Acta Agriculturae Zhejiangensis

Genetic diversity analysis of sweet maize inbred lines in Southern Zhejiang by SSR markers

YUE Gaohong, PAN Binrong, LIU Yongan, MEI Xixue, XU Likui, ZHANG Zongchen, ZHOU Zhihui

2019, 31(7): 1029-1036. DOI: 10.3969/j.issn.1004-1524.2019.07.01

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To evaluate the genetic diversity of sweet maize inbred lines and to guide new sweet maize varieties breeding, 37 sweet maize inbred lines from Southern Zhejiang were analyzed using SSR molecular markers. The results showed that 209 alleles were detected by 37 polymorphic SSR markers, with an average of 5.65 alleles per SSR marker. Polymorphism information content (PIC) values of SSR markers were 0.62-0.95, with an average of 0.82 per primer pair. Similarity coefficients among inbred lines ranged from 0.12 to 0.94, with an average of 0.40, which suggested these sweet maize inbred lines had abundant genetic diversity. The 37 sweet maize inbred lines were classified into three groups by UPGMA method, which was consistent with the pedigree analysis and geographical distribution.

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Morphological diversity of hulless barley accessions from Qinghai-Tibetan Plateau

XU Xiao, LUAN Haiye, ZHANG Yinghu, LU Jian, QIAO Hailong, ZANG Hui, YANG Hongyan, SHEN Huiquan

2019, 31(7): 1037-1044. DOI: 10.3969/j.issn.1004-1524.2019.07.02

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To study the genetic diversity of hulless barley accessions from Qinghai-Tibetan Plateau and improve their utilization efficiency, the morphological diversity of 86 hulless barley accessions from Qinghai-Tibetan Plateau was identified in this study. The results showed that genetic diversity of hulless barley accessions was ample, morphological diversity index of main panicle length was the highest with the value of 2.05. Plant type had the lowest genetic diversity index with the value of 0.47. In general, genetic morphological index of quantitative traits were greater than those of the quality traits. The tested materials were divided into four groups by cluster analysis. Barley accessions in group Ⅰ were two-rowed, high plant height, big spike and big grain. Barley accessions in group Ⅱwere short plant height, multi grain and long spike. Barley accessions in group Ⅲ were short panicle. Barley accessions in group Ⅳ were high plant height and multi grain. Based on the principal components, comprehensive evaluation of various materials was carried out, seven principal components were extracted to summarize most of the biological information of all traits. Excellent germplasm resources suitable for growth in Jiangsu Province were screened out. This study provided a theoretical basis for the collection and utilization of hulless barley accessions.

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Response mechanism and stress resistance of maize inbred lines to high temperature stress at seedling stage

FANG Fang, HE Xuchen, ZHANG Zhihao, ZHANG Qin, GUAN Yajing, HU Jin, HU Weimin

2019, 31(7): 1045-1056. DOI: 10.3969/j.issn.1004-1524.2019.07.03

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High temperature stress affects the growth of maize inbred lines during seedling period and field tidiness as well as seed yield, therefore, exploring the response mechanism of maize seedling stage to temperature stress is conducive to breeding and screening varieties with high resistance. The mechanism was studied through the determination of chlorophyll content, antioxidant enzyme activity and gene expression of two different phenotypes after high temperature stress treatment at 45 ℃. The results showed that chlorophyll a and chlorophyll b content, chlorophyll a/b value, SOD activity, POD activity, CAT activity, APX activity and GR activity in heat sensitive inbred lines decreased dramatically compared with heat resistant lines after high temperature challenging and recovery experiment ,while the proline content increased slightly. The expression of ZmP5CS and ZmProDH, two key enzyme genes of proline metabolic pathway, and heat shock protein genes ZmHSP70, ZmHSP90 under high temperature stress were analyzed by qRT-PCR. Our result showed that ZmP5CS, ZmHSP70 and ZmHSP90 were significantly induced by heat stress, and the induction of these genes in heat sensitive inbred lines were mild in comparison with heat resistant inbred lines, while the expression of ZmProDH was significantly higher. These results showed that the accumulation of proline, activity of antioxidant enzymes and expression of heat shock protein genes involved in maize seedlings response to high temperature stress.

