Acta Agriculturae Zhejiangensis

Genetic diversity analysis of alpine potato germplasm resources by isozyme

HONG Senrong, ZHANG Mingxin, YE Siyu, NING Bensong

2018, 30(9): 1445-1453. DOI: 10.3969/j.issn.1004-1524.2018.09.01

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The genetic diversity of alpine potato germplasm resources in Yunnan Dehong, Yunnan Qujing, Hubei Enshi and Jiangxi Huaiyushan was analyzed by peroxidase (POD), esterase (EST) and polyphenol oxidase (PPO) isozyme in this paper. The results showed that Yunnan Dehong alpine potato, Yunnan Qujing alpine potato and Hubei Enshi alpine potato belonged to the same type, and the degree of their genetic differentiation was low, while the alpine potato in Jiangxi Huaiyushan was a separate group. Isozyme analysis of tubers and leaves would result in the difference of results, and isozyme analysis should ensure the consistency of sampling. The results of this study can provide the basis for further genetic improvement of potato varieties, selection of hybrid parents and utilization of alpine potato germplasm resources.

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Expression of Mel1c mRNA in various tissues of goose

WANG Shujuan, LIU Wenju, WEN Aiyou, PANG Xunsheng

2018, 30(9): 1454-1459. DOI: 10.3969/j.issn.1004-1524.2018.09.02

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This research investigated the expression of Mel1c in different tissues of goose (including heart, liver, kidney, lung, pancreas, spleen, ovary, brain, breast muscle and F1, F2, F3, F4, F5 stage follicles) using qRT-PCR. The results showed that Mel1c mRNA was expressed in the above mentioned tissues of goose, but the expression levels of Mel1c mRNA were different among various tissues. The expression levels of Mel1c mRNA in pancreas, spleen, kidney and ovary were higher than that in other tissues, followed by lung, the expressions in heart, breast muscle and brain were at a similar level, and the least was in liver. The expression levels of Mel1c mRNA were also different among various stages of follicles. The highest expression of Mel1c mRNA was found in F4 follicles, followed by F5 follicles, and the least was in F1 follicles. Thus, Mel1c was widely expressed in goose tissues, which further confirmed its involvement in the broad physiological functions of melatonin, especially the development of follicles in ovary.

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Expression of classical swine fever virus E2 protein in outer membrane vesicles of Escherichia coli and evaluation of its immunogenicity

HUANG Jie, GONG Yongping, WEN Jifeng, YANG Rui, REN Lu, YAN Qigui

2018, 30(9): 1460-1466. DOI: 10.3969/j.issn.1004-1524.2018.09.03

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In order to investigate the immune effect of E. coli outer membrane vesicles (OMVs) as presentation vector of classical swine fever virus E2 protein, the classical swine fever virus E2 gene was ligated to the C-terminus of pBAD18-Cm-ClyA after excision of the transmembrane region, and then transformed into E. coli DH5α. Inducted with 0.2% arabinose, the OMVs containing the E2 protein were collected and the rabbits were immunized. Western blotting showed that the OMVs could specifically bind to CSFV antibody. Indirect ELISA showed that the recombinant OMVs could induce high level of IgG antibody in rabbits. After immunization, rabbits could well protect the live CSFV challenge. All these results indicated that E. coli CSFV E2 protein had good immunogenicity, which laid the foundation for the research of OMVs presentation of classical swine fever virus E2 protein vaccine.

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Screening of strains for inactivated vaccine of Erysipelothrix rhusiopathiae

