Journal of Agricultural Science and Technology

Situation of China's Animal Husbandry Development and High-quality Development Strategy Selection

Xuezhen XIONG, Chun YANG, Xiaoping MA

2022, 24(3): 1-10. DOI: 10.13304/j.nykjdb.2021.0549

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Animal husbandry is important for promoting the prosperity of rural industry， increasing farmers' income and improving people's life. Through the combination of quantitative analysis and qualitative analysis， this paper reviewed the development of animal husbandry in China since the reform and opening up， comprehensively analyzed the key constraints of animal husbandry according to the high-quality development objectives， and systematically put forward the basic strategies of animal husbandry high-quality development. Results showed that the production scale of Chinese animal husbandry was significantly expanded， and product structure was optimized， production way was upgraded， development concept changed obviously， which greatly enriched and satisfied the people's increasing need of a better life； in the economic， yield， protein etc. dimensions， relatively stable production layout had formed， fromed the traditional incremental oriented development era into high quality development in the new period； however， in order to achieve the goal of high-quality development， there were still some key constraints， such as improved breeds of livestock and poultry， animal diseases， breeding technology， shortage of resources and environmental protection. Finally， the high-quality development strategies were proposed from the following eight aspects including seed industry security， supply stability， technical support， structure optimization， green development， appropriate scale， internal and external circulation， and policy stability.

Spatial Temporal Differences and Influencing Factors of Agricultural Water Use Efficiency

Jie SHANG, Haoran YU, Xu YANG

2022, 24(3): 11-19. DOI: 10.13304/j.nykjdb.2021.0346

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To explore the effect of technological progress on temporal and spatial differences of agricultural water use efficiency under， firstly， super efficiency SBM （slacks-based measure） model was used to calculate agricultural water use efficiency of major grain producing areas in China from 2009 to 2018； secondly， the Theil index was used to analyze the regional differences of agricultural water use efficiency； finally， the panel random effected model was used to analyze the influencing factors of agricultural water use efficiency in different regions. The results showed that the agricultural water use efficiencies of 13 provinces （autonomous regions） had shown a fluctuating upward trend from 2009 to 2018. The regional differences were decreasing， and the difference within region was increasing， so， controlling the expansion of difference within region was the key to improve the efficiency of agricultural water use. Economic development level， annual precipitation， irrigation water price， the technical level of water-saving agriculture and water resource endowment had a certain impact on agricultural water use efficiency in China’s main grain producing areas， but there were differences in different regions. It provided a theoretical basis for formulating more targeted policies according to different situations of provinces， promoting the progress of water-saving agriculture and improving the agricultural water use efficiency.

Research on the Transgenic Threshold System in China Based on Lowlevel Presence of Genetically Modified Products

Yue JIAO, Zhi WANG, Zhenmin ZHANG, Xuanzi PENG, Haibin FU, Pengyu ZHU, Chunmeng HUANG, Yongjiang ZHANG, Wei FU

2022, 24(3): 20-27. DOI: 10.13304/j.nykjdb.2020.0984

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With the development of global economic and trade integration， the commercialization of genetically modified （GM） products brings infinite opportunities and challenges to multilateral international trade. As an unavoidable practical problem， the low-level presence （LLP） of GM products has become a frontier issue in international trade. As an important factor for the international community to alleviate the problem of low low-level presence （LLP） of GM products， the transgenic threshold system has gradually attracted the attention of governments around the world. Based on the current situation of low-level presence of GM products， this paper analyzed the necessity of establishing GM threshold system to optimize the regulation system and its related long-term mechanism in China from the technical and policy aspects. From the perspective of GM products labeling system and LLP threshold system， this paper summarized the role of GM threshold system in maintaining national biosafety and smooth trade. This paper would have reference value to improve the GM threshold system and develop quantitative testing standards.

Research Progress on Forage Utilization of Shrub Plants in Arid Area of Northwest China

Chunyan LIU, Jianwei ZHOU, Xiaofei MA, Zhongkui XIE, Guo YANG

2022, 24(3): 28-39. DOI: 10.13304/j.nykjdb.2021.0074

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There are many species and resources of shrub plants in arid areas of Northwest China. Some shrub plants have high nutritional and medicinal value， which are regarded as potential important feed sources for green antibiotic-free breeding. This paper summarized and analyzed the current situation of shrub plant resources in northwest arid area， the feeding utilization of typical shrub plants （Leguminosae， Chenopodiaceae， Compositae， Elaeagnaceae Hippophae） and other potential forage shrub plants （Berberidaceae， Salicaceae， Labiatae， Zygophyllaceae， Rosaceae）， in order to fully tap the feeding value of different shrub plants， broaden the source of forage species and provide ideas and methods for farmers and herdsmen to develop and utilize forage resources. It also provided data support for alleviating the shortage of forage in winter and spring， reducing the breeding cost and land pressure during rest grazing period， improving the productive efficiency of livestock farming and enthusiasm of breeding， and promoting the economic benefits of livestock farming in the arid area of Northwest China.

