Acta Agriculturae Zhejiangensis

Effects of nitrogen fertilizer regulation on soil properties of paddy fields and rice yield with full amount returning of straw in Northern Zhejiang

WANG Baojun, CHENG Wangda, CHEN Gui, SHEN Yaqiang, SHEN Meng, YUAN Ye, WANG Lei, ZHANG Hongmei

2020, 32(2): 183-190. DOI: 10.3969/j.issn.1004-1524.2020.02.01

Abstract ( 711 )

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In the present study, a field positioning experiment with randomized block design was successively conducted during 2016-2017. The rice cultivar Jiayouzhongke 6 was used as test material, and four nitrogen application levels (based on N) were set: N0, no N fertilization; N1, 225 kg·hm^-2; N2, 300 kg·hm^-2; N3, 375 kg·hm^-2, to explore the effects of nitrogen fertilizer regulation on soil nutrients, carbon pools, microorganisms and rice yield of paddy fields in Northern Zhejiang. It was shown that the amount of soil organic matter, total nitrogen, available phosphorus, available potassium, carbon pool and microorganism in paddy field increased first and then decreased with the increasing nitrogen application rate. Compared with N0, the contents of total nitrogen, ammonium nitrogen, nitrate nitrogen and easily-oxidized organic carbon of N1 treatment were significantly (P<0.05) increased by 7.14%, 9.86%, 54.74% and 21.70%, respectively; the contents of total nitrogen, available potassium, ammonium nitrogen, nitrate nitrogen, soluble carbon, easily-oxidized organic carbon, microbial carbon, soil bacteria, fungi and actinomycetes of N2 treatment were significantly (P<0.05) increased by 32.59%, 20.16%, 12.12%, 58.34%, 54.45%, 29.57%, 56.49%, 211.16%, 241.61% and 96.10%, respectively; and the total nitrogen, ammonium nitrogen, nitrate nitrogen, easily-oxidized organic carbon, microbial carbon and fungi of N3 treatment were significantly (P<0.05) increased by 28.57%, 16.84%, 61.72%, 27.45%, 49.79% and 231.54%, respectively. The yields of N1, N2 and N3 treatments were significantly (P<0.05) increased by 37.97%-45.47%, 41.85%-53.35% and 38.85%-47.57%, respectively, compared with N0. In conclusion, under the experimental conditions, the application of 300 kg·hm^-2 N combined with full amount returning of straw could improve soil nutrients, soil carbon pool and soil microbial activity, and increase rice yield.

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Difference of light and temperature resources in tray seedling and its effect on seedling quality in rice

SHAO Wenqi, ZHONG Ping, DONG Yubing, SUN Chunmei, JI Li, ZHUANG Chun, CHEN Chuan, ZHANG Ankang

2020, 32(2): 191-199. DOI: 10.3969/j.issn.1004-1524.2020.02.02

Abstract ( 1223 )

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Tray seedling is a kind of open-air seedling raising method. Under different weather conditions, the light intensity and temperature changes of the upper, middle and lower seedling platforms were measured and analyzed, and the differences of temperature and light resources among different seedling platforms were found out. Nanjing 9108 and indica rice Y Liangyou 900 were used as materials to compare the quality differences of seedlings raised by different seedling platforms. The results showed that light intensity of each seedling platform increased first and then decreased, reaching the peak value in the afternoon, and the difference between different seedling platforms was significant at P<0.05. In sunny days, there were significant differences in tray water temperature, root soil temperature and seedling temperature among the three seedling platforms (P<0.05). In the same seedling platform, tray water temperature>root soil temperature>seedling temperature. In cloudy days, there was no significant difference between the middle platform and the lower platform (P>0.05). In Nanjing 9108, the order of seedling forming rate was as follow: middle platform>upper platform>lower platform. Compared with middle platform and lower platform, the height of upper platform seedlings decreased by 19.2% and 19.6%, respectively, and the leaf age increased by 17.6% and 29.0%, the stem base width increased by 14.8% and 24.0%. Leaf SPAD value, dry weight of upper part of ground, number of roots and rooting ability also increased significantly (P<0.05), the K value decreased, and the dry matter accumulation increased. Y Liangyou 900 showed similarly trend as Nanjing 9108. Therefore, temperature and light resources in the upper platform were the best, and the seedlings were the most robust. Quality of seedlings in the middle and lower platform were obviously weakened. In order to reduce the differences of light and temperature resources and improve the consistency of seedling quality, the distance between scaffolds and seedling platforms could be increased appropriately.

