Journal of Henan Agricultural Sciences

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2023, 52(8): 0.

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Research Progress of Porcine Epidemic Diarrhea Vaccine for Pigs

LIANG Yuxuan, PANG Shengmei, LIU Mei, WANG Longlong, DUAN Qiangde

2023, 52(8): 1-10. DOI: 10.15933/j.cnki.1004-3268.2023.08.001

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Porcine epidemic diarrhea（PED）caused by porcine epidemic diarrhea virus（PEDV）is an acute and highly contagious enteric disease of pigs，which leads to high morbidity and mortality in the suckling piglets，thereby bringing huge economic losses to the global pig industry.Vaccination is currently the most economical and effective measure for the prevention of PED，but due to the continuous emergence of PEDV variants，the immune protection of the vaccine is not effective.Therefore，the development of safer and more effective vaccines for preventing PED is urgently needed. Here we mainly reviewed the pathogenic characteristics，the pathogenic mechanism of PEDV，and the latest progress in PEDV vaccine research. Futhermore，the research strategy of a novel and effective PEDV vaccine was also prospected，to provide a reference for effective prevention and control of PED in clinical settings.

Effect of Planting Density on Stem Strength and Ear Characters of Maize

XU Lina, AN Zhiliang, CHEN Shilin, ZHANG Huaisheng, JIN Xining, WANG Pingxi

2023, 52(8): 11-17. DOI: 10.15933/j.cnki.1004-3268.2023.08.002

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Five planting densities of 67 500（D1），75 000（D2），82 500（D3），90 000（D4）and 97 500（D5）plants/ha were set up to study the effects of planting density on stem strength，ear traits and yield of Baiyu 393，and the relationship between maize plant morphology and stem strength was analyzed，so as to provide theoretical basis and technical guidance for high‑yield cultivation of summer maize in Huang‑Huai‑Hai region.The results showed that as the planting density increased，the ear height and ear height ratio of maize increased，the stem circumference decreased，and there was no significant change in plant height；The stem puncture strength，breaking strength and crushing strength of maize all decreased；The ear length，row number per ear，grain number per row，cob diameter，100‑grain weight and grain number per ear of maize all showed a downward trend，but there was no significant change in ear diameter，while the bald tip length increased；The maize yield first increased and then decreased，D3 treatment was the highest，followed by D2 treatment，the difference between the two treatments was not significant，while D5 treatment was the lowest.There were significant negative correlations between stem puncture strength，breaking strength，crushing strength and ear height，ear height ratio. In summary，when the planting density is 75 000—82 500 plants/ha，the ear height and stem diameter are moderate，the stem quality is good，the ear traits are superior，and the yield is higher.

Effects of Intercropping of Two Genotypes of Wheat on Grain Filling Characteristics and Yield

ZHAO Lishang, WANG Xiangsheng, GAO Nanan, HAN Pengbin, LI Jie, REN Yongzhe, LIN Tongbao, WANG Zhiqiang, LIAN Yanhao

2023, 52(8): 18-25. DOI: 10.15933/j.cnki.1004-3268.2023.08.003

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In order to explore the intercropping effect between common wheat and colored wheat，a field experiment was conducted. Common wheat monoculture（W）and colored wheat monoculture（H）were used as controls，and intercropping treatment between common wheat and colored wheat（W||H）was set up to investigate the effect of intercropping on the grain filling characteristics and yield of different genotypes of wheat. The results showed that，compared with monoculture treatment，the SPAD value and net photosynthetic rate of flag leaves of colored wheat of intercropping treatment significantly increased at 25 days after flowering，which further increased the accumulation of grain dry matter at 30—35 days after flowering，and 1 000‑grain weight and grain weight per ear significantly increased by 4.9% and 15.2%，respectively；grain filling duration and effective filling duration of intercropping treatment increased by 1.90 d and 1.06 d for colored wheat，and decreased by 2.89 d and 1.08 d for common wheat，respectively.The total ear number and yield of intercropping treatment significantly increased by 8.5%and 15.1% compared with colored wheat monoculture treatment，and significantly decreased by 4.7%and 21.5% compared with common wheat monoculture treatment，respectively.The land equivalent ratio of intercropping treatment was 0.91.Correlation analysis showed that yield was positively correlated with theoretical maximum grain weight and effective filling duration，and the correlation coefficients were 0.891 and 0.920，respectively.Overall，intercropping between colored wheat and common wheat can improve photosynthetic and grain filling characteristics of colored wheat，which has intercropping advantages.