Development and Utilization of KASP Marker LCd-38 for Cadmium Accumulation in Rice Grain

Jun XU, Ting LI, Minjun HU, Yugen JIANG, Huili YAN, Wenxiu XU, Yijun YU, Zhenyan HE

2022, 24(3): 40-47. DOI: 10.13304/j.nykjdb.2021.1037

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Rice （Oryza sativa L.） is one of staple food in China， and the cadmium pollution of rice threatens food security. Screening and breeding of rice varieties with low-cadmium accumulation can effectively reduce the risk， and accurate molecular markers play vital roles in it. In this study， taking the rice mini-core collection as the material， a KASP molecular marker LCd-38 was developed based on the functional SNP site in the gene related to grain cadmium accumulation. The cadmium-polluted soil safe to use was chosen as the experimental area， and LCd-38 was used to genotype and screen rice varieties with low cadmium-accumulation in grain. The developed marker LCd-38 could effectively divide different rice varieties into high-cadmium accumulation genotypes （CC） and low-cadmium accumulation genotypes （TT）. 5 low-cadmium accumulation rice varieties and 5 high-cadmium accumulation rice varieties were quickly identified in the experimental area using leaves at seedling stage， which were consistent with the results of measured grain cadmium concentration at maturity stage. These results indicated that the molecular marker LCd-38 could efficiently and accurately predict the cadmium accumulation characteristics of different rice varieties and be used for early screening and molecular marker-assisted selection breeding of low-cadmium accumulation rice varieties.

Mining of Genetic Loci and Screening of Candidate Genes for Seed Tocopherol Content in Soybean

Ning QIN, Junru LI, Rui TIAN, Zhenqi SHAO, Xihuan LI, Caiying ZHANG

2022, 24(3): 48-56. DOI: 10.13304/j.nykjdb.2021.0599

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Tocopherol plays important medical function for human health， such as preventing and curing the arteriosclerosis and cardiovascular diseases. Relative higher content of tocopherol exists in soybean seed， while the genetic loci and candidate genes for tocopherol are still largely unknown. In this paper， one recombinant inbred line （RIL） soybean population was used to assess the seed tocopherol content by the performance liquid chromatography method， and the genetic loci and candidate genes were identified by combining the SNP linkage map and transcriptome data of RIL population. The results showed that there was relative wide genetic variation of seed tocopherol in the RIL. The variation coefficients of α-， γ-， δ- and total-tocopherol contents were ranged from 9.24%~36.62%， and the variation coefficients of proportions of α-， γ- and δ-tocopherol to total-tocopherol were ranged from 5.05%~35.59%. In total， 7 pleiotropic QTLs were detected to control the various tocopherol contents with the phenotypic variation explained （PVE） 3.08%~21.92%. Among these QTLs， qTOC?A2， was identified to confer 5 related traits （α-tocopherol， δ-tocopherol， total-tocopherol contents， α-tocopherol proportion and γ-tocopherol proportion） with the PVEs 3.85%~6.77%. Meanwhile， qTOC?A1 was found to control the α-， γ-， total-tocopherol content， α-tocopherol proportion and γ-tocopherol proportion with the PVEs 6.34%~21.92%. Furthermore， some candidate genes participated in the biosynthesis pathway of soybean tocopherol， Glyma.12G014200， Glyma.12G014300 and Glyma.18G141100 etc.， were screened out for their different expression levels between the RIL parents. Thus， these results provided selection markers and candidate genes for the seed tocopherol molecular genetic improvement and genetic mechanism dissection in soybean.

Analysis of Agronomic and Quality Characters of Beer Barley from Gansu and Europe， North America

Qijun BAO, Yongdong PAN, Huayu ZHANG, Xiaoning LIU, Dongjia ZHANG, Feng ZHAO, Xiaoxia NIU, Jun CHEN

2022, 24(3): 57-66. DOI: 10.13304/j.nykjdb.2020.1011

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To evaluate the breeding values of introduced varieties， 33 malting barley from Gansu， Europe and North America were as materials. Agronomic， yield and quality characters were identified. The results showed that there were significant differences among varieties from different regions in agronomic traits. There were more differences among varieties from Europe， varieties from North American were followed， while there were less differences among varieties from Gansu. There were significant differences among varieties in yield traits， and there were significant difference among varieties from Europe and Gansu. The average yield of tow-row varieties from North America was highest， those from Europe， Gansu and multi-row varieties from North America were followed. Among 33 varieties， the yield of Ganpi 7 was the highest with 9 364.28 kg·hm^-2，and Ganpi 6 （9 269.03 kg·hm^-2）， MERIT （9 223.32 kg·hm^-2） and Z090M066M （9 143.31 kg·hm^-2） were followed. There were significant differences among varieties in protein content， thousand-grain weight and fullness， and the average thousand-grain weight of varieties from Gansu were highest， the fullness of varieties from Europe were highest. In terms of malt quality， the turbidity，fine powder extract and the content of water protein in varieties from North American were lower， while the soluble nitrogen， kolbach index， α-amino nitrogen， α-amylase and diastatic power were higher； those varieties from Gansu showed high the turbidity， fine powder extract and contents of water， protein and β-glucanase， and the contents of β-glucan in varieties from European were low. So 33 varieties from European， North American and Gansu had respective advantages and disadvantages， and they should be given full attention and utilizationin the breeding of Gansu barley varieties.