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Prokaryotic expression and bioinformatics analysis of PPV7 Cap gene

WANG Xiaopeng, ZHAO Liang, LIU Zimin, BAI Caixia, YANG Kankan, ZHANG Da, SUN Pei, JIANG Shudong, LI Yongdong, WANG Yong

2020, 32(2): 200-209. DOI: 10.3969/j.issn.1004-1524.2020.02.03

Abstract ( 1132 )

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PDF (1946KB) ( 2021 )

The porcine parvovirus 7 (PPV7) Cap gene was amplified by PCR,and the amplified product was cloned into the prokaryotic expression vector pGEX-6P-1.The recombinant plasmid pGEX-6P-1-Cap was identified by sequencing and the recombinant plasmid was transformed into E. coli Rosetta cells and induced by IPTG. The expression products were then identified by SDS-PAGE and Western-blot. At the same time, physical and chemical properties,secondary structure,signal peptide and transmembrane domain of the gene encoded protein were predicted using the bioinformatics softwares. The results showed that the recombinant plasmid pGEX-6P-1-Cap was successfully constructed and the expressed Cap protein was about 78 ku, which was consistent with the expectation. The induced Cap protein could react specifically with GST monoclonal antibody and had good reactivity. Bioinformatics analysis results showed that the Cap protein was stable hydrophilic protein,with 62.90% irregular curl(c)structure in the secondary structure, 11.09%,4.05% and 21.96% of α-helix(h), β-turn(t)and extended(e)chain respectively. Moreover, there was no signal peptide area and transmembrane domain. There were 62 phosphorylation sites,12 B cell antigen epitopes,2 CTL epitopes and 3 Th epitopes. In this study, PPV7 Cap protein was successfully expressed and its biological characteristics were predicted, which could provide a reference for the study of biological function of PPV7 Cap protein.

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Establishment of multiplex PCR assay for major bacterial pathogens in respiratory tract infection in beef cattle

ZHANG Yulong, MA Zhiyu, CUI Yaocheng, TAN Tianyu, YAO Caixia, FAN Lihong, ZUO Zhicai, CAI Dongjie

2020, 32(2): 210-217. DOI: 10.3969/j.issn.1004-1524.2020.02.04

Abstract ( 591 )

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To establish a multiplex PCR assay for simultaneous detection of Klebsiella pneumoniae, Acinetobacter johnsonii, Pasteurella multocida of beef cattle, specific primers were designed based on Khe gene of Klebsiella pneumoniae, Ptk gene of Acinetobacter johnsonii, and Abhd gene of Pasteurella multocida. The reaction conditions and system of the multiplex PCR detection method were established by specificity test, sensitivity test, primer concentration test and annealing temperature test. The results showed that the method can simultaneously amplify Klebsiella pneumoniae, Acinetobacter johnsonii and Pasteurella multocida, and the similarity between bacterial sequences of three kinds of target bacteria amplification and sequencing on GenBank were more than 99%. Meanwhile, the amplification results of the other 10 kinds of beef respiratory pathogens were all negative. The detection limits of the above three pathogen genomic DNA were 69.8×10^-5, 208.9×10^-4, 70.8×10^-3 ng·μL^-1, and the optimal primer concentration ratio was 1:1:1. The optimum annealing temperature was 58 ℃. The method had a strong specificity and high sensitivity, and provided a convenient, rapid and accurate tool for rapid detection and identification of the above three pathogens and diagnosis of clinical bovine respiratory diseases.

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Single nucleotide polymorphism screening and bioinformatics analysis of ATF4 gene in Cherry Valley ducks

TAN Guanghui, QIN Yuanyu, LI Jiezhang, WU Lei, YUE Yong, ZHANG Yiyu

2020, 32(2): 218-225. DOI: 10.3969/j.issn.1004-1524.2020.02.05

Abstract ( 843 )

