Abstract:Ninty-two accessions of ‘Shazikongxinli’ germplasm with elite traits were selected by visiting and surveying to evaluate the genetic diversity of Prunus salicina Lindl. ‘Shazikongxinli’ IRAP primers were developed based on the conserved regions of RT sequences of plum reverse transcription transposons Ty1-copia and Ty3-gypsy. L₁₆（4³） orthogonal experiments were designed to optimize the main factors affecting content of IRAP-PCR with 10 μL volume. 18 IRAP primers were used to analyze the genetic diversity and construct the fingerprint of the germplasm tested. The results showed that the optimized 10 μL IRAP-PCR reaction system was 1.3 μL of 5-10 mol/L IRAP primers， 5.0 μL of PCR mixture， 1.0 μL of template DNA（30 ng/μL）， and the number of PCR cycles was 40 times. A total of 189 loci were amplified from 18 IRAP primers with good repeatability and high polymorphism， including 180 polymorphic loci.The average value of observed number of alleles（N_a）， effective number of alleles（N_e）， Nei’s gene diversity（H_e） and Shannon’s information index（I） for all primers was 1.930，1.426，0.261 and 0.405， respectively. The 92 accessions tested were clustered into 4 groups using the neighbor-joining method. The IRAP primers Ty3-2 and Ty3-6 were identified as core primers， which can be used to efficiently construct the fingerprints of 92 accessions tested.

Abstract:The genetic diversity of Hylocereus germplasm resources was analyzed and evaluated to provide a scientific basis for the innovative utilization of Hylocereus germplasm resources.14 qualitative traits and 9 quantitative traits in 58 Hylocereus germplasm were observed and described.The phenotypic traits were evaluated by variation analysis，index of diversity，correlation analysis.The results showed that most of the traits in the 58 tested germplasm had the characteristics of high degree of variation and rich types.The diversity index（H′） of qualitative traits was 0.234-1.809.The variation range of 9 quantitative traits was large，and the coefficient of variation was 11.25%-35.32%，among which the coefficient of variation of Vc content was the largest.The results of correlation analyses showed that most of the quantitative traits had significant or extremely significant correlations.It is indicated that there are real genetic differences among the 58 Hylocereus germplasm resources，and the genetic diversity is rich.

Abstract:The six morphological traits including plant height，leaf length and bulb diameter，leaf width，mid-plant width and root beard length of Allium macrostemon from different habitats in Guizhou were compared to comprehensively evaluate the germplasm resources of Allium macrostemon Bunge with elite traits，high content of amino acid and good flavor quality.The content of 17 free amino acids in its bulbs was determined with HPLC.The taste of amino acids and the principal components were analyzed.The results showed that the six traits including plant height，bulb diameter，leaf length，leaf width，mid-plant width and root beard length of A.macrostemon were significantly different among the 9 populations （P<0.05），with coefficients of variation greater than 10%.The 9 populations were clustered into 2 categories with Euclidean distance clustering analysis.The morphological traits of category Ⅱ were more prominent.The results of principal component analysis showed that the cumulative contribution of the first principal component reached 80.967%.The results of comprehensive evaluation showed that the Qiannan population had the highest overall score.The average content of total free amino acid （TFAA） in each population was 6 078.52 mg/kg，with higher TFAA content in the Qiandongnan （10 365.90 mg/kg） and Guiyang （8 174.55 mg/kg） population.Flavor intensity value TAV>1 indicated that the amino acid contributed to the flavor of the samples.The bitter Arginine （TAV=6.81） was the main factor affecting the flavor of A.macrostemon.The results of principal component analysis showed that the cumulative contribution of the first four principal components reached 90.144%，and the highest overall score was obtained by the Qiannan population.It is indicated that there are regional differences in morphological traits and content of flavoring amino acid in A.macrostemon.The Qiannan population has outstanding morphological traits，excellent flavor quality，and high value of development and utilization.

Abstract:Expansin is a kind of protein widely found in plants.It may relax the cell wall and plays an important role in the growth and development，and the stress response of plants.The PavEXPA2 gene was cloned and bioinformatically analyzed to uncover the structure and function of expansingene（EXPA） in sweet cherries.The gene expression in different tissues including stems，flower buds，blooming flowers，young leaves，old leaves，petioles of young leaves，petioles of old leaves，normal fruit stalks at the 2 abscission peaks and about to abscission，the normal fruits at 2 abscission peaks and shedding，and under the abiotic stresses including using 20% PEG6000 and 20 mmol/L NaCl solutions to simulate drought and salt stress for 0，2，4，6，and 8 h was profiled.The results showed that the full length of PavEXPA2 was 1 035 bp with the open reading frame （ORF） of 852 bp，encoding 283 amino acids.The putative protein has an isoelectric point of 8.90 and a molecular mass of 30.81 ku，containing two transmembrane helical structures and a signal peptide.The results of subcellular location showed that the protein of gene was located in the cell wall.The results of tissue expression analysis showed that the expression level of PavEXPA2 was higher in the easily abscised tissues of sweet cherry including flowers，stalks，fruits and petioles，with the highest level in petioles about to abscission.Compared with the samples untreated，the expression of PavEXPA2 in the drought-treated samples increased，and the expression reached the highest at 6 h，and then decreased.Under the salt stress，the expression level of PavEXPA2 decreased first，then increased and then decreased，and the expression level reached the highest at 6 h.Therefore，sweet cherries may resist stress by promoting abscission through the up-regulation of PavEXPA2 gene.It will lay a theoretical foundation for further understanding the role of PavEXPA2 in the growth and development of sweet cherries.

