Phoebe bournei （Hemsl.） Yang is an important and precious tree species in China. This study aimed to establish a genetic transformation system for P. bournei， pCAMBIA1300-GFP plasmid was constructed and transformed into seedlings with Agrobacterium rhizogenes. To optimize the transformation process， injection and soaking in bacterial solution were compared. Subsequently， an orthogonal ［L9（3³）］ experiment was employed to determine the optimal combination A. rhizogenes strain type， bacterial solution concentration， and seedling age. In addition， the effects of light intensity on induction and transformational rate of P. bournei hairy roots were also examined. The results showed that hairy roots induction and transformation rate with injection method were 80.0% and 66.7% respectively， whereas only 41.2% and 35.3%with soaking method. The main factors affecting the hairy root induction rate and genetic transformation of P. bournei were strain species. Notably， strain type exhibited a substantial influence on both induction and transformation efficiency of hairy roots. The maximum induction and transformation rates were 87.5% and 70.6% respectively. The optimal strain was K599 with concentration of OD₆₀₀=1.2， and the seedlings at the three-leaf stage was the best The seedlings growth， hairy roots induction and transformation efficiency of P. bournei seedlings under lower light intensity （50 μmol·m^-2·s^-1） were more favorable for seedling growth and transformation than high light intensity （100 μmol·m^-2·s^-1）. This study established an efficient and steady transgenic system for P. bournei mediated by A. rhizogenes， thereby obtained transgenic hairy roots plants. That provided a useful platform for molecular genetic research of P. bournei and laying the foundation for important gene exploration， new germplasm development and genetic improvement of P. bournei.

Mulching technique is a widely used agricultural technology. The traditional plastic film currently in use brings huge economic benefits， but also induces serious ecological pollution problems and affects the sustainable development of agriculture， so the development of environmentally degradable mulching films is an inevitable trend. This study systematically describes the research progress and application status of the preparation materials， preparation technologies and products of photodegradable mulching film， biodegradable mulching film， photo/biodegradable mulching film， liquid mulching film and plant-fiber mulching film at home and abroad， as well as the advantages and shortcomings of the five types of degradable mulching films， and provides an outlook on the research direction and development prospects of plant-fiber mulching film. The results of this study provide a theoretical basis for further development of green， environmentally friendly and completely biodegradable agricultural mulching films to promote green and sustainable development of agriculture.

To make full use of shark cartilage resources， taking the osteoblasts proliferation rate as an indicator， on the basis of optimizing the enzymatic hydrolysis process of promoting osteoblast proliferation collagen peptides， the relative molecular weight， amino acid composition and stability of the hydrolysates were analyzed in the study. The results showed that acid protease was the optimal protease among all types of protease. Under the conditions of enzyme dosage of 5 100 U·g^-1， solid-liquid ratio of 1∶50 （g·mL^-1）， enzymatic hydrolysis time of 4.14 h and temperature of 55 ℃， the enzymatic hydrolysates yield was 91.23% and the osteoblast proliferation rate and hydrolysis degree of the prepared hydrolysates were 141.23% and 25.03%， respectively. Shark cartilage collagen peptides showed a certain degree of stability and were insensitive to ultraviolet light. Appropriate heating could enhance their osteoblast proliferation rate， but excessively high temperatures led to a significant decrease in osteoblast proliferation rate. After simulated gastrointestinal digestion， the osteoblast proliferation rate of the hydrolysates was significantly decreased. The prepared hydrolysates were mainly composed of hydrophobic amino acids with peptide molecular weights generally less than 3 kDa. They demonstrated the ability to promote osteoblast proliferation， differentiation， and mineralization， with the best effect observed at a concentration of 1.0 mg·mL^-1. This study provides a theoretical basis for the deep processing and high-value utilization of shark resources.

