Acta Agriculturae Zhejiangensis

Effects of nitrogen reduction in wheat/rape season and nitrogen fertilizer management in rice season on crop yield and nitrogen uptake in crop rotation system

MA Peng, YANG Zhiyuan, LI Yu, LIN Dan, SUN Yongjian, MA Jun

2019, 31(11): 1769-1778. DOI: 10.3969/j.issn.1004-1524.2019.11.01

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In order to reveal the effects of nitrogen reduction in wheat/rape season and nitrogen fertilizer management in rice season on crop yield, nitrogen uptake and partial factor productivity in crop rotation system, a field experiment of wheat-rice rotation and rape-rice rotation was conducted in 2017-2018. In this rotation system, conventional nitrogen rate (N 150 kg·hm^-2 in wheat season or 180 kg·hm^-2 in rape season) and reduced nitrogen rate (N 120 kg·hm^-2 in wheat season or 150 kg·hm^-2 in rape season) were set. Based on the application rate of 150 kg·hm^-2 N in rice season, 3 models named M1-M3 were also set, of which the application rate of base fertilizer, tiller fertilizer and panicle fertilizer was 2∶2∶6, 3∶3∶4, and 4∶4∶2, respectively. It was shown that the yield, biomass and nitrogen uptake in aboveground part of wheat was significantly (P<0.05) reduced under reduced nitrogen rate in wheat season by 15.36%, 14.21% and 17.14%, respectively, yet the partial factor productivity of wheat was significantly (P<0.05) increased by 5.79% in wheat-rice rotation system. Furthermore, under the conventional nitrogen rate in wheat season, the highest rice yield was recorded in M3 model, while the highest yield, nitrogen uptake in aboveground part and partial factor productivity were recorded in M2 model under the reduced nitrogen rate in wheat season. In rape-rice rotation system, reduced nitrogen rate in rape season significantly (P<0.05) reduced the yield and nitrogen uptake in aboveground part of rape by 14.28% and 16.76%, respectively. Under both conventional and reduced nitrogen rate in rape season, the highest yield, aboveground biomass, and partial tactor productivity of rice were recorded in M3 model.

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Phenotypic diversity of rice resources in multiple provinces and screening of excellent resources

CHEN Yue, ZHANG Dunyu, DING Mingliang, WANG Lingxian, XIAO Suqin, KE Xue, CHENG Zaiquan

2019, 31(11): 1779-1789. DOI: 10.3969/j.issn.1004-1524.2019.11.02

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In order to study the level of phenotypic diversity of rice resources, 60 rice resources from 6 provinces in China were analyzed by variation coefficient, genetic diversity index, cluster analysis, correlation analysis, principal component analysis and stepwise regression analysis. These results suggested that the variation coefficient of 15 phenotypic traits were 9.58%-47.15%, the variation coefficient of grain length was the smallest, and the secondary branch number was the largest. The 15 phenotypic diversity indices were 1.8101-2.0411, flag leaf length diversity index was the largest, and the seed setting rate diversity index was the smallest. The genetic diversity indices of 6 provinces were 0.944 6-1.963 6, and the genetic diversity index of rice resources in different provinces was different. The result of cluster analysis showed that 60 rice resources could be clustered into 3 groups at 0.4 European distances, and 15 major phenotypic traits of each group were different. Principal component analysis and comprehensive evaluation of 15 phenotypic traits data showed that Sichuan's Shuhui 527 was the best resource of phenotypic comprehensive traits. At the same time, six indices, including plant height, grain length, grain width, number of first panicle branch, number of secondary panicle branch and thousand seeds weight were selected as comprehensive evaluation key indices for rice germplasm resources. The above phenotypic trait data and the selection of germplasm resources with better comprehensive characteristics could provide excellent parents and intermediate materials for rice breeding.

