Acta Agriculturae Zhejiangensis

Genome-wide association study of seed nutritional quality in sweet corn

WANG Changjin, XU Yunlin, CHENG Xinxin, ZHOU Yi, YU Haibing

2020, 32(3): 383-389. DOI: 10.3969/j.issn.1004-1524.2020.03.01

Abstract ( 811 )

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In this study, a 56K SNP chip was used to evaluate the structure of natural population in 100 sweet corn inbred lines and to locate the seed nutritional quality with association mapping. The results showed that 100 inbred lines were divided into two subgroups, the subgroup 1 contained 92 germplasms and the subgroup 2 contained 8 germplasms. PIC values of 37 297 high-quality SNPs with uniform genome coverage were concentrated at 0.19, and the variation of gene diversity was concentrated between 0.36 and 0.38. The starch content of seed was in 53.91%-73.70%, the protein content was in 8.96%-18.01% and the fat content was in 5.53%-18.50%. There were 14, 15 and 20 SNP molecular markers revealed by GLM-Q model for starch content, protein content and fat content in sweet corn seeds which could explain 3.45%-51.69% of phenotypic variation. At -log₁₀P>3.50 level, the qSTA-3-1 that was on Affx-115329496 of No.3 chromosome could explain 20.90% of starch variation. qPRO-1-1 and qPRO-9-2 were the significant association locus with protein content of sweet corn, which were on the Affx-91181539 of No.1 chromosome and on the Affx-115333989 of No.9 chromosome. qFAT-5-1 on Affx-91137282 of No.5 chromosome was associated with fat content of sweet corn.

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Effect of backfat thickness on body condition score and reproductive performance of sows during pregnancy

LIU Bin, CHEN Ying, JIANG Xiaobing, GUO Zhixian, HE Zhiping, ZHONG Zhijun, ZHANG Shunhua, ZHU Li

2020, 32(3): 390-397. DOI: 10.3969/j.issn.1004-1524.2020.03.02

Abstract ( 777 )

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Historical reproductive data of 2 552 Yorkshire sows were used to analyze the relationship between backfat thickness and body condition score and main reproductive traits and correlation analysis was carried out on the thickness and reproductive traits of primiparous sows and sows at different stages of pregnancy. The results showed that the body condition scoring method could not accurately judge the backfat thickness and reproductive performance of sows. There was no significant correlation between the backfat thickness and the main reproductive traits at different gestation stages of primiparous sows. The backfat thickness in different stages of multiparous sows was significantly (P<0.05) correlated with reproductive traits. The variation of backfat thickness during pregnancy was significantly (P<0.05) correlated with reproductive traits. According to the regression analysis, in order to optimize the reproductive performance of the sows, the backfat thickness of sows during pregnancy should be controlled within the range of 10-14 mm, and kept stable during gestation period. Precise feeding should be carried out according to the thickness of the sow's backfat at different stages of pregnancy to ensure that the sows could reach the optimal backfat thickness range and maintain relatively stable throughout the pregnancy, and it will be helpful to improve the reproductive performance of sows.

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Analysis of correlation between polymorphism of IGF-1R gene and body size traits in egg quail

BAI Junyan, LU Junhao, FU Xueyan, WU Xiaohong, YANG Youbing, LEI Ying, PANG Youzhi, LU Xiaoning, GONG Huirong, HU Luxing, LIU Hongtao, FAN Hongdeng, CAO Heng, SHI Kunpeng, CHEN Mengke, MA Yongkang

2020, 32(3): 398-405. DOI: 10.3969/j.issn.1004-1524.2020.03.03

Abstract ( 817 )