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To screen out the mutant individuals of activating transcription factor 4 (ATF4) gene in Cherry Valley duck population and breed excellent poultry breeds with good egg shell quality, a DNA mixing pool was constructed with Cherry Valley duck as the test object. The ATF4 gene coding sequence was obtained by common PCR fragmentation amplification and screening. single nucleotide polymorphism sites (SNPs) and bioinformatics analysis were examined. The results showed that the coding region of ATF4 gene of Cherry Valley duck was 1 065 bp in length, encoding 354 amino acids. The protein was unstable and soluble. There were no signal peptide but two N-glycosylation sites. Four SNPs were screened in the CDS region of ATF4 gene, namely A⁹⁰⁹G, G⁶³⁶A, G⁸¹³A and T⁸⁶⁷A, except that T⁸⁶⁷A was a missense mutation. All of them were synonymous mutations. Four SNPs caused changes in the secondary structure and free energy of RNA and gene frequency. The primary components of the secondary and tertiary structures of proteins were α-helix, random curl and extended chain. After T⁸⁶⁷A mutation, the secondary and tertiary structures of proteins had all changed, and the contents of α-helix, extended chain and β-fold had all increased, while the contents of random curl had decreased. In conclusion, ATF4 gene of Cherry Valley duck had abundant polymorphism, which provided a theoretical basis for molecular marker-assisted selection to improve the egg shell quality of Cherry Valley duck.

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Sequencing and analysis of several genes of a virulent duck enteritis virus strain ZJ2016

ZHANG Hongli, HUANG Jing, LIU Xia, WU Yunhong, FENG Xiaoxiao, WU Xuejun, XU Hui

2020, 32(2): 226-233. DOI: 10.3969/j.issn.1004-1524.2020.02.06

Abstract ( 593 )

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In 2016, a duck enteritis virus (DEV) strain ZJ2016 was identified in a duck farm infected with DEV in Zhejiang province. The antigen and virulence-related genes of ZJ2016 strain sequencing analysis was conducted using second-generation sequencer. The nucleic acid and amino acid sequences of the major envelope glycoprotein genes gB, gC, gG, gH, gI, gK, gL, gM, gN and pathogenicity genes LORF11, UL2, UL12, UL41, UL47, US10 were analyzed and compared with those of the published viruses and vaccine strains (VAC strain, clone-03 strain). The results showed that the sequence of ZJ2016 strain envelope glycoprotein associated with vaccine immune protection antigen did not change significantly compared with that of vaccine strain. However, the gene structure and homology of LORF11, UL2, UL12, UL41, UL47 and US10 of ZJ2016 strain were significantly different from the amino acid sequence of vaccine strain, and the homology of other virulent strains in China, such as LH2011, CHv and CV, were higher than that of vaccine strain. The results showed that ZJ2016 had the genotype characteristics of the virulent strain.

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Study on crop growth environment factors in mini-greenhouse in balcony based on internet of things

ZHANG Fang, WANG Peixin, HE Yong, LUO Huifeng, SHOU Guozhong

2020, 32(2): 234-242. DOI: 10.3969/j.issn.1004-1524.2020.01.07

Abstract ( 329 )

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In order to accurately control the growth environment of greenhouse crops, cherry tomato Jinzhu was used as the research object to monitor the environmental factors of mini-greenhouse on the balcony by using a next generation internet of things system, and diurnal variation of crops in various environmental regions was studied. The results showed as follows: (1) Light intensity outside the greenhouse was higher than that in the greenhouse. And there were significant differences existed in light intensity in diverse areas of greenhouse. The light intensity in upper area was stronger than that in lower area. In addition, the light intensity decreased from south to north. (2) Air temperature in the greenhouse was higher than that outside the greenhouse. In the greenhouse, air temperature in the whole greenhouse was similar at seedling stage, air temperature in inner group was higher than that of outer group during the flowering stage and fruiting stage. Additionally, soil temperature in outer group was higher than that in inner group of greenhouse throughout the growth period. (3) Air humidity outside the greenhouse was significantly higher than that in the greenhouse. Also, air humidity in inner group was higher than that in outer group of greenhouse at seedling stage. After entering flowering stage, air humidity in outer group was 4%-6% higher than that in inner group of greenhouse. During the fruiting stage, air humidity was apparently higher. Furthermore, diurnal variation of humidity had small fluctuation. (4) Carbon dioxide concentration in outer group was higher than that in inner group of greenhouse.

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Effect of exogenous calcium on lotus adaptation to salt stress

LIU Yiping, SU Shaowen, ZHANG Lin, LIU Ying, HUANG Zhiyuan, HE Dan, KONG Dezheng

2020, 32(2): 243-252. DOI: 10.3969/j.issn.1004-1524.2020.02.08

Abstract ( 1338 )