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Analysis of influencing factors for determination of inorganic phosphate concentration in rice leaves

XU Jiming, MAO Wenxuan, HE Qiuju, JIANG Xiaoyan, MAO Chuanzao

2019, 31(11): 1790-1795. DOI: 10.3969/j.issn.1004-1524.2019.11.03

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To provide guidance for the measurement of inorganic phosphate concentration, the effect of sampling tissue, sampling time, preservation temperature and seedling age on inorganic phosphate concentration determination of leaves in rice (Oryza sativa L. ssp. Japonica cv. Nipponbare) were analyzed. 21-day-old rice seedlings grown under normal rice culture solution were used for inorganic phosphate concentration determination. Different leaves, different parts of a same leaf or leaves of plant in different ages were sampled for inorganic phosphate concentration determination. Effects of preservation temperature and time on phosphate concentration were analyzed. And also, phosphate concentration of leaves sampled at different time in a day was measured. The results indicated that different sampling tissues had great influence on the determination of inorganic phosphorus. Phosphate concentration of old leaves was higher than that of new leaves in the plant, and flag leaves before flowering had a higher inorganic phosphate concentration than these after flowering. The basal part of leaves had a lower phosphate concentration than those of the apex and middle parts of leaves. There was no difference between leaves sampled at different time in a day. Preservation temperature and time had no significant influence in inorganic phosphate concentration determination. These results suggested that sampling tissues or leaves should be consistent when we measure inorganic phosphate concentration. Other factors such as sampling time, temperature and storage time had little effect on the results of inorganic phosphate concentration.

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Comparative study of yield and nitrogen efficiency between dwarf variety and normal variety in oilseed rape (Brassica napus L.)

LI Hongqiao, DUAN Qiuyu, LIU Shishan, YANG Yunfei, LI Mengying, WU Yongcheng

2019, 31(11): 1796-1802. DOI: 10.3969/j.issn.1004-1524.2019.11.04

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To explore the differences and commonness of agronomic traits, yield and nitrogen utilization characteristics between dwarf and high Brassica napus rapes under different nitrogen application rates, field experiment was carried out under the condition of rice-rape rotation in Sichuan basin. Dwarf rape MJ01 and high-stalk rape Chuanyou 36 were used as experimental materials. From 2014 to 2015, they were planted in the field. Two treatments of dwarf rape and high-stalk rape were set with different varieties of rapeseed as the main factors. 0, 135, 225 kg·hm^-2 were set with different nitrogen application amounts as auxiliary factors, respectively represented by N₀, N₁ and N₂. The main agronomic traits and yield of the plants were determined at maturity stage, and the nitrogen accumulation then analyzed and calculated the nitrogen efficiency. The results showed that plant height, branching height, main inflorescence length and pod number per plant of dwarf rape were significantly lower than those of high-stalk rape. Under the same nitrogen application condition, there was no significant difference in the grain yield between high-stalk and dwarf rape. Compared with high-stalk rape, the seed N content and harvest index of dwarf rape were relatively low, but there was no significant difference. The nitrogen utilization efficiency and nitrogen physiological efficiency of dwarf rape were higher than those of high-stalk, and the difference of nitrogen physiological efficiency was significant. The nitrogen absorption efficiency of dwarf rape was similar to that of high-stalk rape. With the increase of nitrogen application, the nitrogen absorption efficiency of both dwarf rape and high-stalk rape decreased, while the nitrogen physiological efficiency increased. Dwarf rape had higher harvest index, nitrogen utilization efficiency and nitrogen physiological efficiency, and the yield was similar to that of high-stalk rape under the reasonable nitrogen application.

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Screening of immunological adjuvant for inactivated vaccine against Erysipelothrix rhusiopathiae

CHEN Zhang, LIU Xiaolu, YAO Yanbin, WU Qiongjuan, SUN Pei, WEI Jianzhong, LI Dongfeng, LI Yu

2019, 31(11): 1803-1811. DOI: 10.3969/j.issn.1004-1524.2019.11.05

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To screen out the best immunoadjuvant for Erysipelothrix rhusiopathiae inactivated vaccine, five adjuvants (polymer adjuvant, mineral oil adjuvant ISA 201 VG, propolis adjuvant, Freund's adjuvant, aluminum gel adjuvant) were used to prepare 15 inactivated vaccines with three strains of Erysipelothrix rhusiopathiae(AEr21, AEr31 and AER32), respectively. Mice were immunized by the vaccines which had passed physical property, sterility and safety test, serum antibody IgG and cytokines (IL-4, IL-10, TNF-β, IFN-γ, MCP-1) levels were measured by ELISA. Calculating the protective rate of each immunization group after challenge by intraperitoneal injection and gavage. The results showed that all the inactivated vaccines prepared by five adjuvants and three strains could stimulate mice to produce good humoral and cellular immunity. The levels of IgG and cytokines induced by mineral oil adjuvant ISA 201 VG vaccine in mice were the highest, which was significantly different from that of aluminum gel adjuvant and Freund's adjuvant vaccine (P<0.05), but not significantly different from that of polymer adjuvant and propolis adjuvant vaccine(P>0.05). The mineral oil adjuvant ISA 201 VG vaccine had the highest immune protection rate after challenge, reaching 100%、100%、80% for intraperitoneal injection and 80%、80%、60% for gavage, respectively. The results showed that mineral oil adjuvant ISA 201 VG could be used as a candidate immunoadjuvant for the preparation of inactivated vaccine against Erysipelothrix rhusiopathiae.