WU Qiongjuan, YANG Zhipeng, YAO Yanbin, LU Ping, WEI Jianzhong, SUN Pei, LI Yu

2018, 30(9): 1467-1475. DOI: 10.3969/j.issn.1004-1524.2018.09.04

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In order to screen out appropriate Erysipelothrix rhusiopathiae vaccine strains, which had strong pathogenicity, antigenicity and excellent genetic stability, four strains named AEr9, AEr21, AEr31 and AEr32 were screened from 42 clinically isolated strains of Erysipelothrix rhusiopathiae by lethality test in mice. The half lethal dose (LD₅₀) of these strains was determined by modified Karber’s method, the reactivity was determined by microplate agglutination test and agar diffusion test, the immunogenicity was determined by immunization test in mice, and the genetic stability of the 10th, 20th, 30th generation of the tested strains was evaluated by LD₅₀, precipitation antibody titer test and inactivated total bacterial immune protection rate test in mice. The results showed that the LD₅₀ of AEr9, AEr21, AEr31 and AEr32 were 845, 50.3, 35.5 and 10.1 cfu·mL^-1, respectively. The strains AEr21 and AEr31 with high reactivity were further screened by microplate agglutination test and agar diffusion test. The immune protection test showed that the immune protection of AEr31 was the best. Pathogenicity tended to be weakened in the virulence of the two strains after 10 generations, and the pathogenicity tended to be stable on the 10th, 20th and 30th generation strains, and the level of antibody precipitation of AEr21 was more stable. The results showed that the strains AEr21 and AEr31 could be used as candidate strains for inactivated vaccine of Erysipelothrix rhusiopathiae with the characteristics of strong virulence, good antigenicity and genetic stability.

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Immunohistochemical localization of interleukin-21 in cecal tonsil of 42 day old Chinese Yellow Feather quail

LI Qin, HE Min, ZHAO Piao, CHEN Xiaomei, LYU Yingying

2018, 30(9): 1476-1481. DOI: 10.3969/j.issn.1004-1524.2018.09.05

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To investigate the mechanism of interleukin-21 in the immune regulation of the Chinese Yellow Feather quail body, the distribution characteristics of IL-21 were observed. The quail tonsils of 42 day old Chinese Yellow Feather quail were taken, immunohistochemical SABC method was used for histological localization of interleukin-21 in the tonsil, and the morphology and distribution of the IL-21positive cells were observed. The results showed that the IL-21 positive reaction cells were round or elliptic, and a few were fusiform, some were clumpy. The positive reaction cells were mainly distributed in the lamina propria of the underlying layer of the epithelium of cecal tonsil, and a few were around the intestinal gland. There was also a small amount of IL-21 positive cells around the germinal centers. The results confirmed that IL-21 was widely distributed in the cecal tonsil of quail. The distribution and reaction strength of IL-21 positive cells were related to the local immune cells and the immune state of the body.

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Pharmacokinetics of enrofloxacin in largemouth bass (Micropterus salmoides)

HE Xin, WANG Yang, BEI Yijiang

2018, 30(9): 1482-1488. DOI: 10.3969/j.issn.1004-1524.2018.09.06

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To investigate the metabolic rate of enrofloxacin in largemouth bass (Micropterus salmoides) and facilitate dosage decisions, the pharmacokinetics of enrofloxacin in largemouth bass were studied after 5 d fed with 30 mg·kg^-1 (oral doses, based on body weight) enrofloxacin under (25±2) ℃. The concentrations of enrofloxacin in largemouth bass were determined by high performance liquid chromatography, and the drug-time curves were calculated. It was shown that the peak times of enrofloxacin in blood, muscle and liver were all 4 h under the experiment conditions. The absorption half lives of enrofloxacin in blood, muscle and liver were 0.998, 2.176, 1.892 h, respectively, and elimination half lives were 8.494, 23.84, 37.53 h, respectively. The area under drug concentration-time curves were 132.23 μg·mL^-1·h in plasma and 273.50, 247.12 μg·g^-1·h, respectively, in muscle and liver. Recommended withdrawal period of enrofloxacin in largemouth bass was 15 d under 25 ℃.

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Screening of cowpea genotypes with high-frequency regeneration in Agrobacterium-mediated transformation

ZHOU Wen, WU Xinyi, WANG Baogen, WU Xiaohua, LU Zhongfu, WANG Ying, XU Pei, LI Guojing

2018, 30(9): 1489-1495. DOI: 10.3969/j.issn.1004-1524.2018.09.07

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In this study, 51 cowpea genotypes were tested for tissue culture and shoot induction in Agrobacterium-mediated transformation. After a preliminary screening for regeneration, the rate of shoot regeneration was graded and 10 genotypes with a regeneration rate above 80% were tested further in three replicates. White August Cowpea was found to show the highest reproduction coefficient and induction rate of adventitious buds, which were 1.93 and 86.40%, respectively. Therefore, this genotype may be used as a good explant source in the future transgenic studies.

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Genetic and QTL analysis of seed traits in melon (Cucumis melon L.)