Study on Chloroplast Ultrastructure of Flue-cured Tobacco Leaves and Its Relationship with Degrading Products of Plastid Pigment

Yu WANG, Chunguang LI, Huan LIU, Yuehua ZHANG, Xiaomin FENG, Yaoguang LI, Huaiqi LI, Yanqiu JING, Mi SUN

2022, 24(3): 67-76. DOI: 10.13304/j.nykjdb.2021.0573

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In order to clarify the relationship between chloroplast ultrastructure and degrading products of plastid pigment in flue-cured tobacco leaves， Yunyan 87 was used as experimental materials to observe and analyze the chloroplast ultrastructure of unripe and ripe leaves at lower， middle and upper positions， and determine degrading products of plastid pigment in flue-cured tobacco leaves at different position. The results showed that the number of starch granules， osmiophilic granules and chloroplast granum， and the proportion of high granum lamella in the chloroplast of unripe tobacco leaves were significantly different among different leaf positions， which showed upper leaves > middle leaves > lower leaves. The trends of number of starch granules and osmiophilic granules in the chloroplast of ripe leaves at different leaf positions were consistent with unripe leaves， while the trends of number of chloroplast granum and the proportion of high granum lamella in the chloroplast of ripe leaves at different leaf positions were opposite with unripe leaves， which showed upper leaves < middle leaves < lower leaves. The contents of the degrading products in plastid pigment of the flue-cured tobacco were extremely significantly positively correlated with the number of starch granules and osmiophilic granules in unripe and ripe tobacco leaves， were extremely significantly positively correlated with the number of chloroplast granum and the proportion of high granum lamella in unripe tobacco leaves， and were extremely significantly negatively correlated with the number of chloroplast granum and the proportion of high granum lamella in ripe tobacco leaves. In conclusion， the number of chloroplast granum and the complexity of granum lamella structure in the unripe leaves and the disintegration degree of granum lamella structure in the ripe leaves were close relations with the contents of degrading products of plastid pigment， which should provide theoretical basis for improving aroma quality and aroma quantity of tobacco leaves.

Photosynthetic Response and Spectral Characteristics of Cherry Rootstocks Under Salt Stress

Wengyou TIAN, Hao LIU, Chaolin GAN, Liufen WU, Ai LI, Lifang YANG, Ying GAO

2022, 24(3): 77-83. DOI: 10.13304/j.nykjdb.2021.0108

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To research the effect of different salt stress on the photosynthesis and the changes in reflectance spectrum characteristics of cherry rootstock seedling， the cherry rootstock ‘Daqingye’ was used as experimental material， and 4 treatments of salt stress were set according to 0， 75， 150 and 300 mmol·L^-1 NaCl. Using spectrophotometer， CI-340-photosynthesis system and CI-710 leaf spectrometer， the chlorophyll content， photosynthesis and spectrum were measured for studying the changes of indexes in the leaves of cherry rootstock seedlings and the correlation among indexes. The results showed that the net photosynthetic rate （P_n）， transpiration rate （T_r）， stomatal conductance （G_s） and intercellular carbon dioxide concentration （C_i） all increased firstly and then decreased with the increase of salt concentration. The contents of chlorophyll a+b and chlorophyll a showed similar trend with photosynthetic index， while the contents of chlorophyll b decreased with the increase of salt concentration. The contents of 3 chloroplast pigments reached the highest in 75 mmol·L^-1 NaCl treatment. With the change of salt content， the reflectance of cherry rootstock varied in different wavebands， however， the trends of spectral characteristic curves were consistent， and there were one “green peak”， one “red valley” and one reflection platform. The reflectivity in the near infrared and green light region was the highest in 75 mmol·L^-1 NaCl treatment and was the lowest in 150 mmol·L^-1NaCl treatment. However， in the bands of blue violet and visible red light， the reflectivity of 150 mmol·L^-1 NaCl treatment was the highest. The results indicated that the proper low-salt treatment could promote the photosynthetic pigment content and photosynthesis of the leaves of the cherry rootstock， and the spectral reflectance could also reflect the degree of salt stress of the plant to a certain extent.