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Genetic correlation analysis between the longevity and first parity reproduction traits of Large White sows

ZHAO Yunxiang, YANG Wenpan, GAO Ning, PENG Xing, ZHANG Conglin, CHEN Yaosheng, LIU Xiaohong

2019, 31(11): 1812-1818. DOI: 10.3969/j.issn.1004-1524.2019.11.06

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To explore the genetic structure of traits related to the longevity of Large White sows and to achieve early selection, genetic correlation analysis was carried out on large white sow longevity and sow first parity reproduction traits. In this study, the reproductive traits of Large White pigs collected during the January 1998 to August 2014 in the South China Pig Genetic Evaluation Network of the National Pig Industry System were used. The DMU (V6) analysis was used to calculate the heritability and genetic correlations between the age at first farrowing, the total number born parity 1, the number born alive parity 1, the accumulated born alive to parity 3, the accumulated born alive to parity 5, the stayability to farrowing parity 3, the stayability to farrowing parity 5, the accumulated lifetime total number born, the number of piglets born alive during the life and the length of life. The results showed that the total number born parity 1, the number born alive parity 1, the accumulated lifetime total number born, the number of piglets born alive during the life and the length of life and the stayability to farrowing parity 5 of the Large White sows ranged from 0.132 to 0.198 and belong to low heritability traits; the accumulated born alive to parity 3, the accumulated born alive to parity 5, the stayability to farrowing parity 3 ranged from 0.230 to 0.271, which were moderate heritability traits; the age at first farrowing and the length of life heritability is between 0.492 and 0.642, which is a high heritability trait. Large White sows have a stronger the total number born parity 1, the number born alive parity 1, the accumulated born alive to parity 3, the accumulated born alive to parity 5, the accumulated lifetime total number born and the number of piglets born alive during the life. The positive phenotype correlation is genetically related and has a weak positive phenotype correlation with the length of life and is genetically related, and has a weak positive phenotype correlation with the stayability to farrowing parity 3, the stayability to farrowing parity 5 and is genetically related. There was a negative genetic correlation between the age at first farrowing of the sow and the number of piglets born alive during the life, and the age at first farrowing and the length of life were strongly positively related. It is possible to better use the traits related to the age of the sow by estimating the genetic parameters of the sow longevity, and to carry out early seed selection from the genetic correlation analysis between the traits related longevity of the sow and other traits.

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Prokaryotic expression of Core protein of bovine viral diarrhoea viruses and preparation of polyclonal antibodies

ZHANG Kang, ZHANG Xuan, YAN Zunxiang, WANG Lei, ZHANG Kai, ZHANG Jingyan, LUO Yongjiang, QIU Zhengying, XUE Huan, LI Jianxi

2019, 31(11): 1819-1824. DOI: 10.3969/j.issn.1004-1524.2019.11.07

Abstract ( 780 )

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In order to obtain the Core protein of bovine viral diarrhea virus (BVDV) and its polyclonal antibody, a pair of specific primers was designed and synthesized according to the coding sequence of the Core protein, and the BVDV Core gene was amplified by RT-PCR and inserted into the Pet30a vector. The recombinant plasmid Pet30a-Core was constructed and transformed into Escherichia coli TOP 10 competent cells by enzyme digestion. The positive recombinant bacteria were screened and the recombinant Core protein with molecular mass of 20 ku was induced to express with IPTG. The protein was purified by Ni column affinity method of the fusion protein, and the polyclonal antibody was prepared by immunizing New Zealand white rabbit with the purified recombinant protein, and the polyclonal antibody titer was determined by indirect ELISA to reach 1∶512 000. Western blot and indirect immunofluorescence assay (IFA) confirmed that polyclonal antibodies reacted with BVDV antigens in cells and had good immunogenicity and specificity. The rabbit polyclonal antibody against BVDV recombinant Core protein was successfully prepared, which laid a foundation for the detection of BVDV and the study of Core protein function.

