of B46 were small under salt stress compared with that of NC236. While the amplitude change of the non-photochemical quenching coefficient (NPQ) was large. B46 showed stomatal limitation under the NaCl concentration from 0 to 165 mmol/L because of stomatal closure, and had non-stomatal limitation under the NaCl concentration of 220 mmol/L because the photosynthsis system was damaged; NC236 showed stomatal limitation in the NaCl concentration from 0 to 110 mmol/L, and non-stomatal limitation in the NaCl concentration from 165 to 220 mmol/L.

  Sweet Maize Variety ‘Mintian 6855’: Genetic Analysis Chen Zhijian 2021, 37 (5):  15-20.  DOI: 10.11924/j.issn.1000-6850.casb2020-0085 Abstract + ( 738 )   HTML ( 16 )   PDF ( 1172KB )   ( 115 ) The study aims to explore the high and stable yield characteristics, growth dynamics and reasonable high yield population structure of ‘Mintian 6855’, so as to provide a scientific basis for the supporting cultivation. The experimental and demonstration output data from 2011 to 2019 were collected to analyze the high and stable yield of the variety. The agronomic characters and growth dynamics of the variety were analyzed based on the multi-year test data, and the density test was mainly designed to screen the suitable planting density of the variety. The high-yield character of ‘Mintian 6855’ was closely related to the growth and development dynamics of excellent agronomic characters, early growth and rapid development. Considering the plant type characteristics and the marketability of panicle, the suitable planting density of ‘Mintian 6855’ ranged from 45000 plants/hm 2to 48750 plants/hm2, and the light transmittance of panicle layer and ground was 37.3%-43.8% and 10.6%-13.1% respectively from silking to filling stage, LAI reached 4.68 at silking stage, and still remained above 4.20 at filling stage. The LAD was 131.5 and kept increasing steadily. NAR was 8.27 at filling stage. The key measures for high-yield cultivation of ‘Mintian 6855’ are to select suitable planting density and effectively regulate photosynthetic indexes in different growth periods.

  Low-amylose Rice Resources: Screening Chen Tingmu, Wang Baoxiang, Hu Mingzhu, Chi Ming, Xu Bo, Xu Dayong 2021, 37 (5):  21-25.  DOI: 10.11924/j.issn.1000-6850.casb20190500098 Abstract + ( 557 )   HTML ( 7 )   PDF ( 1203KB )   ( 94 ) To improve the appearance and taste quality of rice simutaneously, the amylose contents in more than 1000 rice varieties from IRRI and China Rice Germplasm Resource Bank were determined, and the appearance quality of IRRI resources was identified. The results showed that most of rice varieties with good taste had poor appearance quality and the “soft rice” standard was deficient. The amylose contents of rice were widely distributed, and the number of varieties in the soft rice range was small. The glutinous rice varieties were slightly more than “soft rice” varieties, and they were divided into high-quality glutinous rice and low-quality glutinous rice. The other types had the largest number of variety and the largest variation in amylose content, the soft rice type had significantly higher protein content and higher amylose content than glutinous rice. Twelve soft rice resources were screened in this experiment, which provided diversified resources for soft rice breeding, and a criterion for judging soft rice.