To study the mass spectral fragmentation pathways of primary aromatic amines by ultra-performance liquid chromatography coupled to quadrupole orbitrap high-resolution mass spectrometry. The data was collected under electrospray negative ion mode, and the fragmentation pathways of 14 primary aromatic amines were derived by the precise mass-to-charge ratio of the first and second mass spectrometry ions. The results showed that the existence of amino groups in molecular structure could easily be protonated to form [M+H]⁺, and the cracking process mainly lost the neutral molecule NH₃ and produced [M+H-NH₃]⁺. After that, the chlorinated anilines underwent carbocation rearrangement and then lost the chlorine atoms, resulting in characteristic fragment ion [·M+H-NH₃-Cl]⁺. Methoxy substituted anilines lost the CH₃O group and produced [M+H-NH₃-CH₃O]⁺, or carbocation transferred and rearranged to benzyl, further losing CH₃ and CH₃O groups. Methyl or methoxy substituted benzidine compounds also can undergo CN bond cleavage to form [M+H-NH]⁺, and then lost the neutral molecule NH₃ to produce [M+H-NH-NH₃]⁺. Azobenzene compounds are not easy to break the azo bond with high bond energy, and the fragment ions are mainly formed by breaking the CN bonds on both sides. The best ionization mode and mass spectral fragmentation pathways proposed in this study provides an important basis for the rapid identification and analysis of such primary aromatic amines.

NAC transcription factors are involved in plant growth and development， fruit pigment accumulation， cell wall morphogenesis， and plant senescence. To systematically study the precise function of SNAC4 （SlNAC48， Gene ID： 101247735） and SNAC9 （SlNAC19， Gene ID： 101248665） in the tomato ripening and aging， we designed SNAC4/9 knockout targets and constructed a single guide RNA （sgRNA） expression cassette through Overlapping Polymerase Chain Reaction （Overlapping PCR） method. Single or multiple sgRNA expression cassettes were assembled into pYLCRISPR/Cas9 vector by the Golden Gate cloning method. PCR and sequencing results showed that the SNAC4/9 knockout vector was successfully constructed. The genes encoding Cas9 protein and sgRNA were introduced into Micro-Tom tomato cells by the Agrobacterium transformation method， and the target and off-target of positive seedlings were detected. The results showed that tomatoes were mutated successfully without off-target. The identification of T₁ mutants further demonstrated that CRISPR/Cas9 gene editing targets in tomato could be inherited stably between generations. Compared with wild type， SNAC4/9 knockout fruits had less pigment accumulation and delayed ripening， suggesting that SNAC4/9 played an essential role in tomato fruit ripening. This study provided genetic material and an experimental basis for further exploring the mechanism of SNAC4/9 regulating pigment metabolism and cell wall metabolism in tomatoes.

Phytoene Synthase 1 （SlPSY1）， a key rate-limiting enzyme of carotenoid synthesis， directly affects the accumulation of carotenoids in tomato fruit. We constructed and transformed the bait vector pSlPSY1pro-AbAi into the yeast cell to explore the transcriptional regulation of SlPSY1. Then， the AP2/ERF family transcription factor SlJERF1 and 10 other proteins were screened by yeast-one-hybrid experiment using the yeast hybrid cDNA library built by mixed tissue of tomato. Subsequently， the sequence of SlJERF1 gene was cloned and the recombinant vector pGADT7-SlJERF1 wasconstructed. The molecular interaction between SlJERF1 and SlPSY1 promoterwas varified through yeast-one-hybrid point-to-point test. The results showed that the yeast in the control group could not grow normally under 150 ng·mL^-1 Aureobasidin A （AbA）， while the yeast transformed with SlJERF1 could grow normally， indicating the interaction between SlJERF1 and the promoter of SlPSY1 gene. This result provides an important theoretical basis for the regulatory network of carotenoid synthesis， and confers new ideas for further study in the future.