Drought Resistance Index Screening and Drought Resistance Evaluation of Dactylisglomerata Germplasm Resources During Seedling

Jiangyan LI, Xianhua ZHANG, Xiaoqiang YUAN

2022, 24(3): 84-94. DOI: 10.13304/j.nykjdb.2020.1080

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In order to screen the drought resistance indexes of Dactylisglomerata at seedling stage， 7 Dactylisglomerata germplasms from different sources were used as test materials， and 3 treatments were set including suitable water， mild and severe drought stress. The relative water content， relative electrical conductivity， antioxidant enzyme activities and other physiological and biochemical indexes of the leaves were measured after 30 d of drought treatment. The drought resistance of 7 Dactylisglomerata germplasms were evaluated using drought resistance measurement value， comprehensive drought resistance coefficient and weighted drought resistance coefficient by principal component analysis， membership function analysis and gray correlation analysis. The results showed that， with the intensification of drought stress， the relative water content and chlorophyll content gradually decreased， the relative electrical conductivity， the osmotic adjustment substances and malondialdehyde content gradually increased， and the activities of antioxidant enzymes increased. Comprehensive index evaluation showed that the relative water contents of leaves were sensitive indicators under mild and severe drought stress； while the contents of chlorophyll and malondialdehyde were also sensitive indicators under mild drought， and the contents of soluble protein and soluble sugar changed greatly under severe drought stress. In conclusion， the drought resistance of Dactylisglomerata should be comprehensive evaluation. Among different Dactylisglomerata germplasms， wild Dactylisglomerata from Xinjiang showed stronger drought resistance under different drought stresses， which had great potential for exploitation for drought-resistant breeding.

Study on Expressions of CNR1 and FABP4 Genes in Ovine Intramuscular Preadipocytes

Wei YAN, Yutao WANG, Yonghao ZHANG, Haixia LIU, Dayong HAN, Aiwen ZHU

2022, 24(3): 95-102. DOI: 10.13304/j.nykjdb.2021.0120

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To study the pattern and difference of expression of CNR1 and FABP4 during the period of proliferation and differentiation of adipocytes， the longissimus dorsi muscle tissue sourced from a 3-day-old Hu lambs was collected， and then digested by the type II collagenase to separate and observe the primary preadipocytes. The preadipocytes were cultured and the growth curve was drawn. The preadipocytes were induced by insulin， dexamethasone and 3-isobutyl-1-methylxanthine， and the morphology of mature adipocytes was also observed by oil red O staining. The expressions of CNR1 and FABP4 genes were detected using real-time PCR method at different time of the adipocytes differentiation. The results showed that the preadipocytes were successfully isolated from the longissimus dorsi muscle of lamb， and the adherent cells were shown to be spindle shape. The formation of lipid droplets were observed in the preadipocytes stained with oil red O， which showed the characteristics of adipocytes. The relative expression levels of CNR1 and FABP4 genes were lower at the early stage of differentiation， then gradually increased at the middle and late stage. There were no significant differences in relative expression level of CNR1 and FABP4 on the 2^nd， 4^th and 8^th day， but the relative expression level of FABP4 was significantly higher than that of CNR1 on the 12^th day. It showed that CNR1 and FABP4 genes showed different expression characteristics in ovine intramuscular fat cells， which provided reference data for further revealing the regulatory relationship between two genes of intramuscular fat deposition and improving ovine meat traits.

Estimating of Wheat Ears Number in Field Based on RGB Images Using Unmanned Aerial Vehicle

Yinyan GAO, Yi SUN, Baochun LI

2022, 24(3): 103-110. DOI: 10.13304/j.nykjdb.2021.0335

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Ears number per unit area is the key element of wheat yield， so estimating ears number in field quickly and accurately based on aerial photographs and information extraction could provide the direct support to wheat growth monitoring and production estimates. This study acquired the unified standard and high resolution RGB aerial photographs using unmanned aerial vehicle （UAV） controlled by fragmentation monitoring and analysis with aerial photography （FragMAP）， then obtained the training model by quick and efficient target detection method （YOLOv3） and realized identifying wheat ears automatically， and finally established the estimation model of wheat ears number based on the relationships of the wheat ears number measured by proposed method （FY） and traditional methods. The results showed that the sampling efficiency and monitor area of FY were significantly higher than that of traditional method； the mean accuracy rate of identification based on YOLOv3 model was above 90%； the wheat ears numbers measured by FY and traditional method were significant linear correlation， and the estimate model was established as y=0.816x-14.863 （R²=0.790， P<0.001）. The results showed that the wheat ears estimation based on the unified standard and higher resolution images collected by UAV and deep learning was accurate， and could effectively monitor wheat growth and predicting the wheat yield.