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Differences in jejunum microbes of goats with different phosphorus true digestibility

JIN Lei, WANG Lizhi, WANG Zhisheng, XUE Bai, PENG Quanhui

2019, 31(7): 1057-1065. DOI: 10.3969/j.issn.1004-1524.2019.07.04

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Improving animal digestion and utilization efficiency of phosphorus were of great significance for reducing animal breeding costs and environmental pollution. The objective of this study was to compare the structure of jejunum microorganism of goats with different true digestibility of feed phosphorus using Illumina MiSeq sequencing technology. Twenty-four Nubian black goats, aged 10 months on average and weighed (24.25±2.47)kg, were selected as the experimental animals. The contents of jejunum of each goat in the HP and LP groups were collected and total genomic DNA was extracted, and the high variable region of 16S rRNA gene of bacteria was sequenced by high throughput sequencing platform. Bioinformatics analysis of sequencing data was carried out using QIIME software. At the phylum level, Firmicutes and Bacteroidetes were the dominant bacteria of the jejunum microbiota in goats, and the relative abundance of Firmicutes in HP group was extremely significantly lower than that in the LP group (P<0.01), while the relative abundance of Bacteroidetes was extremely significantly higher than that in the LP group(P<0.01). At the genus level, the relative abundances of Prevotella, Rikenellaceae_RC9_gut_group, Fibrobacter, Ruminococcus_2 and Clostridium_sensu_stricto_1 in HP group were significantly higher than that in the LP group (P<0.05), and the relative abundances of Desulfovibrio and Victivallis were significantly lower than that in LP group(P<0.05). There were significant differences in structure of jejunum microorganisms among goats with different true digestibility of feed phosphorus.

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Molecular detection of Bartonella infection in ixodid ticks collected from yaks in Shiqu County of Sichuan Province

TANG Tiancai, LIU Chengcheng, YUAN Dongbo, GUO Li, HOU Wei, MO Xi, YANG Aiguo, HAO Lili, LI Rui

2019, 31(7): 1066-1072. DOI: 10.3969/j.issn.1004-1524.2019.07.05

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In order to investigate tick species and its Bartonella infection from yaks in Shiqu County of Sichuan Province, the ticks collected from yaks were classified by morphological identification. The total DNA of ticks was extracted and partial sequences of COⅠ and gltA gene of ticks and Bartonella were amplified by PCR, respectively. The positive products were sequenced and compared through the NCBI database. Phylogenetic tree was constructed based on COⅠ and gltA for determination species of ticks and Bartonella, respectively. A total of 818 ticks were collected from 4 villages in Shiqu County and only Dermacentor everestianus (78.97%, 646/818) and Haemphysalis qinghaiensis (21.03%, 172/818) were found. The total infection rate of Bartonella in ticks was 30.07% and the infection rates of Arizha, Maga, Derongma and Changxuganma townships were 4.76%, 76.79%, 12.50% and 17.95%, respectively. Compared with other villages, the infection rate of Bartonella in Maga was higher (P<0.01). In Maga, no significant difference was observed (P>0.05), though the infection rate of Bartonella in Haemphysalis qinghaiensis(79.07%)was higher than that in Dermacentor everestianus (69.23%). At last, three sequences of gltA were obtained (uncultured Bartonella sp. shiqu 1, uncultured Bartonella sp. shiqu 2 and uncultured Bartonella sp. Shiqu 3). Phylogenetic analysis showed that uncultured Bartonella sp. Shiqu 1 and uncultured Bartonella sp. Shiqu 2 had the closest relationship with the undetermined Bartonella spp. RF124HAIN (FJ464240) and uncultured Bartonella sp. Shiqu 3 had the closest relationship with the human pathogenic Bartonella melophagi. At present, Dermacentor everestianus and Haemphysalis qinghaiensis were found in Shiqu County with high infection of Bartonella, and there existed high risk of human infection.