Abstract:The cDNA sequence of HpGST gene was cloned，and bioinformatics analysis and expression analysis of it were carried out to study the function of glutathione S-transferase gene （HpGST） in Hylocereus.The results showed that the cDNA sequence of HpGST was 666 bp in length，encoding 221 amino acids.The encoded protein belonged to non-secretory unstable hydrophilic protein，and its subcellular localization predicted its role in the cytoplasm.The phylogenetic tree shows that it is closely related to Chenopodium quinoa，and belongs to the Tau family of glutathione transferases.The results of real-time fluorescent quantitative PCR analysis showed that HpGST was expressed in the flesh of different color types of Hylocereuss.The expression levels of HpGST in purple and pink flesh of Hylocereuss with pigment accumulation were significantly higher than those in white flesh types without pigment accumulation.The expression trend was first increased and then decreased with the development of fruit.Its expression level was positively correlated with content of betaine，and the expression trend in different varieties is highly consistent with the accumulation trend of betaine.It is indicated that HpGST gene plays an important role in the synthesis and distribution of betaine in Hylocereus.

Abstract:The LcC2DP1 gene was cloned from the Lotus corniculatus L.by RACE method to study the function of C2 calcium dependent protein kinase gene LcC2DP1 of Lotus corniculatus L.in the process of adventitious root development.The spatial expression mode of LcC2DP1 gene was detected with qRT-PCR.The overexpression and function of LcC2DP were identified by Agrobacterium mediated transient expression system.The results showed that the full length of LcC2DP1 gene was 705 bp，encoding 235 amino acids.Its molecular weight was 25.95 ku，with the highest homology of Medicago truncatula （82%）.It was continuously expressed during the differentiation of adventitious roots in Lotus corniculatus L..The expression sites were roots，stems and leaves.Compared with wild-type parents （WT），the adventitious root differentiation of the LcC2DP1 transgenic Lotus corniculatus L. plants（TP） was 1-2 days earlier.On the 9th to 15th day of adventitious root differentiation，the total root length was 168% and 155% of WT，the root volume was 249% and 161% of WT，and the number of root tips was 156% and 137% of WT，respectively.The total root length （P<0.01），root volume （P<0.01） and number of root tips （P<0.05） of TP root had certain advantages of development，indicating that LcC2DP1 gene may be related to the regulation of adventitious root development in Lotus corniculatus L..

Abstract:The endangered plant Oreocharis esquirolii and two species of the same genus including O.elegantissima and O. duyunensis were used to compare the photosynthetic physiological characteristics and anatomical structures of leaves in the same cultivation habitat to study the differences in photosynthetic capacity between O. esquirolii and two species of the same genus.The results showed that Chl a and （Chl a+Chl b） of O. esquirolii was significantly lower than that of the other two kinds of Gesneriaceae （P<0.05）.The results of chlorophyll fluorescence characteristics showed that F_o was significantly higher（P<0.05）， F_v/F_m，F_v/F_o，Y（Ⅱ） and ETR were the smallest among the three plants.During the photosynthetic diurnal process， the P_n of the three plants showed a relatively consistent bimodal curve.The intercellular CO₂ concentration trend had a “W” shape， and the stomatal conductance had a downward trend with the passage of time.The transpiration rate had a downward trend， then increased and then decreased with the passage of time， and the three plants all had obvious photosynthetic “napping” phenomenon.Each index showed the lowest characteristic of O. esquirolii.In the photo response， the average P_max value of O. esquirolii was 2.24 μmol/（m²·s）， which was significantly lower.The average value of R_d and LCP was 1.14 μmol/（m²·s） and 51.85 μmol/（m²·s）， significantly higher than that of the other two plants（P<0.05）.The results of CO₂ response curve fitting showed that the v_cmax and J_max of O. esquirolii were 7.6 μmol/（m²·s） and 26.04 μmol/（m²·s）， significantly lower than that of the other two plants（P<0.05）.The results of histological section showed that the upper epidermis and the lower epidermis of O. esquirolii were 37.80 μm and 38.09 μm， higher than that of the other two plants.The PT and ST of O. esquirolii were 40.79 μm and 30.07 μm， significantly lower than that of the other two plants（P<0.05）， which may be related to the long-term adaptation of O. esquirolii to shady and barren habitats.It is indicated that the photosynthetic physiological characteristics of O. esquirolii are overall lower than two species of the same genus including O. elegantissima and O. duyunensis， and its ability to adapt to the light environment and the utilization rate of light energy is relatively weak， which may be one of the main internal factors of the endangered species.

Abstract:In the process of transplanting and acclimating tissue culture seedlings of Bletilla striata in summer，they will face fluctuating light and heat stress at the same time.The tissue culture seedlings of Bletilla striata in June 2021 transplanting greenhouse were used to determine the variation trend of the acclimation time on the growth and physiological indexes of Bletilla striata transplanting seedlings to study the effect of light-temperature coupling in summer on the growth and development changes of acclimated seedlings of Bletilla striata and provide a scientific basis for the adaptive exercise of Bletilla striata in summer.At 90 days of acclimation，the temperature （25 ℃，30 ℃，35 ℃ and 38 ℃） and fluctuating light （50 mmol/（m²·s），2 min； 1 000 mmol /（m²·s），2 min） were set to simulate the light and temperature stress of Bletilla striata in summer.The results showed that the root-shoot ratio of Bletilla striata seedlings increased first and then decreased within 90 days.The content of polysaccharide in the tuber increased by 51% in 90 days compared with that in 60 days.Under the combined stress of fluctuating light and high temperature，the amount of carbon assimilated by Bletilla striata was lost 2-3 times.The F_v/F_m，F_PSII，qP，F_v'/F_m' and ETR of transplanted Bletilla striata seedlings were reduced，and F_NPQ and NPQ were increased with the increase of temperature.It is indicated that the high temperature and fluctuating light in summer cause serious harm to the growth and development of Bletilla striata，which is not conducive to the transplantation and domestication of Bletilla striata.