ZHANG Kexin, DAI Dongyang, WANG Haonan, YU Mingyue, SHENG Yunyan

2018, 30(9): 1496-1503. DOI: 10.3969/j.issn.1004-1524.2018.09.08

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Crossing of F_2∶3 was made from cantaloupe ms5 and muskmelon HM1-1 as parental to study the genetic inheritance of seed related traits by Major Gene and Poly-gene Genetic Model, and genetic map and QTL analysis were conducted by F_2∶3 families. The results indicated that seed coat color (SCC) was controlled by a single dominance gene, and white dominated to yellow. 100 seed weight (SW) and seed diameter (SD) were quantitative traits fit for the A-1 model, which was under one additive-dominance single major gene control. Seed length (SL) fitted the B-1 model, which was controlled by two additive-dominance major genes. By using F₂ generation, a genetic map containing 153 CAPS (cleaved amplified polymorphism suquences) markers was constructed, which covered 1 104.2 cM in melon genome, and the average genetic distance was 7.2 cM. The SCC gene was mapped on the 5 linkage group, and the interval makers were HD0520 and HD0519 with the distance of 13.3 cM and 7.0 cM, respectively. SW was mapped on the linkage group 6 and 11, with sw6.1 linked to E0615 and E0618, and sw11.1 linked to E1113 and P1117. SL located on the linkage group 7 and 11, with sl7.1 linked to E0716 and HD0713, and sl11.1 and sl11.2 linked to makers E1110 and E1112, XB1114 and E1113, respectively. SD was linked to makers XB0207 and E0219 on the linkage group 2. The results would provide theoretical basis for gene fine mapping on seed related traits and gene clone.

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Climatic suitability regionalization of Actinidia chinensis in China

WANG Rulin, LI Qing, WANG Mingtian

2018, 30(9): 1504-1512. DOI: 10.3969/j.issn.1004-1524.2018.09.09

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Actinidia chinensis, originating in China, is a main cultivar in China, whose planting scale has been gradually rising in recent years. In this study, based on climatic factors and distribution records, MaxEnt(the maximum entropy model) was used to simulate the potential distribution of Actinidia chinensis in China and analyze the suitable bioclimatic characteristics of Actinidia chinensis. Response curves which indicated the relationships between climatic factors and the predicted probability of presence of Actinidia chinensis were drew up by MaxEnt, and correlation analysis was used to decrease the number of factors for the final distribution model, dominant factors were chosen in this paper by Jackknife test, while receiver operating characteristic curve (ROC) was used to evaluate the simulation. The results showed that, the AUC of high values referred to good results that significantly differed from random predictions. The accuracy of prediction of Actinidia chinensis in the current period was found to be “excellent” (AUC_mean=0.960) according to the evaluation criterion. The predicted result of MaxEnt modeling was imported into ArcGIS10.0 for further analysis and it showed that, under the present climatic conditions, the potential suitable regions for Actinidia chinensis were mainly distributed from 25°N to 36°N in latitude, and from 101°E to 122°E in longitude. The highly suitable areas were in Sichuan, Shaanxi, Chongqing, Hubei, Guizhou, Zhejiang, Hunan, Anhui, Henan, Jiangsu and Gansu provinces, whereas the moderately suitable areas were in Henan, Hubei, Anhui and Shandong provinces. The important climatic factors affecting the distribution of Actinidia chinensis were mean temperature of driest quarter (bio11), maximum temperature in April (tmax4), minimum temperature in October (tmin10), mean temperature in May (tmean5), precipitation in May (pre5) and mean diurnal range (bio2). So the results may provide reference for Actinidia chinensis planting pattern and countermeasures to cope with climate change impact in China.

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Isolation, drug resistance of Klebsiella pneumoniae from waxberry and its virulence gene analysis

