Table of Content

01 April 2023, Volume 25 Issue 4

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AGRICULTURAL INNOVATION FORUM

Current Situation and Countermeasures Analysis of China’s Crop Seed Industry

Lingbo KONG, Qiao LIN, Yingli NIE, Jingjing WANG, Hong WEI

2023, 25(4):  1-13.  DOI: 10.13304/j.nykjdb.2022.0507

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Crop seed industry is a national strategic and basic core industry， which is the foundation for promoting the long-term stable development of China’s agriculture and ensuring the national food security. In order to comprehensively study the development status of China’s crop seed industry， there were three dimensions of seed industry had been analyzed， including the seed industry policy， enterprise competitiveness and the supply and demand status of superior seed production. The key points of policy support in crop seed industry were summarized， the core competitiveness of leading enterprises was shown and the advantage had been contrasted with international seed enterprises. Meanwhile， the industrialization characteristics of two superior seed were analyzed， such as hybrid maize and hybrid rice. Based on the content of analyzed， the problems in the development of China’s crop seed industry were summarized. The countermeasures and suggestions put forward for establishing a financial security system， strengthening the protection and utilization of germplasm resources， accelerating the innovation of breeding technology， promoting the joint breeding of science and enterprises， and improving the legal and regulatory system， which would provide reference for the innovation and development of China’s crop seed industry.

Research Progress on Innovation and Utilization of Livestock and Poultry Germplasm Resources

Zifeng GUO, Lei HUANG, Kui LI

2023, 25(4):  14-22.  DOI: 10.13304/j.nykjdb.2022.0744

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Livestock and poultry germplasm resources are the basis of germplasm innovation. It is a great significance to improve the core competitiveness of Chinese animal husbandry in the international market， increase farmers’ income， and realize the sustainable development of animal husbandry by independent cultivation of good seed lines with excellent traits and stable inheritance. The innovation of livestock and poultry germplasm resources is to optimize the germplasm characteristics through modern biological breeding methods， so that the breeding offspring can preserve more genetic information of good parental traits and enhance the economic value of livestock and poultry products. The utilization of livestock and poultry germplasm resources is mainly to supply human nutrition and production needs in the form of meat， milk， eggs and other livestock and poultry products. At present， Chinese germplasm resources are very rich， but there are still deficiencies in the innovation and utilization of germplasm resources. In this review， we summarized the basic situation and existing problems of the conservation and utilization of livestock and poultry germplasm resources， and breeding recommendations for new germplasm of livestock and poultry was expounded. On this basis， it was prospected the breeding goal， breeding considerations and industrial development of new germplasm of livestock and poultry. We hope to provide suggestions for the subsequent breeding of livestock and poultry breeds and the rational utilization of various livestock and poultry germplasm.

BIOTECHNOLOGY & LIFE SCIENCE

Research Progress in Regulation and Efficient Production of Microbial Surfactin Synthesis

Qing LIU, Bo LIU, Xinxin XU, Hongbing ZHANG, Yuhong ZHANG, Wei ZHANG

2023, 25(4):  23-31.  DOI: 10.13304/j.nykjdb.2022.1020

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Surfactin is a kind of lipopeptide produced by the secondary metabolism of microorganisms of Bacillus， which has a variety of biological activities with a broad application prospect in many fields such as food， medicine， daily chemical， oil extraction and biological defense. However， the low production efficiency and high production cost of natural strains of Bacillus sp. have severely limited the practical application of surfactin. The structural properties， application effects and regulation of the microbial surfactin on synthesis pathway were briefly described. Several strategies for increasing the yield of microbial surfactin were emphatically reviewed， and the prospects of its efficient production and application was also prospected.

Effects of Row Space Reduction and Plant Space Expansion on Tillers Number in Wheat and Its Physiological Mechanism