Abstract:Three Stachys sieboldii Miq.varieties were used to study the effects of waterlogging stress on the physiological characteristics of S. sieboldii Miq..Correlation analysis and principal component analysis were used to evaluate the waterlogging resistance of S. sieboldii Miq. to provide a reference for the identification of waterlogging resistance of S. sieboldii Miq..The results showed that the content of chlorophyll，soluble sugar，soluble protein，and the activity of POD and CAT of the three S. sieboldii Miq.varieties increased first and then decreased with the prolongation of waterlogging stress.The content of Pro in Luyin No.1 and Ganyin No.1 first increased and then decreased，while the content of Pro in Guizai No.1 kept increasing.The activity of SOD in Guizai NO.1 and Luyin No.1 increased first and then decreased，while the activity of SOD in Ganyin No.1 kept increasing under the waterlogging stress.The accumulation of MDA in the three S. sieboldii Miq. varieties increased all the time with the extension of stress time.The results of correlation analyses showed that the content of chlorophyll，soluble sugar，soluble protein，Pro，and MDA，the activity of SOD，POD，and CAT of S. sieboldii Miq.was closely related，but the degree of correlation was inconsistent.The results of comprehensively evaluating waterlogging resistance based on the principal component analysis showed that the waterlogging resistance of the three S. sieboldii Miq. varieties was in the decreasing order of Ganyin No.1>Luyin No.1> Guizai No.1.

Abstract:There are spatial differences in fish population structure and individual growth， which are affected by hydrology， water environment， and fishing. In order to study the population structure and growth differences of Megalobrama terminalis in the estuary， dam downstream， and dam upstream in the middle and lower reaches of the Pearl River， a total of 228 fish samples were collected in the middle and lower reaches of Pearl River from July to August in 2020. The body length and weight of the samples were measured， and the scales were used to determine the age. The von Bertalanffy growth equation， Beverton-holt model， and Pauly empirical formula were applied to estimate the growth and death parameters of M. terminalis. The results of comparative analysis showed that the dominant body length of M. terminalis was 17.0-27.2 cm in the Pearl River estuary， 18.9-28.7 cm in the dam downstream， and 28.6-40.0 cm in the dam upstream. The dominant body weight was 93.0-447.9 g in the Pearl River estuary， 148.8-480.0 g in the dam downstream， and 39.5-1 420.8 g in the dam upstream. The dominant ages were 3⁺ （32.14%） and 2⁺ （24.11%） in the Pearl River estuary， 3⁺ （32.14%） and 2⁺ （24.11%） in the dam downstream， and 4⁺ （31.58%） and 5⁺ （26.32%） in the dam upstream. The von Bertalanffy equation of M. terminalis was L=47.2 （1-e^{-0.177（t+0.387）}） in the Pearl River estuary， L=42.9 （1-e^{-0.199（t+0.377）}） in the dam downstream， and L=53.7 （1-e^{-0.155（t+0.401）}） in the dam upstream. The exploitation ratio （E） of M. terminalis was 0.410 in the Pearl River estuary， 0.373 in the dam downstream， and 0.248 in the dam upstream. The critical length （L_c） was 25.1 cm in the Pearl River estuary， 23.0 cm in the dam downstream， and 28.4 cm in the dam upstream. The results of comparative analysis showed that the frequency distribution of body length， body weight， age， and the growth equation of M. terminalis had spatial differences.

Abstract:In order to scientifically formulate the technical plan for the proliferation and release of large water surface and promote the sustainable and healthy development of ecological fishery， this study took the Weishui Reservoir as an example. On the basis of studying the ecological capacity of the reservoir by using the EwE software， 4 sets of proliferation and release schemes were constructed using the Ecopath model and the best scheme was selected through a comprehensive comparison of the ecological， social and economic benefits of each plan. The research results could provide new ideas and references for the scientific formulation of large-surface ecological fishery programs. The results showed that： （1） If economic benefits and social and environmental benefits such as nitrogen and phosphorus removal were taken as the preferred factors， scheme 1 was optimal， that was， breeding and releasing of silver carp and bighead carp， with the annual release numbers of 135 000 and 491 000， respectively. The annual maximum sustainable output of silver carp and bighead carp was 486.6 t and 1 766.8 t， the total output value， total profit value and unit output value are 80.402 million yuan， 70.037 million yuan and 3.502 million yuan/km²， respectively， and the annual net removal of total nitrogen and total phosphorus could reach above 130.41 t and 36.98 t， the total primary productive force/total respiration （TPP/TR） value， connectivity index （CI） value， system omnivorous index （SOI） value and Shannon diversity index value of the ecosystem were 4.030， 0.304， 0.114 and 1.557， respectively. （2） If the health of the ecosystem and the economic benefits of fishery were considered comprehensively， scheme 3 was the best， that was， breeding and releasing of mandarin fish， yellow catfish， common carp， crucian carp， silver carp， and bighead carp with annual discharge numbers of 800，19 000， 9 000， 11 000， 41 000 and 148 000， respectively. The annual maximum sustainable output could reach 1.2 t， 3.8 t， 18.8 t， 5.6 t， 162.8 t and 591.2 t， respectively. The total output value， total profit value and unit output value were 30.418 million yuan， 25.622 million yuan， and 1.281 million yuan/km²， respectively， the annual net removal of total nitrogen and total phosphorus could reach above 46.73 t and 13.21 t， and the TPP/TR， CI， SOI and Shannon diversity index were 4.616， 0.302， 0.117 and 1.597， respectively. The above results show that the Ecopath model can be flexibly used to scientifically formulate large-water ecological fishery schemes according to the corresponding fishery management objectives.