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Cloning, bioinformatics analysis and tissue expression detection of MCUR1 gene in Saba pig

DONG Xinxing, LI Mingli, CUI Yijia, LAN Guoxiang, WANG Xiaoyi, YAN Dawei

2019, 31(11): 1825-1833. DOI: 10.3969/j.issn.1004-1524.2019.11.08

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The aim of this study was to clone the MCUR1 gene from Saba pigs, analyze it by bioinformatics, and detect its expression level in different tissues of Saba pig and Large White pig by real-time fluorescent quantitative PCR. According to the MCUR1 gene sequence published in GenBank (accession number: XM_003128183.4), the primers were designed, and the MCUR1 gene CDS sequence of Saba pig was obtained by PCR amplification and sequencing. The sequence was 1 095 bp in length and encoded 364 amino acids. The molecular formula of MCUR1 protein is C₁₇₈₇H₂₉₄₉N₅₃₃O₅₀₃S₁₄. The molecular weight is 40.398 ku, the theoretical isoelectric point (pI) is 10.27, the instability coefficient is 55.70, the fat index is 95.99, and the average hydrophilicity is -0.213, which belongs to hydrophilic protein. MCUR1 protein has no signal peptide and transmembrane structure, and contains two spiral coiled structure that function primarily in the cytoplasm; contains 32 phosphorylation sites; contains one CpG island; the secondary structure consists of 58.24% alpha-helix, 4.12% beta turn, 30.22% random coil and 7.42% extended chain. The homology of the coding region of the porcine MCUR1 gene with bovine, chicken, dog, goat, human, monkey, mouse, and sheep was 85.3%, 68.0%, 83.6%, 87.9%, 84.4%, 80.3%, 76.8% and 88.2%, respectively, showing close relationship with sheep, goat and cattle, and distant relationship with chicken. The highest expression level of MCUR1 was observed in the liver and the least expression was in the lung. The expression of MCUR1 in the longissimus dorsi of the Large White pig was higher than that of the longissimus dorsi of the Saba pig (P<0.01).

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Potential effect of genetically modified maize DR 12-5 on honey bee (Apis mellifera)

JIANG Yuanyuan, JI Yi, LAI Yongmin, ZHU Xuan, CHEN Xiaoyun, XU Junfeng, MA Lianju, XU Xiaoli

2019, 31(11): 1834-1840. DOI: 10.3969/j.issn.1004-1524.2019.11.09

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Maize DR 12-5 expessing a fused protein Cry1Ab/Cry2Aj is a genetically modified (GM) event that has been approved for preproduction field testing in China. The ecologically and economic important honey bee (Apis mellifera) is a primary non-target arthropod species in environmental risk assessment (ERA) of GM plants. When GM insect resistant plants are planted in field, pollinators may be exposed to the toxin proteins via ingestion of GM pollen. To assess the potential effect of the DR 12-5 to A. mellifera, a laboratory bioassay was conducted using the DR 12-5 pollen and purified Cry1Ab toxin. The results showed that consumption of the DR12-5 pollen or purified Cry1Ab toxin led to detection of low levels of Cry1Ab toxin in the midgut of A. mellifera adults. Neither the DR 12-5 pollen nor 8 μg·mL^-1 purified Cry1Ab toxin showed an adverse effect on the survival rate of A. mellifera adult. In contrast, feeding with 300 mg·L^-1 imidacloprid caused significant toxic effects. These results indicated the minimal risk for potential negative effects on A. mellifera by exposure to the GM maize DR 12-5 or Cry1Ab toxin.