Pan LIU, Shan GAO, Haoyu LI, Yi WANG, Baozhong YIN, Jinkao GUO, Wenchao ZHEN

2023, 25(4):  32-44.  DOI: 10.13304/j.nykjdb.2023.0235

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In order to clarify the effect of row space reduction and plant space expansion （RRPE） on the tillering of winter wheat and its physiological mechanism， ‘Malan 1’ was used as test variety during the winter season from 2019 to 2021. The effects of RRPE treatment on the tillers number and biomass of wheat in the pre-winter stage were studied by setting two row spacing and three sowing dates， and the response characteristics of phytohormones and saccharose （SA） in tillers nodes to RRPE were studied. The results showed that RRPE significantly promoted the tillers number （TN） and biomass of wheat during pre-winter stage，with the average increase 14.5% and 20.9%， respectively， and increased the TN with more than three leaves. RRPE reduced the contents of indoleacetic acid （IAA）， strigolactones （SLs）， gibberellin （GA）， and brassinosterol （BR） in wheat tillers nodes from the trifolium stage to the wintering stage， with decreases of 19.4%， 17.5%， 11.4% and 13.6%， respectively. RRPE treatment significantly increased the content of zeatin nucleoside （ZR）， cytokinin （CTK） and saccharose （SA）， which increased by 13.1%， 54.4% and 15.2%， respectively. RRPE processing also reduced IAA/ZR， BR/SL and BR/CTK， but improved SLs/GA. The correlation coefficient between CTK， BR and tillers number in pre-winter were the highest with average 0.65. BR had the highest positive contribution to TN， while GA and BR/CTK had higher negative contributions to TN. The negative contributions of IAA/ZR through GA and IAA through GA to TN were relatively high. In conclusion， RRPE could promote wheat tillering and increase biomass before winter， which was most closely related to BR and GA contents， as well as the direct effects of BR/CTK， and the indirect effects of IAA/ZR through GA and IAA through GA.

Grain Filling Characteristics of Fresh Waxy Maize at Different Sowing Dates and Its Relationship with Meteorological Factors

Hailong WEI, Yi CHENG, Bi SONG, Jun ZOU, Jin ZUO, Lei LI, Jun ZHANG, Dailing LIU, Tao ZENG, Jingfeng FU, Sheng WEI

2023, 25(4):  45-55.  DOI: 10.13304/j.nykjdb.2022.0735

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To investigate the effect of sowing date on the grain-filling characteristics of fresh waxy maize and its relationship with meteorological factors，a 2-factor split-zone experiment were set to study the grain-filling properties of fresh maize under different sowing periods， using three varieties namely ‘Wannuo 2000’‘Nongkenuo 336’ ‘Caitiannuo 6’ as the material and setting six sowing periods（B1~B6）. The results showed that with the delay of sowing， the fertility period of fresh waxy maize shortened， and the seed weight， active grain filling period， and filling eventually period showed a trend of increasing and then decreasing， with maximum values at sowing B4 （17.32 g 100-grain^-1， 21.84 and 34.94 d）. Grain dry matter accumulation was highly significantly correlated （P<0.01） with maximum filling rate， average filling rate， grain weight at maximum filling rate， and significantly with the active grain filling period， duration of filling （P<0.05）. The average filling rate， grain weight at maximum filling rate， and grain dry matter accumulation were significantly influenced by the main meteorological factors during the filling period， in the following order average daily temperature > sunshine hours > effective cumulative temperature > rainfall， and they all increased with the increase of average daily temperature， sunshine hours and effective cumulative temperature during the filling period， and were positively correlated when the rainfall during the filling period was less than 160 mm and negatively correlated when it was more than 160 mm. With the appropriate delay in sowing， there was a longer active grain filling period and duration of filling， faster average filling rate， higher average daily temperature， cumulative temperature， and suitable rainfall during the grain filling period. Therefore， sowing fresh maize from 9 April to 19 April in central Guizhou was more conducive to grain filling and dry matter accumulation for higher yields. The results could be used as an important reference for determining the suitable sowing date of fresh waxy maize in the central region of Guizhou for high-yield and efficient cultivation.

Quality Comparison and Comprehensive Evaluation of Different Zingiber officinale Rosc. Varieties

Xiangdong WANG, Yue SONG, Yanzhi MA

2023, 25(4):  56-66.  DOI: 10.13304/j.nykjdb.2022.0249

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In order to compare the quality of different ginger varieties， 8 ginger varieties were selected as materials and planted in experimental field in Tangshan of Hebei province， the rhizomes were reserved during harvest. The study measured the quality indexes and yield， and analyzed the membership function of each index， then evaluated their nutritional qualities. The results showed that the different ginger varieties had different quality performance in Tangshan area. ‘Jijiang 1’ had the highest soluble protein content， and ‘Jijiang 18’ had the highest polyphenol content. ‘Shandong Changyi big ginger’ had the highest content of soluble sugar， polysaccharide， curcumin， curcumin， flavonoids and vitamin C. The comprehensive evaluation of membership function showed that the order of ginger qualities in Tangshan area from high to low was ‘Shandong Changyi big ginger’>‘Jijiang 18’>‘Jijiang 7’>‘Jijiang 1’>‘Anhui Tongling ginger’>‘Jijiang 5’>‘Jijiang 2’>‘Shandong wawa ginger’. The varieties with high yield were ‘Shandong Changyi big ginger’， ‘Jijiang 5’ and ‘Jijiang 2’. The results provided theoretical basis for the breeding， development and utilization of new varieties in Hebei.

Identification and Expression Analysis of NAC Gene Family Under Low Temperature in Allium sativum L.