Abstract:To study the utilization and budgets of nitrogen and phosphorus in higher-place aquaculture ponds of gentian grouper （Epinephelus lanceolatus ♂ × Epinephelus luscoguttatus ♀），and to illuminate the dynamics of water quality and the sources and fate of nitrogen and phosphorus，during 55 days of cultivation，fish，pond water，input and output water and feed were regularly sampled and analyzed in three higher-place ponds. The results showed that： （1） the average concentration of dissolved oxygen during culture was between 8.64 and 9.55 mg/L； Ammonia nitrogen，nitrite，nitrate and phosphate showed irregular fluctuation in the three ponds； The contents of total nitrogen and total phosphorus varied from 6.14 to 7.11 mg/L and 0.38 to 1.41 mg/L，indicating serious eutrophication of the aquaculture pond. （2） During the cultivation period，the survival rate of gentian grouper was high. The weight gain rate of fish and feed conversion ranged from 96.0% to 227.0% and 0.55 to 0.90. The utilization rates of feed nitrogen and phosphorus were 47.0%-59.0% and 52.0%-63.0%，respectively. （3） Feed accounted for 61.0%-66.8% of total nitrogen input and 66.9%-71.0% of total phosphorus input. Fish harvest from the ponds accounted for 43.0%-60.9% of nitrogen output and 45.0%-67.7% of phosphorus output. The rest of the nitrogen and phosphorus were exported as drainage，sediment and other ways. The results of the study showed that higher-place aquaculture ponds of gentian grouper had high level nitrogen and phosphorus content， feed is the major way of nitrogen and phosphorus input to the pond and fish harvest is the major way of nitrogen and phosphorus output. The rest output was discharged through aquaculture effluents. Appropriate management of the waste water discharge in aquaculture is needed to decrease negative effect on nearby waterbody.

Abstract:To improve the calculation process of infer consumer trophic position using stable isotope analysis and to reduce the influence of the current methods and sample quality， this paper applied Bayesian mixing model to estimate the trophic position of silver carp （Hypophthalmichthys molitrix） and bighead carp （Hypophthalmichthys nobilis） in Chinese waters from published literature. The results showed that the trophic position of silver carp and bighead carp had no significant correlation with total phosphorus （TP） and total nitrogen （TN） under Bayesian method. Some studies have the limitation of small sample sizes， low sampling frequency， and ignored the seasonal and spatial variations in baseline， thus failing to accurately represent the trophic signatures of target organisms， which may have led to deviation in trophic position estimates. No significant difference between the Bayesian method and the current method indicates that even more accurate models cannot overcomes the limitations of an irrational sampling design. The results of curve fitting show that the Bayesian approach performs more constrained with the sample size ≥6， and the accuracy is improved. Therefore， in the experimental design， we suggest that the sample size should be ≥6， and that seasonal and spatial variations should be considered and avoid single， small collections.

Abstract:To formulate safe， high quality and efficient polyculture technical specifications and explore sustainable development of aquaculture technology， a comparative experiment of three co-culture modes， including experimental group （rice-crab， RC； rice-crayfish-crab， RCC） and control group （intensive crab， IC）， was set up in Suzhou， Anhui Province. By comparing and analyzing the N and P balance， N and P utilization， biomass and diversity of plankton and eco-economic benefits of the three modes， the advantages of rice-fish polyculture and the best rice-crab co-culture mode were explored. The results showed that the content of N and P in the substrate increased in all three culture modes， and the most significant increase was in the IC mode （P<0.05）. The N and P balance showed surplus in all patterns， the N surplus in IC， RC and RCC modes were 1 030.92 kg/hm²， 364.37 kg/hm² and 188.75 kg/hm²， and the P surplus were 171.35 kg/hm²， 81.67 kg/hm² and 76.96 kg/hm²， respectively. The N utilization rate in IC， RC and RCC modes were 16.47%， 48.98% and 65.71%， and the P utilization rate were 7.61%， 18.22% and 24.29%， respectively. Compared with IC and RC modes， the total amount and increase of phytoplankton species and the Shannon-Wiener diversity index were the highest in the RCC mode. The economic benefit of RC and RCC were 22.78% and 4.48% lower than those of IC， respectively. The economic benefit of RCC was not significant different from that of IC. In conclusion， compared with the intensive cultivation mode， the rice-fish co-culture pattern is more friendly to the ecological environment， while RCC has better economic benefits than RC.

Abstract:In order to clarify the characteristics of plankton community structure and understand the current status of water quality in Weishui Reservoir， in this study， plankton and water quality surveys were carried out in the typical area of Weishui Reservoir in July （summer） and November （autumn） 2021， January （winter） and March （spring） 2022. The results showed that there were 75 genera and 129 species of phytoplankton， mainly Chlorophyta， and 23 genera and 31 species of zooplankton （rotifers and planktonic crustaceans）， mainly rotifers. The dominant plankton species mainly included Cyclotella catenate， Scenedesmus biguga， Pseudoanabaena limnetica， Keratella cochlearis， nauplius， etc. The annual mean density and biomass of phytoplankton were 1.656×10⁷ ind./L and 6.32 mg/L， respectively， and the annual density and biomass of zooplankton were 1.75×10² ind./L and 1.92 mg/L， respectively. In terms of spatial distribution， the abundance and biomass of plankton decreased gradually from the upstream channel-type area to the downstream open-water area. Canonical correspondence analysis showed that PO₄^3--P， WT， pH and DO all had important effects on the ecological distribution of plankton communities in Weishui Reservoir， while NO₃^--N and Cond only had an effect on phytoplankton. According to the evaluation of species diversity， the plankton community structure of Weishui Reservoir is relatively stable， and the water quality in the reservoir area is in the mesotrophic status.

Abstract:To clarify the characteristics of rotifer community structure and distribution，and environmental affecting factors in the mainstream of Yangtze River，the habitat space of 27 river segments from the source to the lower reaches of the Yangtze River mainstream were divided into four regions based on physical and chemical parameters of water quality.The community structure and distribution of rotifers in the high mountain area，canyon area，plain area and estuary area was investigated，and biological methods were employed to evaluate the water quality status of the mainstream of Yangtze River.The results showed that 85 rotifer species belonging to 37 genera were identified，containing 63 indicator species，mainly oligosmal species.There were 12 dominant species in the four research areas，and Keratella ualega and Keratella cochlearis were dominant in most water areas.The average zooplankton density and biomass were 19.66 ind./L.and 0.11 mg/L，respectively.The distribution patterns of rotifers were as follows： the density and biomass of rotifers were the highest in the canyon area，followed by the plain area，high mountain area and estuary area.The average Shannon-Wiener diversity index and Pielou evenness index were 2.62 and 0.78，respectively.Specifically，Shannon-Wiener index showed significant differences among different regions （P<0.05），and the Pielou index in each region was relatively uniform.The results of NMDs analysis suggested that the similarity of rotifers community structure between crayon and plain areas was higher than that among other areas.The RDA analysis indicated that WT，density of the phytoplankton，DO，and TP were important factors affecting the spatial distribution of rotifers in the mainstream of Yangtze River.In conclusion，the community structure of rotifers in different areas of the Yangtze River mainstream showed high spatial heterogeneity，which was jointly caused by the change of natural environment and the disturbance of human activities.