To explore the mechanism of Eriobotrya japonica in the prevention and treatment of type 2 diabetes, Network pharmacology and molecular docking technology were used to explore the common target of loquat leaf and type 2 diabetes. In this study, TCMSP, Uniprot, Genecards, Venny, DAVID and other databases were used to map the interaction network and perform GO(Gene Ontology) and KEGG(Kyoto Encyclopedia of Genes and Genomes) enrichment analysis. The molecular docking was verified by autodock tools. 19 ingredients and 294 related targets were collected from TCMSP datebase, then 89 common targets of type 2 diabetes and loquat leaf active components were obtained in Venny 2.1.0, corresponding to 10 active substances such as EGCG, quercetin, kaempferol and β-sitosterol. Then the ‘active ingredient-disease target’ network map was constructed. The results indicated that the active components of loquat leaves regulated type 2 diabetes through regulating oxidative stress response, serine/threonine kinase activity, responding to lipopolysaccharide and epithelial cell proliferation, then regulating AGE-RAGE(Advanced glycation end products and the receptor for advanced glycation end products), HIF-1(Hypoxia inducible factor-1) and PI3K-Akt(Phosphatidylinositol 3 Kinase-protein kinase B) signaling pathways. The molecular docking results showed that the binding energy of the main active components on α-glucosidase was less than-9.0 kcal·mol^-1, which had very strong binding activity. The semi-inhibitory concentrations of 7 active ingredient such as EGCG, quercetin and kaempferol on α-glucosidase were in the range of 1.11~80.04 μmol·L^-1, as measured by in vitro enzyme activity assay. The inhibitory effects were better than those of acarbose, which can be used as efficient α-glucosidase inhibitor as the main active ingredient of loquat leaf in the prevention and treatment of type 2 diabetes. This study investigated the mechanism of active ingredients of loquat leaf on the prevention and treatment of type II diabetes, and provided research ideas for the follow-up development of hypoglycemic drugs from natural products.

Phosphorus deficiency in the soil is a key factor limiting the growth and development of rice （Oryza sativa L.）. It is of great significance to elucidate the morph-physiological changes of rice in response to low phosphorus stress and further understand the mechanism underlying the phosphorus uptake and transport， which is also crucial to alleviate phosphorus stress on rice yield and quality. This paper mainly reviewed the changes in the morphology of roots and shoots as well as the physiological and molecular mechanisms of phosphorus uptake and utilization of rice under low phosphorus stress， and proposed crop management practices to enhance phosphorus uptake and utilization in rice. The key points for future researches were also discussed， that is， effect of interaction between rice roots and soil on the release of soil organic phosphorus， regulation and mechanism of plant hormones， especially new plant hormones， on phosphorus absorption， transport and distribution in rice plants， and development of rice varieties with high phosphorus utilization efficiency and exploring cultivation techniques to improve phosphorus use efficiency. This review is expected to provide theoretical guidance for screening and breeding rice varieties with tolerance to low phosphorus stress （phosphorus efficient varieties） and the cultivation regulation for improving phosphorus utilization efficiency.

Tomato brown rugose fruit virus （ToBRFV） belongs to the genus Tobamovirus in the Virgaviridae family and is classified as a quarantine virus in China， posing a serious threat to the safety of tomato production. Signal transduction system plays an important role in plant disease resistance， and phospholipid signaling is crucial in the process of extracellular resistance signal transduction. Phospholipase C （PLC） is critical in the transmembrane signaling of the phospholipid signaling system. In this study， we first identified 10 tomato PLC genes based on bioinformatics， including seven phosphati-dylinositol-specific phospholipase C （PI-PLC） and three non-specific phospholipase C （Non-specifc -PLC， NPC）， the seven PI-PLC PLC proteins have three core structural domains （PLC_X c， PLC_Y c， C2） and an EF_hand-like structural domain， and the three NPC proteins only have a phosphoesterase structural domain. 10 tomato PLC proteins can be divided into seven branches according to their structural similarity， namely NPC1， NPC2， NPC6， PI-PLC2， PI-PLC3， PI-PLC4 and PI-PLC6. In addition， the 10 tomato PLC secondary structures were similar in proportion， but there were significant differences in tertiary structures. Co-linearity analysis showed that there were 3， 12 and 16 pairs of co-linear relationships between the distribution of tomato PLC genes and rice， Arabidopsis and Raymond-type cotton PLC genes. Finally， to clarify which tomato PLCs are involved in the plant defense response against ToBRFV， this study examined the relative expression levels of the PLC gene family after ToBRFV inoculation by transcriptome sequencing， and the results showed that SlNPC1， SlNPC6 and SlPLC4 were expressed at higher levels in the ToBRFV-inoculated samples， while the expression levels of other PLC genes were reduced after ToBRFV inoculation. This study lays the technical and theoretical foundation for tomato ToBRFV resistance research and breeding.