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Effects of three promoting labels on the soluble expression of giant panda rotavirus structural protein VP6-VP7

WEN Jifeng, SHEN Huanhuan, GONG Yongping, YI Keke, YANG Zhijie, DENG Ying, YAN Qigui

2019, 31(7): 1073-1078. DOI: 10.3969/j.issn.1004-1524.2019.07.06

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Giant panda rotavirus (GPRV) is the main cause of diarrhea in young giant pandas, and it has a great harm to captive giant pandas. The rotavirus structural protein VP6 is a carrier protein that mediates mucosal immune responses, and VP7 is the major neutralizing antigen in rotavirus structural proteins. Therefore, the fusion expression of VP6-VP7 as a candidate antigen has important significance for the prevention and treatment of this disease. However, the prokaryotic expression of traditional E. coli has the disadvantages of low expression, poor solubility and low purity. In this study, three kinds of fusion tags, aldolase (EDA), glutathione S-transferase (GST) and maltose-binding protein (MBP), were used to obtain GPRV-VP6-VP7 protein with high expression and high purity. The VP6 and VP7 genes were constructed by homologous recombination into the expression vector pET21b containing three kinds of facilitating tags, and the recombinant plasmid was transformed into E. coli Rosetta (DE3) competent cells for low temperature induction. The target protein was purified by Ni-column affinity chromatography, and the protein expression was analyzed by SDS-PAGE and Image J. Western blot analysis showed that the recombinant protein was correct and had activity of protein. The experimental results showed that the EDA tag could significantly promote the prokaryotic soluble expression of VP6-VP7 protein and increase the expression of VP6-VP7 protein.

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Effect of supplemental lighting with different light quality on fruit quality and related enzymes activities in pitaya

CHEN Xinyuan, YIN Yiming, ZHU Lixin, TAO Ningying, MAN Kun, JIA Huijuan

2019, 31(7): 1079-1085. DOI: 10.3969/j.issn.1004-1524.2019.07.07

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In this study, a red pitaya cultivar, Zimilong was used as the experimeatal matertal. Two levels of blue to red light ratios (1∶4 and 1∶2) in light emitting diode (LED) were set up as the treatments, and no artificial light group was the control. By measuring the content of sucrose, glucose, fructose as well as activities of sucrose metabolism-related enzymes in the flesh of pitaya at three important stages, we attempted to preliminarily explore the mechanism of light supplementation regulating sugar accumulation. Results showed that the total soluble solid (TSS) and sucrose content in fruits under LED light supplementation with blue and red light ratio of 1∶2 were higher than other treatments, the activity of sucrose phosphate synthase (SPS) and sucrose synthase (SS) showed the same as well, while the activity of acid invertase (AI) was opposite. There was no significant difference except for fructose content and AI activity in mature fruit in the treatment of 1∶4 was lower than the control. Overall, the sucrose content of the first batch of spring pitaya was improved in the LED light supplementation with blue and red light ratio of 1∶2. Maybe, less red light ratio could promote sucrose, reduced glucose and fructose by inhibiting the activity of AI and promoting the activity of SPS and SS so as to promote sucrose and TSS in fruit.

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Alleviation of aluminum stress by exogenous oxalic acid in root system of Pinus massoniana Lamb.

GUO Ni, LIU Yamin, ZHOU Wenying, LIU Yumin, ZHANG Shengnan

2019, 31(7): 1086-1095. DOI: 10.3969/j.issn.1004-1524.2019.07.08

Abstract ( 458 )

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Two different families of Pinus massoniana Lamb., namely aluminum-resistant type FJ5 and aluminum-sensitive type GD20 were used as test materials to provide theoretical basis for the regulation of aluminum toxicity in P. massoniana Lamb. in soil acidification areas. The effects of oxalic acid on root morphology and physiological characteristics of P. massoniana Lamb. seedlings under aluminum stress were studied, and the dominant physiological factors affecting alleviation effect of oxalic acid were explored. It was shown that under aluminum stress, the total root length, root surface area, root volume and root activity of P. massoniana Lamb. seedlings were reduced, while the activities of root antioxidant enzymes (superoxide dismutase, peroxidase, catalase), osmotic adjustment substances (soluble sugar, soluble protein and proline) significantly (P<0.05) increased, and membrane lipid peroxidation aggravated. The variation of these indices in GD20 was higher than that in FJ5. It indicated that active aluminum could produce toxicity to P. massoniana Lamb., and active aluminum had greater toxic effects on aluminum sensitive species. After application of exogenous oxalic acid, the root activity of P. massoniana Lamb. increased, the content of malondialdehyde and osmotic adjustment substances in roots decreased, and the antioxidant enzymes activities maintained a high level. When oxalic acid concentration did not exceed 0.2 mmol·L^-1, the aluminum content in root and root tip decreased. The variation of these indices with oxalic acid application in GD20 was greater than that in FJ5. These results indicated that exogenous oxalic acid could effectively alleviate the aluminum toxicity of P. massoniana Lamb. seedlings, and the alleviation effect on aluminum-sensitive type was better than that on aluminum-resistant type. The alleviation effect on P. massoniana Lamb. varied with different concentrations of exogenous oxalic acid, and the optimum application concentration was 0.2 mmol·L^-1. It was revealed by principal component analysis that contents of proline and soluble protein might be the dominant physiological factors to regulate alleviation effect of oxalic acid on aluminum toxicity.