Abstract:In order to obtain the best coverage of Ipomoea aquatica floating-bed in pond culture of Qihe crucian carp， Carassius auratus， a total of 360 individuals of Qihe crucian carp were randomly cultured in four groups with coverage of the I. aquatica floating-bed of 0（C0）， 10%（C1）， 20%（C2） and 30%（C3）， respectively， with 3 replicates per group and 30 fish per replicate. After culture for 90 days， the aquaculture water quality， growth， general nutritional composition and amino acid contents were examined， and the differences were compared. The results showed that only the contents of three amino acids （glycine， valine and arginine） were significantly affected by I. aquatica floating-bed coverage （P<0.05）， with the maximum value mostly in group C1， followed by the control. In addition， the changes of valine and arginine contents were consistent with that of weight gain rate among the four treatments. Moreover， compared with C0， the crude protein and ash contents of the three treatments （C1-C3） were higher， and the crude lipid content was lower， among which 10% treatment （C1） exhibited the highest crude protein content and lowest crude lipid content. Therefore， we suggest that 10% I. aquatica floating-bed coverage is most beneficial to the excellent quality of Qihe crucian carp， but too high coverage would have opposite effect.

Abstract:Freshwater product logistics plays an important role in connecting fishing， processing， and marketing of freshwater products. It is a major way to ensure the large-scale circulation of freshwater products and solve the problems of consumption imbalance. China is a major producer and consumer of freshwater products. Freshwater products are perishable， seasonal， and regional， which bring some challenges to the circulation of freshwater products. In this paper， the present situation of China’s freshwater products logistics was introduced， including freshwater product production， circulation form， infrastructure， and policy environment. And the present problem was analyzed， such as freshwater product processing capacity， storage and transportation equipment， management system， information construction， logistics standard， cold-chain logistics personnel， and other aspects. Some suggestions were put forward to improve the freshwater product logistics industry in China. It was anticipated to provide references for promoting the development of freshwater product logistics industry.

Abstract:Fresh and frozen surimi were prepared by ozone rinsing， and the effects of ozone rinsing and frozen storage on protein oxidation and flavor of silver carp surimi were investigated.Ozone rinsing decreased water-soluble protein content and increased salt-soluble protein content in fresh surimi.After frozen storage， the contents of water-soluble and salt-soluble protein were significantly decreased （P<0.05）.The content of active sulfhydryl in fresh surimi was significantly decreased by ozone rinsing and frozen storage， but the decrease by frozen storage was smaller than that by ozone rinsing.The results of the electronic nose and electronic tongue showed that there was significant difference in the smell and taste between frozen surimi and fresh surimi.However， the ozone rinsing surimi and water rinsing surimi could not be effectively separated.Ozone rinsing and frozen storage significantly decreased the free amino acid content.A total of 59 volatile flavor compounds were identified by GC-IMS.The unsaturated alcohols in ozone-rinsing surimi were significantly lower than those in water-rinsing surimi.After freezing， alcohols decreased， aldehydes increased significantly.The results can provide a theoretical basis for the application of ozone rinsing in surimi and surimi products.

Abstract:The basic nutrient composition， minerals， amino acids and fatty acids of the gill edge meat， fish face meat and fish brain of bighead carp （Aristichthys nobilis） head were determined， and the differences of the nutrients in the three parts of bighead carp head were analyzed to study the edible value of bighead carp head and expand the development of its product.The results of comparing the basic nutrient composition of the edible part of bighead carp head showed that the content of protein was in the decreasing order of gill edge meat>fish face meat>fish brain， and the content of fat was in the increasing order of gill edge meat <fish face meat<fish brain.Compared with the three edible parts of the bighead carp head， the content of potassium， phosphorus， calcium and zinc in the gill meat was higher.The content of various minerals in the fish brain was relatively low.Twenty-six kinds of fatty acids were detected in the meat of fish face and brain of bighead carp， and 25 kinds of fatty acids were detected in gill edge meat.The value of n-6/n-3 in edible parts of bighead carp head was 1.80，1.83 and 1.86， in line with the ideal ratio recommended by the Chinese Nutrition Society. The first limiting amino acid is tryptophan， the second limiting amino acid is methionine + cysteine.The essential amino acid index （EAAI） of bighead carp head is 75.48， which can be used as a source of protein.It is indicated that bighead carp head is a high-quality food source with rich nutrition， reasonable composition of amino acids and fatty acids.

Abstract:The collagen extracted from fish scales is processed into fish scale jelly， which is safe and healthy. It contains a large amount of water-soluble collagen， and has the effects of calcium supplementation， beauty， body strengthening and brain strengthening. Fish scale jelly is easier to be digested and absorbed by the human body compared with other collagen proteins. The process of production is simple and can be completed without large equipment. In this article， we optimized the simmering technology of prepared food from the silver carp scale jelly and studied its gelation characteristics. The response surface experiment design was used to study the effects of simmering temperature， simmering time， carrageenan dosage and water to scale ratio on the yield and strength of gel to optimize the simmering process and study the gelation characteristics of fish scale jelly under different conditions. The gelation characteristics of fish scale jelly were analyzed with differential caloric method， nuclear magnetic imaging and dynamic rheological methods. The results showed that the water to scale ratio had the greatest influence on the yield and strength of gel. The yield of gel increased gradually and the strength of gel decreased gradually with the increase of water to scale ratio. According to the comprehensive score of the yield rate and strength of gel， the optimized conditions were as that：the total mass of water and fish scales as 100%,water to scale ratio of 3∶1， simmering temperature of 80 ℃， simmering time of 90 min， carrageenan dosage of 1%. Through the validation test， the yield rate of fish scale jelly was 3.62%， the strength of gel was 206.59 g·mm， and the comprehensive weighted score was 145.699. The proportion of free water in fish scale jelly was over 89%， and the melting temperature was 24-28 ℃.The content of free water gradually increased and the mobility was enhanced with the increase of water to scale ratio. The elastic modulus and enthalpy value gradually decreased. It is indicated that the silver carp scales can be used for processing new type of prepared food with gel.