  Effect of Different Fertilizer Application Frequency on Yield and Quality of Tomato Liu Zhongliang, Gao Luyang, Gao Junjie, Chen Zhen, Yan Weiqiang, Gu Duanyin 2021, 37 (5):  26-30.  DOI: 10.11924/j.issn.1000-6850.casb2020-0133 Abstract + ( 419 )   HTML ( 6 )   PDF ( 1237KB )   ( 57 ) The purpose is to determine the suitable frequency of fertilizer application in tomato cultivation, and provide the theoretical support for scientific fertilization. Using tomato cultivar Lycopersicon esculentum Mill. ‘Xi Linmen’ as material, five fertilizer application frequency were set up, in which the total fertilizer quota (N 542.30 kg/hm 2, P2O5 212.6 kg/hm2, K2O 680.4 kg/hm2) was the same, and the effect of fertilizer application frequency on tomato yield, quality and substrate nutrient accumulation were studied. The results showed that the tomato yield first increased then decreased with the fertilizer application frequency increase, and the yield of T2 treatment was the highest, up to 157251.64 kg/hm2, 18.69% higher than that of CK. Suitable fertilizer application frequency could improve the taste and quality of fruit, the vitamin C content of T3 treatment and lycopene content of T2 treatment reached the highest of 14.16 mg/100 mg, 4.44 mg/100 mg, respectively, and the sugar-acid ratio was the highest in T2 treatment, followed by that of T1 treatment, while that of CK was the lowest. Meanwhile, the fertilizer application frequency significantly increased substrate nutrient accumulation, improved pH and reduced EC value, among which, the contents of total nitrogen, available nitrogen, available phosphorus and available potassium in the substrate increased by 6.25%~31.25%, 1.88%~25.20%, 5.51%~21.50% and 10.34%~27.58%, respectively. In addition, the pH value was 6.22~6.89, EC value was 466.04~763.46 μs/cm, the correlations among substrate nutrient, tomato yield and quality were significant. In summary, suitable fertilizer application frequency could improve the yield and quality of tomato, and the effect of T2 is the best.

  Dynamic Response of the Soil Physical and Chemical Properties Under Simulated Snow Cover in the Sanjiang Plain Chai Chunrong, Ni Hongwei, Liu Yingnan, Zhang Rongtao, Yang Jixian 2021, 37 (5):  31-37.  DOI: 10.11924/j.issn.1000-6850.casb2020-0065 Abstract + ( 381 )   HTML ( 4 )   PDF ( 1391KB )   ( 35 ) To study the dynamic response of soil physical and chemical properties to temperature changes under different snow treatments, soil samples from the Calamagrostis angustifolia wetland in the Sanjiang Plain were collected, and four snow treatments W0 (31.05%), W1200 (42.66%), W3000 (51.21%) and W6000 (76.66%) were simulated in the laboratory, and soil physical and chemical properties were tested. The results showed that the treatment of W6000 significantly increased soil pH; the three snow treatments significantly increased the content of soil soluble organic carbon; the treatment of W3000 and W6000 significantly increased the content of soil ammonium nitrogen; the treatment of W6000 significantly reduced the soil nitrate nitrogen content; different snow treatments had no significant effect on soil total phosphorus and available phosphorus; W1200 treatment significantly increased soil microbial biomass carbon, while W6000 treatment significantly reduced soil microbial biomass carbon; W1200 treatment significantly increased soil microbial biomass nitrogen, W3000 treatment significantly reduced soil microbial biomass nitrogen. Soil temperature under different snow treatments was the main influencing factor for the change of soil physical and chemical properties. Different snow treatments would change the physical and chemical properties of the soil during the freezing and thawing period, which had an important impact on the carbon and nitrogen cycle of the wetland ecosystem.

  Salinity Characteristics Analysis of Saline Alkali Soil in Yinbei Irrigation District of Ningxia Guo Juncheng, Wang Mingguo, Geng Rong, Li Xin, Yin Xuehong, Wei Guning 2021, 37 (5):  38-42.  DOI: 10.11924/j.issn.1000-6850.casb2020-0070 Abstract + ( 803 )   HTML ( 9 )   PDF ( 1191KB )   ( 84 ) To find out the main ions of salinization in Yinbei irrigation area of Ningxia, soil salinization characteristics were studied to provide a theoretical basis for improving salinized farmland. The method of correlation analysis and principal component analysis were used. The results showed that the surface accumulation was obvious in spring, and had strong spatial difference. The total salt content had a significant correlation with SO42-, Cl-, Ca2+, Mg2+, Na+ and K+ in 0-20 cm of the soil depth, the main harmful ion was Cl-, Na+and Mg2+, and the type of salinization was mainly chlorinated salinized soil. The total salt content had a significant correlation with K+, Cl- and SO42-, which were also the main harmful ions in 20-50 cm soil, and the type of salinization was mainly chlorinated salinized soil and sulfuric acid saline soil.