Preparation of EM Selenium‑Enriched Yeast Agent and Its Application in Selenium‑Enriched Rice Production

ZHAO Biao, FENG Xu, HE Fumeng, XU Yongqing, SHI Qihai, FENG Yanzhong, LI Fenglan

2023, 52(8): 26-35. DOI: 10.15933/j.cnki.1004-3268.2023.08.004

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The EM selenium‑enriched yeast agent preparation process conditions were optimized by response surface methodology based on single‑factor test with organic selenium concentration as the evaluation index，the optimal EM selenium‑enriched yeast agent preparation process conditions were determined，and the EM selenium‑enriched yeast agent was applied in rice production to investigate its effects on rice yield and quality，so as to provide reference for the functional development and utilization of selenium‑enriched agricultural products.The results showed that the optimal process conditions for the preparation of EM selenium‑enriched yeast agent were yeast inoculation of 10%，inorganic selenium concentration of 5 g/L，fermentation temperature of 30℃，pH value of 4.0，and fermentation time of 3 d in 3 L EM bacterial solution.The organic selenium concentration was 833.61 mg/L under above conditions.The results of the field trial showed that compared with the treatment of spraying water（CK）and treatment of spraying Jinguo organic selenium，the organic selenium content in the leaves of EM selenium‑enriched yeast agent‑treated rice significantly increased at the milky stage；the shrunken grain rate significantly decreased by 24.84% and 21.23%，the yield increased by 8.38% and 7.52%，respectively；the starch content increased by 20.60% and 30.86%，and the selenium content was 0.24mg/kg，which was 23 times higher than that of CK and conformed to the standard of GB/T 22499—2008 Selenium rich rice.

Effect of Functional Leaves at Different Positions on Grain Filling Characteristics and Quality of Different Panicle Types of Rice Varieties

XIE Wenxiao, JIANG Xiuying, LÜ Jun, PAN Zhengyan, HAN Yong, WANG Qingxin, LI Jianguo

2023, 52(8): 36-44. DOI: 10.15933/j.cnki.1004-3268.2023.08.005

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In order to clarify the correlation between functional leaves at different positions and grain‑filling characteristics，yield and quality，Liaojing 401（semi‑erect large panicle rice variety ）and Liaojing 371（curved panicle rice variety）were used as materials，the effects of functional leaves at different positions［cutting flag leaf（T1），cutting second leaf from top（T2），cutting third leaf from top（T3）and no cutting（control，CK）］on the filling characteristics of superior and inferior grains，yield and quality of different panicle types of rice varieties were studied，and the relationship between grain‑filling characteristics and quality indexes was analyzed.The results showed that the absence of flag leaf and second leaf from top significantly decreased the maximum and average filling rate of superior and inferior grains of Liaojing 401 and inferior grains of Liaojing 371.The absence of functional leaves at different positions significantly extended the active filling period of Liaojing 401，and shortened the active filling period of Liaojing 371.The absence of functional leaves at different positions advanced the maximum filling time of Liaojing 401，and delayed the maximum filling time of Liaojing 371.The absence of flag leaf and second leaf from top significantly decreased seed setting rate，grain plumpness and 1 000‑grain weight，and then significantly decreased the yield. The order of effects on the above indexes was flag leaf>second leaf from top>third leaf from top.Compared with CK，1 000‑grain weight of Liaojing 401 and Liaojing 371 of cutting flag leaf treatment decreased by 18.32% and 6.44%，and the yield decreased by 16.52% and 8.05% respectively.With the elevation of cutting leaf position，milling and appearance qualities，breakdown and final viscosity gradually decreased，and the effects on chalkiness and chalky grain percentage were greater.The effect of functional leaves at different positions on yield and quality of curved panicle type of rice variety was smaller than that of semi‑erect large panicle type.In summary，the order of effect of functional leaves at different positions on filling characteristics，yield and quality of rice is flag leaf>second leaf from top>third leaf from to top，and the effect on semi‑erect large panicle type is greater than curved panicle type.