Flavonol synthase （FLS） is a key enzyme in the flavonol biosynthesis pathway in plants. To investigate the mechanism of flower color formation in different species of Yulania， the flavonol contents of Y. denudata and Y. liliiflora were measured by the ultra-performance liquid chromatography （UPLC） at five key stages of flowering. The FLSs genes were cloned by RNA-seq in Y. denudata and Y. liliiflora. The expression patterns of FLSs genes in different tissues and tepals at five flowering stages were detected using quantitative real-time PCR （qRT-PCR）. Subcellular localization of FLSs proteins were performed by transient transformation technique in onion epidermis. The functions of FLSs genes were verified by heterologous transformed in tobacco， and the difference in flavonol contents in the transgenic tobacco corolla was analyzed by UPLC. The results showed the flavonol content of Y. denudata tepals was first increased and then decreased during flowering， while the flavonol content of Y. liliiflora tepals gradually decreased. YdFLS and YlFLS were conserved in sequence. The highest expression level of the YdFLS gene was found in flowers， and YlFLS had the highest expression level in young leaves. The expression of YdFLS was gradually increased and peaked at the bloom stage， while YlFLS showed a declining expression pattern. Both YdFLS and YlFLS were located in the cytoplasm. Overexpression of YdFLS and YlFLS genes in tobacco caused a light corolla phenotype and flavonol accumulation. In conclusion， this study verified that FLSs genes conservatively functioned on promoting flavonol synthesis in Yulania species. This study revealed the important function of FLS gene in flower color formation of Magnolia.

Irradiation mutagenesis tends to generate chromosome structural variations. So far few studies have been reported using the BSA-seq technique to map radiation-induced mutations. In order to explore the feasibility of using BSA-seq for mapping genes in radiation-induced mutants， this study isolated an Arabidopsis thaliana mutant using irradiation mutagenesis and crossed it with the wild type. Individual plants in the F₂ segregating population were screened based on phenotypes， and two pools of offspring with extreme phenotypes were collected. The two offspring pools and the wild type pool were sequenced using whole genome sequencing， and various strategies including MutMap， QTL-seq， and GPS methods were used to analyze the sequencing data of these three pools. It was found that three strategies generated similar results and the mutated gene was located to an interval of 7 Mb on chromosome 2. With visualizing the genomic region within this interval by IGV software， a 25 189 bp deletion was found in the mutant genome. The deletion region was annotated using the SnpEff annotation program， and 6 genes were found in this region， among which the AT2G28610 gene was identified to be the candidate gene and verified through genetic experiments. This study provided a reference for the application of BSA-seq based approaches to map radiation-induced mutations.

To investigate the pattern of chloroplast codon usage in cowpea （Vigna unguiculata）， the complete cowpea genome sequence was downloaded from NCBI and structurally analysed in this study. The sequences were screened to obtain 50 protein-coding sequences （CDS）， which were analysed by CodonW and CUSP to obtain important parameters such as GC1， GC2， GC3， RSCU， CAI， CBI， Fop， ENc， RFSC， and further analysed by neutral plot analysis， PR2-plot analysis， ENc-plot analysis， correspondence analysis， optimal codon analysis and comparative analysis of other species. The results showed that cowpea chloroplast gene codons preferred to end at A or U（T）， and G and C were lower in all positions of codons， with a mean value of 36.31%. The mean value of the effective codon number ENc was 44.903， with weak codon preference； there was correlation between GC1 and GC2 and GC3， indicating that base mutations also had an effect on codon selection. From the neutral plot， PR2-plot and ENc-plot， it is clear that cowpea chloroplast codon usage bias is influenced by both base mutations and natural selection. In this study， totally 20 optimal codons were successfully screened. Compared with other species， cowpea and tomato have high similarity in codon usage frequency. This study provides a reference for improving the efficiency of cowpea chloroplasts genes as an exogenous gene expression.