Yiwei YAN, Jie TIAN

2023, 25(4):  67-76.  DOI: 10.13304/j.nykjdb.2021.0794

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To dig up the members of NAC family of transcription factors in Allium sativum L. and discuss the different expression in low temperature stress，NAC transcription factors were identified based on the result of transcriptome sequencing， and the different expression was analyzed. The results showed that 49 members of NAC gene family were screened in Allium sativum L.， which were divided into 10 subfamilies. The length of sequences varied and ranged from 81 to 613 aa， and the molecular weights were 9 293.6~70 229.04 Da. The total average hydrophobic index were less than 0， which indicated all the NAC proteins were hydrophilic proteins. According to the analysis of conserved domain， most of them had conserved N-terminal， of which 18 NAC proteins had motif 3， motif 4， motif 1， motif 2， and motif 5 conserved domains at the N-terminu. AsNAC001， AsNAC010， AsNAC013， AsNAC014， AsNAC017 and AsNAC047 were randomly selected for predicting secondary and tertiary structures， and the results showed the random coil was the main component， and the alpha helix and extended strand were followed， which meant NAC proteins were highly similar to each other. The real-time fluorescence quantification showed 4 genes containing AsNAC001， AsNAC010， AsNAC013 and AsNAC014 were significantly upregulate expression under low temperature stress 12 and 24 h， while 2 genes containing AsNAC017 and AsNAC047 were significantly down-regulate expression under low temperature stress 4 h. Among them， the expression level of AsNAC010 gene was significantly higher than others. All the results indicated that the NAC transcription factors played an important role in responsing to low temperature stress of Allium sativum L.， which provided a theoretical foundation for further study on physiological regulation function of NAC genes in Allium sativum L..

Effects of Red-blue LED Bight Supply Modes on Growth and Quality of Purple Leaf Lettuce Under Continuous Light

Mingjie SHAO, Yanqi CHEN, Wenke LIU

2023, 25(4):  77-85.  DOI: 10.13304/j.nykjdb.2021.0927

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In order to explore the effects of red and blue light supply mode of light emitting diode （LED） under continuous light （CL） on the growth， yield and quality of purple leaf lettuce， six treatments were set in the artificial light plant factory. Two conventional illumination treatments with constant spectral photon flux density （SPD） were set， one group maintained the photoperiod （RB， 16 h/8 h） and the other group began to receive CL （RB’， 24 h/0 h）. In addition， four CL treatments with regular changes of SPD， in which two staggered light treatments were alternately illuminated once and twice with blue light， red-blue light （4R： 1B） and red light in the order of 24-hour light period （S1 and S2）； blue light and red light were alternately irradiated once and twice， respectively （A1 and A2）. The CL treatments had same quantum numbers of red and blue light with the spectral light intensity 200 μmol·m^-2·s^-1. The growth， yield and quality of lettuce under different treatments were determined. The results showed that continuous light significantly increased the yield of lettuce， and the treatments of alternating red and blue light had the most obvious effect on the shoot biomass of lettuce. The alternating and temporally overlapped light treatments significantly increased the contents of hydrogen peroxide， superoxide anion and malondialdehyde， but did not cause serious photo oxidative stress， and increased the activities of antioxidant enzymes and the contents of anthocyanin and total phenols， however， the nitrate content in lettuce leaves was also increased by dynamic light. In conclusion， the effect of the treatment alternately irradiated twice with red and blue light was the best.

Effect of Thermal Environment on Tartaric Acid Degradation of ‘Italian Riesling’ Wine Grape in Hexi Corridor

Yanfang ZHANG, Yanfang ZHU, Yan HAO, Yu’an WANG

2023, 25(4):  86-99.  DOI: 10.13304/j.nykjdb.2022.0314

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Tartaric acid is the main contributor to the acidity of wine. Due to the rapid temperature rise， high effective accumulated temperature and short frost free period in the grape wine producing area of Hexi corridor， the tartaric acid in grape fruit degrades too fast. In order to explore the main degrdation period of tartaric acid， we took ‘Italian Riesling’ as the research sample in Wuwei， Gansu province to analyze the influence of the changes of temperature， humidity， light， solar radiation and ground temperature on the change of tartaric acid content in grape berry fruits at the rapid long-maturity stage. The results showed that the tartaric acid content of ‘Italian Riesling’ grape decreased first and then increased slowly in the long-term ripening period of grape berries. In the color transformation stage， tartaric acid content decreased sharply from 14.67 to 6.59 mg·g^-1. Through correlation analysis， the daily cumulative hours of sunshine， daily average temperature， daily minimum temperature， daily average ground temperature of 5， 10， 15， 20 cm were the key factors affected tartaric acid in fruits. The diurnal variation of tartaric acid in ‘Italian Riesling’ fruit showed a trend of increasing first and then decreasing. In the long-term ripening period of grape berries， the content of tartaric acid reached the peak at 13∶00 in a day and night， and reached the peak at 21∶00 in the fruit maturity period. During the diurnal growth and development of the fruits， the degradation time of tartaric acid was mainly from 13∶00 to 1∶00 in the morning of the next day. Through correlation analysis， the diurnal variation of tartaric acid was related to air temperature， daily average ground temperature of 5， 10， 15， 20， 40 cm and 40 cm soil humidity，which showed a very significant positive correlation. In conclusion， the degradation of tartaric acid in ‘Italian Riesling’ grape fruit mainly occurred in the fruit color transition period， and mainly occurred in the afternoon in a day and night. The direct effects on tartaric acid content were the daily cumulative number of sunshine， daily average temperature， daily minimum temperature and 5—40 cm ground temperature. Therefore， this study provided a theoretical basis for slowing down the degradation of tartaric acid.