Establishment and Evaluation of Copper Soap Colorimetric Method for Acid Value Determination of Slight Amount of Sesame Sample

JU Ming, LI Hailing, YUAN Qingli, MA Qin, DUAN Yinghui, LIU Yangming, YAN Kerun, ZHANG Haiyang, MIAO Hongmei

2023, 52(8): 45-55. DOI: 10.15933/j.cnki.1004-3268.2023.08.006

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In order to quickly and accurately determine the acid value of trace sesame samples，13 sesame oil samples and seeds of 20 sesame varieties were selected to improve the formula of copper soap staining solution and analyze the color development intensity of copper soap reaction，and then a colorimetric method of copper soap for determining acid value of slight amount of sesame sample was established for the first time.Results showed that the optimum wavelength for determining sesame oleic acid samples was 710 nm.The minimum amount of sesame oil for single sample determination was 60 mg，and the average dosage of sesame seed sample was 0.11 g.Among the range of 0.1—10 mg/mL oleic acid，the standard working curve equation of copper soap colorimetric method was y=0.199x+0. 017 2（R²=0.999 7）and the acid value of sesame samples was 0.18—17.50 mg/g by the method.Determination results showed that the acid value of 13 sesame oil samples and 20 sesame seed samples were 1.36—6.32 mg/g and 1.02—5.03 mg/g，respectively.Compared with the standard acid‑base titration，copper soap colorimetric method had higher precision and accuracy，and the difference between the two results was not significant.Therefore，the copper soap colorimetric method can be used instead of the standard acid‑base titration method to determine the acid value of sesame seeds and sesame oil.Moreover，the copper soap complex should be used for determination as soon as possible after preparation as the assay time also had influence on the acid value of sesame samples.

Study on Spatio‑Temporal Variation of Climatic Suitability of Sesame Planting in Henan Province

HU Feng, ZHANG Jiantao, ZHANG Jie, GAO Tongmei, ZHAO Qiaoli, ZHENG Guoqing, LI Guoqiang, LIU Lijie

2023, 52(8): 56-68. DOI: 10.15933/j.cnki.1004-3268.2023.08.007

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This study aimed to clarify the spatial and temporal distribution characteristics of the climatic suitability of sesame in Henan Province and to guide the layout of sesame production by establishing climate suitability models for sesame growth using fuzzy mathematics method based on the light，temperature，and water requirements of sesame.The temperature，light，precipitation，and comprehensive climate suitability of sesame were calculated using the daily meteorological data of 15 meteorological stations in Henan from 1961 to 2019.The results showed that temperature suitability（0.938—0.956）was higher than light suitability（0.568—0.657）and precipitation suitability（0.492—0.595）of sesame in 15 stations in Henan Province，and the comprehensive climate suitability was 0.641—0.712.From 1961 to 2019，the light and comprehensive climate suitability of sesame in Henan Province showed asignificant downward trend，decreasing by 0.032 and 0.012 every 10 years.The change trends of temperature and precipitation suitability were not significant.The light，precipitation，and comprehensive climate suitability decreased gradually from north to south，while the temperature suitability increased gradually from northwest to southeast. The findings suggest that the temperature suitability of Henan sesame is higher and the heat resources are rich，the light suitability is gradually decreasing and not conducive to the growth of sesame，the precipitation suitability is the lowest，and precipitation is the main climatic factor that restricts the production of sesame in Henan.In the production of Henan sesame，it is of great significance to consolidate the advantages of traditional sesame producing areas such as Zhumadian and Zhoukou in southeastern Henan，expand the planting range of high climate suitability areas such as northern and eastern Henan，improve the irrigation and drainage facilities to improve the utilization rate of sesame climate resources and ensure the stable yield and yield increase of Henan sesame.

Effects of Drought Stress on Photosynthesis and Physiological Characteristics of Platycodon grandiflorum