Abstract:A silver carp head processing device was designed based on machine vision to solve problems including the lack of domestic freshwater fish head processing equipment and the low degree of mechanization of fish head processing.This device is composed of a fish body conveying device，fish body image acquisition device，fish body turnover part，vertical clamping conveyor belt，fish head cutting part，fish head sectioning part，device control system.The fish body image acquisition device obtains the fish body image on the conveying device and calculates the fish head cutting path.The fish body enters the vertical clamping conveyor belt through the fish body turnover part and moves forward under the action of the vertical clamping conveyor belt.When the fish body reaches the fish head cutting position，the vertical clamping conveyor belt stops after adjusting the fish body position，the fish head cutting part cuts the fish body according to the fish head cutting path and resets，and the vertical clamping conveyor belt drives the fish head forward.The cut fish head is a section in half through the fish head sectioning part.The performance of the prototype was tested with silver carp.The results showed that the determination coefficients of the linear fitting between the actual horizontal distance from the upper cutting point and the lower cutting point and the predicted horizontal distance after the fish head was cut were 0.911 and 0.985，with the root means square errors of 6.31 mm and 2.61 mm.The detection time of fish head cutting path，the processing time of fish head，and the appearance score of the fish head was （0.055±0.009） s，（13.28±0.35） s，and 0.88±0.02，meeting the production requirements of the silver carp head processing.It will provide new methods and equipment for the industry of silver carp head processing and theoretical and methodological references for the automatic processing of silver carp head.

Abstract:The field plot experiments were conducted to apply organic fertilizer to vegetables including cabbage， radish， pepper for three consecutive seasons and citrus （Majia pomelo） for many years to compare the effects of applying organic fertilizer instead of chemical fertilizer on the yield， quality of fruits and vegetables and the content of heavy metals in soil. Using no fertilization （CK） and fertilizer application （CF） as the control， two organic fertilizer treatments with equal nitrogen fertilizer application including OF1， OF2 were set up. The results showed that both OF1 and OF2 treatments ensured that the yield of vegetables in the first two seasons and Majia pomelo do not decrease， and significantly increase the contents of soluble solids in Majia pomelo and the content of organic matter in vegetable soil compared with CF treatment. There was no significant difference in the content of heavy metals between vegetables under different treatments in the first two seasons， but the content of Pb in the edible part of radish treated with OF1 and OF2 was close to the limit standard. In the vegetables of third season， the contents of Cr， As， Cu and Zn in edible parts of pepper treated with OF1 and OF2 were significantly higher than those treated with CF. The content of Pb in the pulp and peel of Majia pomelo fruit treated with OF1 exceeded the limit standard， and that with OF2 treatment was close to the limit standard. The content of various heavy metals in vegetable soil was far lower than the value of risk control， but the content of Pb， Cd， Hg had significantly accumulated compared with CF treatment， among which the content of Hg was the fastest. It is indicated that the application of two organic fertilizer with equal nitrogen fertilizer can increase the yield and quality of fruits and vegetables， improve the physical and chemical properties of soil in a short time， but increase the accumulation of heavy metals in soil as well. Therefore， continuous application of organic fertilizer will lead to the risk that the content of heavy metals in fruits and vegetables exceeds the limit standard.

Abstract:The topsoil （0-20 cm） and subsoil （20-40 cm） under five typical vegetations including Carex cinerascens， Triarrhena lutarioriparia， Phragmites australis， Miscanthus sacchariflorus， and Cynodon dactylon was collected in Sizhoutou wetland of Poyang Lake to study the effect of soil texture on the content of soil organic carbon （SOC）. The distribution of soil particle size was identified with laser particle size analyzer. The parameters of soil grain size were calculated with the Folk-Ward formula. The characteristics of soil grain size distribution were discussed. The relationship between composition of soil grain size and SOC was analyzed with structural equation model （SEM） and Pearson correlation. The results showed that the soil texture of Sizhoutou wetland was mainly silty clay and sandy loam， and the soil sorting was poor. The texture of silty clay was mainly composed of silt （67.76%-79.28%）， with mean value of main grain size of 6.91 Φ. The frequency curves of grain size presented a distribution with bimodal or three peaks. The texture of sandy loam was mainly composed of fine sand （32.90%-56.55%）， with mean value of main grain size of 3.00 Φ. The frequency curves of grain size presented a unimodal distribution. The content of SOC in silty clay （（10.52±3.86） g/kg） was significantly higher than that in sandy loam（ （1.67±1.66） g/kg， P<0.05）. The texture of soil had a direct impact on the content of SOC. Clay， silt and sand were important factors affecting the content of SOC. The retention capacity of clay and silt to soil organic carbon in the area studied was significantly higher than that of sand. It is indicated that the impact of the texture of soil on the sequestration of carbon should be emphasized in protecting the wetland of Poyang Lake.