  Effects of Inhibitor NAM on Corn Yield and Agronomic Utilization Efficiency of Nitrogen Fertilizer in Saline-Alkali Soil Guo Yanchun, Sun Xianmin, Zeng Lusheng, Li Xulin, Song Xiangyun, Liu Xinwei, Cui Dejie 2021, 37 (5):  43-48.  DOI: 10.11924/j.issn.1000-6850.casb2020-0038 Abstract + ( 530 )   HTML ( 16 )   PDF ( 1397KB )   ( 89 ) To improve the utilization rate of nitrogen fertilizer in saline-alkali soil, reduce nitrification and reduce the loss of nitrogen nutrition, a field plot test was conducted. The test was set as: no fertilization as control, conventional fertilization, conventional fertilization + NAM (long-acting compound fertilizer additive), conventional fertilization 80% + NAM. The changes of saline soil nutrients and corn yield in different treatments were studied. The results indicated that compared with conventional fertilization, conventional fertilization + NAM treatment increased soil nutrient content such as alkaline nitrogen, available phosphorus, available potassium and organic matter, and reduced soil alkalinity; increased soil CEC (cation exchange capacity) and water-soluble base ions K+, Ca2+ and Mg2+.The soil pH did not change significantly, and the conductivity decreased to some extent. The yield of corn increased by 10.30%, and the agronomic utilization efficiency of nitrogen fertilizer increased by 34.38%.The corn yield of conventional fertilization 80% + NAM treatment is equivalent to that of conventional fertilization, however, it has higher partial fertilizer productivity and agronomic utilization efficiency of nitrogen fertilizer, and could be recommended for application in production.

  Cluster Evaluation and Characteristics of Climate at Tobacco Field Period in Qianxinan of Guizhou Li Zhen, Huang Hong, Chen Mengsi, Guo Yali, Ma Ying, Deng Xiaohua, Zhang Zhongwen, Jian Zhimin 2021, 37 (5):  49-56.  DOI: 10.11924/j.issn.1000-6850.casb2020-0057 Abstract + ( 511 )   HTML ( 5 )   PDF ( 1290KB )   ( 75 ) To clarify the climate characteristics of tobacco planting in Qianxinan of Guizhou, the temperature, precipitation and sunshine duration of tobacco field period in different months were selected, and then comparative study, similarity analysis and cluster analysis were used to study the difference and similarity of climate in tobacco field period between the region with major domestic and overseas tobacco-growing areas. The results show that: the average daily temperature in Qianxinan of Guizhou during tobacco field period is above 20℃, the precipitation is above 900 mm, and the sunshine hours are over 700 hours. It has the characteristics of moderate daily average temperature, more precipitation, sunshine and warmth, and has the basic conditions and advantages of high quality tobacco planting. The climate of tobacco field period in the region is moderately similar to Zunyi, Yuxi and Longyan in China, but less similar to Chenzhou in China and tobacco planting areas in Brazil and Zimbabwe. The climate of tobacco field period in Zhenfeng County is quite different from that in other five counties (cities) of the prefecture. Thus, the monthly average meteorological factors in the tobacco field period can better clarify the climate characteristics of the tobacco area.

  Suitable Sowing Date of Soybean in the Frigid Region Gong Lijuan, Wang Ping, Jiang Lanqi, Li Xiufen, Zhao Huiying 2021, 37 (5):  57-64.  DOI: 10.11924/j.issn.1000-6850.casb2020-0088 Abstract + ( 439 )   HTML ( 14 )   PDF ( 1838KB )   ( 104 ) This research aims to investigate the optimum sowing date of soybean in frigid region under the background of climate change. Based on the daily average temperature and minimum temperature from 1971 to 2018 and daily average ground temperature at the soil depth of 0~5 cm from 1971 to 2015 of 140 meteorological stations in the frigid region, the temporal - spatial distribution of the first date of the temperature reaching 8℃, 0~5 cm ground temperature reaching 8℃, 9℃, 10℃, and the variation of ≥10℃ accumulated temperature were analyzed. The trend of the first date for temperature reaching 8℃ was clearly ahead in recent 48 years. While the first date of 0~5 cm ground temperature reaching 8℃, 9℃ and 10℃ advanced. The largest advance of the first date of 0~5 cm ground temperature reaching 8℃, 9℃ and 10℃ was in the four eastern leagues (Hulun Buir, Hinggan League, Tongliao and Chifeng of Inner Mongolia), and the smallest was in Liaoning. The first date of temperature reaching 8℃ and 0~5 cm ground temperature reaching 8℃, 9℃ and 10℃ were postponed from south to north in space, and the first date in Liaoning was the earliest, followed by that in Jilin and south of the four eastern leagues, and was relatively late in Heilongjiang and the north-central of the four eastern leagues. 0~5 cm ground temperature reaching 9℃ could be regarded as the agro-meteorological index of sowing date in Heilongjiang, Jilin and Liaoning, while 0~5 cm ground temperature reaching 10℃ could be used as the index of sowing date in the four eastern leagues. The spatial optimization of sowing date for soybean which combines agro-meteorological with variety maturity is critical for production layout against climatic change.