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Type 1 insulin-like growth factor receptor (IGF-1R) gene is the main effector of insulin-like growth factor (IGFs). It has important influence on the growth and development of the body. To investigate the correlation within IGF-1R and body size traits of egg quails, the polymorphism of IGF-1R gene was analyzed by direct sequencing of PCR products in Chinese yellow quail, Beijing white quail and Korean quail, and the correlation within the polymorphism of IGF-1R gene and body size traits of quail was analyzed. The results showed that two mutation sites of IGF-1R gene A57G and A72T were detected in three egg quail populations. A/G base mutation occurred at A57G site, including three genotypes of AA, AG and GG. A/T base mutation occurred at A72T site, including three genotypes of AA, AT and TT. The A57G locus of Chinese yellow quail had significant (P<0.05)effects on tibia length, sternal length and tibia circumference, A72T locus had significant (P<0.05) effects on body weight and sternal length, combination genotype AGAA had significant (P<0.05) effects on body weight, combination genotype AAAA had significant effects on tibia length, sternal length and tibia circumference (P<0.05). The A57G locus of Beijing white quail had significant effects on body weight, tibia length, body length and tibia circumference (P<0.05), A72T locus had significant (P<0.05) effect on sternal length, combination genotypes AAAA had significant (P<0.05) effects on body weight and sternal length, and combination genotypes AAAT, GGAA and GGAT had significant (P<0.05) effects on tibia length, the combined genotype GGAA had significant (P<0.05) effect on chest depth. The A57G locus of Korean quail had significant (P<0.05) effect on body weight, and the A72T locus had significant (P<0.05) effect on sternal length and tibia circumference, the combined genotype AGAA had significant (P<0.05) effect on body weight, and the combined genotype AGAT had significant (P<0.05) effect on tibia length and chest width. Therefore, the IGF-1R gene could be used as a candidate gene for molecular marker-assisted selection of body size traits in egg quails.

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Bioinformatics analysis and prokaryotic expression of FIPV AH1905 strain N gene

WANG Yuanhong, XING Xue, LI Chuanfeng, ZHU Jie, WANG Yong, LIU Guangqing

2020, 32(3): 406-414. DOI: 10.3969/j.issn.1004-1524.2020.03.04

Abstract ( 908 )

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To understand the molecular epidemiological and genetic variation characteristics of feline infectious peritonitis virus (FIPV) in China, the N gene of FIPV AH1905 strain was cloned by PCR, and the bioinformatics softwares were used to predict the N protein. Then, N gene was cloned into a prokaryotic vector pGEX-4T-1 and was successfully expressed. The expressed protein was purified, and identified by SDS-PAGE and Western blot. The results showed that the N gene of FIPV, 1 134 bp, encodes 377 amino acids. The molecular bioinformatics analysis showed that the nucleotide homology and the amino acid homology between FIPV AH1905 strain and the reported FIPV reference strains were 90.2%-92.4% and 91.8%-93.9%, respectively. The phylogenetic analysis showed that FIPV AH1905 belongs to the FIPV gene type Ⅰ, the same as other isolates in China. The prediction of the secondary structure of the N protein showed that the protein was a hydrophilic stable protein with 14.06% α-helix (h), 15.12% extended chain (e), 3.71% β turn (t) and 67.11% random spiral (c). There were no signal peptide region and transmembrane domain. It may have 48 phosphorylation sites. Moreover, there may exist six B cell epitopes, two CTL epitopes and two Th epitopes. The molecular weight of expressed protein is approximately 68 ku, mainly expressed in inclusion body form with good reactogenicity. In conclusion, the present study has successfully expressed the N protein of FIPV, and prepared the multi-antiserum, which laid the foundation for further research on epidemiology and molecular biology of FIPV.

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Study on subculture stability and serum-free acclimation of Marc-145 cells in low serum adaptation culture

AYIDING Aerzuguli, LU Meilin, LI Ziliang, HE Dan, QIAO Zilin, ABUDUREYIMU Aymuguri

2020, 32(3): 415-420. DOI: 10.3969/j.issn.1004-1524.2020.03.05

Abstract ( 603 )

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A serum-free suspension culture Marc-145 cell line was established through domestication, and the effects of domestication on cell characteristics were analyzed to provide basis for mass production of host cells for vaccines. The serum concentration in the slow drop culture medium was used to subculture for 50 generations, and the serum-free medium was used for suspension culture and domestication. The morphology, doubling time, growth curve and sensitivity to PRRSV of P10, P20, P30, P40 and P50 passage cells during passage and domestication were compared and analyzed. Results showed that Marc-145 cells grew like flat polygons. The doubling time of P10 passage cells was 34.15 h, while the doubling time of P50 passage cells was 36.16 h, and the doubling time of P50 passage cells was slightly prolonged, but the difference was not significant. The growth curves of P10, P20, P30, P40 and P50 Marc-145 cells were “S” type, and the chromosome numbers of P10 and P50 passage cells were between 88 and 90. After inoculating the virus, there was no significant difference in TCID₅₀ values between P10, P20, P30, P40 and P50 cells, indicating that there were no significant change in cell characteristics after 50 generations of cell passage. Therefore, P50 cells were cultured and domesticated in serum-free suspension culture. After 48 h of serum-free suspension culture, the cell density of P50 cells reached 4.14×10⁶ mL^-1.