Abstract:QuEChERS pretreatment combined with ultra performance liquid chromatography tandem mass spectrometry （UPLC-MS/MS） method was developed and used to determine pesticide residues including phoxim，cypermethrin and spinetoram in T. wilfordii root and its rhizosphere soil to establish the method for detecting the content of three pesticide residues commonly used in the process of planting Tripterygium wilfordii. The sample was soaked with appropriate amount of water and then extracted by acetonitrile ultrasonic，purified by N-propyl ethylenediamine （PSA） adsorption，detected by optimized UPLC-MS/MS method，and quantified by matrix external standard method. The results showed that the detection limit of pesticides in root like matrix was 0.001-0.714 μg/kg，LOQ was 0.002-2.380 μg/kg。The limit of detection （LOD） of three pesticides in root and soil samples was 0.001-0.714 μg/kg and 0.002-0.810 μg/kg，respectively. The limit of quantitation （LOQ） of three pesticides in root and soil samples was 0.002-2.380 μg/kg and 0.006-2.410 μg/kg，respectively. The linear relationship，recovery rate and relative standard deviation were in line with the relevant provisions of detecting pesticide residue. It is indicated that the method established is simple，rapid，sensitive and accurate，and can meet the requirements of rapidly determining three pesticide residues in Tripterygium wilfordii and rhizosphere related soil.

Abstract:The whole area of soil and typical profiles in Jianshi County were used to analyze the characteristics of the content of selenium in different soil types， the distribution of the content of selenium in vertical soil profiles， and the correlation between the content of in soil and the physical and chemical properties based on the survey results of geochemical evaluation of land quality in Jianshi County， Hubei Province from 2015 to 2020 to study the characteristics and influencing factors of selenium enrichment in the soil in Jianshi County. Results showed that the content of Se in the soil in Jianshi ranged from 0.08 mg/kg to 64.20 mg/kg， with a mean of 0.94 mg/kg. In general， the content of Se in the soil in Jianshi reached the level of seleniferous soils. Among the main types of soil in Jianshi County， the content of selenium in red soil， brown soil and yellow soil was relatively higher than that in other soil types， and the content of selenium in purple soil was the lowest. The depth of soil profile had a significant effect on the content of selenium in soil. The content of selenium in soil was gradually decreased with the increase of the depth of soil profile， consistent with the change trend of organic matter in soil. The content of SiO₂， Al₂O₃， TFe₂O₃ and CaO in the soil was significantly positively correlated with the content of selenium in the soil. In addition， the content of selenium in the soil was strongly correlated with the content of Cr， Cd， Ni， and Mo in the soil， indicating that the source of Se in the soil is closely related to organic matter in the soil. At the same time， the content of available Se in soil was significantly positively correlated with the pH in soil， indicating that increasing the pH in soil is an effective approach for improving the bioavailability of Se in soil.

Abstract:Combined with the soil conditions of water chestnut planting field and the existing manual harvesting methods， a self-propelled water chestnut harvester for harvesting with water was designed to solve the problem of the high labor intensity of water chestnut harvesting and the lack of harvesting machines that can be used in practical production. The machine is composed of walking system， transmission system， rotating disturbance device， lifting and separation device， collection device， etc. It can conduct the excavation of water chestnuts， separation of fruit and soil， lifting and collection of water chestnut and other work at one time. The transmission system of the whole machine is divided into hydraulic transmission part and mechanical transmission part. The hydraulic transmission part provides power for the walking system of the harvester and the digging and harvesting device， which can realize the walking speed control of machines， the height adjustment of the digging and harvesting device， the speed control of the rotating disturbance device and the speed control of the lifting and separation device. The mechanical transmission part provides a stable speed difference between the rotating disturbance rollers at all levels and the lifting and separation device to ensure the smooth progress of the harvesting process. The three-stage rotating disturbance roller forms a rotating disturbance device to realize the full disturbance and mixing of soil and water. The toothed digging shovel and lifting chain form a lifting and separation device to perform the excavation of water chestnut fruits， the separation of fruit and soil and lifting of water chestnut fruits. The performance of the track chassis of this type of water chestnut harvester was analyzed theoretically. The results showed that the theoretical minimum steering radius of chassis differential steering， the theoretical steering radius of in-situ steering， the theoretical value of the uphill limit overturning angle， and the theoretical value of the downhill limit overturning angle was 1.5 m， 1.0 m， 55.63° and 55.08°， respectively. It is indicated that the machine has small turning radius and large ultimate overturning angle， which is very suitable for the working environment of water chestnut planting field. The results of the field trial showed that the maximum driving speed of this type of water chestnut harvester on the field road， the minimum steering radius of differential steering the in-situ steering radius， the maximum climbing angle， the fruit digging rate， and the damage rate under the experiment conditions is 0.97 m/s， 2.1 m， 1.3 m， 24.2°， 53.19%， and 4.21%， which can meet the performance requirements of water chestnut mechanized harvesting to a certain extent.

Abstract:The truss structure of header in the caterpillar type rapeseed windrower is complex and changeable，which leads to the problem of large vibration of the header.Based on the variable density method，the multi-objective topology optimization of frame structure of the header was carried out to reduce the vibration of the header under different working conditions. The topology optimization model of header was established by using Hypermesh software. The virtual prototype model of rapeseed windrower based on RecurDyn was established by using multi-body dynamics method. The dynamic loads of the moving pair of the header under parts debugging conditions，transport conditions and field operation conditions were obtained. The comprehensive objective function of static stiffness and dynamic frequency of the header was constructed with the compromise programming method. The weight of each sub- object was determined according to the analytic hierarchy process （AHP）. Taking the volume fraction and maximum load of moving pair as constraints，the ideal material density distribution of the header spatial structure was obtained. Considering the practical engineering application，the optimized frame of header was normalized. The finite element model of the optimized frame of header was established and the finite element static analysis and modal analysis were carried out. The vibration amplitudes at the measuring points of the header before and after optimization were compared and analyzed. The results showed that the maximum stress value decreased from 107.99 MPa to 65.45 MPa after optimization. The maximum deformation decreased from 0.82 mm to 0.36 mm. The natural frequencies of the first three orders were increased to varying degrees，and the natural frequency of the first order was increased to 24.187 Hz. The results of actual vibration test showed that the vibration amplitude of each measuring point of the header decreases after optimization. The overall vibration of the header decreased，in which the amplitude of the longitudinal cutter support decreased from 4.83 m/s² to 1.49 m/s². It will provide reference for the structure improvement and optimization of rapeseed windrower.