DAI Baoling, YANG Hua, DAI Xianjun, YANG Guiling, WANG Wen, XIAO Yingping

2018, 30(9): 1513-1518. DOI: 10.3969/j.issn.1004-1524.2018.09.10

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Waxberry is easy to be polluted by pathogenic bacteria in the process of production and transportation, the main purpose, therefore, is to analyze the carrying status, drug resistance characteristics and virulence genes of Klebsiella pneumoniae in waxberry. 90 samples were collected from Hangzhou market and base. To determine coliform contamination and Klebsiella pneumoniae, the bacteria isolated from the samples were identified by Vitek Auto Microbic System and 16S rRNA sequence. The resistant phenotype of Klebsiella pneumoniae was analyzed by VITEK 2 negative bacteria susceptibility card. Drug resistance genes and virulence genes were detected by PCR amplification. The results showed as follows: 51 samples were contaminated by coliforms in the 90 samples, and the pollution rate was 56.7%; 9 strains of Klebsiella pneumonia were detected, the positive rate was 10%, of which 8 strains were clustered into a cluster with high homology, and the homology of another was significantly different. These 9 strains of Klebsiella pneumonia showed different resistance to ampicillin, cefazolin and nitrofurantain. The resistant rate to ampicillin reached 88.89%. tetA gene was detected in all the 9 strains, and positive rate of drug resistance gene blaTEM, gyrA, aadA1 and AAC(6')-1b were 88.89%, while blaCTX-M, floR, ereA, ermB and mecA gene were not detected. The virulence genes of wcaG, magA, rmpA and Aerobactin were not detected. Qualitative analysis showed that waxberry had a certain contamination of Klebsiella pneumoniae, but these strains did not carry virulence genes such as wcaG, magA, rmpA and Aerobactin.

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Effect of picking time on lignin metabolism and activities of related enzymes of Sichuan-okra fruit

XIN Songlin, XIANG Zepan, KANG Xiaoqin, XIAO Chuan, QIN Wen

2018, 30(9): 1519-1525. DOI: 10.3969/j.issn.1004-1524.2018.09.11

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To find out the characteristics and regularity of lignin change in okra fruit at different picking time and determine the appropriate picking time for Sichuan-okra, content of lignin in okra was determined and analyzed at different picking time. The results showed that the content of lignin and cellulose in okra increased significantly in 3-5 d after flowering. Phenylalanine ammonia-lyase (PAL) and cinaamate 4-Hydroxylase (C4H) decreased significantly after 5 d, while 4-coumarate-CoA ligase (4CL), peroxidase (POD), pectin and flavonoids reached the maximum value in 4-5 d. Considering the nutritional value, health function and food quality of okra, the best picking time for okra fruit was 4-5 d after flowering.

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Analysis of plant selection and landscaping design for rain garden: a case study of Gongkang Rainwater Garden in Shanghai

MA Xiaoyuan, SHU Ye, SHI Yan, BAO Zhiyi

2018, 30(9): 1526-1533. DOI: 10.3969/j.issn.1004-1524.2018.09.12

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The rain garden, which is represented by the low-impact development model, is a green “sponge” constructed in a sponge city. In view of the climate adaptability of plants, this research focused on the selection and allocation of plants and recorded the undergrowth plant landscape in plant configuration of rain garden by the methods of field survey and data analysis. Analytic hierarchy process was used to evaluate the distribution effect of undergrowth plants in the garden. The result showed that the commonly used plants in rain gardens in Gongkang Rain water Garden were mainly drought-tolerant and had well-developed roots. The main plant species were as follows: trees, such as Metasequoia glyptostroboides, Salix babylonica, Paulownia tomentosa, Acer palmatum ‘Atropurpureum’; shrub species, such as Fatsia japonica, Aucuba japonica ‘Variegata’, Loropetalum chinense; herbs, such as Hemerocallis fulva, Farfugium japonicum, Stipa tenuissima; aquatic plants, such as Phragmites australis, Gladiolus× gandavensis, Iris pseudacorus, Iris tectorum, Lythrum salicaria, Cyperus alternifolius. According to the growth area and ornamental characteristics of plant, plant species and distribution pattern of undergrowth plants with good landscape effect were selected as follows: mode A, Iris pseudacorus+Thalia dealbata+Lythrum salicaria+ Phalaris arundinacea+ Typha orientalis+ Iris germanica; mode B, Lythrum salicaria+ Cordyline fruticosa+ Iris tectorum+ Cyperus alternifolius+ Thalia dealbata+ Gladiolus × gandavensis+ Juncus setchuensis; mode C, Cyperus alternifolius+ Iris germanica+ Iris tectorum+ Cordyline fruticosa+Hemerocallis fulva+Thalia dealbata+Iris pseudacorus.