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Effects of exogenous calcium on the growth of lotus flower, physiological and biochemical indices and expression of Ca²⁺-related genes under salt stress were studied, which could provide theoretical guidance for further study on molecular mechanism of salt tolerance in lotus and the improvement of salt tolerance of lotus resources by molecular-assisted breeding. Pot experiment was carried out with Fengwu, Fenmeiren, Honglou, Xianjiao, Chunhong and Shuijingfen No. 7, five salt concentration gradients were set, and salt damage index was used to screen salt sensitive varieties and salt-resistant varieties. After treatment with exogenous calcium, effects of calcium on the physiological process of lotus growth and the expression of NnCIPK6 gene under salt stress (100 mmol·L^-1)were studied. The results showed that 150 and 200 mmol·L^-1 NaCl significantly inhibited the growth of lotus. Under salt stress, physiological indices of lotus seedlings showed a trend of rising first and then decreasing with the increase of Ca²⁺ amount, and chlorophyll content of lotus was significantly reduced, and the decline of salt-sensitive variety Fenmeiren was more obvious. Under the treatment of 10,15 mmol·L^-1CaCl₂, antioxidant enzyme superoxide dismutase(SOD) activity and active oxygen scavenging ability were increased, and soluble substance proline accumulation increased,which indicated that the appropriate concentration of exogenous calcium could alleviate lotus salt damage. Under the salt stress treatment, the expression levels of NnCIPK6 genes in Fanmeiren and Jingfenfen No. 7 showed a significant increase trend, and the salt-sensitive variety Fanmeiren showed the most significant change.The variation of the sensitive variety Fenmeiren was the most significant. Treatment with 10 mmol·L^-1 CaCl₂ had a better effect on salt stress, which was beneficial to improve the growth and development of lotus.

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Effect of selenium fertilizer on growth and mineral element accumulation of tomato in substrate culture

LI Le, TIAN Minjiao, GAO Yanming, LI Jianshe

2020, 32(2): 253-261. DOI: 10.3969/j.issn.1004-1524.2020.02.09

Abstract ( 1129 )

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In order to study the biological effects of exogenous selenium on tomatoes in substrate cultivation conditions, sodium selenium was used as the selenium source, and the selenium concentrations were set to 0 (CK), 0.25, 0.50, 1.00, 2.50, 5.00, 10.00, 20.00, 40.00 and 80.00 μmol ·L^-1, respectively. Effects of exogenous selenium on tomato biomass, yield, quality, selenium accumulation, transport and accumulation of other mineral elements in various organs were studied. The results indicated that the above-ground dry matter content of 0.25, 1.00 and 5.00 μmol·L^-1 treatments were higher than other treatments, and below-ground dry matter content of 1.00 and 5.00 μmol·L^-1 treatments were lower than that of 0.50 μmol·L^-1 treatment and higher than that of 0.25 μmol·L^-1 treatment. Contents of vitamin C (V_C) and soluble sugar of 40.00 μmol·L^-1 treatment were the highest, and nitrate content of 40.00 μmol·L^-1 treatment was second to 80.00 μmol·L^-1 treatment. Contents of V_C, soluble sugar and nitrate of 0.25 and 5.00 μmol·L^-1 treatments were second to the 40.00 μmol·L^-1 treatment. Nitrate content of 0.50 μmol·L^-1 treatment increased by 21.52% compared with control group. Except 20.00 μmol·L^-1 treatment, sugar-acid ratio of other treatments were higher than that of CK. Yield of 5.00 μmol·L^-1 treatment was significantly higher than those of other treatments. However, the yields became lower than CK when the concentration of Se was higher than 10.00 μmol·L^-1. Selenium application promoted the accumulation and transport of selenium in tomato organs. Selenium accumulation in fruits increased exponentially with the increase of exogenous selenium concentration. Leaves of tomato exhibited the strongest capacity of selenium transport while fruits had the weakest. Contents of N and Ca in tomato of 5.00 μmol·L^-1 treatment were significantly higher than those of other treatments, which increased by 10.75% and 295.20% respectively compared with CK. Content of P in tomato of 1.00、2.50、5.00 and 10.00 μmol·L^-1 treatments were significantly higher than those of other treatments. Selenium application promoted the absorption of Mg (except 10.00 μmol·L^-1 treatment) and iron (except 20.00 μmol·L^-1 treatment). Appropriate selenium concentration could increase plant dry matter content, improve quality, increase yield and promote mineral element absorption. In the production of selenium-enriched tomatoes, we suggested to apply the concentration of 5.00 μmol·L^-1 selenium to increase the yield and quality.