Identification of Mango Planting Regions in Huaping County， Yunnan Province Based on Sentinel⁃2 Images and MaxEnt Model

Guanyue ZHAO, Qin LIU, Peihao PENG

2022, 24(3): 111-119. DOI: 10.13304/j.nykjdb.2021.0409

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Huaping county of Yunnan province is one of the main mangos producing areas in China， and has vigorously developed mango planting and peripheral industries in recent years， which has promoted the rapid development of local agriculture and tourism. In order to plan and control manage mango planting areas in a more scientific and efficient way on the spatial scale， this study used multi-temporal sentinel-2 remote sensing images to build a variety of vegetation indexes， combined with the auxiliary terrain factors and the point data of mango planting areas that had been put into production obtained from field survey， and MaxEnt model was used to classify and identify the mango planting areas in Huaping county. Finally， binarization classification and accuracy evaluation of the predicted results were carried out according to different thresholds. The results showed that the highest threshold rule of binarization classification accuracy was 10 percentile training presence， the corresponding threshold was 0.257， and the overall classification accuracy was 93.72%. Under this threshold， the estimated area of mango planting area putting into production was about 1.07×10⁴hm²， which was close to （1.13~1.20）×10⁴ hm² of mango planting area putting into production in Huaping county during the research period. Therefore， the combination of vegetation indexes and terrain factors selected in this study achieved good results in the application of identification of mango planting areas by MaxEnt model， which provided some references for similar research and application in other areas， and provided some data references and decision supports for the development and planning of mango planting industry.

Measurement and Analysis on Suspension Velocity of Aquaculture Pellets Feed

Kaiyi SHAO, Zhiyou NIU, Chongyang YU, Wentao WU

2022, 24(3): 120-129. DOI: 10.13304/j.nykjdb.2020.1036

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In order to obtain suspension velocity parameters of aquaculture pellets feed， the suspension velocity of extruded feed and pellet feed was measured by using self-designed suspension velocity measuring instrument. At the same time， the effects of particle size（1~4 mm）and moisture content（5%~25%）on suspension velocity were analyzed by double factor equal repeated experiments and response surface method. The results showed that particle size and moisture content had significant effects on the suspension velocity of extruded feed and pellet feed， and the effect of particle size was more significant than that of moisture content， but the interaction of particle size and moisture content had no significant effect on suspension velocity. Suspension velocity of extruded feed and pellet feed increased with the increase of particle size and moisture content. Besides， taking the R² and CV as the evaluation indexes， the cubic model for the suspension velocity of extruded feed was best， with the R² of 0.993 1； 2FI model for suspension velocity of pellet feed had the best effect， with the R² of 0.959 1. After verification， the relative error range of the suspension velocity prediction model of extruded feed and pellet feed wass ±5.4% and ±6.1%， which indicated that the prediction model was reliable. The experiment results provided reference and basis for the design of pneumatic automatic feeding device， pneumatic conveying device and sorting device.

Design and Experiment of a Two-Stage Segmented Drum Screening Device for Black Soldier Fly Insect Sand

Qin FANG, Shisheng SONG, Ting ZHOU, Caiwang PENG, Songlin SUN, Haiying ZHU

2022, 24(3): 130-139. DOI: 10.13304/j.nykjdb.2021.0673

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Aiming at the problems of high impurity rate and high loss rate of black soldier fly larvae during the sorting process of black soldier fly insect sand， combined with the mechanical and physical characteristics of black soldier fly insect sand， a black soldier fly insect sand separation device was designed. The device was mainly composed of two-stage drum screen， sprocket and motor. Taking drum speed， drum inclination angle， and feeding amount as the test factors， impurity rate and loss rate as evaluation indexes， a three-factor three-level orthogonal test was designed to study the influence of each factor on the screening performance of the black soldier fly insect sand with a water content of 30.2%. The results showed that the order of the factors to impact the impurity rate was the feed amount， the drum speed and the drum inclination angle； the order of the factors to the loss rate was the drum speed， the feed amount and the drum inclination angle. Using Design-Expert software analysis， the best combination of the factors was obtained as follows： the drum speed was 30 r·min^-1， the drum inclination angle was 7°， and the feed amount was 1.6 t·h^-1， the impurity rate was 1.109%， and the loss rate was 8.430%. The results of verification test showed， the impurity rate was 1.165%， the loss rate was 8.877%， which was basically the same as the verification test results. The research results provided reference for the design of black soldier fly insect sand screening equipment and optimization of operating parameters.

Inhibitory Effect of Nano-Mg（OH）₂ with Different Morphology on Pathogen Mango Phoma Leaf Spot

Dingyang ZHANG, Saifei QIU, Wenhua RAO, Xueping GUO, Fang CAO, Tianyun ZHAI, Xiong GUAN, Xiaohong PAN