INTELLIGENT AGRICULTURE & AGRICULTURAL MACHINERY

Operational Optimization of CCHP Systems on Deep Reinforcement Learning Under Influence of Demand Charge

Wenzhong GAO, Yi ZHANG

2023, 25(4):  100-109.  DOI: 10.13304/j.nykjdb.2023.0121

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In the present time of global energy stress， the combined cold， hot and power （CCHP） system is gaining importance due to the advantages of energy cascade utilization and high primary energy utilization. However， due to the complex and variable influencing factors， especially the presence of the demand charge， the CCHP system is difficult to operate in real time with the existing control methods to meet the energy requirements on the customer side under economic objectives. To minimize operating costs with the demand charge， a control strategy optimization of the system based on the TD3 algorithm was proposed. The individual units of the system were modelled and the CCHP system operation optimization problem was transformed into a Markov decision problem， and solved using the TD3 algorithm. Then， the experimental verification analysis was carried out. The results showed that the TD3 agent with demand charge balanced the demand charges and real-time operating costs well， and was generalizable， which reduced the total operating costs by 41.5% and 8.6% compared to the historical operating strategy and the TD3 agent without demand charge， respectively. Above results provided a new solution for reducing the cost and improving the economics of agricultural energy supply.

Simulation and Optimization of Pneumatic Conveying System for Hybrid Rice Pollen Collection Device

Fenfang XIAO, Conghe ZHANG, Hui WANG, Yafeng YE, Daolin ZHANG, Heting WANG, Bo LI, Yuejin WU, Binmei LIU

2023, 25(4):  110-122.  DOI: 10.13304/j.nykjdb.2022.0048

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In order to solve the problem of mechanized and efficient collection of paternal pollen of hybrid rice， a hybrid rice pollen collection device was designed and the pneumatic conveying system was simulated and optimized. Firstly， the computational fluid dynamics-discrete phase model （CFD-DPM） was established for pneumatic conveying system. Furthermore， the CFD-DPM and the response surface method were combined to optimize and verify the system，which took the inner diameter of the tube， the length and width of the inlet as factors，and the air flow uniformity and total pressure difference as indexes. The results showed that the inner diameter， the length of the inlet，the width of the inlet， the interaction of inner diameter and length， and the interaction between length and width had significant effects on the airflow uniformity and total pressure difference in the system.The two indexes increased with the increase of the inner diameter， the uniformity of powder absorption first increased and then decreased with the increase of length and width， and the total pressure difference increased with the increase of length and width. The optimal parameter combination of pneumatic conveying system was 200.00 mm inner diameter， 564.40 mm length and 192.48 mm width. Simulation of the optimized system structure showed that the variable velocity and total pressure difference of airflow velocity were 16.03% and 238.37 Pa respectively. The relative errors were 4.91% and 3.39%， respectively. Compared with the initial structure， the two indexes were reduced by 56.29% and 31.57% respectively， indicating that the optimization effect was obvious. This study provided a method for rapid optimization design of pneumatic conveying system of hybrid rice pollen collection unit， and the results could provide reference for optimization design of pneumatic conveying system of hybrid rice pollen collection unit.

ANIMAL AND PLANT HEALTH

Comparison of Resistance of Several Chestnut Varieties to Alternaria alternata and Fungicide Screening in Laboratory

Jianing LI, Aixia LI, Jiahuan HUO, Lina FENG, Sirou GUO, Jianhua WANG, Xiaolei WEN, Weiming SUN, Huixia QI