To clarify the molecular mechanism of spike of mutant sui1， the phenotype identification and the transcriptome analyses of rachis and peduncle in different growth stages （tooting stage as T1 and filling stage as T2） were performed. The results showed that the spike mutant had shorter length of rachis and peduncle， lower plant height and aggravated incidence of FHB. Results of transcriptome analyses showed that at the same period， the differentially expressed genes between mutant and parent in peduncle was more than that in rachis， and there were more differentially expressed genes at tooting stage than at filling stage in rachis. A total of 2 526 differentially expressed genes was screened， among which 890 were up-regulated， 1 636 were down-regulated. The study of gene ontology classification found that genes annotated with molecular functions in different tissues were equally enriched and most of them were focused on ATP binding. KEGG enrichment analysis showed that plant-pathogen interaction pathway had the most enriched genes. The highest enrichment factors of rachis in different stages were carbon fixation in photosynthetic organisms. The highest enrichment factor of peduncle in different tissues was photosynthesis-antenna proteins pathway. From plant-pathogen interaction pathway， 160 related genes were selected. There were 63 genes related to the defense response （39%）， 21 genes related to protein kinase activity （13%） and 18 genes related to ADP binding（11%）. It is speculated that these genes may be important for the rachis and spike type of wheat mutant sui1. This study provides data support for further exploring the molecular mechanism and gene regulation network of wheat spike type variation in the future， and also provides important information for the wheat yield and disease resistance.

The fertility， adaptability and stability of potato are important indicators for potato popularization and application. Because of the differences in the performance of different characters by various environmental factors， it is necessary to screen and identify varieties （lines） in different ecological zones. In this study， the yield and plant traits of advance lines and main cultivars were analyzed by GGE （Genotype + genotypes and environment interactions） biplot， and the potato varieties （lines） with wide adaptability， high yield， stability and suitable for mechanization were selected. The effect of genotype-environment interactions on yield traits and plant traits were detailed， which provide a reference for potato breeding and selection of varieties in different ecological regions. Twenty two advance lines and thirteen main cultivars were selected to plant in three pilot sites in Weiyuan County， Anding District and Yongchang County of Gansu province from 2020 to 2021. Eight plant traits such as number of main stems and nine yield traits such as plot yield were measured. Analysis of variance was applied for analysis of significance. GGE biplot was used for analysis of adaptability， productivity and stability. Concurrently， the distinctiveness and representativeness of pilot sites were evaluated. Variance analysis showed that the effect of genotype on natural and absolute plant height were significant， and the sum of squares of genotype effect and the ratio to total variance was 66.63% and 56.56% respectively. The effect of genotype-environment interactions on peduncle length and yield of large tuber per plant were significant， and the sum of squares of interactions effect and the ratio to total variance was 27.86% and 27.05% respectively. The effect of environment on number of branches and yield of tuber per plant were significant， and the sum of squares of environment effect and the ratio to total variance was 55.82% and 25.52%. GGE analysis showed that yield and stability of varieties （lines） were generally consistent in different years. The genotypes with highest yield were G1， G33 and G10 in Weiyuan County， Anding District and Yongchang County. G32 was the most stable in the three pilot sites. Yongchang County had the strongest distinctiveness among varieties （lines） in 2020. Anding District had the strongest representativeness to target environment in 2021. GGE biplot can intuitively showed the results of varieties （lines） test in three sites between 2020 and 2021， and screen and evaluate varieties （lines） were G33， G12 and G3 were high yield， stable and suitable for mechanization， while G28， G26 and G23 were high yield， unstable and unsuitable for mechanization. The genotype-environment interactions had the greatest influence on peduncle length and yield of large tuber per plant. Combined with distinctiveness and representativeness， Weiyuan county was the best pilot sites in this experiment. According to the adaptability and stability of varieties （lines）， the varieties （lines） suitable for planting in different ecological regions with high yield， stability and suitable for mechanization were selected， which will provide reference and theoretical basis for the subsequent registration and promotion of varieties.