2022, 24(3): 140-147. DOI: 10.13304/j.nykjdb.2021.0977

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Mango phoma leaf spot is a severe leaf disease that caused yield and quality reduction. Nano-Mg（OH）₂ is widely used in antibacterial field because of simple preparation， environmental friendliness， and wide antibacterial spectrum. Through morphological observation and sequence analysis of ITS-rDNA as well as phylogenetic comparison， the isolated pathogen was identified as mango phoma leaf spot which belonged to Diaporthe musigena. In this study， 3 different morphologies nano-Mg（OH）₂ was synthesized and named as MHNPs-MgO600， MHNPs-MgO80， and MHNPs-MgCl₂， respectively. X-ray powder diffraction （XRD） and Scherrer equation were used to calculate the sizes of nano-Mg（OH）₂ at （101） direction， which were 60.50， 11.63， and 13.52 nm， respectively. They were characterized by scanning electron microscopy， specific surface area analyzer， and Zeta potential analyzer， and the results showed that the 3 kinds of nano-magnesium hydroxide were regular flakes， petals， and hexagons， and there were great differences in specific surface area and surface charge. The inhibition rate of nano-Mg（OH）₂ against pathogen was calculated by plate coating method， the result suggested that 3 types of nano-Mg（OH）₂ had inhibiting effect， and the MHNPs-MgO80 manifested the best inhibition effect owing to its maximum specific surface area and minimum potential. Furthermore， with an increase in concentration， the inhibiting effect was more obvious. This study compared the inhibitory effect of different nano-Mg（OH）₂ on pathgen of mango phoma leaf spot， with specific surface area and Zeta potential as the factors affecting the inhibition effect of nano-Mg（OH）₂ on pathogenic bacteria. The findings of this study provide scientific basis and technical support for the selection of efficient and environmentally friendly nano magnesium hydroxide antifungal agents.

Identification of the Pathogen of Chinese Chestnut Yellow Crinkle and Its Control

Wenjie YANG, Xiaolei WEN, Lina FENG, Nana ZHANG, Weiming SUN, Huixia QI

2022, 24(3): 148-156. DOI: 10.13304/j.nykjdb.2021.0603

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To identify the pathogen of Chinese chestnut yellow crinkle （CnYC） and explore an effective comprehensive prevention and control technology， the pathogen was identified by the combination of morphology and molecular biology and agricultural antibiotics were screened by hanging bag infusion perforated in the field. The results showed that the pathogen causing Chinese chestnut yellow crinkle was Candidatus Phytoplasma castaneae belonged to 16SrXIX-A subgroup， and the strain number was CnYC-Hebei； the tetracycline hydrochloride showed the best control effect on CnYC， and its control rate was 85.3%. The control technology included as follows： tetracycline hydrochloride was infused into the diseased plant of CnYC in pre-deciduous stage， the diseased branches were pruned after defoliation stage， brassinolide and foliar fertilizer were sprayed on the leaves at the leaf development stage， and stinging insects were trapped and killed in growth stage. The control rate of comprehensive prevention and control technology reached 86.4%， the single fruit weight was 8.1 g， the full fruit rate was 91.9%， the chestnut size was 49.3 mm×42.3 mm， and the leaf size was 18.1 mm×7.5 cm. The indicators were all significantly better than the control group （P<0.05）. This technology not only effectively controled the disease， but also restored the production of diseased trees， which provided an effective comprehensive prevention and control technology for CnYC.

Research and Application Prospect of Quinoa Cultivation Technology

Tianming QI, Zhijian LI, Peiyou QIN, Guixing REN, Bangwei ZHOU

2022, 24(3): 157-165. DOI: 10.13304/j.nykjdb.2021.0190

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Quinoa is an annual dicotyledonous plant of the genus quinoa， which originated in the Andes Mountain of South America. It has become an important new crop of food and feeding in China after introduction. At present， quinoa has been mainly planted in Qinghai-Tibet Plateau， Yunnan-Guizhou Plateau， North China Plain， Northeast Plain， Northwest China and Central China. Due to different geographical location and climate characteristics， its cultivation measures and the threat of diseases and pests are also different. In view of the wide range of quinoa planting areas， the confusion of cultivation techniques and the diversity of planting problems in China， this paper summarized the relevant cultivation techniques of different quinoa planting areas in China， and systematically elaborated the current situation of quinoa cultivation in China from the aspects of planting measures， field management， pest control and so on. The existing problems and future development prospects were proposed. According to the actual situation， all regions should fully tap the potential of quinoa production combined with respective ecological characteristics， which provided reference for further promoting the rapid development of quinoa industrialization in China.

Effect of Long-term Straw Returning on Soil Organic Carbon Fractions Composition in Rice-Wheat Rotation Ecosystem

Linlin DONG, Jinfang ZHA, Mingxing SHEN, Haihou WANG, Linlin SHI, Yueyue TAO, Xinwei ZHOU, Changying LU