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Study on vernacular landscape protection of Wenzhou Sanyang wetland based on landscape fragmentation analysis

REN Wei, ZHANG Xuewei, LI Fangying, DONG Jianwen

2019, 31(11): 1841-1854. DOI: 10.3969/j.issn.1004-1524.2019.11.10

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The study of vernacular landscape protection is an important and urgent issue in the implementation of the rural revitalization strategy. Vernacular landscape of Sanyang wetland in Wenzhou was selected as the research object. The research method of landscape fragmentation analysis was learned from and used to study the spatial characteristics, spatial composition change, spatial and temporal evolution of landscape fragmentation and its driving factors in 2012 and 2017. The results showed that: (1) Urban environmental renewal and industrial transformation were the main causes of the spatial dynamic change as well as the spatial and temporal evolution of landscape fragmentation of vernacular landscape. (2) The overall landscape fragmentation index decreased from 0.006 3 to 0.005 9. The four types of patches in green space, modern building space, modern public space and farmland were the main driving factors. (3) The reduction trend of landscape fragmentation index in the core region was significant than that in the outer ring region. Modern building space, traditional building space, farmland and pond were the main driving factors for the reduction of landscape fragmentation index in the core region. Green space, modern building space, modern public space and traditional industrial land were the main driving factors for the reduction of landscape fragmentation index in the outer ring region. Finally, from the four aspects of constructing a benign social foundation, continuation of spatial composition features, monitoring spatial composition change and controlling main driving factors, we proposed the protection and sustainable development suggestions of vernacular landscape in Sanyang wetland under the background of rapid modernization and urbanization.

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Effects of leaf-to-fruit ratio on pruning efficiency and leaf physiological characteristics of Kyoho grape

SHANG Jiayin, LI Kai, WANG Chaoxia, JI Xian, SUN Jianjun, WANG Dan, SU Hong, TIAN Shufen

2019, 31(11): 1855-1862. DOI: 10.3969/j.issn.1004-1524.2019.11.11

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In order to investigate the effect of different leaf-to-fruit ratio on pruning efficiency and leaf physiological characteristics of Kyoho grape, the leaf-to-fruit ratio during the grape growing season was set to 8∶1, 12∶1, 16∶1, 20∶1 treatment. From 25 days after full-bloom stage, the summer pruning time and the quality of pruning waste were investigated every 10 days for a total of 13 times. The leaves were sampled at 85 d, 95 d and 105 d after flowering to determine malondialdehyde, proline, protein, vitamin C, ascorbate peroxidase, ascorbate oxidase. Correlation analysis was used to analyze the correlation between the indicators. The results showed that the higher the leaf-to-fruit ratio, the longer the working time, the less pruning waste produced. The leaf-to-fruit ratio 8∶1 and 20∶1 treatments were more efficient. Leaf membrane lipid peroxidation level at low leaf-to-fruit ratio treatments was higher than that in high leaf-to-fruit ratio treatments. The activity of protective enzymes in high leaf-to-fruit ratio treatment was higher than that in other treatments, and the rate of leaf senescence was slower. As a result, the best leaf-to-fruit ratio was 8∶1 for Kyoho grape during the growing season.

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Construction of DNA fingerprinting of Zhejiang eggplant varieties

WEI Qingzhen, WANG Wuhong, HU Tianhua, HU Haijiao, WANG Jinglei, BAO Chonglai

2019, 31(11): 1863-1870. DOI: 10.3969/j.issn.1004-1524.2019.11.12

Abstract ( 874 )

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In order to effectively and quickly identify and distinguish eggplant varieties of Zhejiang eggplant, and to provide the basis for the identification of the specificity and authenticity of Zhejiang eggplant varieties, SNP markers developed from eggplant genome data were screened, and SNP fingerprints were constructed for 6 eggplant varieties of Zhejiang eggplant type. Results showed that 48 SNPS were converted into KASP markers, and then used to KASP genotyping for 46 eggplant materials. According to the genotyping results and polymorphism information, 34 SNP markers could be used as core markers, which were used to construct a fingerprint map of the 6 Zhejiang eggplant varieties. The fingerprint map constructed herein could provide theoretical basis for eggplant cultivar identification and the protection of intellectual property.