  Climatic Suitability Planting Regionalization of Orah’s Fruit Quality Grade in Guangxi Tan Zongkun, Luo Zenggui, Wang Jing 2021, 37 (5):  65-74.  DOI: 10.11924/j.issn.1000-6850.casb20200300251 Abstract + ( 721 )   HTML ( 7 )   PDF ( 3827KB )   ( 204 ) In this study, the climate suitability planting map of Orah’s fruit quality grade in Guangxi was compiled, aiming to provide a basis for optimizing the layout of citrus industry. Based on the “3S” technology and the climatic factor suitability index in the critical periods of citrus fruit quality formation, the climatic factor suitability of Guangxi high-quality Orah’s fruit was evaluated. There is no obvious regional difference in climate suitability from the flower bud to the full flowering period and the physiological fruit-falling period, and most areas are of the best or high-quality grade; the climate element suitability of the fruit expansion period to the mature harvest period has obvious regional characteristics. Among them, the climate suitability grade of fruit coloring stage and maturity stage showed a decreasing trend with increasing latitude, which is consistent with the winter temperature decreasing with latitude and unable to meet the caloric conditions required for the fruiting and ripening of Orah’s fruit. The most suitable climatic region for excellent Orah’s fruit quality grade in Guangxi is mainly distributed in the areas near north-link line, Youjiang River valley, southwestern Guangxi, and etc.

  Microbial Agents Mixed with Saline-alkaline Soil: Effect of Prevention of Stem Basal Rot and Growth-promoting on Maize Sha Yuexia, Li Mingyang, Wu Shunhua, Zhang Ang 2021, 37 (5):  75-82.  DOI: 10.11924/j.issn.1000-6850.casb2020-0077 Abstract + ( 604 )   HTML ( 16 )   PDF ( 2421KB )   ( 83 ) The aim is to develop microbial agents that promote the maize growth and prevent maize stem basal rot in saline-alkaline soil in Yinbei of Ningxia. The microorganisms with high saline tolerance were used as experimental materials, the antagonistic bacteria against Fusarium and other pathogens were screened and the ability to produce enzyme and compatibility were detected using plate antagonistic culture. In addition, the effects of prevention of maize stem basal rot and growth-promoting were tested relying on the microbial agents mixed with saline-alkaline soil in field trail. The results showed that four antifungal bacteria were screened against a variety of pathogens such as Fusarium with high producing enzyme ability among 237 saline-alkaline isolates. Strains B-2 and N-16 were identified as Bacillus sonorensis, N-17 as B. pumilus, and B-26 as B. paralicheniformis. The four strains could not inhibit each other, and microbial agents contained the mix powder of the four strains, soil conditioner, microelement and vector. The preventive effect of microbial agents YF or JF mixed with saline-alkaline soil against the maize stem basal rot could reach beyond 60%, showing evident growth-promoting and yield-increasing effect. Microbial agents YF or JF mixed with saline-alkaline soil could promote maize growth and prevent maize stem basal rot in Yinbei of Ningxia, and the study has certain significance for effective use of saline-alkaline soil.