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Effects of bio-organic fertilizer on twig blight disease control and recovery of tree vigor in bayberry

LIN Rui, REN Haiying, AN Xiaoxiao, ZHENG Xiliang, LIANG Senmiao, ZHANG Shuwen, QI Xingjiang

2019, 31(7): 1096-1104. DOI: 10.3969/j.issn.1004-1524.2019.07.09

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Twig blight disease of bayberry is the most important disease in bayberry industry at present. In this study, the effects of three bio-organic fertilizers, chicken manure, sheep manure and earthworm manure, on the disease control and tree vigor recovery were studied. The results showed that the control effect of three bio-organic fertilizers on twig blight disease was 35.2%-49.6%. The contents of nitrogen, potassium, iron, copper, zinc, calcium and manganese in leaves of three bio-organic fertilizer treatments were higher than those of the control. The content of organic matter and soil elements such as nitrogen, phosphorus, potassium, sulfur, boron, zinc and copper were higher than those of the control. Plant shoot diameter, leaf length, chlorophyll content and photosynthetic rate were 15.0%-24.5%, 4.3%-12.7%, 1.4%-6.5%, 40.2%-81.3% higher than those of the control, respectively. The contents of soluble solids, vitamin C and total sugar were increased by 10.2%-19.0%, 0.3%-23.9%, 3.3%-11.2% respectively and titratable acid was decreased by 2.2%-22.0% compared with the control. In summary, bio-organic fertilizer could reduce the occurrence of bayberry twig blight disease, promote the plant growth and restore the tree vigor of bayberry, and improve fruit quality. It was suggested that appropriate amount of bio-organic fertilizer should be applied as base fertilizer in bayberry production.

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Screening, identification and biocontrol effect of microbial antagonist against Fusarium solani causing potato dry rot

LIU Zhihui, HAO Rongrong, XU Yongfeng, YANG Chengde, ZHANG Junlian

2019, 31(7): 1105-1111. DOI: 10.3969/j.issn.1004-1524.2019.07.10

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In this study, Fusarium solani was used as indicative fungi, 30 antagonistic bacteria whose inhibition rates were higher than 70.00% from 120 endophytic bacteria were selected with the method of plate confrontation. Among them, 265ZY1, 265ZY3 and 265XY6 had strong antagonistic effects on F. solani, the inhibition rates reached 72.20%, 73.00% and 72.80%, respectively. Combining them with the ratio of 1∶1∶1, the inhibition rate reached 79.75%. The results showed that 265ZY1, 265ZY3 and 265XY6 had excellent biological functions, which could be developed as biocontrol bacteria. With the observation of morphology and 16S rDNA gene sequence analysis, 265ZY1, 265ZY3 and 265XY6 were identified as Bacillus vallismortis, Bacillus amyloliquefaciens and Bacillus methylotrophicus, respectively.

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Pathogen identification of bacterial fruit blotch of melon on sweet potato in Zhejiang Province

HONG Xianxian, WU Xiuqin, LUO Jinyan, WANG Yanli, SUN Guocang, AN Qianli, QIU Wen, LI Bin

2019, 31(7): 1112-1118. DOI: 10.3969/j.issn.1004-1524.2019.07.11

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Bacterial stem and root rot of sweet potato is an important quarantine disease. In the current study, four isolates of suspected diseased sweet potato induced a hypersensitive response on tobacco plants. These isolates were then identified into Acidovorax citrulli (formerly Acidovorax avenae subsp. citrulli) based on morphology, Gram's stain reaction, 16S rRNA sequence and pathogenicity analysis. Results here showed that the sequence homology of the novel isolates was as high as 99.00%-100.00% compared with A. citrulli, the bacterial pathogen of bacterial fruit blotch of cucurbits, which was the key quarantine pathogen of China. The current report indicated the importance of disease management for efficient controlling of bacterial fruit blotch of watermelon in Zhejiang Province.