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Effects of different characteristic organic fertilizers on premature senescence tree's growth,quality,yield and nutrition status of top grafting Satsuma mandarin

LI Yongjie, YI Shilai, GAO Hengjin, ZHU Xiaoting, QIN Yu, JIN Guoqiang

2019, 31(11): 1871-1879. DOI: 10.3969/j.issn.1004-1524.2019.11.13

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In order to alleviate the negative impact of Satsuma mandarin premature aging on citrus tree growth, yield and quality, different organic fertilizers were applied to investigate their effects on the restoration of weak tree growth. The results showed that organic fertilizer promoted the growth of spring and autumn shoots in varying degrees. The treatment of 5 kg Nangbowang compound microbial fertilizer(HF)behaved better compared with other groups,the average length of annual spring shoots and autumn shoots increased by 10.0% and 19.3% compared with the control,in 2017,and the number of autumn shoots was 1.87 times over the control. In 2018,the amount of spring shoots of each organic fertilizer treatment group was significantly higher than the control,as the number and the yield of fruits also reached significant difference. Compared with the fruit yield of CK, the HF and 10 kg microbial fertilizer (NF) treatments were 20.1% and 127.0% higher in 2017 and 2018,respectively. It is noteworthy that there was no significant change in citrus yield of the control group during the two years. The organic fertilizer could also enhanced the soluble solids (TSS) content,the TSS value and the solid acid ratio (TSS/TA) of 10 kg Shangcheng biological organic fertilizer (SC) treatment were also higher than other organic fertilizers. Moreover,application of organic fertilizer could also significantly promoted the total potassium(K)absorption of spring leaves,but the variation regularity of nitrogen (N),phosphorus (P) and K content were complicated in other tissues or a certain treatment. In general,the 10 kg Aodimei organic fertilizer(AF)treatment have higher effect on nutrient content. Compared with CK,organic fertilizer and microbial fertilizer could increase available N,P contents in soil. In the third year after high grafting,the absorption amount of N, P and K was 20.43, 1.79 and 14.18 g in fruits with the yield of 8.04 kg per plant per year, while in the shoots and fruit of the year,the values was 42.00, 3.02 and 20.70 g,respectively,which would be helpful to agricultural production.

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Effects of epiphytic algae community on invasion abilities of submerged macrophyte Cabomba caroliniana A. Gray in Taihu Lake

ZHU Hong, ZHOU Tingting, LI Xin, RUAN Honghua, XIE Dong

2019, 31(11): 1880-1887. DOI: 10.3969/j.issn.1004-1524.2019.11.14

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This study explored whether the biotic resistance exists in winter between epiphytic algae from native submerged macrophytes and invasive submerged macrophyte Cabomba caroliniana A. Gray, as well as effects of epiphytic algae communities on the growth of C. caroliniana in winter Taihu Lake. Fragments of C. caroliniana were cultured in dialysis bags with epiphytic algae from native submerged macrophyte, invasive submerged macrophyte and both macrophytes for 4 weeks. Then the fragments were harvested, and the final epiphytic algae density, community composition and growth attributes were measured. The final epiphytic algae density and community composition were significantly affected by epiphytic algae treatment and showed diverse density levels. Fragments in epiphytic algae from invasive submerged macrophyte treatment showed higher growth rate, regeneration and colonization ability than native and mixed epiphytic algae treatments. Epiphytic algae community from native submerged macrophytes performed biotic resistance against C. caroliniana in short time period. It significantly depressed the growth, colonization and regeneration abilities of C. caroliniana comparing with invasive epiphytic algae. However, with the native submerged macrophytes gradually dying in winter Taihu Lake, their epiphytic algae community could perish and lose the resistance ability against the invasion of C. caroliniana. Such, this partly explained the reason for invasion and superiority community of C. caroliniana in Taihu Lake in winter and provided theoretical basis for the management of invasive submerged macrophytes.

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Analysis on cp gene sequences of potato virus Y from some places in Qinghai Province

CHENG Liang

2019, 31(11): 1888-1895. DOI: 10.3969/j.issn.1004-1524.2019.11.15

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Potato virus Y(PVY)is one of the main viruses, which can cause serious losses in potato production. PVY is prone to gene mutation and plant differentiation under natural conditions. To understand the sequence variation of cp gene in PVY, cp gene of 16 isolates from Qinghai was amplified by RT-PCR. SDT, DNAMAN, RDP, and MEGA software were used for analysis. In multiple sequence alignments of cp gene, 16 isolates contained 801 base pairs with the identity of 98.0%-100% and encoded 267 amino acides with the identity of 94.8%-100%, respectively. Recombinant analysis indicated that no gene recombination was found in 16 isolates. Phylogenetic analysis showed that 11 isolates was clustered with isolates belonging to PVY^N-Wi strains, suggesting that the 11 PVY isolates shared high homology with PVY^N-Wi strain and accounting for 68.7% of total isolates. 5 PVY isolates were in the same branch with the reference PVY^O strains, indicating 5 PVY isolates were closer to PVY^O. PVY^C, PVY^N, PVY^E and PVY^NTN strains were not detected.