  Biocontrol Bacteria Against Northern Corn Leaf Blight: Screening, Identification and Application Zhang Qifeng, Li Yonggang, Liu Bo 2021, 37 (5):  83-87.  DOI: 10.11924/j.issn.1000-6850.casb2020-0071 Abstract + ( 546 )   HTML ( 18 )   PDF ( 2295KB )   ( 67 ) In order to explore the biological way to effectively control the damage of northern corn leaf blight in corn production, Setosphaeria turcica was used as the targeted strain. The biocontrol bacteria were obtained using confrontation method and pot inoculation test. The control effect of pot inoculation test was determined. The results showed that one strain with the best antagonistic effect was obtained from 128 strains of endophytic bacteria. The ratio of the longest radius to the shortest radius was 2.9. The biocontrol bacteria YD7 was screened from corn endophytic bacteria and it had relatively strong antagonistic effect against S. turcica. According to the morphological, physiology-biochemical characteristics and 16S rDNA sequence analysis, YD7 was identified as Bacillus amyloliquefaciens. By two potted experiments, the control effects of YD7 were 78.2% and 77.8%, respectively. Thus, YD7 has well developing prospect on controlling northern corn leaf blight.

  Image Segmentation for Maize Leaf Disease Based on U-Net Liu Yongbo, Hu Liang, Cao Yan, Tang Jiangyun, Lei Bo 2021, 37 (5):  88-95.  DOI: 10.11924/j.issn.1000-6850.casb2020-0051 Abstract + ( 703 )   HTML ( 19 )   PDF ( 2453KB )   ( 140 ) In this paper, a grading method of maize disease course based on U-Net algorithm model is proposed, which can quickly, accurately and objectively classify the degree of four kinds of common maize leaf diseases. In this method, the semantic segmentation of corn leaf disease spot image is realized by parallel operation of two groups of U-Net models. In the test image segmentation experiment, the MIoU value of disease spot segmentation is 93.63%, and the MIoU value of leaf segmentation is 96.33%, and the operation speed is completed in 1 second. The experimental results show that this study collects data sources by means of mobile phone photos, can achieve rapid grading of maize diseases without relying on professional instruments and equipment, and replace the previous method of disease identification by manual visual inspection. The accuracy and objectivity of disease grading are improved. Combined with the Internet of Things equipment, the model can achieve the goal of early warning of maize diseases, reducing the impact of diseases, increasing both production and income by science and technology benefiting farmers.

  The Dynamic Changes of Blood Physiology, Biochemistry and Hormone Indexes of Ili Horse Under Long-distance Transport Stress Wang Zihao, Liu Luo, Tang Anqi, Mai Zhanhai, Wang Jinquan, Hu Yan 2021, 37 (5):  96-103.  DOI: 10.11924/j.issn.1000-6850.2020-00013 Abstract + ( 493 )   HTML ( 5 )   PDF ( 1391KB )   ( 37 ) The purpose is to explore the dynamic changes of blood physiological and biochemical indexes during the long-distance transportation of Ili horse. In this experiment, 6 male Ili horses were selected for transportation of 400 km lasting for 480 min. And jugular venous blood was collected for blood index detection at 8 time points (including before transportation, during transportation, and after transportation). The results showed that the total number of red blood cells (RBC) and the ratio of lymphocytes (LYM%) in horse blood decreased significantly (P<0.05), while the granulocyte (GRAN) and granulocyte ratio (GRAN%) increased significantly (P<0.05) after the horses were transported for 4 hours. After 6 hours of transportation, Triiodothyronine (T3), Tetraiodothyronine (T4), Growth Hormone (GH), Cortisol (COR), Albumin (ALD), Cholesterol (CHOL) all increased significantly (P<0.05), and Hematocrit (HCT) and Urea (UREA) decreased significantly (P<0.01). Long-distance transportation can change the blood indexes of horse and make them first increase and then decrease. The change peak mainly occurs at the 6th hour of transportation. The above indicators can be used as the key to determine whether the horse has transportation stress.