XIN Longfei, LOU Chuang, JI Baoyi, LIU Hongyun, ZHANG Yanling

2023, 52(8): 69-77. DOI: 10.15933/j.cnki.1004-3268.2023.08.008

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Two‑year‑old Platycodon grandiflorum was used to explore the effects of drought stress on its photosynthesis and physiological characteristics.The response of P.grandiflorum to different degree of drought stress was analyzed by measuring the photosynthetic and physiological characteristics under different soil moisture conditions.The soil relative water content was 80%（control），60%（mild drought），40%（moderate drought）and 20%（severe drought），respectively.The findings suggested that the net photosynthetic rate，stomatal conductance，intercellular CO₂ concentration，light saturation point，apparent quantum yield and dark respiration rate of P.grandiflorum leaves decreased gradually with the increasing degree of drought stress.The light compensation point increased gradually.When the soil relative water content was 20%，the highest light compensation point achieved 74.45 μmol/（m²·s），which increased by 67.76% compared with the control.However，the content of photosynthetic pigments in leaves increased first and then decreased with the increasing degree of drought stress.The contents of chlorophyll a，chlorophyll b and carotenoids were the highest under soil relative water content of 60%，which increased by 18.71%，28.48%，and 12.25% respectively compared with the control.Moreover，the contents of malondialdehyde，proline，soluble sugar and soluble protein in P.grandiflorum increased with the increasing degree of drought stress.The catalase activity in P.grandiflorum leaves enhanced first and then weakened.The activity was the highest when the soil relative water content was 40%，which was 21.01% higher than that of the control.In summary，P.grandiflorum showed adaptability to mild and moderate drought.The accumulation of osmotic adjustment substances and the increase of antioxidant enzyme activity were the key physiological response processes of drought tolerance of P.grandiflorum.However，the lipid peroxidation of P.grandiflorum was aggravated under severe drought stress，and the photosynthetic productivity decreased significantly，which eventually led to serious inhibition of the growth of P.grandiflorum.To maintain the normal growth of P.grandiflorum，soil relative water content should not be lower than 40% for a long time.

Phosphorus Solubilizing Characteristics of Phosphorus Solubilizing Bacteria in Yellow Soil of Central Guizhou and Their Effects on Soil Microbial Carbon Cycling Genes

QIAO Zhiwei, ZHANG Yongjie, XIE Meifang

2023, 52(8): 78-86. DOI: 10.15933/j.cnki.1004-3268.2023.08.009

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The purpose of this study was to explore the phosphorus solubilization characteristics of phosphorus solubilizing bacteria in yellow soil in central Guizhou Province. QZW‑3（Burkholderia sp.），QZY‑5（Pseudomonas sp.）and QZY‑6（Sinorhizobium sp.），which were screened from farmland soil in Anshun city of Guizhou Province，were used as the test strains.The phosphorus solubility of the strains under different carbon and nitrogen sources was studied by indoor culture experiment，and the influence of the strains on soil nutrients and microbial carbon cycling genes was studied by pot experiment.The results showed that the three strains had strong ability to dissolve all kinds of insoluble phosphorus.QZW‑3，QZY‑5 and QZY‑6 all took glucose as carbon source and had the highest soluble ability of tricalcium phosphate，which were 603.13，645.82 and 672.21 mg/L，respectively.Nitrogen source had less effect on phosphorus solubility than carbon source.The fresh weight of rape in the combination treatment of three strains was significantly higher than that of other treatments，which was 37.89 g/pot.There was no significant difference in soil pH between the treatments of phosphorus soluble bacteria and substrate.The contents of soil available phosphorus and organic matter in the treatments of phosphorus soluble bacteria were higher than those in the substrate treatment.The relative abundance of GHs genes of soil microbial carbon cycle in each treatment of phosphorus solubilizing bacteria was higher than that in the substrate treatment，while the relative abundance of CEs，PLs，AAs genes in each treatment of phosphorus solubilizing bacteria was not significantly different.Soil pH value was extremely significantly negatively correlated with AAs relative abundance，and extremely significantly positively correlated with PLs relative abundance.Soil available phosphorus was significantly positively correlated with GHs relative abundance and extremely significantly negatively correlated with PLs relative abundance.Soil organic matter was not significantly correlated with various genes of microbial carbon cycle.

Cabbage Yield and Nutrient Utilization under Substitution of Organic Manure for Fertilizer in Vegetable‑Rice Rotation in Lateritic Red Soil