2023, 25(4):  123-131.  DOI: 10.13304/j.nykjdb.2023.0015

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In order to clarify the resistance of different chestnut varieties to Alternaria alternata and screen out effective fungicides to inhibit the pathogen， the resistances of 14 chestnut varieties to A. alternata were identified by in vitro inoculation method. The resistance of different varieties was graded by incidence rate， average diameter of lesion and cluster analysis. The toxicities of 7 fungicides to A. alternata were determined by mycelium growth rate method. The results showed that the incidences and lesion diameters of ‘Yanshanduanzhi’ and ‘Dabanhong’ were 44.45%， 51.11% and 0.13， 0.20 cm after inoculation 9 d， respectively， while those of ‘Zunyu’ were 100% and 0.90 cm. Among the tested varieties， ‘Yanshanduanzhi’ and ‘Dabanhong’ had relatively strong resistance to A. alternata， while ‘Zunyu’ had relatively weak resistance to A. alternata. The results of fungicide screening showed that fludioxonil had the best inhibitory effect on A. alternata， which the inhibition rate and EC₅₀ were 93.75% and 69.94 mg·L^-1， respectively. Above results provided more references for screening high-quality disease-resistant varieties of chestnut in planting and carrying out field efficacy trials.

Simulation and Optimization on Ultraviolet LED Nutrient Solution Sterilization Module Based on Response Surface Method

Haochun KE, Kun LI, Ruifeng CHENG

2023, 25(4):  132-146.  DOI: 10.13304/j.nykjdb.2022.1068

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In order to reveal the influence of structural parameters on distribution of ultraviolet radiation in the ultraviolet LED nutrient solution sterilization （UV-NSS） module and optimize key structural parameters， the engineering software Tracepro was used to model and ray-trace the UV-NSS module. The inner diameter of tube， the thickness of tube wall， the tube-lamp distance and the bidirectional reflectance distribution function （BRDF） of the inner surface of light bar were the parameter factors， the effective UV radiation ratio （EURR） and the irradiance dispersion （ID） were the response. The results showed that when the UV-NSS module model had the tube inner diameter of 28 mm， the tube wall thickness of 2 mm， the tube-lamp distance of 4 mm， and the BRDF of 0， its EURR was 12.14%， ID was 0.320 6， and the difference between the simulated value and the measured value of ultraviolet irradiance was only 3.68%， which meaned that the model could accurately show the irradiance distribution in the module. Based on the model， the central composite bounded design was carried out， and the response surface method was used to analyze the quadratic regression equations of EURR and ID. Their determination coefficients were 0.962 0 and 0.967 8， respectively， which meaned the fitting was significant （P<0.05）. With the goal of maximizing EURR and minimizing ID， the optimal combination of parameter factors was determined with response surface method under the consideration of actual situation： the inner diameter of tube was 50 mm， the thickness of tube wall was 3 mm， the tube-lamp distance was 0.6 mm， BRDF was 0.55. After being substituted into model， its EURR and ID were 32.11% and 0.317 8， which increased and decreased by 164.50% and 0.87% compared with before optimization， respectively. Using these parameters to manufacture the UV-NSS module， the difference between the measured value and the simulated value of the ultraviolet irradiance was only 1.73%.

BIO-MANUFACTURING & RESOURCE AND ECOLOGY

Effects of Shading Treatment on Growth and Enzyme Activity of Bonsai Ganoderma lucidum

Xin JIN, Lu ZHANG, Peng WU, Ping LI, Wei TAN, Mingying GUI

2023, 25(4):  147-156.  DOI: 10.13304/j.nykjdb.2021.0782

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To explore the effects of shading treatment on the growth and development of bonsai Ganoderma lucidum and the contents of active components and related enzyme activities in fruiting bodies at different growth stages， ‘Bonjing Ganoderma lucidum 3’ was used as the experimental research strain， and shade nets of different densities were used to control the light intensity， with 0% （T0）， 50% （T1）， 70% （T2） and 90% shading rate （T3）. The agronomy characters and changes of polysaccharide of bonsai Ganoderma lucidum under different shading conditions were analyzed， and the contents of triterpenoid， soluble protein and the related enzyme activities in different growth stages were determined. The results showed that Ganoderma lucidum of T2 treatment appeared earlier， more number of primordia， golden yellow cap， bright color， glossiness and uniformity at the mature stage， which was better than other treatments with the highest polysaccharide content. Under T0 treatment， the lid diameter， thickness， stipe length and yield of Ganoderma lucidum fungus were the worst， with the lowest polysaccharide content and the highest soluble protein content. With the increase of the shading rate， the activity of ligninase in Ganoderma lucidum increased gradually， the activity of laccase was the lowest in the primordial stage， and the manganese peroxidase was the highest in the primordial stage. The activities of superoxide dismutase， catalase and peroxidase in Ganoderma lucidum of T2 treatment were significantly higher than other treatments. In conclusion， the light intensity not only affected the growth and development of Ganoderma lucidum， but also affected the contents of secondary metabolites and enzyme activities in Ganoderma lucidum. Natural light intensity had stress on Ganoderma lucidum， which stimulated the reactive oxygen species in Ganoderma lucidum and increased sharply the activities of antioxidant enzymes， indirectly reduced the catalytic activity of ligninase. Above results showed that 70% shading rate was in favour of the growth and development of bonsai Ganoderma lucidum.