  Shigella LAMP Detection Method Based on ipaH Gene: Establishment and Application Wen Ying, Liu Yongsheng 2021, 37 (5):  104-110.  DOI: 10.11924/j.issn.1000-6850.casb2020-0084 Abstract + ( 366 )   HTML ( 6 )   PDF ( 1924KB )   ( 35 ) To establish a LAMP detection method which is rapid, specific and sensitive for Shigella, the sequence of invasion plasmid antigen H gene (invasion plasmid, ipaH) of Shigella was used as target sequence to design a set of specific primers, the LAMP method was established after condition optimization, specificity and sensitivity verification, and applied to detect clinical samples. The results showed that the amplification products could be obtained within 1 h at 62℃. The standard Shigella strains showed the positive result, while Salmonella, Escherichia coli, Staphylococcus aureus, Bacillus subtilis and the negative control showed the negative result. The detection limit of the LAMP method for Shigella was 120 fg/μL. 20 suspected strains and 38 fecal samples were tested by the established method. The results showed that 20 suspected bacteria and 27 fecal samples were positive, and the positive rate was 100% and 71.05%, respectively, indicating that this LAMP assay was a specific and sensitive method, and it had advantages and application prospects in the detection and identification of Shigella in clinical samples such as feces.

  Evaluation of Nutritional Components and Nutritive Quality in the Muscle of Acrossocheilus parallens Qin Zhiqing, Lin Jianbin, Liang Ping, Qiu Manli 2021, 37 (5):  111-116.  DOI: 10.11924/j.issn.1000-6850.casb2020-0090 Abstract + ( 531 )   HTML ( 6 )   PDF ( 1244KB )   ( 48 ) To provide a scientific basis for the nutritional evaluation of Acrossocheilius parallens muscle, the contents of routine nutrition components, fatty acids and amino acids in muscle were determined and analyzed by biochemical method. The results showed that the contents of water, crude protein, crude fat and crude ash in A.parallens muscle were (77.20±0.42)%, (19.70±0.22)%, (3.25±0.07)% and (1.30±0.01)%, respectively. There were 21 kinds of fatty acids in the muscle, including 8 saturated fatty acids (SFA) and 13 unsaturated fatty acids (UFA). The proportion of UFA and essential fatty acid (EFA) was 68.07% and 21.76%, respectively. There were 17 kinds of amino acids in the muscle, including 7 essential amino acids (EAA), 2 semi-essential amino acids (HEAA) and 8 non-essential amino acids (NEAA). EAA and umami amino acid (UAA) accounted for 40.85% and 37.55% of the total amino acids, respectively. The amino acid composition of A.parallens muscle was well balanced. The amino acid score (AAS) of A.parallens muscle was more than 1 except Valine, the chemical score (CS) was more than 0.5, and the essential amino acid index (EAAI) was 86.19, indicating that the quality of protein was good. To sum up, the high nutritional value of the A.parallens is a kind of high-quality economic freshwater fish with high development value.

  Comparative Studies on the Morphology Between Cipangopalndina chinensis and Cipangopalndina cathayensis Huang Jiarui, Dan Xiaoqin, Wen Yanhong, Luo Fuguang, Huang Jie, Wang Weimin 2021, 37 (5):  117-123.  DOI: 10.11924/j.issn.1000-6850.casb20200300279 Abstract + ( 1669 )   HTML ( 22 )   PDF ( 1438KB )   ( 231 ) To study the morphological differences between Cipangopaludina chinensis Gray and Cipangopalndina cathayensis, 11 characteristic indexes and 23 trait parameters of 185 specimens were analyzed by one-way analysis of variance, principal component analysis, cluster analysis and discriminant analysis. The results of one-way ANOVA showed that the morphological differences between the two species were significant (P< 0.05). Six principal components were constructed by principal component analysis, and their contribution rates were 37.278%, 17.038%, 11.606%, 11.606%, 9.912%, 7.471% and 6.228%, respectively. The cumulative contribution rate of them was 89.533%. In the scatter plot constructed by principal component 1 and principal component 2, the specimens’ differences between the two species were obvious, which mainly focused on the characteristics of the spiral part and the contour of the body, and were consistent with the results of cluster analysis. Two characteristic of body height / body width and helix width/ body width were selected from 23 morphological proportion parameters by stepwise discriminant method. Two discriminant functions were established: Y = -609.11+1067.27X1 + 528.48X2, Z = -673+1084.59X1+579.95X2. By testing the data back to the function, the comprehensive discriminant rate could reach 95.15%, indicating that the two species can be effectively distinguished. These differences and discriminant functions can provide foundation data for the genetic breeding and identification of Cipangopaludina chinensis and Cipangopalndina cathayensis.