ZHANG Licheng, LI Juan, ZHANG Mingqing, GU Zuchao

2023, 52(8): 87-95. DOI: 10.15933/j.cnki.1004-3268.2023.08.010

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In order to improve the efficiency of fertilizer utilization，the cabbage breed Zhonggan 8 was taken as the test material，and field experiments were carried out in the vegetable‑rice rotation area in southern Fujian with five fertilization treatments（customary fertilization，recommended fertilization，organic manure substitution of 25% fertilizer，organic manure substitution of 50% fertilizer，organic manure substitution of 100% fertilizer） and no fertilization treatment（control，CK）.The effects of different treatments on yield and nutrient utilization of cabbage were studied.The results showed that substitution of organic manure for fertilizer could promote the growth of cabbage ball.The weight and compactness of cabbage ball in organic manure substitution of 50% fertilizer treatment were significantly higher than those of other treatments. Through the analysis of cabbage yield under different fertilization treatments，the highest yield was 3 824.13 kg/ha in the treatment of organic manure substitution of 50% fertilizer，which was significantly higher than that in the treatment of organic manure substitution of 25% fertilizer，organic manure substitution of 100% fertilizer，customary fertilization and no fertilization，but compared with the recommended fertilization treatment there was no significant difference.The treatment of organic manure substitution of 50% fertilizer and the treatment of organic manure substitution of 25% fertilizer had higher nitrogen and phosphorus utilization rates，which were 40.82% and 30.82% respectively.Compared with the customary fertilization，the treatment of organic manure substitution of 50% fertilizer increased the nitrogen fertilizer utilization efficiency of cabbage by 13.14 percentage point.By comprehensive analysis of cabbage yield and nutrient utilization efficiency，organic manure substitution of 50% fertilizer is recommended as the application amount in cabbage production of vegetable and rice rotation in the lateritic red soil of southern Fujian Province.

Correlation Analysis between the Resisitance of Wheat to Black Point and Leaf Blight at Seedling Stage Caused by Bipolaris sorokiniana

LI Haiyong, LI Mengyu, GAO Chuang, XU Hao, YIN Guihong, DONG Chunhao, NIU Jishan, LI Qiaoyun

2023, 52(8): 96-104. DOI: 10.15933/j.cnki.1004-3268.2023.08.011

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To understand the relationship between the resistance to black point and leaf blight caused by Bipolaris sorokiniana in wheat，the correlation between black point incidence and the percentage of diseased leaf area under artificial inoculation with B.sorokiniana at seedling stage was analyzed based on the identification results of 50 wheat cultivars（lines）with different black point resistance，using the method of spraying spore suspension and bagging for moisture for two consecutive years in 2018—2019 and 2019—2020.The results showed that the average black point incidences were 15.9% and 17.4% in 2019 and 2020，respectively，under inoculation condition with B.sorokiniana，and only three germplasms ［（SN5300709，Wenmai 10 and 11‑253（LWX）］showed resistance in both years，accounting for 6.0% of the cultivars（lines）tested. There was a significant negative correlation between black point incidence and the percentage of diseased leaf area（P<0.01），with the correlation coefficients ranging from -0.914 to -0.845. The concordance between resistance identification of 50 wheat cultivars（lines） under artificial inoculation with B.sorokiniana and speculation result was 90.0%，according to the regression equation（y=-0.585x+48.444，x and y represented percentage of diseased leaf area and black point incidence，respectively）between black point incidence and the percentage of diseased leaf area with the highest correlation coefficient in 2020.It suggests that black point incidence caused by B.sorokiniana could be predicted by the percentage of diseased leaf area of leaf blight at seedling stage，which provides a basis for the establishment of a rapid identification method of cultivars（lines） with black point resistance in wheat breeding.

Effects of Different Color Fruit Bags on Berry Russet and Quality of Shine Muscat Grape during Ripening

LOU Yusui, SHANG Hongquan, FAN Hongjie, LI Zheng, ZHANG Ke, CUI Xiaoyue, LÜ Zhongwei

2023, 52(8): 105-114. DOI: 10.15933/j.cnki.1004-3268.2023.08.012

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The effects of different color fruit bags on berry russet and quality of Shine Muscat grape were studied to lay the foundation for selecting suitable fruit bags to produce high quality fruit.Ten‑year‑old Shine Muscat grapevines were used as materials.Five different color fruit bag treatments were set to compare the changes of berry russet rate and fruit quality during ripening.No bagging clusters were as the control.Results showed that the berry russet rate of Shine Muscat increased first and then stabilized with the process of fruit maturity.The berry russet rate reached a high level for the control，red bag，white bag，blue bag，green bag，and black bag at 97 d，107 d，107 d，107 d，122 d，and 107 d after full bloom，respectively. At this time，the berry russet rate was 19.47% for the control，12.48% for red bag，12.42% for white bag，9.62% for blue bag，7.59% for green bag，and 0.84% for black bag.The control and blue bag treatment had a higher peel brightness than other treatments，while the black bag had a lower peel brightness than other treatments.Berry weight of the control and treatments of white bag and blue bag reached the maximum at 107 d after full bloom，while berry weight of other treatments reached the maximum at 122 d after full bloom.The white bag had the highest berry weight at all，which was 15.57 g，followed by blue bag.The control and treatments of white bag and black bag had a higher berry firmness than other treatments，while the treatments of green bag and blue bag had a lower berry firmness than other treatments.The total soluble solids（TSS）content and TSS/titratable acid（TA）of the control and treatments of white bag，blue bag and red bag were higher than other treatments，and the TSS content reached 18% or above at 97 d after full bloom. The TSS content of the treatments of green bag and black bag reached 18% or above at 107 d after full bloom. In conclusion，the blue bag can be a good choice for producing high quality fruit，which could decrease berry russet rate significantly and has little effects on fruit quality.