2022, 24(3): 166-175. DOI: 10.13304/j.nykjdb.2020.0545

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In order to study the effect of long-term straw returning on content of soil organic carbon （SOC） in Taihu Lake rice-wheat rotation region， based on 10 years field positioning experiments， 4 treatments were set including no rice straw+all wheat straw returning （W）， all rice straw+no wheat straw returning （R）， half of rice straw and wheat straw returning （HRW） and all rice straw and wheat straw returning （ARW）， and no straw returning was control （CK）. The contents and components of SOC in different treatments were determined. The results showed that straw types and returning amounts significantly influenced the contents and compositions of SOC in rice-wheat rotation system. Compared with 2007， the growth rates of SOC， heavy fraction organic carbon （HFOC） and light fraction organic carbon （LFOC） were 0.18~0.46， 0.15~0.42 and -0.03~0.02 g·kg^-1·a^-1， respectively； the content of SOC and HFOC significantly increased in R， HRW and ARW treatments， and the carbon contents in light fraction organic matter （LFOM-C） decreased significantly in all treatments， which the decreased range of ARW treatment was more than other treatments. HFOC was the main component and accounted for more than 80% of SOC in all treatments， which the proportions of HFOC increased in W and HRW and decreased in CK， R and ARW treatments. Straw returning reduced the relationship between rice yield and the contents of SOC or components， and LFOC had more influence on rice yield than HFOC. In conclusion， all amount of rice and wheat straw returning could increase the content and stability of SOC， which could be considered as an ideal straw returning model in Taihu Lake region.

Effects of Water and Fertilizer Coupling on the Physical and Chemical Properties of Rice Soil and Yield Based on Soil Organic Reconstruction

Zhenjia HE, Wangtao FAN, Yichun DU, Qilong WANG

2022, 24(3): 176-185. DOI: 10.13304/j.nykjdb.2020.0850

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In order to study the effects of water and fertilizer coupling on soil physical and chemical properties and rice yield in organically reconstituted soil， the organically reconstituted soil at Xiayukou of Hancheng in Shaanxi was experimental field， and nine treatments were set including 3 irrigation levels including high water 4 500 m³·hm^-2 （W1）， suitable water 3 750 m³·hm^-2 （W2）， water saving 3 000 m³·hm^-2 （W3） and 3 fertilization levels induding high fertilizer 162 kg·hm^-2 （F1）， medium fertilizer 135 kg·hm^-2 （F2） and low fertilizer 108 kg·hm^-2 （F3）. The physical and chemical properties of soil and the growth and yield of rice were determined in different treatments. The results showed that the content of total porosity， macro-aggregates， water-stable aggregates and micro-aggregates in soil treated with W2F1 were higher with 48.16%， 92.42%， 28.47% and 3.52%， respectively； the soil pH and electrical conductivity were lower with 7.8 and 173 μs·cm^-1， respectively， which had a better effect on improving physical properties of soil. The contents of organic matter， NH $4 +$ -N， available phosphorus and available potassium of soil in W2F2 treatment were 14.35 g·kg^-1， 37.32 mg·kg^-1， 19.62 mg·kg^-1 and 145.64 mg·kg^-1， respectively， which were all at high levels. So， the number of ears per square meter， 100-grain weight， theoretical yield and actual yield were the highest in W2F2 treatment， which were 352 m^-2， 2.03 g， 30.82 kg·hm^-2 and 25.28 kg·hm^-2， respectively. And the net income of W2F2 treatment reached 9 506 yuan·hm^-2， and the input-output ratio was 0.63， which was the smallest. Based on economic benefits， the W2F2 treatment was the most productive treatment under the experimental conditions， which provided theoretical reference for the application of soil organic reconstruction technology.

Effect of Different Planting Densities and Patterns on Population Structure and Yield of Cyperusesculentus

Peng ZHONG, Lili MIAO, Jie LIU, Jianli WANG, Haiyan LU, Hongjiu YU, Nan ZHANG

2022, 24(3): 186-196. DOI: 10.13304/j.nykjdb.2021.0001

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In order to study the effects of different planting densities and patterns on population structure and yield of Cyperusesculentus， Heiyousha 1 was used as material in 2017—2018. Split plot design was used， which planting density were as main plot with 9×10⁴（A1）， 11×10⁴（A2）， 13×10⁴ plants·hm^-2（A3）； and planting pattern was split plot including 110 cm ridge with three lines （B1）， 65 cm ridge with two lines （B2）， 45 cm ridge with one line （B3）. Growth index， leaf area index （LAI）， percent transimission， chlorophyll content， net photosynthetic rate of leaves， biomass and yield of different treatments were measured. The results showed that the planting densities and patterns had significant effects on plant growth， photosynthetic efficiency of leaves and yield. LAI reached maximum value at late stage of tuber growth under A1 treatment， and reached the maximum value at middle stage of tuber growth under A2 and A3 treatments. Chlorophyll content in canopy and lower leaves of different density treatments reached the maximum at late， middle and formative stages of tuber formation， respectively. Among all treatments， chlorophyll contents and net photosynthetic rates in the canopy and lower leaves of A2B1 treatment were the highest at middle stage of tuber growth. Among all treatments， the yield of A2 treatment （7 469.81 kg·hm^-2） was significant higher than other treatments. In conclusion， reasonable density combined with wide-narrow row planting was an important way to optimize population structure and increase yield， which provided theoretical basis for further improving yield of Cyperusesculentus in cold region.

Effect of Different Fertilizer Applications on Yield， Quality and Economic Benefit of CoffeaArabica L.