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Effects of different photoperiod conditions on the nutritional contents and related enzyme activities of sorghum leaves and Melanaphis sacchari

DU Junli, WU Degong, ZHAN Qiuwen, HUANG Baohong, NI He

2019, 31(7): 1119-1127. DOI: 10.3969/j.issn.1004-1524.2019.07.12

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To clarify effects of photoperiod condition on material contents of sorghum leaves and Melanaphis sacchari, five photoperiod conditions (light∶dark) were set in this paper, which were 2L∶22D, 6L∶18D, 10L∶14D, 14L∶10D and 18L∶6D, respectively. Soluble protein, soluble sugar, free amino acid, starch and chlorophyll content in sorghum leaves were determined. At the same time, activities of aspartate aminotransferase (AST), alanine transaminase (ALT), superoxide dismutase(SOD) and catalase (CAT), contents of soluble protein, soluble sugar, free amino acid and total fat in sorghum aphids were also determined. The results showed that contents of soluble sugar, free amino acid, starch and chlorophyll in sorghum leaves under long photoperiod (10L∶14D, 14L∶10D, 18L∶6D) were higher than those under short photoperiod (2L∶22D, 6L∶18D), protein content in sorghum leaf under short photoperiod (2L∶22D) and long photoperiod (14L∶10D) were lower than those under other photoperiod conditions; ALT and AST activities in sorghum aphid reached the highest values under photoperiod condition of 18h∶6D and reached the lowest values under photoperiod condition of 10L∶14D; SOD and CAT activities in sorghum aphids under short photoperiod (2L∶22D, 6L∶18D) were higher than those under long photoperiod (10L∶14D, 14L∶10D, 18L∶6D); Contents of protein, soluble sugar and total fat in sorghum aphid were the highest under photoperiod condition of 10L∶14D, and free amino acids content in sorghum aphid was the lowest when the photoperiod was 14L∶10D. Content of transaminase in sorghum aphids showed an increasing trend in response to the adverse environment at extreme photoperiod condition and the protective enzyme increased under short photoperiod; the photoperiod of 10L∶14D was suitable for growth and development of sorghum aphid, nutrient contents were higher in this condition. Contents of protein, soluble carbohydrate and total lipid of sorghum aphids showed decreasing trends in extreme photoperiod conditions.

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Dynamics of soil phosphorus in paddy-upland rotation paddy soil under different fertilization modes

WU Chunyan, LIU Xiaoxia, CHEN Yi, LI Yan, TANG Xu, LU Ruohui

2019, 31(7): 1128-1137. DOI: 10.3969/j.issn.1004-1524.2019.07.13

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The changes of phosphorus in topsoil under paddy-upland rotation was studied through a long-term field fertilizer experiment. It was shown that the contents of total phosphorus and Olsen-P exhibited a decreasing trend without P supply, and the soil P balance was defect; while the contents of total phosphorus and Olsen-P exhibited an increasing trend with P supply either in organic or inorganic form. With organic P supply, the contents of total phosphorus and Olsen-P increased more rapidly than that with inorganic P supply, and the soil P balance was surplus. Under the experiment conditions, phosphorus input should not exceed 13.5, 42.4, 31.6 kg·hm^-2 in barley, rice, rape growing season, respectively, to meet the crop growth requirement and keep soil Olsen-P balance.