Physiological Response and Cold Resistance Evaluation of Blueberry Varieties under Low Temperature Treatment

WEI Xin, WANG Sheng, WANG Xingdong, YANG Yuchun, LIU Youchun, LIU Cheng

2023, 52(8): 115-125. DOI: 10.15933/j.cnki.1004-3268.2023.08.013

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To study the physiological response of blueberry to low temperature treatment，screen the evaluation index of cold resistance and comprehensively evaluate the cold resistance of blueberry varieties，one‑year‑old shoots of five varieties of blueberry，Blomidon，Northland，Bluecrop，Misty and Choice，were selected as materials. The relative electrical conductivity，peroxidase（POD） activity，superoxide dismutase（SOD） activity，malondialdehyde（MDA） and free proline content were studied under low temperature treatment（-10，-15，-20，-25，-30，-35，-40℃）.The content of soluble sugar，reducing sugar，soluble protein，starch，cellulose，fructose，glucose，sucrose，total water，free water were detemined，and bound water content，free water content/total water content and bound water content/total water content were calculated. The cold resistance of different blueberry varieties was evaluated by principal component analysis. The results showed that with the decrease of temperature，the relative electrical conductivity and MDA content of shoots of five blueberry varieties increased gradually，showing an“S”shaped curve；POD activity and SOD activity showed a unimodal trend；The content of free proline increased gradually.Blomidon，Northland and Bluecrop had higher soluble total sugar，reducing sugar，glucose，fructose，sucrose，starch，cellulose and soluble protein contents；The total water content，free water content and free water content/total water content of Blomidon were lower；The total water content，free water content and free water content/total water content of Misty were higher，and bound water content/total water content was lower. Relative electrical conductivity，MDA，soluble protein，reducing sugar，soluble total sugar，fructose，free water，bound water content and POD activity could be used as indicators to evaluate the cold resistance of blueberry varieties. Through comprehensive analysis，the cold resistance of the five blueberry varieties tested was determined to be Blomidon，Northland，Bluecrop，Choice and Misty in order from strong to weak.

Correlation between Morphological Traits and Body Weight of 2‑month‑old Siniperca scherzeri

TIAN Tian, ZHANG Fengguang, WANG Maoyuan, HUANG Honggui, QIN Zhiqing, LAI Mingyong, LIU Yinhua, HUANG Liuting, WU Meiying

2023, 52(8): 126-134. DOI: 10.15933/j.cnki.1004-3268.2023.08.014

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In order to explore the relationship between early morphological traits and body weight of Siniperca scherzeri，a total of 100 2‑month‑old individuals were randomly selected from the same batch to accurately measure body weight（Y）and 10 morphological traits including total length（X₁），body length（X₂），head length（X₃），snout length（X₄），body height（X₅），body width（X₆），eye diameter（X₇），eye distance（X₈），caudal peduncle length（X9）and caudal peduncle height（X₁₀）.The data were processed using correlation analysis，multiple regression analysis and path analysis to determine the main morphological traits affecting body weight，establish the optimal linear regression equation，and analyze the influence of each trait on body weight.The results showed that the variation coefficient of body weight of 2‑month‑old Siniperca scherzeri was the largest，indicating the greatest breeding potential；all morphological traits were positively correlated with body weight（P<0.01），and the correlation coefficient between total length and body weight was the largest；the optimal linear regression equation between body weight and four morphological traits including total length，body height，snout length and eye diameter was established by stepwise introduction‑elimination method：Y=-11.578+0.093X₁+0.550X₅+0.263X₄+0.490X₇（R²=0.968）；path analysis showed that total length had the largest direct effect on body weight（0.417），followed by body height（0.307），snout length and eye diameter were smaller（0.168 and 0.146），and the total determining coefficient of the four morphological traits on body weight was 0.967.In conclusion，when the body weight is taken as the breeding target of 2‑month‑old Siniperca scherzeri，total length，body height，snout length and eye diameter can be used as important morphological measurement indexes，among which total length and body height can be the preferred morphological traits.