Effects of Bio-organic Fertilizer Combined with Subsoiling on Farmland Soil Fertility and Crop Yield

Yanjun KE, Yumeng ZHANG, Yanjie GUO, Lijuan ZHANG, Zitao ZHANG, Yanzhi JI

2023, 25(4):  157-166.  DOI: 10.13304/j.nykjdb.2022.0203

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To study the effects of bio-organic fertilizer with deep loosening on soil fertility and crop yield， a field split-zone design was used， with three main zones of 0% （M0）， 10% （M1） and 20% （M2） of bio-organic fertilizer replacing chemical fertilizer N in winter wheat season， and two sub-zones of conventional tillage （P） and deep loosening tillage （S） in summer corn season， the soil physical and chemical properties， microbial load and crop yield were analyzed under different treatments. The results of the 2 years experiment showed that compared with conventional （M0P）， the soil capacity of bio-organic fertilizer replacing 10% and 20% of chemical fertilizer N with deep tillage decreased by 8.03% and 6.57%， respectively， and the content of water-stable macromolecules increased by 46.12% and 28.01%； pH decreased from 8.17 to 7.94 and 8.00. The soil organic matter， nitrate nitrogen， effective phosphorus and fast-acting potassium contents increased with the increase of bio-organic fertilizer replacement， and the effect of deep tillage on soil nutrient enhancement was not significant. Soil microbial carbon and nitrogen increased by 15.77% and 17.28% in wheat season and 66.49% and 55.30% in summer maize season， respectively； total crop yield reached 39 256 and 36 618 kg·hm^-2， increasing by 13.20% and 10.46% compared with the control treatment， respectively. In conclusion， the use of bio-organic fertilizer to replace 10%~20% of chemical fertilizer N in the winter wheat season in combination with the deep pine sowing in the summer maize season could improve the soil physicochemical properties， increase the microbial load and improve the crop yield， which could be used as an effective measure to improve the soil fertility enhancement of farmland in the North China Plain.

Effects of Chemical Detopping on Cotton Plant Growth in Guanzhong Cotton Region

Zhengran SUN, Cuiping ZHANG, Jinli ZHANG, Hao WU, Xiuyan LIU, Zhenkai WANG, Yuzhen YANG, Daohua HE

2023, 25(4):  167-177.  DOI: 10.13304/j.nykjdb.2021.0820

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To gain insight into the effect of chemical detopping on cotton in Guanzhong area， ‘Zhongmian 619’ and ‘Xinong 606’ were as materials， and a field experiment was conducted from 2019 to 2020. Using conventional manual detopping cotton as a control （CK）， two chemical detopping agents， mepiquat chloride compound and flumetralin compound， were studied. The plant height， plant width， number of sympodial branches， the length of upper sympodial branch in plant， bolls spatial distribution， cotton physiological activity， yield components and fiber quality were measured. The result showed that， compared with CK， the chemical detopping increased plant height， number of sympodial branches， number of bolls in the upper part of the cotton canopy， number of bolls per plant and seed-cotton yield， while decreased plant width and length of upper sympodial branches. Compared with CK， the activities of peroxidase and superoxide dismutone of T1 and T2 treatments increased significantly， but the malonaldehyde content decreased significantly. Among chemical detopping treatments， the effect of the mepiquat chloride compound was more significant. Among cotton varieties， spraying of chemical detopping agent had a greater effect on ‘Zhongmian 619’. In conclusion， chemical detopping modified the cotton plant architecture， improved the spatial distribution of cotton bolls， enhanced the anti-oxidation and anti-premature aging ability of cotton， and ultimately increased crop yield without significant decrease of fiber quality. Under the conditions of this experiment， the effect of mepiquat chloride compound was the most significant for ‘Zhongmian 619’.

Analysis and Comprehensive Evaluation of Content of Mineral Elements in Flowers of Different Tea Germplasm Resources

Shulin ZHENG, Yutao SHI, Feiquan WANG, Bangqiang WU, Yuanhua LI, Bo ZHANG, Naixing YE

2023, 25(4):  178-188.  DOI: 10.13304/j.nykjdb.2022.0228

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In order to evaluate the differences in the mineral nutrient quality of the flowers of different tea germplasm resources comprehensively， the contents of 18 mineral elements in 23 tea flower samples were determined by inductively coupled plasma optical emission spectroscopy （ICP-OES） and analyzed by correlation analysis， cluster heatmap analysis and principal component analysis. The results showed that there were abundant genetic variations among the 23 tea flower samples in the content of mineral elements. The coefficient of variation ranged from 11.86% to 48.96% and the genetic diversity index ranged from 1.19 to 2.19. Contents of K， Ca， Mg， P， S， Al， B， Ba， Cr， Cu， Fe， Mn， and Ti obeyed the normal distribution， contents of Na， Co， Ni and Zn obeyed positive skew distribution and content of Se obeyed negative skew distribution by W test. The 23 tea flower samples were divided into three groups by cluster heatmap analysis. According to the principal component analysis， the top five tea flower samples with higher comprehensive score of mineral nutrient quality were ‘Pingyangtezaocha’‘Bayutezao’ ‘Huangjinya’ ‘Mingshanzao 311’ and ‘Dahongpao’， which could be used as good materials for tea flower development and utilization. The results provided a scientific basis for the utilization of tea germplasms and product developing of tea flower.