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Remediation of perchloroethylene and polycyclic aromatic hydrocarbons contaminated soil by foam-blocking coupled with oxidants

ZHANG Hongling, LI Sen, ZHANG Yang, SONG Yifan, SHANG Zhaocong

2019, 31(7): 1138-1144. DOI: 10.3969/j.issn.1004-1524.2019.07.14

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The blocking effect on volatile organic compounds (perchloroethylene) by different foams (produced by AC-645 or protein foaming agent) and the degradation efficiency of polycyclic aromatic hydrocarbons (PAHs) in soil by the coupling of foam and oxidant were investigated in the present study. The results showed that the foams used in this study could inhibit the volatilization of perchloroethylene and oxidize the PAHs in the soil. Among them, foam produced by AC-645 had the best blocking effect on perchloroethylene volatilization. In 3 hours, the blocking effect on perchloroethylene was maintained at about 95.0%. After 24 h, the removal rate of PAHs in soil was above 80.0%. The optimization experiment based on uniform mixing design was carried out, and it was shown that the optimal mass fraction ratio of foaming agent (AC-645), oxidant and water was 29.4%, 1.2%, 69.4%, respectively. Under this condition, the blocking rate of perchloroethylene volatilization was 94.5% within 30 min, and the removal rate of PAHs in soil was 87.8% after 24 h. Validation result showed that the bias of the experiment result and simulation prediction was 0.11%, indicating that the model prediction was accurate.

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Isolation, identification and degradation characteristics of a dibutyl phthalate and di-(2-ethylhexyl) phthalate degrading bacterium

LIANG Haohua, TAO Hong, WANG Yajuan, LI Jiaoling

2019, 31(7): 1145-1153. DOI: 10.3969/j.issn.1004-1524.2019.07.15

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In order to further study the microbial remediation of major PAEs pollutants in soil, a strain, named as AS001, capable of simultaneously degrading dibutyl phthalate (DBP) and Di-(2-ethylhexyl) phthalate (DEHP) was isolated from facility vegetable soil by culture enrichment method. The strain could utilize DBP and DEHP as the sole source of carbon and energy. Based on the morphology, physiological characteristic and 16S rDNA sequence analysis, AS001 was identified as Arthrobacter sp. and the degradation characteristics of phthalate acid esters were investigated under different rotating speeds, pH, initial concentrations, inoculation amount and temperature. The result showed that the optimal degradation condition of strain AS001 was: the rotation speed 175 r·min^-1, pH 7, initial concentration 100 mg·L^-1, inoculum size (V/V) 4%, temperature 35 ℃, and the degradation rate of DBP was higher than that of DEHP under different conditions. This study provided a certain theoretical basis for the environmental conditions of PAEs pollution remediation in soil in this area.

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Purification of α-amylase inhibitor from mulberry pomace by macroporous resin and analysis into its active components

FAN Ming, XIANG Lu, XU Wenhui, CAO Yan, LIU Zhe, LU Shengmin

2019, 31(7): 1154-1160. DOI: 10.3969/j.issn.1004-1524.2019.07.16

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In this research, purification process of α-amylase inhibitors derived from mulberry pomace was optimized, and the effective substances was also studied. The effects of different macroporous resins on the static adsorption and desorption of α-amylase inhibitors were investigated. Furthermore, high performance liquid chromatography (HPLC) was applied to analyze the components of eluents obtained from macroporous resin by deionized water or ethanol solutions with different concentrations (10%, 30%, 50%, 70%, 90%). The results showed that AB-8 macroporous resin was the most optimal resin for separating α-amylase inhibitors. The optimum process parameters for dynamic adsorption and desorption of α-amylase inhibitors from mulberry pomace were as follows: sampling rate of 12 mL·min^-1, eluent of 70% ethanol solution, and elution flow rate of 24 mL·min^-1. It was found that the content of quercetin in the eluent varied accordingly with the α-amylase inhibitory activity of purified mulberry pomace extracts, thus it was inferred that quercetin might be the main contributor of α-amylase inhibitory activity of mulberry pomace extracts.