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Effect of photoperiods on growth and development and population parameter of corn leaf aphids

DU Junli, ZANG Qiluo, WU Degong, YU Haibing, ZHAN Qiuwen, HUANG Baohong

2018, 30(9): 1534-1540. DOI: 10.3969/j.issn.1004-1524.2018.09.13

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In order to clarify the effects of photoperiod on the growth and development of the corn leaf aphid Rhopalosiphum maidis, and to construct its life table under different photoperiods, aphids were reared with leaves in petri dishes under different photoperiods (2L∶22D, 4L∶20D, 8L∶16D, 12L∶12D, 16L∶8D, 20L∶4D, 22L∶2D), and their developmental time, fertility, survival rate and life parameters were measured. The results showed that the developmental time of immature under photoperiods of 20L∶4D and 22L∶2D were significantly longer than those under other five photoperiods (P<0.05).The survival rate of corn leaf aphid under 8L∶16D, 12L∶12D, 16L∶8D were significantly higher than those under photoperiods of 4L∶20D, 20L∶4D, 22L∶2D (P<0.05). The fertility under photoperiods of 8L∶16D, 12L∶12D, 16L∶8D were significantly higher than other photoperiods (P<0.05). The intrinsic rate of increase (r_m), net reproductive rate (R₀) and finite rate of increase (λ) under photoperiod of 12L∶12D were the highest (0.357, 42.06 and 1.43 respectively). The r_m, R₀ and λ under normal photoperiods of 8L∶16D, 12L∶12D and 16L∶8D were significantly higher than extreme photoperiods of 2L∶22D, 22L∶2D (P<0.05). The r_m, R₀ and λ under photoperiod of 2L∶22D were the lowest. The optimal photoperiods calculated with the fitting equation of life parameter and photoperiods was 11-13 h·d^-1. Above results indicated that the normal growth and development of corn leaf aphid under extreme photoperiods were interfered, extremely long or short photophase period would affect the development and dynamic changes of this population.

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Life table and population parameters of sorghum aphid (Melanaphis sacchari) under different temperatures

WU Degong, DU Junli, HUANG Baohong, ZHAN Qiuwen, BI Yaling, HUANG Weidong, LIU Yanlong

2018, 30(9): 1541-1547. DOI: 10.3969/j.issn.1004-1524.2018.09.14

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The life table construction technique was used to study the effects of different temperatures (12, 15, 18, 21, 24, 27, 28 ℃) on the life parameters of the sorghum aphid population. The results showed that the developmental times of nymphs and adult longevity of Melanaphis sacchari decreased significantly as constant temperature increased. The average development period of the nymphs of sorghum aphid was 18.32 d at 12 ℃, 5.04 d at 28 ℃, and 3.63 times the difference between the two. The average longevity of adults was 56.42 d at 12 ℃, 18.23 d at 28 ℃, and 3.09 times the difference between the two. The intrinsic rate of increase (r_m), net reproductive rate (R_o), finite rate of increase (λ), mean generation time (T) and double population time (t) were also significantly different under different temperatures. The intrinsic rate of increase (r_m), net reproductive rate (R_o), finite rate of increase (λ) reached the highest at 24 ℃, as the temperature increased or decreased, the intrinsic rate of increase (r_m), net reproductive rate (R_o), finite rate of increase (λ) all decreased. The intrinsic rate of increase (r_m) and finite rate of increase (λ) were the lowest at 12 ℃, which were 0.126 and 1.134, respectively. The lowest net reproductive rate (R_o) at 28 ℃ was 31.04. The double population time (t) was the shortest at 24 ℃ and the longest at 12 ℃.The mean generation time (T) became shorter with temperature, 33.32 d at 12 ℃ and 12.02 d at 28 ℃. In summary, the temperature had a significant effect on the growth and development of sorghum apid, and the growth and development of sorghum aphid were inhibited and the development was slow at low and high temperatures. 24 ℃ was the optimum growth temperature for sorghum aphid, at this temperature, the intrinsic growth rate of sorghum aphid was high, the generation cycle was short, and the population increased rapidly. These results would help us understand the population dynamics of sorghum aphid on sorghum plants, and lay a solid foundation for the prediction of sorghum aphid.