Effects of Combined Application of Green Manure with Reduced Nitrogen Fertilizer on Yield and Quality of Flue-cured Tobacco

Wenjun ZHAO, Jizhou YANG, Mei YIN, Jianfeng CHEN, Kaizheng XUE, Baowen HU, Libo FU, Wei WANG, Zhiyuan WANG, Yanxian YANG, Hua CHEN

2023, 25(4):  189-196.  DOI: 10.13304/j.nykjdb.2021.0808

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In order to clear the appropriate amount of nitrogen fertilizer for flue-cured tobacco when smooth vetch （Vicia villosa Roth var. glabrescens） was as a green manure， the field experiment was conducted. Two cultivated models were set including fallow （F） and green manure （G） in winter， and five amounts of nitrogen fertilizer were set including 0 （N0）， 55% （N55）， 70% （N70）， 85% （N85） and 100% （N100）. The effects of green manure combined with different nitrogen levels on the agronomic characteristics， yield and quality of flue-cured tobacco were analyzed. The results showed that， compared with F model， the application of G model could significantly improve the agronomic characteristics of tobacco leaves. Under G model， the plant height and effective leaf number of N55， N70 and N85 treatments were significantly increased， the tobacco plant height of N85 treatment increased by 7%； the number of effective tobacco leaves in N55 and N70 treatments increased by 15% and 13%， respectively. Compared with F model， G model significantly increased the output value of flue-cured tobacco， the average price of flue-cured tobacco， the proportion of high-quality tobacco， the proportion of high-quality tobacco， and the yield of flue-cured tobacco. Especially， the N70 treatment of G model had the highest proportion of medium and high-grade tobacco， average price of flue-cured tobacco， and output value of flue-cured tobacco， increased by 18.3%， 14.9% and 11.2% compared with N100 treatment of F model. The chemical quality of flue-cured tobacco under N70 treatment of G model was greatly improved， the total nitrogen content of flue-cured tobacco was significantly increased， the ratio of sugar to alkali was significantly reduced， and the ratio of potassium to chlorine was significantly increased. In summary， the green manure combined with 70% nitrogen fertilizer could effectively improve the agronomic characteristics of tobacco， maximize the output value of flue-cured tobacco， improve the quality of flue-cured tobacco， which provided scientific basis and scientific basis for fertilizer saving， efficiency increase， and sustainable production in Yunnan tobacco areas.

Effects of Lime on Soil Improvement and Plant Growth in Apple Orchards

Lu MENG, Jingwen FAN, Xinyu SAI, Lusheng ZENG, Xiangyun SONG, Dejie CUI

2023, 25(4):  197-204.  DOI: 10.13304/j.nykjdb.2021.0815

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To study the effect of lime on improving the yield and quality of apples， different amounts of lime （4 500， 6 000 and 7 500 kg·hm^-2） were applied on the basis of the application of organic fertilizer， and no lime was as control （CK）. The physicochemical properties of soil and the yield and quality of apple under different treatments were studied. The results showed that the application of lime could improve the physical and chemical properties of the soil， and improve the effectiveness of the soil nutrient ions and the soil nutrient supply condition. Among treatments， the lime treatment of 7 500 kg·hm^-2 had the best effect， which the soil pH and the content of alkaline nitrogen in soil significantly increased and the alkaline nitrogen content increased by 100.8% and 163.3% in the 0—20 and 20—40 cm soil layers compared to the CK. Application of lime significantly improved the photosynthesis and fluorescence parameters of apple leaves. Moreover， the net photosynthetic rate increased by 69.7% after the application of lime 7 500 kg·hm^-2， and the maximum fluorescence value， variable fluorescence value and PIabs increased by 8.6%， 9.8% and 14.7%， respectively. To sum up， the application of lime on the basis of organic fertilizer could improve the growth environment of fruit trees and promote the nutrients absorption of apple trees.