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Effects of exogenous melatonin on physiological and biochemical characteristics in female flowers of Trichosanthes kirilowii under high temperature and strong light

WU Yan, QIAO Xiaoyan, GE Weiqiang, GAO Qinghai

2020, 32(3): 421-429. DOI: 10.3969/j.issn.1004-1524.2020.03.06

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In order to explore the physiological and biochemical changes of exogenous substances on the female flowers of Trichosanthes kirilowii under high temperature and strong light in summer, two-year-old Wanlou 9 was used as material, the effects of 200 μmol·L^-1 melatonin on the activities of antioxidant enzymes, osmotic regulators, H₂O₂, relative conductivity, pollen germination, fruit setting rate and single fruit weight of T. kirilowii under high temperature and strong light were studied. The results showed that the exogenous melatonin significantly increased activities of SOD, POD, CAT and APX, eliminated 34.5% of H₂O₂ compared with the control of T. kirilowii under high temperature and strong light. Moreover, it also promoted the synthesis and accumulation of osmotic regulators. Soluble sugar and proline in female flowers treated with exogenous melatonin increased by 25.8% and 45.5%, respectively, compared with the control. The exogenous melatonin also increased the pollen germination rate, promoted the fruit setting and fruit enlargement, and increased the fruit setting rate of T. kirilowii by 9.1 percent under high temperature and strong light. Above all, exogenous melatonin could significantly relieve the high temperature hazards and improve the fruit-setting rate by increasing the antioxidant enzyme activity and osmotic regulation ability under high temperature and strong light.

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Comparative analysis of mineral elements contents in tomato fruits at different harvest time

QIAO Yali, YU Jihua, LI Wangxiong, JIN Ning, JIN Li, LYU Jian, XIAO Xuemei, TANG Zhongqi, HU Linli

2020, 32(3): 430-436. DOI: 10.3969/j.issn.1004-1524.2020.03.07

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In order to compare and analyze the changes of mineral elements in tomato fruits at different harvest time, eight mineral elements of potassium (K), phosphorus (P), magnesium (Mg), calcium (Ca), copper (Cu), iron (Fe), manganese (Mn) and zinc (Zn) in tomato fruits of Fentailang and 181 at different harvest time were determined by atomic absorption spectrometry and molybdenum antimony colorimetric method. The change trends of mineral elements in tomato fruits at different harvest time were studied. The results showed that there were significant differences in the contents of eight mineral elements in different harvest time. The contents of K, Ca, Mg and Cu in the two varieties showed a general downward trend in the whole harvest time, in which Cu decreased significantly. The contents of Fe in the two fruits showed a trend of first rising, then declining and then rising in the whole harvest time. The content of Fentailang fruit was the highest on April 7th, and that of 181 reached the highest on April 28th. The correlation analysis showed that there was a positive correlation between some mineral elements, there was a significant positive correlation within K, Cu, Zn and Mg in Fentailang fruit and Mg and Ca, Cu in 181 fruit. The results provided theoretical guidance for high quality tomato cultivation and harvest time selection.

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Effect of exogenous proline on degradation of residual chlorothalonil in tomato

LIU Xinyu, CHEN Peng, ZHANG Guanghui, ZHAO Junjie, LI Bohao, ZHANG Nan, SUN Weike, XU Juanjuan, YE Xingtao, WEI Jinpeng, YU Gaobo

2020, 32(3): 437-446. DOI: 10.3969/j.issn.1004-1524.2020.03.08

Abstract ( 1044 )

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In order to explore the regulation of exogenous proline (Pro) on degradation of residual pesticide in tomato,Zheza 205 was taken as the tested plant and the fungicide chlorothalonil was applied to study the effect of exogenous Pro on pesticide residues. The content of reactive oxygen species(ROS),and the activity of antioxidant enzymes and detoxification enzymes after the application of chlorothalonil were investigated. The results showed that pretreatment of Pro (3 mmol·L^-1) reduced the pesticide residue in tomato significantly after 7 days of chlorothalonil application. Compared with the control,exogenous Pro pretreatment could induce the activity of tomato peroxidase (POD), superoxide dismutase (SOD), ascorbate peroxidase (APX), monodehydroascorbic acid reductase (MDAR) significantly after the treatment of chlorothalonil, and increase the GSH/GSSG ratio during the 12-96 h period after pesticide treatment, as well as the activity of glutathione reductase (GR), glutathione S-transferase (GST), and the content of non protein bound thiols (NPT).Therefore, pretreatment of Pro could induce the activity of antioxidant enzymes and GST detoxification enzyme and improve the regeneration of GSH, and thus promote the degradation and metabolism of chlorothalonil in tomato.This study provided a new way to promote the degradation of pesticide residue in vegetables.