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Characterization of Salmonella isolates recovered from processing chicken, retail chicken and chicken processing environment in Zhejiang and Shanghai

CAO Chenyang, ZHANG Yi, ZHANG Qian, XIAO Yingping, ZHAO Ruiting, LIU Chenxing, YANG Hua, ZHAO Min, YANG Baowei

2019, 31(7): 1161-1169. DOI: 10.3969/j.issn.1004-1524.2019.07.17

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One hundred and two Salmonella isolates recovered from processing chickens, retail chickens and environment of chicken processing slaughterhouses that collected in Zhejiang and Shanghai during July to October in 2016 were characterized to determine their prevalence, serotype and antimicrobial susceptibility. Serotype of Salmonella was determined via slide agglutination method using Salmonella hyperimmune sera, the antimicrobial susceptibility was tested by disk diffusion method that recommended by the clinical laboratory standard institute (CLSI). Among 204 samples, 85 samples were tested positive to Salmonella. 32 samples collected from processing chickens were positive to Salmonella, the highest rate of Salmonella positive samples was identified in the cold storage section with the ratio of 70.00%. A total of 15 serotypes were identified among the 102 Salmonella isolates. The most common five serotypes were S.Derby (23.53%), S. Agona (17.65%), S. Indiana (12.75%), S. Typhimurium (11.76%) and S. Dabou (7.84%). S. Derby was tested most prevalent in processing chickens while S. Agona was the most commonly found in retail chickens. All isolates were sensitive to amoxicillin/clavulanate and cefoxitin. Seventy five (73.53%) were resistant to tetracycline, followed by to chloramphenicol (49.02%), ampicillin (41.18%), nalidixic acid (38.24%), sulfamethoxazole/trimethoprim (37.25%), streptomycin (28.43%), ciprofloxacin (23.53%), ceftriaxone (22.55%), cefoperazone (22.55%), kanamycin (20.59%), gentamycin (19.61%) and amikacin (17.65%). Salmonella isolates in retail chickens showed significantly lower resistance to most tested antibiotics than those from processing chickens and slaughterhouse environment. Among 102 Salmonella isolates, 97 (95.10%) were resistant to at least one antibiotic, and 17 (16.67%) to 10 or more than 10 antimicrobials. Among all sampling places, Salmonella positive samples were investigated most prevalent in Shaoxing (78.95%), where the rate of Salmonella positive samples was significantly higher than those in Huzhou and Shanghai. The rates of Salmonella positive samples were found significantly different (P<0.01) in different sampling months, and it was found most prevalent (80.00%) in September. In the whole chicken production and consumption chain, the positive rate, serotype, antibiotic resistance rate, and antibiotic resistance phenotype of Salmonella isolates showed significant changes. Salmonella was not only derived from the chickens carrying bacteria in the batch, but also in various links and carried by the personnel also joined, resulting in the status of the terminal products. Prevalence of Salmonella in processing and retail chickens in Zhejiang and Shanghai was common. Chickens in processing, especially in refrigeration stage were more easily contaminated by Salmonella. The serotype of Salmonella isolates was diverse, and these isolates were resistant to multi-antibiotics.

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Inversion of maize and wheat leaf area index based on particle swarm optimization neural network model

WANG Xiaoxuan, MENG Qingyan, ZHANG Haixiang, WEI Xiangqin, YANG Zenan

2019, 31(7): 1170-1176. DOI: 10.3969/j.issn.1004-1524.2019.07.18

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In this paper, based on GF-1 remote sensing image, three methods, namely particle swarm optimization neural network model, artificial neural network model, vegetation index regression model ,were adopted to invert leaf area index (LAI) of maize and wheat in Langfang City. It was shown that the accuracy of maize and wheat LAI inversion by particle swarm optimization neural network model was the highest. The calculated determination coefficient R² of this method was higher than 0.9, and its root mean square error was lower than 0.196, which could satisfy the requirement of inversion precision. To sum up, maize and wheat LAI inversion based on the proposed particle swarm optimization neural network model was feasible on GF-1 images, and possessed universality.

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Soybean disease detection system based on convolutional neural network under Caffe framework

JIANG Fengqian, LI Yang, YU Dawei, SUN Min, ZHANG Enbao

2019, 31(7): 1177-1183. DOI: 10.3969/j.issn.1004-1524.2019.07.19

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The diseases such as leaf spot, mosaic, downy mildew and gray spot of soybean were analysed, and then a soybean disease identification system based on convolutional neural network was proposed. The training set of the neural network model was obtained by the pretreatments including binarization of disease images and extraction of target regions, moreover, the accuracy of the model was improved, and the model and related parameters were simulated under the Caffe framework. Furthermore, in order to improve the ease and reliability of the system in use, the human-computer interaction interface was designed by using Qt software. The data visualization was further realized.