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Identification and expression analysis of polyamine oxidase (PAO) gene family in apple

QIN Ling, ZHANG Xin, RONG Chunxiao, MO Chuanyuan, FAN Lu, YAN Jie, MENG Ying, ZHANG Manrang

2020, 32(2): 262-273. DOI: 10.3969/j.issn.1004-1524.2020.02.10

Abstract ( 1017 )

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From the genomic database of Golden Delicious, eight family genes encoding polyamine oxidase (PAO) (named as MdPAO1-8) were identified in apples using the BLAST website for physicochemical properties, phylogenetic, protein structure, analysis of gene structure and promoter elements. The results showed that the molecular weight of MdPAO protein ranged from 54.053 to 64.813 ku, and the isoelectric point ranged from 5.16 to 6.02. According to the phylogenetic tree analysis, MdPAO is divided into three subfamilies (Ⅰ,Ⅲ, Ⅳ), and members of the same subfamily share similar protein structure, gene structure and protein conserved motif distribution. The expression of 8 MdPAO genes in different tissues and organs was significantly different using the GEO database. The expression of 8 MdPAO genes in different tissues was determined by real-time quantitative PCR using Nagafu No.2. The results showed that MdPAO3, MdPAO4, MdPAO5/6 and MdPAO8 were highly espressed in flowers. MdPAO1/2 and MdPAO7 had higher expression levels in stems and fruits. Exogenous spermidine treatment showed that the transcriptional level of MdPAO significantly increased except MdPAO3, indicating that MdPAO plays an important role in the PA metabolic pathway.

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Image recognition of millet leaf disease based on CS-SVM

ZHANG Hongtao, LI Yijia, TAN Lian, XU Shuaitao

2020, 32(2): 274-282. DOI: 10.3969/j.issn.1004-1524.2020.02.11

Abstract ( 653 )

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The method of image recognition was used to distinguish the common diseases of millet leaves and provide scientific basis for the development of reasonable disease control measures.The original images of four kinds of leaf diseases including millet blast disease, white hair disease, red leaf disease and rust diseasewere were collected.The maximum variance method based on super green characteristics was used to segment the leaf diseases of millet. A total of 19 features of millet leaf disease were extracted, including color, shape and texture. The experiment adopted ant colony optimization algorithm to select 8 features. Cuckoo search (CS) was used to optimize the penalty factor c and radial kernel function g of SVM, and SVM was used to automatically identify millet leaf diseases. When c=80.2662 and g=1.8467, the average identification rate of millet leaf disease and leaves was reached 99%. These results showed that the method of image recognition based on support vector machine was feasible for the classification of four millet leaf diseases.

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Effects of nano-silver and exotic arbuscular mycorrhizal fungi on chlorophyll fluorescence kinetics of sweet sorghum

SHI Zhaoyong, LI Ke, WANG Fayuan, WANG Xugang, XU Xiaofeng

2020, 32(2): 283-290. DOI: 10.3969/j.issn.1004-1524.2020.02.12

Abstract ( 1075 )

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Nanosilver is one of the most widely used artificial nanomaterials and has certain biological toxicity. Arbuscular mycorrhizal fungi (AMF) can establish a mutualistic symbiotic relationship with 80% of plants on land, and can improve the plant’s absorption of mineral nutrients, promote photosynthesis and improve stress resistance. However, the combining effects of nanosilver and AMF on the chlorophyll fluorescence properties of plants are still not clear. In this experiment, the energy plant sweet sorghum was selected as the tested plant, and the greenhouse pot experiment was conducted in an unsterilized soil to study the effect of inoculation of exogenous AMF on the chlorophyll fluorescence-inducing kinetics of sweet sorghum under different nano-silver levels. As a result, it was found that nano-silver has certain toxicity to exogenous AMF and inhibited mycorrhizal colonization of plant roots. With the increase of nano-silver concentration, the donor side of PSⅡ was injured with the destroyed structure, and the maximum photochemical efficiency (F_v/F_m) and potential activity of PSII (F_v/F_o) were inhibited, and the light efficiency of PSⅡ was reduced. However, the inoculation of exogenous AMF could reduce the damage to the structure of PSⅡ by increasing the heat dissipation, which protected the plant. It was confirmed that the toxicity of nano-silver to sweet sorghum could be alleviated by inoculating AMF under the condition of non-sterilization, but the effect was related to the dosage of nano-silver.