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Effects of different rootstock combinations on physiological characteristics and selenium accumulation of Nasturtium officinale cuttings

HUANG Kewen, LI Keqiang, LIU Ji, SUI Liyun, LIU Lei, WANG Ting, ZHENG Yangxia, LIN Lijin, LIAO Ming'an

2020, 32(3): 447-454. DOI: 10.3969/j.issn.1004-1524.2020.03.09

Abstract ( 758 )

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Pot experiment was carried out with Brassica chinensis, Brassica napus, Raphanus sativus, Rorippa dubia, Brassica oleracea as rootstocks, and Nasturtium officinale was used as the scion. The effects of different rootstocks on the growth, pigment accumulation, protective enzymes activities and selenium accumulation ability of N. officinale cuttings were studied under the conditions of soil selenium concentration of 10 mg·kg^-1. The results showed that after grafting with B. napus, R. sativus and B. oleracea, the biomass of all parts of N. officinale cuttings as well as chlorophyll a, chlorophyll b and carotenoid contents were significantly higher than un-grafted N. officinale. The grafting of R. dubia as a rootstock not only decreased the biomass of the N. officinale cuttings, but also inhibited the activity of SOD, POD and CAT. Although grafting of B. chinensis as rootstock significantly increased the photosynthetic pigment content, SOD and CAT activities of N. officinale cuttings, the biomass of roots, stems and leaves were significantly lower than those of the control. In addition, the grafting treatment with B. oleracea as a rootstock significantly improved the CAT activity and soluble protein content of the N. officinale cuttings, and effectively reduced the malondialdehyde content, and significantly enhanced the selenium-tolerant ability of N. officinale cuttings. There were significant differences in the effects of five kinds of rootstocks on selenium accumulation in N. officinale cuttings. Among them, the grafting treatment of R. sativus as rootstocks maximized the selenium content and selenium accumulation in the shoots of N. officinale cuttings, which could provide some reference for the cultivation and breeding of selenium-accumulation vegetables.

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An efficient utilization method of oviposition substrate for Orius strigicollis

HUANG Jun, QIAN Cheng, LYU Yaobin

2020, 32(3): 455-459. DOI: 10.3969/j.issn.1004-1524.2020.03.10

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Orius strigicollis is a current predatory natural enemy with strong predation ability. In the present study, kidney bean (Phaseolus vulgaris) pods were used as the oviposition substrate for O. strigicollis, and the preference of the oviposition area on kidney bean pods was studied. Additionally, an efficient utilization method of the oviposition substrate was further analyzed. Results showed that more than 90% eggs of O. strigicollis were laid in the pod seams, and more than 50% eggs were laid in the pod seams of the bean tip. Cutting the tip of kidney bean at an angle of 45°and waxing the cut was a feasible method. The method could maintain good sealing of the incision within 5 d, and kept the bean tip fresh, and did not affect the egg hatching, which indicated that this utilization method of oviposition substrate was feasible. The results provided scientific basis for the propagation and product creation of O. strigicollis in future.

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Isolation, identification and characterization of antagonistic actinomycetes A10 and A17 against Botryodiplodia theobromae

GUO Xuesong, TIAN Libo, SHANG Sang, ZOU Kaixi, CHEN Hongrong, LI Wanyu, YUE Xiaoqi