To investigate the expression of Collagen1 and Collagen3 in pulmonary fibrosis tissue of yak and clarify the roles of Collagen1 and Collagen3 in pulmonary fibrosis process of yak. The normal and fibrosis lung tissue of yak were collected and divided into control group and experimental group. HE staining， Masson staining and transmission electron microscope were used to observe the pathological changes of lung ultrastructure and fibrosis state； qRT-PCR， Western-blot， immunohistochemistry and immunofluorescence staining were used to detect the expression of Collagen1 and Collagen3 genes and proteins in groups. The results showed that the yak lung tissue structure of the control group was intact， the alveolar septum was normal and there was no inflammatory exudate in bronchial lumen and alveolar cavity. while in experimental group， lung tissue showed necrosis， nuclear fragmentation and dissolution， severe hemorrhage and extensive pulmonary edema. The expression of Collagen1 in experimental group is higher， while the expression of Collagen3 is lower than that in control group. In experimental group， Collagen1 and Collagen3 proteins were proliferated massively and distributed in alveolar septum extensively. The other distributions were basically the same as control group but stronger than in control group. In conclusion， Collagen1 and Collagen3 play important roles in yak pulmonary fibrosis.

In order to explore the changes of root morphological distribution， nutrient accumulation and yield under different root configuration maize varieties intercropping， monoculture and intercropping treatments were conducted both in the field and pot-cultivation to study the variation characteristics of intercropping of maize （Zea mays L.） on root traits， spatial distribution， nutrient accumulation and grain yield， two maize varieties JS501 （small root angle type） and LY16 （large root angle type） with different root system architecture were used as experimental materials. The results showed that the total root length， total root surface area， total root volume and root diameter of maize population under intercropping treatments increased by 10.19%， 19.55% and 15.95% on average compared with monoculture treatments， respectively. But there was no significant change in root diameter between intercropping and monoculture treatment. In 0~20 cm soil layer， the total root length， total surface area and total volume of maize in intercropping were 15.27%， 21.82% and 9.44% higher than those in monoculture， and 12.95%， 9.18% and 20.31% higher than monoculture at 20~40 cm， respectively. Intercropping enlarged the horizontal distribution of JS501 root and extends outward by 5 cm， deepened root vertical distribution by 10 cm in intercropping treatments and increased root length density by 26.03% on average in 40~60 cm soil layer. Intercropping also significantly improved root activities by 27.83% compared with monoculture. The accumulation of nitrogen， phosphorus and potassium in intercropping population increased by 18.27%， 14.79% and 15.75% on average compared with monoculture， respectively. Land equivalent ratio was more than 1 under intercropping and dry matter weight and grain yield were increased significantly by 11.03% and 15.36% on average compared with monoculture， respectively. Path analysis showed that total root surface areas significantly affected the accumulation of N and K， which indirectly affected dry matter accumulation and 100-grain weight， and significantly increased grain yield under intercropping conditions. However， the correlation coefficient between factors in monoculture was lower than that in intercropping. In summary， intercropping changed the spatial distribution of maize roots with different root architecture and increased the proportion of roots in deep soil. It reshaped root architecture in 40~60 cm soil layer， improved root activities and make use of the root spatial complementary. These characteristics promoted the nutrient accumulation and increased grain yield. This study provided a theoretical and practical strategy for high efficiency of nutrient resources and sustainable agriculture.

In order to identify the main odors in the high-value processing of bovine bone collagen peptide powder and obtain the optimal deodorization process， this study used GC-MS combined with Relative aroma activity value to identify the main odors in the odors peptide powder. The results showed that isobutyric acid， caproic acid， acetic acid， butyric acid， isovaleric acid and valeric acid were the main volatiles of heteroolfactory flavor， which had unpleasant odor. The deodorization of bovine bone collagen peptide powder was realized by ultrasonic-assisted alkaloid-catalyzed esterification of the isooluminescence substance in the peptide powder with ethanol. The deodorization process of bovine bone collagen peptide was optimized by single factor and response surface method. When the reaction time was 28.43 min， the amount of ethanol was 3.19%， and the reaction temperature was 75.41 ℃， the highest score of sensory evaluation was 71.16， which achieved the goal of deodorization. This study provided technical support for the deodorization process and industrial production of bovine bone collagen peptide powder.