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Preparation of terbium doped carbon dots and their antibacterial capacity against Escherichia coli

LI Hong, TIAN Hao, YU Lijuan, GAO Zhe, YANG Yaling, LI Wanyi

2020, 32(2): 291-298. DOI: 10.3969/j.issn.1004-1524.2020.02.13

Abstract ( 590 )

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In this study, carbon dots were synthesized by one-step hydrothermal method using potato as raw material, and Tb-doped carbon dots (Tb-CDs) were prepared by surface modification of carbon dots with rare metal terbium. The Tb-CDs were characterized by scanning transmission electron microscope, ultraviolet spectrum, infrared spectrum, and fluorescence spectrum, and the antibacterial effect of the Tb-CDs against Escherichia coli was explored, along with the feasibility of fluorescence label of E. coli by Tb-CDs. It was showed that the prepared Tb-CDs had small uniform particle size, good dispersibility and strong fluorescence. Due to the rich carboxyl groups and hydroxyl groups in the surface, the Tb-CDs had good water solubility. The Tb-CDs had good antibacterial activity against E. coli under photocatalytic conditions. When the concentration of Tb-CDs was 0.6 mg·mL^-1, the antibacteria rate against E. coli could reach 100% under 60 min of irradiation. Besides, the prepared Tb-CDs could effectively label E. coli with fluorescence.

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Quality risk assessment and management of manure based organic fertilizers in Zhejiang

NI Zhihua, SUN Wanchun, LIN Hui, ZHONG Hang, ZHU Weifeng, LU Ruohui, MA Junwei

2020, 32(2): 299-307. DOI: 10.3969/j.issn.1004-1524.2020.02.14

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In this work, more than 1 000 samples, which included commercial organic fertilizer, farmyard manure compost and raw manure, were collected from Zhejiang Provinces over years. The basic physiochemical properties as well as the contents of nutrients, heavy metals, antibiotics and mineral salts were determined to investigate the quality status and potential risks of commercial manure based organic fertilizers in Zhejiang. It was shown that the average qualification rate of the commercial organic fertilizers collected from 2014 to 2016 was 72.5% according to the national standard of organic fertilizer NY 525—2012 in China, which showed an increasing trend year by year. Heavy metals contents exceeding the standard limit was the main reason for the disqualification of these organic fertilizers. Heavy metals, including As, Cd, Pb, Cr and Hg exceeding the standard limit were found in the samples of this work. The average over standard rate of heavy metals in pig manure based organic fertilizers was higher than that of other organic fertilizers. The heavy metal pollution in the commercial organic fertilizers mainly sourced from livestock manure. Tetracyclines, fluoroquinolones and sulfanilamides antibiotics were also frequently detected in the commercial organic fertilizer samples, and the highest concentration reached 71.0 mg·kg^-1. The salt content in the manure of livestock and poultry could reach 26.1 g·kg^-1. The reasons for the risk of the application of manure based organic fertilizers included the following aspects: the current organic fertilizer standard could not satisfy the actual situation; the current organic fertilizer standard could not be strictly implemented; feed additives failed to meet the requirement of the standard; etc. The strategies for the risk control and safety utilization of manure based organic fertilizers was further discussed, which included the scientific and standardized use of feed additives and the improved monitor management of the organic fertilizer production process and the product quality.

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Effects of nitrogen management on soil microbial community structure in paddy fields

LI Meilin, CHEN Yutiao, HONG Xiaofu, QIAO Yuying, WANG Qingxia, CHEN Xijing, SHEN Alin, YU Man

2020, 32(2): 308-316. DOI: 10.3969/j.issn.1004-1524.2020.02.15

Abstract ( 587 )

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The microbial communities in four nitrogen fertilizer management modes, namely, zero-nitrogen treatment (CK), farmers’ conventional cultivation pattern (FP), modified farmers’ conventional cultivation pattern 1 (OPT1), and modified farmers’ conventional cultivation pattern 2 (OPT2), were studied by phospholipid fatty acid (PLFA) and Biolog-Eco methods to provide references for the rational utilization of nitrogen fertilizer in paddy fields. It was shown that the microbial metabolic activity and carbon source utilization ability increased in OPT1, while reduced in FP and OPT2 compared to CK. The highest amount of total biomass appeared in OPT1 with 42.11 nmol·g^-1, and was followed by OPT2 with 40.16 nmol·g^-1, which were both higher than that in CK (34.19 nmol·g^-1), but the amount of total biomass in FP was 34.16 nmol·g^-1, which was lower than that in CK. Moreover, the diversity of microbial community in OPT1 was more complex, and F/B value was the highest among the 4 treatments. In summary, the OPT1 treatment was more conducive to the stability of ecological environment in soil.