2020, 32(3): 460-468. DOI: 10.3969/j.issn.1004-1524.2020.03.11

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In order to enrich the antagonistic and antibacterial resources of mango stem-end rot and find a non-toxic and non-polluting post-harvest control method instead of chemical fungicide, plate dilution method, scribing purification method and paper diffusion method were used to separate and screen the antagonistic actinomycetes against Botryodiplodia theobromae from mangrove rhizosphere soil. Their taxonomic status was identified, the fermentation conditions were optimized, and the biological control effect was tested. A total of two antagonistic actinomycetes A10 and A17 with strong antibacterial activity against postharvest mango rot fungus (Botryodiplodia theobromae Pat.) were screened. According to the morphological characteristics, physiological and biochemical characteristics and molecular identification, the two actinomycetes were all Streptomyces. The fermentation medium and fermentation conditions of A10 strain were optimized as follows: 2.5% lactose, 2.0% peptone, initial pH 8.0, shaking speed 200 r·min^-1, culture time 120 h. The fermentation medium and fermentation conditions of A17 strain were optimized as follows: 2.0% soluble starch, 2.0% peptone, initial pH 7.0, shaking speed 200 r·min^-1, culture time 120 h. In vivo experiment, on the 4th day, the incidence and disease index of the control group treated with sterile water were 81.7% and 52.5, respectively, 43.3% and 21.7 in the A10 group, 36.7% and 17.5 in the A17 group, and 16.7% and 12.2 in the 450 mg·kg^-1 prochloraz group. Both strains had a certain inhibition effect on the occurrence and expansion of the disease spot, and A17 had a certain inhibition effect on the expansion of the disease spot. There was no significant difference between the inhibitory effect of A17 and that of 450 mg·kg^-1 prochloraz. The results showed that the two strains had some antagonistic effect on the pathogen, which could be further studied.

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Population dynamics of three kinds of fruit-eating male adult in peach orchard and their correlation with temperature and rainfall

QIU Xiaohong, ZHENG Lumin, CHU Shupin, ZHU Youli

2020, 32(3): 469-474. DOI: 10.3969/j.issn.1004-1524.2020.03.12

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The sex pheromone inducing methods were used to study the population dynamics on Grapholitha molesta(Busck), Carposina sasakii Matsumura and Conogethes punctiferalis from 2016 to 2018 in Jurong City, Jiangsu Province. The results showed that the number of Grapholitha molesta among species was the largest in 2016. The large generation and the number of peaksin Grapholitha molesta both appeared in 2016 and 2017, however, the overwintering adult was much lower than the generation in 2018. Carposina sasakii occurred rarely after early September of each year. Compared with 2016 and 2017, the population of Dichocrocis punctiferalis was the highest in 2018, which showed occurrence periods lasted until early November. There were no significant linear relationships between annual average monthly quantity of trapped insects and annual average monthly precipitation in the three pests during 2016-2018 (P>0.05). There was significant positive correlation between the annual average monthly quantity of trapped insects and the sum of monthly temperature in Carposina sasakii (P<0.05).

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Influence of land use changes on soil total organic carbon and dissolved organic carbon in wetland

JIAN Xing, ZHAI Xiaoyu, WANG Yu, CAI Yangyang

2020, 32(3): 475-482. DOI: 10.3969/j.issn.1004-1524.2020.03.13

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In order to explore the effects of land use changes on soil total organic carbon (TOC) and dissolved organic carbon (DOC) in wetland, based on the concept of space as a substitute for time, the contents of TOC and DOC of wetland and four types of land changed from wetland, including two kinds of cultivated lands with different reclamation years, orchard land and woodland, were measured. The results showed that, three years after the wetland was reclaimed as cultivated land, TOC content in 0-30 cm soil layer decreased significantly (P<0.05), and thirty years after reclamation, only 0-10 cm topsoil TOC content was accumulated and restored to the same level as wetland. This indicated that the loss and accumulation of soil carbon were unequal in time and space after reclamation of wetland. The occurrence period of carbon loss was short and concentrated in 0-30 cm soil layer, and carbon accumulation took a long time and carbon was mainly accumulated in surface soils of 0-10 cm. The DOC content of wetland, newly cultivated land and woodland did not show an increasing trend with the increase of soil layer in soil profile, but the DOC/TOC increased with the increase of soil layer in four land use types except newly cultivated land. So, compared with DOC content, DOC/TOC was more sensitive to the change of soil depth, and was more suitable to characterize the change of DOC in the direction of soil profile. It was found that DOC/TOC in 0-20 cm soil layer was irrelevant to land use types, and at the initial stage of wetland conversion to cultivated land, DOC/TOC of soil layer below 20 cm decreased, but increased significantly (P<0.05) after 30 years of cultivation. After three years of conversion from cultivated land to orchard land, DOC/TOC decreased significantly (P<0.05) in 30-50 cm soil layer, while there was no significant difference in DOC/TOC among different soil layers after wetland was transformed into woodland.