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Molecular identification of kiwifruit canker pathogen in Taizhou and screening of its control agents

ZHONG Yongjun, HE Xinwei, YU Dayong, JIANG Jingjing, JIANG Jingyong

2018, 30(9): 1548-1554. DOI: 10.3969/j.issn.1004-1524.2018.09.15

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To control the bacterial canker disease, a strain of Pseudomonas syringae pv. actinidae (Psa) from main kiwifruit planting orchards in Taizhou was isolated by using streak plate method in this study. Biovar specific primer detection results showed that the Psa strain was biovar 3. Through the comparison of antibacterial rings, 23 fungicides were examined. The results showed that the antibacterial effect of different fungicides on the Psa strain was quite different, and tetracycline, ethylicin and eugenol exhibited a strong antibacterial effect (the diameter of inhibitory ring≥15 mm). In addition, the antibacterial effect of nano zinc oxide (nano-ZnO) on the Psa strain was examined by minimum inhibitory concentration (MIC) and in vitro time-kill experiments. The results showed that the MIC value of nano-ZnO was 50 μg·mL^-1, and the antibacterial potential increased with the concentration of nano-ZnO and the time of action.

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Effect of phthalate esters contamination on urease and invertase reaction kinetics of black soil

CHEN Wenjing, WANG Zhigang, XU Weihui, LIU Zeping, LYU Zhihang, WANG Chunlong

2018, 30(9): 1555-1560. DOI: 10.3969/j.issn.1004-1524.2018.09.16

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The responses of invertase and urease reaction kinetics to phthalate esters (PAEs) were assessed in the northeastern black soil by the indoor simulation method. The enzymatic activities of invertase and urease were measured by 3,5-dinitrosalicylic acid method and indophenol blue colorimetric method, respectively, when dimethyl phthalate (DMP) and dibutyl phthalate (DBP) were used as the test materials. The results suggested that the enzyme activities of invertase and urease were inhibited by PAEs in black soil. Based on the linear regression equation of soil enzyme activities and PAEs concentrations, the critical indicators of the slight contamination (ED₁₀) in black soil were obtained. The ED₁₀ values of invertase and urease for DMP contamination in black soil were 24.352 mg·kg^-1 and 5.015 mg·kg^-1, respectively, and the ED₁₀ values of invertase and urease for DBP contamination in black soil were 16.911 mg·kg^-1 and 8.677 mg·kg^-1, respectively. According to the principle that the smaller ED₁₀ the more sensitive, the results indicated that urease was sensitive to PAEs pollution in black soil and could be used as the biochemical index of PAEs contamination. The kinetic parameters of invertase and urease were decreased by DMP and DBP in black soil, which belonged to the anti-competitive inhibition mechanism. PAEs contamination in black soil might change carbon, nitrogen cycle and the ecosystematic function of black soil, and then affect the sustainable development of black soil.

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Effects of carbonization temperatures on structure and properties of cow dung biochars

HUANG Huiqun, CAI Wenchang, ZHANG Jianyu, LI Can, ZENG Heping

2018, 30(9): 1561-1568. DOI: 10.3969/j.issn.1004-1524.2018.09.17

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A series of biochars were obtained under the limited oxygen cracking condition at different carbonization temperatures of 200, 300, 400, 500, 600, 700 ℃, respectively, with cow dung as raw material. The structures and properities of these biochars, i.e. surface morphology, element contents, specific surface area, pore size, surface functional groups and adsorption properties, were examined via scanning electronic microscopy, elemental analyzer, specific surface area and pore size distribution analyzer, and by means of Boehm titration, iodine adsorption and methylene blue adsorption. It was shown that the yields and volatile matter content decreased, while the contents of ash and fixed carbon and pH increased with the increasing carbonization temperature. Besides, the morphological features of biochars became more regular and the pores were denser. When the carbonization temperature was raised appropriately, it was beneficial to form pore and increase the number of micropores pore, the specific surface area and pore volume were increased, yet the pore size was decreased. With the increased carbonization temperature, the C contents of biochars increased, while the H and O contents decreased, and the N contents increased at first and then decreased, and the values of H/C,(O+H)/C and O/C were reduced, indicating that the aromatic properties and structural stability of biochars were enhanced, yet the polarity and hydrophilicity were both weakened. With the increasing carbonization temperatures, the carboxyl contents of surface functional groups were firstly increased and then decreased, the contents of carbonyl groups continuously increased, yet the contents of lactone and phenolic hydroxyl groups, the total contents of acid and oxygen-containing functional groups were gradually decreased. The adsorption value of iodine and methylene blue increased at first and then decreased with the increasing carbonization temperatures, andy both reached the highest value under 600 ℃.