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Comparative analysis of water quality factors and phytoplankton communities in two different aquaculture models

ZHANG Leiming, YUAN Julin, NI Meng, LIU Mei, GUO Aihuan, LIAN Qingping, WANG Haiyang, GU Zhimin

2020, 32(2): 317-326. DOI: 10.3969/j.issn.1004-1524.2020.02.16

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In order to reveal the biodiversity of phytoplankton in IPA model and traditional aquaculture ponds, water quality and phytoplankton communities were monitored. The results showed that 64 phytoplankton species were identified in the IPA model, and 49 phytoplankton species were identified in the traditional aquaculture pond, and the average density and biomass of phytoplankton in the IPA model were 113.55×10⁶ ind·L^-1 and 52.79 mg·L^-1, which were higher than the 78.37×10⁶ ind·L^-1 and 23.22 mg·L^-1 in the traditional aquaculture pond. The mean values of Shannon-Wiener diversity index (H') and Margalef diversity index (D) in IPA mode were 3.80 and 2.25 respectively, which were higher than those in the traditional aquaculture pond. Canonical correspondence analysis (CCA) showed that water temperature, potassium permanganate index, total nitrogen, total phosphorus and total organic carbon were the main driving factors affecting phytoplankton in IPA mode; total nitrogen, total phosphorus, total ammonia nitrogen and nitrite nitrogen were the main driving factors affecting phytoplankton in the traditional aquaculture pond.

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Optimization of fermentation techniques on yield of exopolysaccharide produced by Lactobacillus pentosae YY112

WANG Mingzhe, YANG Ying, TANG Weimin, LIU Zhe, SUN Peilong, LU Shengmin

2020, 32(2): 327-336. DOI: 10.3969/j.issn.1004-1524.2020.02.17

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In order to improve the yield of exopolysaccharide produced by Lactobacillus pentosae YY112, the nutritional conditions and fermentation technology of the strain were optimized by single factor test, orthogonal test and Box-Behnken response surface design. The results showed that: within the scope of this study, MRS medium was the appropriate basic one, using 3% (m/V) sucrose was the appropriate carbon source, 1% (m/V) soybean peptone was the appropriate nitrogen source and 2% (m/V) yeast powder could increase polysaccharide yield of the strain. The initial pH value of the medium was 6.0, and the inoculation amount of the strain was 4% (V/V). The optimum fermentation temperature was 29.5 ℃, and the best fermentation time was 24.5 h. Under the optimized culture conditions, the yield of exopolysaccharide reached (380.97±0.45) mg·L^-1, which was basically consistent with the predicted value of response surface analysis, an increase of 46.52% compared with that before optimization.

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Transcriptome analysis of fruiting bodies of Lactarius deliciosus at two developmental stages

SONG Zhiqiang, DING Xiang, TANG Xian, ZHU Miao, HOU Yiling

2020, 32(2): 337-347. DOI: 10.3969/j.issn.1004-1524.2020.02.18

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In this study, the fruiting bodies of Lactarius deliciosus were sequenced by de novo sequencing and bioinformatics analysis. The differences of gene expression between young mushroom (LDG-1) and mature mushroom (LDG-2) during the growth and development of fruiting bodies of Lactarius deliciosus were explored, and the main genes and metabolic pathways related to the growth and development of Lactarius deliciosus were also studied. The sequencing results showed that a total of 7.44G (LDG-1) and 7.21G (LDG-2) clean reads were obtained. The results of KOG functional annotation showed that Lactarius deliciosus had comprehensive and complex gene functional categories at LDG-1 and LDG-2. The results of GO enrichment indicated that there were some differences in the bio-metabolic functions of Lactarius deliciosus at different growth stages (LDG-1 and LDG-2). The analysis of gene expression level and cluster showed that the main high-expression genes were ATPase, multifunctional chaperone family genes, etc., which played an important role in energy metabolism and cell cycle regulation. Analysis of differentially expressed genes showed that compared with LDG-1, there were 16 789 differentially expressed genes in LDG-2, in which 7 635 genes were up-regulated and 9 154 genes were down-regulated. KEGG pathway enrichment of differential expression gene results showed that oxidative phosphorylation was the key pathway of energy metabolism during the growth and development of Lactarius deliciosus. Further analysis showed that MAPK signaling pathway was the key signaling pathway affecting the development of fruiting body of Lactarius deliciosus, which plays an important role in promoting sexual reproduction and regulating polar growth of mycelium of fruiting body of Lactarius deliciosus.