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Processing adaptability and storage characteristics of four whole fruit drinks of hybrid citrus

TANG Weimin, XING Jianrong, YANG Ying, XIANG Lu, WANG Sinong, LU Shengmin

2020, 32(3): 483-489. DOI: 10.3969/j.issn.1004-1524.2020.03.14

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In order to compare the processing adaptabilities and storage properties of four whole fruit drinks prepared by four hybrid citrus (Citrus Changshanensis, Huyou; Citrus Suavissima, Ougan; Citrus wenlinggaochengensis, Gaocheng; and sweet orange pomelo, Tianjuyou), according to the previous formula, four kinds of whole fruit drinks were processed and stored in dark at 40 ℃. The samples were selected to analyze ascorbic acid, total acid, total phenols, anti-oxidative ability, colour and viscosity every 20 days, and sensory evaluation was carried for those samples of 0, 20 and 40 d. During the storage period, ascorbic acid contents of four whole fruit drinks declined, total acid content remained unchanged, the viscosity rose firstly and then declined, as well as the total phenols content and anti-oxidative ability. The colour of four varieties was deep and tended to be consistent. Gaocheng whole fruit drink contained the highest contents of ascorbic acid, total acid and total phenols. There were both advantages and disadvantages for whole fruit drinks produced from different hybrid citrus varieties. Tianjuyou was suitable for exploration as young style products. Huyou and Gaocheng contained high content of active constitutes and were suitable for functional products, and their taste would be better after being stored for a period. Ougan was suitable to be explored into products for people of all ages.

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Effects of physical modification on content, polysaccharide composition and structure of dietary fiber in sweet potato peels

WU Weicheng, DAI Jianbo, CAO Yan, XIA Qile, CHEN Jianbing, MENG Xianghe

2020, 32(3): 490-498. DOI: 10.3969/j.issn.1004-1524.2020.03.15

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In order to further explore the influence of physical modification on soluble dietary fiber (SDF) content, polysaccharide component, and morphological structure of sweet potato peels, ultrasonic, subcritical water and microwave modifications were used to treat the dietary fiber of sweet potato peels. The contents of SDF and neutral and acidic polysaccharides in the dietary fiber of sweet potato peels were determined. The transmission electron microscope (TEM), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) were used to characterize the shape and structure of the dietary fiber. The results showed that the effect of subcritical water modification on the yield of SDF, total dietary fiber (TDF) and neutral polysaccharide was significant (P<0.05). The SDF yield and the proportion of neutral polysaccharide were related to the degree of dietary fiber destruction. The highest proportion of acid polysaccharides eluted by 0.1, 0.2, 0.3 and 0.5 mol·L^-1 NaCl were found in unmodified samples, which were 8.48%, 19.52%, 28.44% and 2.32%, respectively. The highest proportion of acid polysaccharides eluted by 0.4 mol·L^-1 NaCl was found after subcritical water modification (10.99%), and the highest proportion of acid polysaccharides eluted by 0.6 mol·L^-1 NaCl was found after ultrasonic modification. TEM showed that the subcritical water modification had the most obvious structural damage to TDF of sweet potato peels, as its specific surface area increased, which showed a more complex spatial structure. FTIR analysis showed that the modified dietary fiber still had functional groups of polysaccharides. The polygalacturonic acid structure of pectin was found in unmodified and physically modified dietary fiber, and the total content of pectin in dietary fiber of sweet potato peels increased after physical modification. XRD results showed that both subcritical water and microwave modification converted the cellulose crystal form of TDF in sweet potato peels from type I to type II. Among them, the subcritical water modification exhibited the most serious damage to crystal shape. It was calculated that the crystallinity after subcritical water modification was 21.33%, which was 15.12, 7.85 and 4.41 percent lower than that of unmodified sample, and samples after ultrasonic and microwave modification, respectively.