Cloning，Expressing and Anti‑BmNPV Infection Research of Antimicrobial Peptide Gloverin 2 Gene from Bombyx mori

TANG Fenfen, YANG Weike, ZHANG Zuyun, LI Na, LIU Na, XIE Kun

2023, 52(8): 135-141. DOI: 10.15933/j.cnki.1004-3268.2023.08.015

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In order to obtain BmGloverin 2 and study its role in anti‑infection of Bombyx mori nucleopolyhedrovirus（BmNPV），cDNA from 3 days of the third instar larvae midgut of Bombyx mori induced by BmNPV was used as template.Based on the sequence of BmGloverin 2 gene in GenBank，specific primers were designed.The BmGloverin 2 gene，without the signal peptide part（1—18 aa），was cloned and connected with the expression vector pET28a（+）to construct pET28a（+）‑BmGloverin 2 and the strain containing pET28a（+）‑BmGloverin 2 recombinant plasmid was induced to express proteins.To obtain high concentration of target protein，the recombinant antimicrobial peptide protein was then subjected to Ni‑IDA affinity chromatography，dialysis and concentrated filtration.The bioactivity of recombinant BmGloverin 2 protein was detected by bacteriostatic assay.Finally，the effects of BmGloverin 2 on BmNPV infection were tested by feeding silkworm with the recombinant BmGloverin 2 protein and BmNPV after mixed trreatment for 4 h，and feeding silkworkm directly with BmNPV and sterile water treatments were taken as the control groups.The results showed that the BmGloverin 2 gene was successfully cloned and the recombinant pET28a（+）‑BmGloverin 2 was constructed.The recombinant BmGloverin 2 protein was obtained by inducing expression at 37℃ and 0.5 mmol/L IPTG.The molecular weight of BmGloverin 2 was 19.1 ku according to SDS‑PAGE analysis，which was consistent with the expected size.Finally，the recombinant protein BmGloverin 2 was obtained by purification and concentration.The bacteriostatic test showed that the recombinant BmGloverin 2 protein had biological activity.Compared with the BmNPV control group，the larval survival rate was increased in the group fed with the mixture of recombinant BmGloverin 2 protein and BmNPV.The results suggest that BmGloverin 2 plays a role in the resistance of silkworm to BmNPV infection.

Extraction and Application of Maize Leaf Inclination Angle Using Digital Images

BAO Congcong, ZHANG Baolin, NIU Panting, PAN Lijie

2023, 52(8): 142-154. DOI: 10.15933/j.cnki.1004-3268.2023.08.016

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Leaf inclination angle is one of the major features of maize population canopy.The rational distribution of leaf inclination angles is of great importance in light use efficiency and production potential.After digital image processing，including gray‑scale，histogram equalization，median filter，Otsu segmentation，morphological operation，connectivity identification and skeletonization，Freeman codes were used to identify maize stem leaf joints and then leaf inclination angles were extracted.Leaf apex and joints were correctly identified by 94.47% and 93.94%，respectively.The correlation coefficient between observations and calculations of leaf inclination angle was 0.94.This method showed high efficiency and accuracy in leaf inclination angle extraction.Maize leaf inclination angle decreased with the lowering of leaf positions，and increased with the growth of NDVI.The quick and precise extraction of leaf inclination angle will provide scientific basis for phenotype retrieval，growth and development monitoring and agricultural resource use.

Research on Cultivated Land Quality Evaluation Based on Ensemble Learning Method

CHENG Guifang, WANG Yuxin, SHEN Huishi

2023, 52(8): 155-162. DOI: 10.15933/j.cnki.1004-3268.2023.08.017

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In order to fully understand the county‑level cultivated land resources，improve the efficiency and accuracy of cultivated land quality evaluation，and reduce the influence of human subjective factors，we selected Shanzhou District of Sanmenxia City in Henan Province as the research object and graded its cultivated land quality in this paper.The characteristic variables were divided into categorical variables and numerical variables according to the characteristics of data. For numerical variables，the Chi‑square binning method was used for processing.The processed results and categorical variables were assigned by one‑hot encoding，and the SMOTE method was used to balance the sample data for data with a small number of sample categories.Then the method of machine learning was used，and the quality of arable land was graded using XGBoost，LightGBM，ANN，and a combined XGBoost‑LightGBM‑ANN model.The results showed that，when the processed unsampled data were used as the training set and substituted into the single models as well as combined models for training and prediction of cropland quality evaluation，metrics such as accuracy，precision，recall，and F1 scores all reached values of over 0. 97.Among them，the values of the indicators corresponding to the single models ANN，LightGBM and XGBoost were increasing，indicating that the application of machine learning models in the evaluation of cropland quality produced good results.Compared with the unsampled data，the sampled data as a training set produced a significant improvement in the model performance.In the prediction of single models and the combined model，the values of each index reached more than 0.99，and the XGBoost‑LightGBM‑ANN combined model based on the integrated learning voting algorithm had an obvious advantage，with an accuracy of 0.998 3.