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Screening of high efficient sludge degrading strains and their potential in sludge composting

RUAN Xinyi, LIU Xi, GUAN Yue, KONG Hainan, LIN Yan

2018, 30(9): 1569-1575. DOI: 10.3969/j.issn.1004-1524.2018.09.18

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Four sludge composting strains were isolated from high temperature samples, and were classified into the genus of Bacillus. These strains were mixed in the same proportion as microbial inoculum, and were added to the composting system to study the suitable microbial inoculum concentration and application potentials in sludge composting. The results showed that the temperature rising rate, water content decreasing rate and the maximum temperature of those treatments with inoculation were higher than the control (treatment without inoculation). The inoculated treatments completely maturated, while the control did not reach maturity standard. When the inoculating amount was 3%, the effect was the most obvious, as the maximum temperature was 63 ℃, the high temperature above 55 ℃ lasted for 4 days, and the seed germination index was 134.1% after composting. These results suggested that the proposed microbial inoculum had potential in sludge composting.

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Prediction of soil total nitrogen content from hyperspectral data based on charateristic wavelength selection and modelling

WANG Wencai, ZHAO Liu, LI Shaowen, QI Haijun, JIN Xiu, WANG Shuai

2018, 30(9): 1576-1584. DOI: 10.3969/j.issn.1004-1524.2018.09.19

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In this paper, a total of 115 lime concretion black soil samples collected from the northern Anhui Plain, China, were used as research objects to obtain hyperspectral data. Competitive adaptive reweighted sampling (CARS), successive projections algorithm (SPA), and random forest feature selection (RFFS) were used to select the characteristic wavelength of soil total nitrogen content from 224 wavelengths of the hyperspectral data. Partial least square regression (PLSR), support vector regression (SVR), and least absolute shrinkage and selection operator (LASSO) were applied to establish the spectral regression model of soil total nitrogen content. It was shown that all of the wavelength-selecting models outperformed the full-wavelength models except for the CARS-PLSR model. By comparison of all the prediction models built by different combinations of wavelength-selecting methods and regression algorithms with respect to the prediction performance, it was found that the RFFS-LASSO model with 20 characteristic wavelengths got the best prediction results. The coefficient of determination (R²) and relative percent deviation (RPD) value of the model prediction set were 0.787 1 and 2.130 1, respectively. The results illustrated that RFFS-LASSO model was simple and effective for the prediction of soil total nitrogen content, and it had certain guiding significance for the development of proximal sensor of soil total nitrogen content.

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Ecological safety assessment of Bcillus cereus D7 isolated from shrimp

ZHANG Hongyu, WANG Haibo, YANG Yibin, ZHAO Mingjun, XIA Lei

2018, 30(9): 1585-1591. DOI: 10.3969/j.issn.1004-1524.2018.09.20

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In order to evaluate the ecological safety of Bacillus cereus D7, the effects of Bacillus cereus D7 on concentration of ammonia nitrogen, nitrite and phosphate were tested. The research of safety on Chlorella vulgaris, Daphnia magna, Danio retio, Penaeus vanmamei and Ctenopharyngodon idella were also carried out. The results showed that Bacillus cereus D7 (≥1×10⁷ cfu·mL^-1) reduced ammonia nitrogen and nitrite concentration significantly (P<0.05). When the concentration of Bacillus cereus D7 was below 1×10⁶ cfu·mL^-1, there were no significant influence on ammonia nitrogen and nitrite concentration. When the concentration of Bacillus cereus D7 was between 10⁴~10⁸ cfu·mL^-1, there was no significant influence on phosphate. Concentration of Chlorella vulgaris showed positive correlation with Bacillus cereus D7. The death rate of Daphnia magna, Danio retio,Penaeus Vanmamei had no significant difference after 96 h treatment. When the concentration of Bacillus cereus D7 was between 10⁸~10¹² cfu·mL^-1, there was no obvious influence on death rate of Ctenopharyngodon idella after 96 h. The results showed that Bacillus cereus D7 could have no adverse effects on water and aquatic animals, which could be used as a kind of ecological safety probiotics.