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Breeding efficiency measurement and subsidy policy benefit evaluation of scale hog in China

LI Xiaogang, XIONG Tao

2019, 31(7): 1184-1192. DOI: 10.3969/j.issn.1004-1524.2019.07.20

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In this paper, the changes of hog breeding efficiency from 2001 to 2016 in China before and after the implementation of hog subsidy policy were analyzed to scientifically evaluate the effectiveness of China's hog subsidy policy based on the Malmquist-Dea index and difference-in-difference approach (DID) methods. Results showed that China's large and medium scale hog-breeding scale efficiency increased slightly in general, while technical efficiency and pure technical efficiency decreased significantly, and there were differences in the total factor productivity with different hog-breeding scales. On the time series, fluctuation amplitude of technical efficiency change index was not large, but that of the total factor productivity and technological progress change index was large, and the trend of changes kept consistent. Moreover, the hog subsidy policy reduced the scale efficiency of hog breeding on the whole. Finally, further analysis found that the input of factors such as feed had significantly different impact on the different scale hog-breeding scale efficiency, which showd that the more input and the higher the regional GDP, the greater the scale efficiency of pig breeding. Hog export big county rewards and livestock standard breeding subsidy policy reduced the scale efficiency of large-scale and medium-scale hog farmers. This study showed that hog subsidy policy can hardly improve the scale efficiency of hog breeding. More efforts should be made to improve breeding technology.

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Analysis of spatial-temporal pattern and scenario simulation of green infrastructure in Wuyi County based on morphological spatial pattern analysis and CA-Markov model

LIN Hongyu, QIAN Jing, YAN Lijiao, HUANG Shaorong

2019, 31(7): 1193-1204. DOI: 10.3969/j.issn.1004-1524.2019.07.21

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In the context of rapid global urbanization, green infrastructure (GI) has attracted attention in urban planning and construction due to its good ecological and environmental benefits. In the present paper, Wuyi County, Jinhua City, Zhejiang Province was selected as the research area, and ArcGIS, GuidosToolBox, Conefor 2.6 and other softwares were applied to analyze the morphological spatial pattern of the land use type of Wuyi County in 1990, 2005 and 2018. The three scenarios of urban development priority, ecological protection priority and natural development were set up, and the CA-Markov model was used to predict the future green infrastructure spatial pattern under the three scenarios. The results showed that the ratio of the area of green infrastructure in Wuyi County to the total area of Wuyi County in 1990—2018 decreased. The area of important core areas and island-like plaques was decreasing, while the area of bridges, pores and branch lines was increasing, and the problem of landscape fragmentation was aggravated. In the scenario simulation in 2030, the GI area of Wuyi County under natural development and urban development priority scenarios would decrease by 171.79 km² and 225.73 km², respectively, and the core area would decrease by 84.81 km² and 126.76 km², respectively. Under the ecological protection priority scenario, the GI area in Wuyi County would increase by 25.52 km², and the core area would increase by 69.60 km². The results showed that if people pursue blindly of rough economic development and neglect ecological protection, the landscape fragmentation in Wuyi County would be further aggravated. Based on this, priority should be given to ecological protection, and tourism development should be moderately regulated in the central and southern regions, to achieve sustainable development in accordance with economic growth and environment.

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Roles of bZIP transcription factors in plant growth and development and abiotic stress response

LIU Huijie, XU Heng, QIU Wenyi, LI Xiaofang, ZHANG Hua, ZHU Ying, LI Chunshou, WANG Liangchao

2019, 31(7): 1205-1214. DOI: 10.3969/j.issn.1004-1524.2019.07.22

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During the plant life cycle, different sets of genes are designated to express at specific growth and developmental stage, or induced under certain circumstance such as drought, heat and so on. Gene expression is fine regulated by transcription factors. One catalog of transcription factor, the basic leucine zipper (bZIP) transcription factors, are involved in the regulation of various biological processes from development to stress response. During growth phase transformation or under stress, plant transcript profile is changing fast and dramatically. bZIP transcription factors are one of those regulators conduct this transcription reprogram. This paper mainly focused on the recent advances in bZIP transcription factor, including structures, sorts, roles in plant developments and abiotic stress.

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