Quality of Flour and Steamed Bread Made from Black Wheat

HAO Zirui, JIA Yuku, GE Zifei, BI Xintong, ZHANG Jian, XIE Yingxin, WANG Chenyang, MA Dongyun

2023, 52(8): 163-170. DOI: 10.15933/j.cnki.1004-3268.2023.08.018

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To provide useful information for the development and utilization of black wheat flour，three wheat varieties in black grain coat（HBS1，JZ439，SDZM1）and a white wheat variety（YM49‑198）were used to analyze flour quality，color，texture structure and sensory evaluation of steamed bread made with flour by three different milling methods（whole flour，partially debranned grain flour，refined flour）.Results showed that the protein content of partially debranned grain flour was higher and the sedimentation value of refined flour was the highest.The color of wheat flour and steamed bread by refined milling method had the brightest skin color，with L* values of 91.33 and 73.85，respectively.The texture analysis of steamed bread showed that HBS1 had the lowest values of hardness，gumminess and chewability，while SDZM1 showed higher values under the corresponding grinding method.The sensory evaluation showed that the total score of steamed bread decreased with the increase of bran retention，with refined flour being the highest and whole flour being the lowest. Under the same milling method，the total score of steamed bread from HBS1 was the highest，followed by SDZM1，and no significant difference was observed between steamed bread made from refined flour and partially debranned grain flour.

Comprehensive Extraction and Antioxidant Activity Research of Polysaccharides and Flavonoids from Ginkgo biloba Leaf Residue

WANG Jinghe, HU Qingfeng, LIU Jie, CHENG Yaobo, YAN Xuerong, WANG Jian, HUI Ailing, ZHANG Wencheng

2023, 52(8): 171-180. DOI: 10.15933/j.cnki.1004-3268.2023.08.019

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The polysaccharides and total flavonoids from Ginkgo biloba leaf residue were obtained by water extraction and alcohol precipitation method and complex enzyme assisted alcohol water solvent extraction method respectively.DPPH free radical，ABTS⁺free radical and hydroxyl free radical scavenging assays were used to investigate their antioxidant activity in vitro.The results showed that when Ginkgo biloba leaf residue was extracted by pure water at 1∶9 and 85℃ for 3 h，the yield of crude polysaccharide was 17.90% and the extraction rate of polysaccharide was 3.03%. After polysaccharide extraction，Ginkgo biloba leaf residue was added with β‑glucoglycase，cellulase and pectinase（1∶1∶2）complex enzymes，the addition amount was 8.0%，the pH value was 5，and enzymolysis was conducted at 50℃ for 2.5 h.Then，the extraction rate of total flavonoids from Ginkgo biloba leaf residue was 0.59‰ under the conditions of 80% ethanol，1∶8 to liquid and 80℃ for 4 h.The extraction rate of three free aglycones（quercetin，kaempferol and isorhamnetin） was 0.93‰.Compared with the total flavonoids extracted by 80% ethanol，the extraction rate of total flavonoids increased by 126.9% and the extraction rate of free aglycones increased by 102.2%.The scavenging rates of DPPH free radical，ABTS⁺free radical and hydroxyl free radical of 3.0 mg/mL polysaccharide were 67.59%，52.56% and 56.47%，respectively.The IC₅₀ values of total flavonoids from Ginkgo biloba leaf residue by complex enzyme assisted alcohol water solvent extraction（0.63，1.08 and 0.35 mg/mL）were generally lower than those obtained by solvent extraction.To sum up，polysaccharides and total flavonoids in Ginkgo biloba leaf residue had better antioxidant activities，and the content of free aglycone in total flavonoids of Ginkgo biloba leaf residue and the antioxidant activity were increased by complex enzyme assisted alcohol water solvent extraction method.

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