  Efficacy of an Antivirus Drug on Treating Anguillid Herpesvirus Disease of Cultured American Eels Fan Haiping, Zhong Quanfu, Yang Han, Hu Bing, Zeng Zhanzhuang, Lin Xiang, Wang Yanyan, Lin Caiping 2021, 37 (5):  124-129.  DOI: 10.11924/j.issn.1000-6850.casb2020-0040 Abstract + ( 429 )   HTML ( 6 )   PDF ( 1284KB )   ( 30 ) Anguillid herpesvirus disease is a common disease of cultured Anguilla rostrata, with the symptoms of red liver disease and mucus sloughing and hemorrhagic septicemia disease. The mortality of the disease is up to 60%. The efficacy of three kinds of compound drugs on the diseased eel were tested using continuous medicated bath with timing changing water and drugs. The results showed that Eel paoKang No. 2 and Eel paoKang No. 3 had therapeutic effect on Anguillid herpesvirus disease, and Eel paoKang No. 3 had better efficacy. 3‰~6‰ salt showed cooperative effects with the compound drugs. The best prescription and dosage is 8 mg/L Eel paoKang No. 3 with 3‰ salt, which has better curative effect, especially for severe diseased eel.

  Experimental Study on Direct Shear and Compression of Ectopic Fermented Mattress Material Ye Dingcheng, Tao Zhiying, Huang Ehui, He Jincheng 2021, 37 (5):  130-136.  DOI: 10.11924/j.issn.1000-6850.casb2020-0424 Abstract + ( 270 )   HTML ( 4 )   PDF ( 1832KB )   ( 32 ) To study the change law of shear strength, cohesiveness, internal friction coefficient and compression load of ectopic fermentation mattress under different moisture content, the soil mechanics test method was used to determine the relevant parameters of five different water content of cushion. The results show that the shear strength and the angle coefficient of internal friction increase with the rise of the water content when the water content of the cushion is 29.22%~36.13%. When the moisture content is 45.55%~61.11%, the shear strength and the angle coefficient of internal friction decrease with the increase of moisture content. The cohesiveness does not change obviously with the change of water content. The compression load of cushion increases with the increase of loading time, and the increasing amplitude rises gradually.

  The Influence of Market Economy on Cultivated Land Resources in Planned Tobacco Area of Yunnan Lu Weikun, Pang Tao, Yu Lingxiang, Zhang Jiayun 2021, 37 (5):  137-142.  DOI: 10.11924/j.issn.1000-6850.casb2020-0078 Abstract + ( 502 )   HTML ( 4 )   PDF ( 1856KB )   ( 51 ) To understand current situation of farmland resource allocation and the influence of market economy on the slope of Yunnan planned tobacco area, the distribution and difference of slope types in core, high quality and suitable area were analyzed, based on the latest results of flue-cured tobacco planting zoning data and slope grid data. On this basis, combined with the data of rural per capita disposable income of each city, the impact of market economy on the slope of tobacco planting area was analyzed. The results showed that the planned area of flue-cured tobacco accounted for 47.9% of the total area of class Ⅰ and Ⅱ, and accounted for merely 18.7% of the total area of class I to III which was suitable for planting flue-cured tobacco in the whole province. However, 40.0% of the latest planned tobacco fields were in class III farming areas, and 26.3% in class IV and V areas. The percentage of class III to V flue-cured tobacco planning area in each prefecture and city was positively proportional to the per capita disposable income in rural areas, which indicated that the higher the disposable income, the more obvious the tobacco planting area developing to cultivated land with large slope. In general, under the effect of market economy, the development of flue-cured tobacco industry in Yunnan is at disadvantage in the allocation of cultivated land resources.