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Changes of bioactive compounds and volatile compounds contents in goji juice fermented by different probiotics

LIU Yuxuan, CHENG Huan, YE Xingqian, LIU Huiyan, FANG Haitian

2020, 32(3): 499-509. DOI: 10.3969/j.issn.1004-1524.2020.03.16

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In order to evaluate the quality and volatile flavor compounds of goji juice fermented by four strains, Lactobacillus reuteri, Bacillus bataviensis, Lactobacillus rhamnosus and Bacillus licheniformis, which were previously isolated from fermented foods in our laboratory. Flavonoids, protein, phenols and volatile flavor components were determined and analyzed. The results showed that flavonoids contents in each fermented goji juice increased significantly. The protein content of fermented goji juice with Lactobacillus reuteri was the highest, which was (599.50±1.53) μg·mL^-1, and fermented with Bacillus bataviensis was the lowest, which was (168.11±1.00) μg·mL^-1. The highest phenolic content was fermented goji juice with Bacillus bataviensis, which was 1.10-3.01 times of other probiotics strains. A total of 52 volatile flavor components were detected in fermented goji juices, including 24 common components, but the content of the common components varied. Acid had a great influence on the flavor of fermented goji juice. It was suggested that Bacillus bataviensis was one of the best strain for fermented goji juice. The fermented juice had a better flavor, and the quality index and sensory evaluation were superior to other fermentation groups.

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Process conditions and quality of loquat paste made from loquat sugar solution

LIU Zhe, ZHU Mengjie, XIANG Lu, FAN Ming, LU Shengmin

2020, 32(3): 510-517. DOI: 10.3969/j.issn.1004-1524.2020.03.17

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To effectively use loquat sugar solution, a by-product of candied loquat production, it was used as a raw material to produce loquat paste. Effects of salt addition and soluble solids content on total phenolic content, total flavonoid content, free radical scavenging abilities and sensory quality of loquat sugar solution and (or) loquat paste were investigated. Results showed that the yield of loquat sugar solution and its total phenolic content, total flavonoid content, as well as free radical scavenging abilities were improved by the addition of salt in the production of candied loquat. Moreover, total phenolic content, total flavonoid content and free radical scavenging abilities of loquat paste were increased with soluble solids content increasing. However, there was no significant difference between 60 and 70^OBrix. Finally, based on the results of sensory evaluation, it was suggested that the optimum amount of salt should be 1%, the soluble solids content of loquat paste should be 60^OBrix.

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Design and experiment of precise seeding control system for rapeseed seeding machine based on GIS

ZHANG Jinran, LI Cunchao, LI Xun, SUN Guojun, HE Ruiyin, WEI Qing

2020, 32(3): 518-526. DOI: 10.3969/j.issn.1004-1524.2020.03.18

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Under the rice-oil rotation model in Jiangsu Province, an electric control seeding system was designed to solve the leakage problem during seeding caused by the ground wheel slippage due to the wetness of rice soil, and the automation transformation of the current mechanical double seeder for rapeseed was conducted. In the proposed system, the seeding parameters were determined and sent to the main processing controller according to the computer-loaded sowing operation information, map data and real-time acquired GPS position during the seeding operation, and the PID control algorithm was introduced. The closed-loop control algorithm combined the target hole distance and the forward speed, and used a DC motor to control the rotation speed of the seeding shaft to achieve accurate seeding of rapeseed. The test results showed that the highest variation coefficient of motor rotation speed was 4.85%, and the highest variation coefficient of the target hole distance in the bench test was 15.28%, which was higher than that of the traditional method, and the work response time was short.

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Construction of PLSR prediction model for detecting color of Jingyuan yellow beef by hyperspectral technique

YU Wenjie, WANG Caixia, QIAO Lu, WANG Songlei, HE Xiaoguang

2020, 32(3): 527-533. DOI: 10.3969/j.issn.1004-1524.2020.03.19

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The PLSR prediction model for beef color of Jingyuan yellow cattle was constructed by hyperspectral image. The hyperspectral images of samples were obtained by visible near-infrared hyperspectral imaging system, the spectral information of the interest regions were extracted, and the average spectrums were calculated. The Monte Carlo method was used to eliminate the abnormal samples, then the sample set was divided and the sample data was preprocessed. Results showed that model with the lightness (L^*) pretreated by the Deresolve method performed best while $R_{C}^{2}$ was 0.979 0 and $R_{P}^{2}$ was 0.976 6. Model with the redness (a^*) pretreated by convolution smoothing (Smoothing-SG) method performed best while $R_{C}^{2}$ was 0.807 0 and $R_{P}^{2}$ was 0.915 5. Model with the yellowness (b^*) pretreated by convolution smoothing (Smoothing-SG) method performed best while $R_{C}^{2}$ was 0.931 1 and $R_{P}^{2}$ was 0.950 6. Characteristic wavelengths were extracted by using competitive adaptive re-weighting method (CARS), continuous projection algorithm (SPA) and non-information variable elimination algorithm (UVE) respectively. The partial least squares regression (PLSR) model based on characteristic band was achieved and further optimized. The best prediction model was combined with the spatial depth and stereoscopic degree of the vision to extract and distinguish form and color perception of the sample. Therefore, it was feasible to construct the PLSR model by using hyperspectral imaging based on values of L^*, a^* and b^*, and the theoretical basis for online rapid detection of beef quality was provided.