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Construction of compound bacteria for polluted water purification based on mixed culture and PCR-denaturing gradient gel electrophoresis

WANG Xin, TANG Jiangwu, WU Yifei, YAO Xiaohong, SUN Hong, SHEN Qi, LI Yuancheng

2019, 31(11): 1896-1902. DOI: 10.3969/j.issn.1004-1524.2019.11.16

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In the current study, 11 strains with different water purification functions were chose to be cultured together in LB medium, and PCR-denaturing gradient gel electrophoresis (DGGE) was used to reveal the changes of bacterial community after co-culturing to determine the coexistence and growth characteristics of these strains. The dominant strains in mixed culture were used as the core to form different compound bacteria, and their functional effects were determined through water purification experiments. The results showed that strains AOZ1 or BSK9, W14 or BSK3 could grow effectively under mixed culture conditions, and were the dominant bacteria in mixed culture. With strains AOZ1 or BSK9 as the core strains, the compound water purification functional bacteria could be constructed. Among them, the compound bacteria composed of strain AOZ1, BSK9, W14 and BSK3 had high removal rates of chemical oxygen demand (COD) and ammonia nitrogen, which reached 48.0% and 76.8%, respectively. The results suggested that compound water purification bacteria could be effectively constructed by the liquid co-culture method along with PCR-DGGE.

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Rapid determination of heavy metals in soils based on portable X-ray fluorescence spectroscopy

YANG Guilan, NI Xiaofang, ZHANG Changbo

2019, 31(11): 1903-1908. DOI: 10.3969/j.issn.1004-1524.2019.21.17

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In the present study, the precision and accuracy of portable X-ray fluorescence spectroscopy (PXRF) in heavy metal (Cr, Cu, Zn, As, Pb and Ni) determination in six typical soils were investigated to reveal its feasibility. It was shown that under the premise of processing, the determination precision of heavy metals in 6 typical soils by PXRF method was within 0.14% and 11.40%. By taking the results of inductively coupled plasma optical emission spectrometry (ICP-OES) method as reference, the determination accuracy of PXRF method in 5 typical soils was within 75% and 125%, which could meet the requirements of rapid determination of heavy metals in soil, but the accuracy of Cr and low concentration of As in latosol was low by PXRF method, which could not meet the requirement and should be further improved.

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Inventory and characteristics of agricultural nitrous oxide emissions in China

WEI Lianghuan, LIN Ning, MO Zhixin

2019, 31(11): 1909-1917. DOI: 10.3969/j.issn.1004-1524.2019.11.18

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In the present study, agricultural N₂O emissions inventory and characteristics of 31 provinces (municipalities, autonomous regions) were explored in 2000-2016 in China. It was shown that the agricultural N₂O emission in China (Hongkong, Macau, Taiwan excluded) increased from 71.801 3×10⁴ t in 2000 to 95.354 9×10⁴ t in 2016, with an increase of 32.80% and an average annual increase of 1.79%. The N₂O emission from agricultural land was the main source of agricultural N₂O emission, which accounted for 63.47%-77.26%. There were obvious regional differences for the agricultural N₂O emissions in 31 provinces (municipalities, autonomous regions). Guangxi, Guangdong and Yunnan showed the highest agricultural N₂O emission, which was higher than that in Beijing, Shanghai and Tianjin. The highest N₂O emission from agricultural land occurred in Guangxi, with an amount up to 45.320 2×10⁴ t in 2016, while the lowest N₂O emission from agricultural land occurred in Tibet, which was 0.005 3×10⁴ t. Besides, the direct emission accounted for 69%-87% in the case of N₂O emission from agricultural land. N₂O emission from livestock and poultry manure management was relatively high in Sichuan, Henan, Inner Mongolia, Yunnan and Shandong, while it was relatively low in Shanghai, Beijing, Tianjin, Zhejiang and Hainan.