Abstract:Aiming at the problem of poor single seed and uniformity of the existing seed metering device under the condition of small plant spacing and dense planting， according to the agronomic requirements of soybean maize strip composite planting mode， a small plant spacing and dense planting air suction precision seed metering device with double seed clearing function is designed.By analyzing the working principle of the seed metering device and determining the structural parameters of key components， taking the qualified rate， over-seeding rate， and missed seeding rate as the evaluation indexes， and taking the number of holes in the seed metering disc， the outer clearing distance， and the inner clearing distance as the experimental factors， the three-factor five-level orthogonal test is carried out to determine the primary and secondary order and the optimal level of the experimental factors.Through the central combination test， the test factors and levels are optimized and verified.The results showed that the number of holes in the seed metering disc and the distance between inner and outer seed eliminating had significant effects on the seed metering performance； The optimal working parameter combination of corn seed metering is 35 holes， the outer seed eliminating distance is 6.2 mm and the inner seed eliminating distance is 1.6 mm； The optimal working parameter combination of soybean seed metering is 62 holes， the outer seed eliminating distance is 4.1 mm and the inner seed eliminating distance is 1.6 mm.The results showed that the qualified rate of maize seed metering was 95.40%， the over-seeding rate was 1.50%， and the missed seeding rate was 3.10%.The qualified rate of soybean seed metering was 97.78%， the over-seeding rate was 0.32%， and the missed seeding rate was 1.90%， which was consistent with the optimization prediction results， and all indexes met the seeding demand.

Abstract:A double-layer paddle piglet milk mixing tank was designed to study the effects of agitator parameters in piglet milk mixing tank on mixing effect of milk.The method combining CFD numerical simulation and response surface analysis was used. A four factor and three-level orthogonal simulation experiment was designed by taking the rotating speed, layer spacing, paddle angle and distance from the bottom as the design optimization parameters, and the mixing power, mixing time and average temperature rise rate as the response indexes. The regression model of response index was established. The parameters of double-layer paddle agitator were optimized. The results showed that the rotating speed and blade angle significantly affected the mixing power. The rotating speed, layer spacing, blade angle and distance from the bottom had a significant impact on the time of mixing. The rotating speed had an extremely significant impact on the average rise rate of temperature. The layer spacing and blade angle had a significant impact on the average rise rate of temperature. The rotating speed had the greatest impact on the performance of the agitator. The response surface regression model had good fitting. The parameters optimized by the response surface regression model were the speed of 80 r/min, the layer spacing of 170 mm, the blade angle of 30°, and the distance from the bottom of 100 mm. Compared with that before optimization, the stirring power and the time of mixing was reduced by 27.08% and 70.15%, respectively. The average rise rate of temperature was increased by 9.57%. The cloud diagram distribution of turbulent flow energy and temperature were significantly better than those of the primary model. It will provide theoretical basis and reference for the design and application of agitator in piglet milk preparation tank.

Abstract:For the application of deep learning in the field of Chinese herbal medicine， especially in the field of southern Chinese medicine， the complex background will reduce the accuracy of recognition.If a complex network structure is used， high computing power is required to support training and detection， but the actual embedded or mobile devices are difficult to meet， which affects the effect of on-site detection.This article proposed to improve the EfficientNetv2 network model to classify and identify 8 kinds of southern Chinese medicine leaves in the complex background collected in the field.The network structure was redesigned.The scope of the Fused-MBConv and MBConv architectures was adjusted.Some 3×3 convolutional kernels were replaced with 5×5 convolutional kernels to increase the perceptual field size， reduce the number of convolutional layers of the network， and to further reduce the network complexity.The transfer learning was introduced to train the model.The adaptive moment estimation optimization algorithm was used to optimize the hyperparameters with multiple tests to determine the learning rate.MultiMarginLoss was selected as the loss function to solve the problem of complex background information affecting the accuracy of recognition.The diversity of the data set was increased and the problem of model over-fitting was avoided by adopting data augmentation methods including affine transformation and Gaussian blur and other methods to the experimental data set to improve the stability of the model training process.The results showed that the model improved achieved 99.12% accuracy in recognizing the image of southern Chinese medicine leaves with complex backgrounds， 1.17% more accurate than the baseline model EfficientNetv2-S.The size of parameters was reduced by 85% approximately.The average training time was reduced by 47.62%.The improved model had significant advantages in model storage space， accuracy， and training time， comparing with lightweight models including DenseNet121， ShuffleNet， and RegNet.It is indicated that the model proposed performs well in classifying leaves of multi-variety southern Chinese medicine.The lightweight degree and performance of the model are further improved.

Abstract:As one of the important raw materials for sugar production，sugar cane extracted is not only a necessity but also belongs to national strategic reserve materials. At present，the sugarcane industry as a whole is inefficient，especially in terms of machine seeding，and the efficiency of manual seed cutting is low. The developed methods for sugarcane stem node identification are all based on clean background conditions，but the working environment of agricultural machinery is disgusting. A large amount of debris，miscellaneous leaves and other dirt produced by seed cutting will lead to background pollution in image acquisition area and reduce the recognition ability of algorithm. Therefore，a sugarcane stem node identification method is put forward based on improving YOLOv5 to solve the problems of low recognition accuracy of sugarcane stem node under complex background. To optimize the neck structure and enhance the information fusion capability among different levels by using cross-level connection. At the same time，the model loss function is improved. On the one hand，EIoU loss is introduced to replace original CIoU loss to improve the precision of boundary box regression； on the other hand，Focal loss function is used to replace the cross-entropic loss function to solve the problem of unbalanced proportion of positive and negative samples. Finally，Ghost module is introduced to lightweight network model. The experimental results show that compared with the original model，the average precision value of the model proposed in this study is increased to 97.80%，the single detection time is 16.9 ms and the memory of the model is only 11.4 Mb，which realizes the identification of sugarcane stem joints in different chaotic scenes and reduces the impact of background chaos when cutting injurious buds.