  Agricultural Land Transfer Behavior and Influencing Factors of Yongchang County in Hexi Corridor Yan Jixuan, Kang Xia, Zhang Meihua, Sun Dongyuan, Qiao Hongqiang 2021, 37 (5):  143-148.  DOI: 10.11924/j.issn.1000-6850.casb20200300224 Abstract + ( 471 )   HTML ( 3 )   PDF ( 1278KB )   ( 46 ) To improve social stability and land utilization, China has introduced “the system for separating the ownership rights, contract rights, and management rights for contracted rural land” to promote land circulation. This paper takes Yongchang County as an example, and uses a statistical model to study the farmers’ farmland transfer behavior and influencing factors, in order to provide a basis for government policy formulation. The results of the study show that: 1) the willingness to transfer agricultural land in the sample area is strong, and the agricultural land transfer rate is 79.61%; 2) the scale of agricultural land transfer per household is relatively small, with 78.14% of households transferring out scale less than 0.30 hm 2, and 65.21% of households transferring in scale more than 0.30 hm2;3) the main subject of agricultural land transfer is the villagers, relatives and friends of the group, and the transfer method is mainly leasing; 4) the reasons for the transfer in and transfer out of agricultural land are obviously different; 5) there are differences in the significance of the influencing factors, among which the importance of contracted land, the per capita agricultural income of households, the perception of agricultural policies, and the land transfer of village collective organizations have a significant impact on the farmland transfer behavior of farmers. In summary, land transfer is obviously affected by national policies, and further transfer efforts are needed.

  The Willingness of Farmers to Participate in the Later Stage Management of Permanent Prime Farmland Liang Yupei, Wang Wenchang 2021, 37 (5):  149-155.  DOI: 10.11924/j.issn.1000-6850.casb2020-0538 Abstract + ( 436 )   HTML ( 2 )   PDF ( 1336KB )   ( 59 ) The purpose is to analyze the factors affecting the later stage management and protection of permanent prime farmland from the perspective of farmers’ willingness to participate, so as to improve the status quo of the “attaching importance to construction but belittling management” and put forward some suggestions and countermeasures for the later stage management and protection of permanent prime farmland. Based on the data of 485 households’ willingness to manage and protect permanent prime farmland in Xin'an County, Luoyang City, Henan Province, using the binary Logistic model, this study took the willingness of farmers to participate in the management and protection of permanent farmland as a dependent variable. Twenty-four independent variables were selected and analyzed from five aspects: basic individual characteristics, basic family characteristics, cognition of permanent prime farmland, behavior attitude and subjective norm. According to the results, the following are significant factors affecting farmers’ willingness to participate in later stage management and protection of permanent prime farmland: gender; occupation; the number of permanent prime farmland owned by families; the source of household income; the possibility to build kilns, houses and graves, excavate sand, dig stone, mine, collect earth and pile up solid wastes in the permanent prime farmland protection area; the trust level of government work; the satisfaction degree of information disclosure; the satisfaction degree of government feedback; the influence of friends and relatives; the influence of publicity of government policies. Based on the above analysis results, taking the willingness of farmers to participate in the later stage management and protection of permanent prime farmland as the starting point, the paper puts forward countermeasures and suggestions on the management and protection.

  Optimizing the Layout of Rural Residential Area in Ethnic Minority Areas Based on Complex Network-- Taking Liping County in Guizhou Province as an Example Chai Jiaojiao, Yang Liu, Suo Mengmeng 2021, 37 (5):  156-164.  DOI: 10.11924/j.issn.1000-6850.casb2020-0243 Abstract + ( 412 )   HTML ( 3 )   PDF ( 2345KB )   ( 39 ) The rural residential area in the ethnic minority areas needs to be transformed due to the influence of national policies and human activities. Exploring the layout optimization mode of the rural residential area in this region is conducive to promoting the land space governance and the overall realization of rural revitalization. This study took Liping County, Guizhou Province as an example, and adopted AHP method, GIS spatial analysis method, complex network, Python language programming and other methods to analyze the optimal layout pattern of rural residential area. The results show that: (1) the comprehensive influence of rural residential area in the study area ranges from 22.30 to 76.09, and the middle and high level rural residential areas are the majority and the comprehensive influence of rural residential area distributes unevenly in space; (2) taking the comprehensive influence of rural residential area as the entry point, the constructed complex network of rural residential area has strong connection and centrality, but the centrality is general; spatially, the network nodes are unevenly distributed with obvious differences and the nodes with strong centrality have clustering distribution. After weighting and summing the five indexes of the complex network, the rural residential areas in Liping County can be classified into five optimal layout modes, namely, agglomeration development mode, key development mode, potential optimization mode, scale control mode, and village relocation and merger mode.