In order to obtain standardized irradiation sterilization processes for dried sweet potato， the effects of different irradiation sources of γ ray and electronic beam， irradiation doses and dose rates on the main components， appearance quality and storage characteristics of dried sweet potato were investigated. The results showed that no microorganisms were detected in the dried sweet potato after irradiated with γ-ray dose≥4 kGy and subsequently incubated at 36 °C for 10 d or stored at room temperature for 90 d. The same result was observed in the dried sweet potato irradiated with γ-ray dose≥6 kGy and incubated at 36 ℃ for 30 d at constant temperature or stored at room temperature for 360 d. No significant changes in soluble solids， carotenoid contents， and sensory indexes were observed in dried sweet potato after treatments with γ-ray irradiation. The higher the dose rate at the same dose， the greater the influence on the appearance of dried sweet potato. Due to the high dose rate of electron beam， the appearance of dried sweet potato changed significantly after irradiation. Thus， the minimum effective dose was recommended to be 4 kGy for irradiating dried sweet potato with a shelf life of 90 d. The results would provide basis for the establishment of irradiation sterilization process for dried sweet potato.

To clarify the effects of storage time and low storage temperature on the nutrition quality of rapeseed stem， two oil-vegetable rapeseed cultivars Zheyou 51 and Zheyouza 108 were used as materials. 3 storage times （stored at 4 ℃ for 1， 2， 3 d） and 3 storage temperatures （stored at -20， -40， -80 ℃ for 10 d） were set， and the contents of sugars， vitamins， cellulose and lignin during storage were analyzed. The results showed that vitamin C and vitamin B₁ showed a rising trend first and then falling in two varieties， while vitamin B₆， fructose， sucrose and cellulose showed an upward trend with the extension of storage time under 4 ℃. Vitamin E were raised in Zheyouza 108， while it increased first and then decreased in Zheyou 51. The starch content gradually decreased in two varieties. Paraffin section staining results showed that the cellulose area in Zheyou 51 and lignification area in Zheyouza 108 were increased with the extension of storage time. Under different storage temperatures， the content of all the nutrition except cellulose were the highest in fresh sample， while cellulose contents reached the highest in -20 ℃. Fructose， sucrose and cellulose contents can match the fresh level at -80 ℃ in two varieties， while the content of vitamin B₁ and E were better under -40 ℃ in Zheyou 51. In conclusion， the appropriate shelf life of rapeseed stem should be within 2 d when storing at 4 ℃. For low storage temperature， -40 ℃ and -80 ℃ were better than -20 ℃. The results of this research provides a theoretical basis for daily storage and consumption of rapeseed stem and the multi-functional utilization of rapeseed.

To clarify the current situation of heavy metal content in the muscles of commercially available freshwater fish in Hubei， Guangdong， Henan and Heilongjiang provinces， 133 samples of 11 species of freshwater fish were collected from September to October 2021 in 11 cities and districts the above four provinces， Concentrations of chromium （Cr）， copper （Cu）， total arsenic （As）， cadmium （Cd）， mercury （Hg） and lead （Pb） in muscle were determined by inductively coupled plasma-mass spectrometry （ICP-MS）. The results of the pollution evaluation according to the National Standard for Food Safety Limits for Contaminants in Food （GB 2762-2017） showed that the five heavy metals Cr， Cu， Cd， Hg and Pb did not exceed the limits in the tested samples， while the content of As in freshwater Lateolabrax japonicus and Channa argus exceeded the limit （0.1 mg·kg^-1）， with levels of 0.182～0.738 mg·kg^-1 and 0.180～0.628 mg·kg^-1， respectively.Both of them were cumulatively significantly different （P<0.05） with other freshwater fishes. Samples with total As content above 0.1 mg·kg^-1 were further tested for inorganic arsenic by liquid chromatography-atomic fluorescence spectrometry （LC-AFS）. The results were all non-detect， indicating that their inorganic arsenic content was in a very low percentage of the total arsenic content. The single pollution index and integrated pollution index method were used to evaluate the contamination status and variability of the six heavy metal elements in the tested freshwater fish， and the results showed that a low risk of heavy metal contamination in currently commercially freshwater fish in the four provinces， providing a reference for clarifying the quality and safety of freshwater fish in these regions and carrying out aquatic product safety assessment.