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Production of bacterial cellulose by Gluconacetobacter xylinus using rice milk

CAO Yan, XIA Qile, CHEN Jianbing, SHAN Zhichu

2019, 31(11): 1918-1925. DOI: 10.3969/j.issn.1004-1524.2019.11.19

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In order to utilize rice milk effectively and reduce its discharge amount, the differences in the physicochemical indexes between rice milk and naturally fermented coconut water were compared, and the correlation analysis within physicochemical indexes and bacterial cellulose (BC) yield was conducted. The BC production based on rice milk medium was optimized, and some physical properties and chemical composition of the produced BC were investigated. The results showed that the contents of fructose, glucose, sucrose, acetic acid and protein in rice milk were significantly (P<0.05) lower than those in the naturally fermented coconut water, and these substances affected BC yield significantly (P<0.05). The optimal fermentation condition for rice milk was as follows: 35.0 g·L^-1 glucose as carbon source, and mixture of 3.0 g·L^-1 yeast extract and 3.0 g·L^-1 tryptone as nitrogen source. After optimization, the BC yield could reach 9.3 g·L^-1 (dry weight). BCs produced from either rice milk or the naturally fermented coconut water had nano-porous microstructure, and there was no significant difference in the water content, water holding capacity and hardness between them. Infrared spectroscopy and X-ray diffraction analysis showed that BCs produced from either rice milk or the naturally fermented coconut water were composed of β-glucan and type Ⅰ_α cellulose, and the crystallinity was 82.7% and 84.6%, respectively, indicating that BCs produced from rice milk and the naturally fermented coconut water were almost the same. Therefore, rice milk would be a promising material to produce BC.

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Evaluation of agricultural sustainable development level in Zhejiang Province

MAO Xiaobao, FU Linlin, MAO Xiaohong, AIHAITI Adila

2019, 31(11): 1926-1934. DOI: 10.3969/j.issn.1004-1524.2019.11.20

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In the present study, 25 national agricultural sustainable development experimental demonstration counties (cities, districts) in Zhejiang Province were selected as investigation objects, and a multi-level comprehensive evaluation index system was constructed based on 6 aspects, namely, agricultural resource endowment, agricultural development level, agricultural practitioners' technology level, economic benefit, social benefit and ecological benefit. By using data dimensionless treatment and coefficient of variation method, the sustainable development level was evaluated from both subsystem score and synthesis score. It was shown that the subsystem score of agricultural resource endowment, agricultural development level, agricultural practitioners' technology level, economic benefit, social benefit and ecological benefit of 25 national agricultural sustainable development experimental demonstration counties (cities, districts) was 0.071 1-0.642 9, 0.195 4-1.311 9, 0.093 1-1.066 8, 0.587 0-1.720 1, 0.012 3-0.917 9, 0.383 3-1.880 9, respectively, and the synthesis score was 3.261 1-5.946 4. Deqing got the highest synthesis score, and was followed by Anji and Dinghai, while Lanxi got the lowest synthesis score. In general, the sustainable development level was balanced among the 25 demonstration counties (cities, districts). In these subsystems, the score rate of agricultural development level and ecological benefit was higher than 50%, yet the score rate of agricultural practitioners' technology level and social benefit was less than 40%. According suggestions were put forward such as enhancing talent cultivation, focusing on the sustainable development of agricultural ecology, improving the development balance within regions.

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Study on promotion of tourism experience in Tengtou Village of Fenghua City of Ningbo based on web text and ASEB grid analysis

SONG Nannan, CUI Huiping, ZHANG Jianguo, ZHANG Mingru

2019, 31(11): 1935-1944. DOI: 10.3969/j.issn.1004-1524.2019.11.21

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Tengtou Village of Fenghua City, Ningbo, as a 5A-level scenic spot, is a typical case of transforming the achievements of new rural construction into a scenic spot, which is called a scenic village in Zhejiang Province of China. It is of great significance for the construction of scenic villages during rural revitalization in recent years. In this paper, taking Tengtou Village of Ningbo as an example, we used two methods of web text analysis with the ROST Content Mining6 software and ASEB grid analysis to study tourism experience, and proposed some tourism experience improvement strategies for Tengtou Village. The results showed that tourists had the worst experience in facilities service and tourism activities, followed by poor experience in the village nature style and humanities, while they had the best experience in the scenic environment. According to the results, we proposed three suggestions to improve the quality of tourism experience for tourists in scenic village. Firstly, Tengtou village should condense its characteristics and develop advantages. Secondly, it must improve management ability and facilities services of the scenic spot. Thirdly, the village should innovate projects of experience activities and develop cultural products.

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