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Optimization of structural parameters of drum type tea re-dryer

LI Weining, BAI Xuanbing, LI Bing

2020, 32(2): 348-358. DOI: 10.3969/j.issn.1004-1524.2020.02.19

Abstract ( 558 )

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In order to solve the problems that the broken tea rate is too high and the quality of tea is affected by the drum type tea re-dryer during the roasting process, based on the theory of discrete element method, the three-dimensional geometric model of the drum type tea re-dryer was established by SolidWorks 2014, and the numerical simulation of the baking process was carried out by EDEM 2018. The movement of tea particles under different rotational speed and inclination angle of drum was studied, and the influence of rotational speed and inclination angle on the baking effect of tea was analyzed. The Lu’an Guapian was used as test material, the quadratic orthogonal rotation combination test was adopted, and the baking test of drum type tea re-dryer was carried out. The results showed that the structure parameters affecting the baking effect of the drum type tea re-dryer were rotational speed and the inclination angle of the drum. The parameters were optimized as rotational speed of the drum was 33 r·min^-1, and the inclination angle of the drum was 3.7 °. Under this condition, the broken tea rate was 6.7%, and the sensory score was 90.6, indicating the produced tea had good baking effect.

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Hyperspectral retrieval modelling for chlorophyll contents of japonica-rice leaves based on machine learning

WANG Nianyi, YU Fenghua, XU Tongyu, DU Wen, GUO Zhonghui, ZHANG Guosheng

2020, 32(2): 359-366. DOI: 10.3969/j.issn.1004-1524.2020.02.20

Abstract ( 753 )

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Chlorophyll content is an important indicator to characterize the growth status of japonica-rice. Hyperspectral remote sensing technology can obtain the chlorophyll content of japonica-rice leaves speedily without loss. This study used the hyperspectral data of japonica-rice leaf blades in Liaozhong Rice Experimental Station of Shenyang Agricultural University from 2015 to 2017, and used three methods including main component analysis method (PCA),typical correlation analysis method (CCA),nuclear typical association analysis method (KCCA) to reduce dimensions for japonica-rice blade hyperspectral information, and selected the better spectral parameters as the input variable of chlorophyll content inversion model. We used support vector machine regression (SVR), neural network (NN), random forest (RF), least-multiplied (PLSR) four machine learning algorithms to establish an inversion model of chlorophyll content japonica-rice leaves. The results showed that KCCA’s lower-dimensional method had better effect on the hyperspectral reduction of japonica rice leaves than that of PCA and CCA. The model of japonica-rice leaf chlorophyll content inversion model established by KCCA-SVR method had the coefficient of R² =0.801, RMSE=1.610, and the japonica-rice chlorophyll content inversion model had the highest accuracy. The model’s good predictive ability provided data support and model reference for inverse research and nutrient diagnosis of chlorophyll content in japonica-rice leaves.

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Analysis on influencing factors of farmers’ land circulation willingness from perspective of behavioral economics: a case study of Zhejiang farmers

XU Lianjun

2020, 32(2): 367-372. DOI: 10.3969/j.issn.1004-1524.2020.01.21

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Based on 282 households’ questionnaire in Ningbo City and Lishui City of Zhejiang Province, a theoretical analysis of farmers’ willingness to land circulation was conducted from the perspective of behavioral economics. It was determined that the three factors affecting farmers’ land circulation willingness consisted of basic situation of farmers, land circulation environment, and the expected benefit from land circulation. An empirical study was conducted by using Logistic model. It was shown that the age and gender, annual income, employment status of farmers, the expected reasonable rent, and the land circulation mode had significant impact on farmers’ land circulation willingness.

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Research advances of zinc finger protein transcription factor Di19 in regulation of soybean responding to drought stress

ZHANG Guwen, SHEN Li, ZHENG Huazhang, LIU Na, FENG Zhijuan, GONG Yaming

2020, 32(2): 373-382. DOI: 10.3969/j.issn.1004-1524.2020.02.22

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Drought is one of the most serious natural disasters faced by human beings, and also the most important environmental factor affecting crop production. Zinc finger protein refers to a class of proteins containing zinc ion and finger-like domains. It is the most common type of transcription factor found in plants and plays the most important role in plant drought response. Di19 is a newly discovered small zinc finger protein containing two C2H2 type zinc finger domains, which is induced by drought and high salt, and plays an active role in plant drought response. Soybean roots are underdeveloped, require more water, sensitive to drought, and water deficit is the most important environmental factor that restricts their yield and quality. In this paper, the research status of soybean drought tolerance, the role of zinc finger protein and its newest member Di19 in drought tolerance response of soybean were reviewed in order to provide reference for drought tolerance improvement of soybean.

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