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Study on operation of ground source heat pump air-conditioning system in greenhouse

BAO Lingling, ZHU Shujing, GENG Jiewen

2020, 32(3): 534-542. DOI: 10.3969/j.issn.1004-1524.2020.03.20

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Greenhouse, as the main part of facility agriculture, is particularly important to adjust the temperature in the growing environment. Through the ground source heat pump air conditioning system, the greenhouse stored heat across seasons. It had the advantages of high efficiency, energy saving, cleanliness and environmental protection. A greenhouse in Beijing and its source heat pump air conditioning system were used as the research objects to analyze the operating performance of cross-season heat storage system in the greenhouse. DeST software was used to modeling and analyze the variation of load and room temperature and determine the operating characteristics of the system. Combined with the actual engineering data, the operation effect of ground source heat pump air conditioning system was explored, and the stability of the system was analyzed. The results showed that the total heat and cold load ratio of the whole year was 1.0:1.1. The room temperature of the greenhouse was maintained at 20.0-25.0 ℃, which could meet the growth temperature requirements of high-grade flowers. The water inlet temperature on the source side of the heat pump was maintained at 11.4-23.7 ℃, which met the requirements of relevant specifications. The annual soil temperature of buried pipes increased by 1.3 ℃, and the change of soil temperature was relatively stable. The ground source heat pump system worked well in greenhouse and was stable. It had good economic, energy saving and emission reduction benefits.

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Study on coupling relationship between reserve resources development and ecological environment of cultivated land in Xinjiang

MENG Mei, YANG Yawei, YANG Lei

2020, 32(3): 543-551. DOI: 10.3969/j.issn.1004-1524.2020.03.21

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The reserve resource of cultivated land is an important guarantee for the implementation of the balance of cultivated land occupation and compensation. Xinjiang is located in the inland of northwest China, with a relatively lower level of land development. It is the main district where China's cultivated land reserve resources are concentrated. Its utilization potential is huge. According to the actual situation in Xinjiang, the principal component analysis method and the coupled model were used to explore the coupling degree and influence mechanism between the cultivated land reserve resources and the ecological environment. The results showed that there was a significant spatial difference in the distribution of cultivated land reserve resources in Xinjiang. The ecological environment index of each region was generally low. Most of the cultivated land reserve resources were classified into medium and severe imbalance development types. Changji, Altay and Tacheng regions had better coupling degree. Finally, according to the special geographical types and huge ecological pressures in Xinjiang, it was proposed to evaluate the impact of resource development on local ecology first before development.

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Research progress of influencing factors of livestock wastewater purification by microalgae

LUO Longzao, LIN Xiaoai, YANG Jia, LIU Ye, TIAN Guangming

2020, 32(3): 552-558. DOI: 10.3969/j.issn.1004-1524.2020.03.22

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Recently, the environmental pollution problems caused by the livestock wastewater have become an important bottleneck to hinder both the healthy development of livestock industry and the construction of ecological civilization. The wastewater treatment technology based on the microalgae cultivation can not only solve the environmental pollution in the livestock industry, but also produce high value-added biomass products, which has attracted more and more attention. This paper briefly summarized the removal mechanism of carbon, nitrogen, phosphorus, antibiotics and heavy metals from livestock wastewater by microalgae. The influence factors for the microalgae technology such as microalgae species, pretreatment of livestock wastewater, cultivation system and conditions were expounded emphatically. The future research should be focused on screening more efficient microalgae species to enrich the germplasm bank of microalgae, developing corresponding compound microalgae-bacteria agents for different types of wastewater, and enhancing the development of downstream products of microalgae to realize the transformation from wastewater to biomass products.

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