Effects of Fermented Peanut Shell and Cow Dung Instead of Peat Substrate on Tomato Seedling

Chunlin CHEN, Linyang WANG, Mengwei SHAN, Tiantian PEI, Jiqing WANG, Huaijuan XIAO, Juanqi LI, Meng LI, Qingjie DU

2023, 25(4):  205-214.  DOI: 10.13304/j.nykjdb.2022.0965

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To investigate the feasibility of fermented peanut shell and cow dung instead of peat substrate for tomato seedling and determine the optimal ratio of peanut shell， cow dung and perlite for tomato seedlings. The changes of physicochemical properties of substrate， and the nutrient content and morphology of seedlings were studied under peanut shell∶cow dung∶perlite （volume ratio） of 0∶6∶3 （T1）， 2∶4∶3 （T2）， 4∶2∶3 （T3） and 6∶0∶3 （T4）， compared with peat∶perlite 6∶3. The key physicochemical properties of substrates affecting seedlings were identified，and the seedling rearing effect was evaluated comprehensively. The results showed that the contents of total P， total K， olsen P， Mg and catalase activity under T1~T4 were significantly increased， while the contents of total N， alkali N and Ca were significantly decreased compared with CK. In different fermented peanut shells and cow dung substrates， the activities of urease and phosphatase increased but EC， bulk density and available K declined with increasing peanut shell. All plant morphological parameters were the highest under T3， which were significantly different with CK. The content of K in plants treated with fermented peanut shells and cow dung substrates was significantly higher than CK， but the contents of N， Ca and Mg were significantly lower than CK. The content of P in plants was the highest in T4 and the lowest in T2， respectively. The comprehensive traits of tomato plants were significantly positively correlated with pH， total K， olsen P， Mg， catalase and urease in the substrate， but negatively correlated with EC， organic matter， total N， alkali N and available K. The tomato seedlings grown under T3 presented the optimal comprehensive traits by comprehensive evaluation. Therefore， the fermented peanut shell and cow dung could replace peat using to tomato seedlings substrate， and the suitable peanut shell∶cow dung∶ perlite was 4∶2∶3， which provided theoretical basis and guidance for the substrate utilization of agricultural waste.

MARINE AGRICULTURE & FRESHWATER FISHERIES

Assessment of Carbon Neutrality Capacity of China’s Marine Fisheries

Hongjun GUAN, Yuhuan CHEN, Aiwu ZHAO

2023, 25(4):  215-224.  DOI: 10.13304/j.nykjdb.2021.0903

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Marine fisheries have the dual attributes of “carbon source” and “carbon sink”. Accurate assessment of the carbon neutral capacity of marine fisheries is an effective way to promote the sustainable development of marine fisheries. Using the relevant data of 11 coastal provinces （autonomous region， municipality） in China from 2010 to 2019， the carbon emissions， carbon sinks and net carbon emissions of China and the coastal provinces were calculated. The results showed that， during the study period， marine fisheries carbon emissions peaked in 2015 and had shown a downward trend since 2016， while marine fisheries carbon sinks had continued to grow. In general， China’s marine fisheries were in a partly carbon neutral state， but the net carbon emissions of marine fisheries had decreased rapidly after 2015， and the overall trend was good. In addition， China’s marine fishery carbon emissions and carbon sinks showed obvious regional differences. The path of healthy and sustainable development should be followed according to specific conditions. Finally， the countermeasures and suggestions were put forward in terms of reducing emissions and increasing sinks to provide references for the low-carbon development of China’s marine fisheries.

Construction of Method for Age Identification of Sardinops sagax in the North Pacific Ocean

Chao YANG, Haibin HAN, Bo WEI, Heng ZHANG, Chen SHANG, Bing SU, Siyuan LIU, Peiwei JIANG, Delong XIANG

2023, 25(4):  225-233.  DOI: 10.13304/j.nykjdb.2022.0636

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To make fish age identification more accurate and efficient， based on the biological data such as fork length， weight， and otolith weight measured by 948 samples of Sardinops sagax from 2020 to 2021， and combined with the traditional otolith age wheel observation method， a new method for age identification of Sardinops sagax was constructed. Firstly， the otolith was buried， ground， and photographed. Its accurate age was preliminarily interpreted by the wheel pattern observation method scenario. Three ways were newly built based on the univariate linear regression equation， the multiple linear regression equation， and the deep learning model. The construction and accuracy improvement process of the age identification method of Sardinops sagax were elaborated. By analyzing the R² of the univariate linear regression equation fitted by a single biological feature， the correlation coefficient between the weight of the otolith and the age observed by the rotting method was the highest. According to the age identification of the unary linear regression equation fitted by the weight of the otolith and compared with the age identification results obtained by the multiple regression linear equation and the deep learning model， it could be seen that the identification results of the univariate regression linear equation， the multiple linear regression equation， and the deep learning model were 43.6%， 54.0%， and 71.6% respectively under the standard of no error compared with the wheel pattern observation method. This method would greatly improve the accuracy and efficiency of the age identification of Sardinops sagax， and provide new methods and ideas for fish age identification.