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Changes of biogenic amines in large yellow croaker stored at different conditions

ZHU Zuoyi, ZHANG Yu, WANG Junhong, LI Xue, WANG Wei

2018, 30(9): 1592-1598. DOI: 10.3969/j.issn.1004-1524.2018.09.21

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In order to investigate the changes of biogenic amines (BAs) in large yellow croaker preserved at different temperature and salinity, seven BAs (putrescine, cadaverine, histamine, spermidine, phenylethylamine, spermine and tyramine) were analyzed by ion chromatography (IC) coupled with suppressed conductivity and ultraviolet detection. The results indicated that no histamine and spermine were detected in the large yellow croaker muscle during the whole storage. During the storage of 16 d at 0 and 4 ℃, BAs in large yellow croaker increased slowly, and the variation range of total BAs content were 1.41-17.53 mg·kg^-1 and 1.53-187.63 mg·kg^-1, respectively. During the storage of 6 days at 25 ℃, BAs in large yellow croaker increased sharply, especially putrescine, cadaverine and tyramine. The variation range of total BAs content was 9.44-2 539.22 mg·kg^-1. With different contents of salt processing under 25 ℃ for 6 days, the content of BAs in large yellow croaker decreased obviously with the increase of the salt content. When the salt content was 5%, the variation range of total BAs content was only 1.32-120.93 mg·kg^-1, which indicated effective control of BAs formation. Besides, total volatile basic nitrogen and BAs in large yellow croaker preserved at different temperature and salinity were investigated, which had a similar trend with BAs. The results above indicated that low temperature preservation and addition of appropriate salt were effective methods to control BAs in large yellow croaker.

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Effect of processing on carbendazim residue in canned citrus

FANG Qi, ZHANG Jun, ZHOU Jinyun

2018, 30(9): 1599-1603. DOI: 10.3969/j.issn.1004-1524.2018.09.22

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In the present study, the effects of different processing conditions on carbendazim residue in canned citrus during prenatal, middle and postpartum phase were studied. It was shown that the residual amount of carbendazim in citrus was increased first and then decreased with the prolonged storage time. During the production, acid process or alkali treatment showed the best carbendazim removal effect. After process, carbendazim residue in the canned citrus remained stable. It was concluded that the canning process could effectively remove carbendazim from citrus flesh, and the removal rate of carbendazim residue could be enhanced by increasing the amount of acid, alkali and washing water during production.

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Identification of geographical origin for wolfberry by an electronic nose in combination with multivariate analysis

TIAN Xiaojing, LONG Ming, WANG Jun, MA Zhongren, WEI Zhenbo, CHEN Shi en, GAO Dandan, DING Bo

2018, 30(9): 1604-1611. DOI: 10.3969/j.issn.1004-1524.2018.09.23

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The aroma profiles of wolfberry were studied by the electronic nose (E-nose) for aim of subjective and fast discrimination of the geographical origin of wolfberry. The effects of sample weight, headspace-generated time, and headspace volume on sensor responses were studied by single-factor experiments. Results of one-way analysis of variance found that the responses of E-nose sensors were significantly affected by these factors. The sample weight showed significant effect on S7 while very significant effect on the other 9 sensors. The effects of headspace-generated time were very significant on the sensors except for S2, S7, S9 and S10. With the help of canonical discriminant analysis (CDA), the optimum experimental parameters were acquired: flow rate of 300 mL·min^-1, 20 g of sample sealed in 500 mL beaker for 30 min headspace-generated time. With the optimum experimental parameters, samples produced in three different regions (Guazhou Gansu, Chaidamu Qinghai, Zhongning Ningxia) were detected. With PCA and CDA, the wolfberries were grouped according to the geographical origin, with three samples from Zhongning overlapped with each other. BPNN were employed to build the predictive model for the geographical origin of the wolfberry fruit samples, with 96% samples correctly predicted. The E-nose was proved to be useful for the identification of geographical origin of the wolfberry samples for its efficiency and high accuracy, which laid solid foundation for the traceability of wolfberry geographical origin.

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Practices and development suggestions for modern small farmers cultivation in Zhejiang

LI Baozhi, QIAN Wenrong, YANG Liangshan, HUANG Hexiao, ZHU Qibiao

2018, 30(9): 1612-1616. DOI: 10.3969/j.issn.1004-1524.2018.09.24

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Introduction of small agricultural production into the track of modern agricultural development is crucial for the implementation of rural revitalization strategy and structural reform in agricultural supply side. In the present assay, practices and experiences of Zhejiang’s docking with the production of small farmers and the development of modern agriculture were summarized. Aimed at the bottleneck of modern small farmers cultivation, suggestion were put forward as “organizing small farmers, serving small farmers, driving small farmers, promoting small farmers, activating small farmers and supporting small farmers”.

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