Yunping DONG, Yuzhou LONG, Xingjun LIN, Lizhen MO, Huakang ZHU, Qingyun ZHAO, Yan SUN

2022, 24(3): 197-203. DOI: 10.13304/j.nykjdb.2020.0907

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In order to optimize fertilizer application of coffeaarabica in Yunnan， 5 treatments were set up including T1（N 33.75+P₂O₅ 8.7+K₂O 36.45 kg·hm^-2）， T2（N 67.5+P₂O₅ 17.25+K₂O 72.75 kg·hm^-2）， T3（N 135.00+P₂O₅34.5+K₂O 145.5 kg·hm^-2）， T4（N 202.5+P₂O₅ 51.75+K₂O 218.25 kg·hm^-2） and T5（N 236.25+P₂O₅60.3+K₂O 254.55 kg·hm^-2）. The yield， bean quality （100-beans weight， bean density and bean size） and economic benefits under different fertilization treatments were studied. The results showed that the yields increased firstly and then decreased with the increase of fertilizing amount， and yield of T4 treatment was the highest. The 100-beans weight and the bean size increased by increasing the fertilizer， while there were no difference in the ratio of cherry to green bean and the bean density among different fertilizer treatments. The bean density was negative correlation with the bean size. The yield and the ratio of cherry to green bean in 2018 and 2019 were significantly higher than those in 2020，which were due to the long term dry weather during fruit development stage. Economic benefit of T2 treatment with 50% fertilizer reduction was the highest with 19 237.67 yuan·hm^-2. In conclusion， T2 treatment was the most economical and effective fertilization scheme with higher yield and lower cost of fertilizer， which provided theoretical reference for saving cost and increasing economic benefit of coffee production.

Effects and Mechanism of Indoleacetic Acid on the Removal of Nitrogen and Phosphorus from Water by Peripheral Organisms

Chenchen SUN, Lan MA, Yonghong WU, Yuanchun YU

2022, 24(3): 204-209. DOI: 10.13304/j.nykjdb.2021.0109

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In order to explore the effects and mechanism of the sequence and concentration of adding indoleacetic acid on the removal of nitrogen and phosphorus from the water by peripheral organisms， the artificially cultivated peripheral organisms were as the research object， and the peripheral organisms that had been pre-cultured with indoleacetic acid （pretreatment group） and those that have not been pre-cultured with indoleacetic acid （control group） were cultured in nitrogen and phosphorus sewage with different concentrations of indoleacetic acid （0， 5 and 10 mg·L^-1）. The results revealed that the addition of indoleacetic acid improved the removal efficiency of nitrogen and phosphorus by peripheral organisms. In control group， the removal rates of NH $4 +$ -N and PO $4 3 -$ -P by peripheral organisms added with 5 mg·L^-1 indoleacetic acid were 99.9% and 95.0%， respectively， on the 2^nd day， and the removal rate of NO $3 -$ -N was 99.0% on the 7^th day， whose removal rates were faster 2 d than those of^{pretreatment group. Indoleacetic acid changed the microbial community structure of peripheral organisms with the total composition of phospholipids fatty acids decreasing， the number of bacteria， actinomycetes and gram-positive bacteria （G⁺） increasing， chlorophyll fluorescence F_t reducing and pH increasing. In conclusion， the addition of indoleacetic acid could promote the growth of algae in peripheral organisms and improve the removal efficiency of nitrogen and phosphorus by periplexus organisms.}

Effect of Ventilation Rate on Treatment of Meat Duck Manure by Ectopic Fermentation System

Jinzhi MA, Zhiping ZHU, Lianshui LU, Wanqin ZHANG

2022, 24(3): 210-217. DOI: 10.13304/j.nykjdb.2020.0895

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To explore the effect of different ventilation rate on the treatment of meat duck manure by an ectopic fermentation system， the sawdust： rice husk （6：4） volume ration had been used as the initial bedding material for fermentation， and 3 treatments （A1，A2，A3） of the ventilation rates were set as 0.02， 0.05 and 0.10 m³·min^-1·m^-3. Quantified duck manure was daily added into the ectopic fermentation device. The physical and chemical indicators and maturity of the litter were monitored within 38 d fermentation process. The results showed that temperatures under A1，A2 and A3 were 49.98， 51.29 and 49.36 ℃， respectively； and the oxygen consumption rates were 0.20%，0.26% and 0.24%·min^-1. During the test， the pH of the 3 treatments were maintained at 7.05～8.10， and the moisture contents were 50%～70%， all of which could provide a suitable environment for the growth and reproduction of microorganisms. At the end of the test， the GI of the 3 treatments were above 95%， fecal coliform was not detected， hatched from eggs mortality was 100%， and the heavy metals of Cu and Zn did not exceed the standard， which met the safety requirements. There were no significant differences on contents of total nitrogen， P₂O₅，_{K₂O， and organic matter between different ventilation rates. Based on the indicators introduced above， ventilation rate of 0.05 m³·min^-1·m^-3 was the best for the treatment of meat duck manure with the ventilation interval of 5 min and 10 min.}

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