2020 Vol. 19 No. 9 Previous Issue    Next Issue

    Crop Science
    Plant Protection
    Animal Science · Veterinary Medicine
    Agro-ecosystem & Environment
    Food Science

      Cover illustration

    For Selected: Toggle Thumbnails
    The untold story between enhancers and skeletal muscle development
    ZHANG Yong-sheng, LU Dan, LIU Yu-wen, YI Guo-qiang, TANG Zhong-lin
    2020, 19(9): 2137-2149.  DOI: 10.1016/S2095-3119(20)63235-X
    Abstract ( )   PDF in ScienceDirect  
    Currently, enhancers have key transcriptional regulatory roles in muscle development.  Skeletal muscle formation involves various molecules, and in animals, enhancers are one of the main types of transcriptional regulatory regions that are of great importance to regulate myogenic gene expression.  In muscle development, enhancers can generate enhancer RNAs (eRNAs) that are involved in the regulation of gene transcription.  The regulation of gene expression by eRNAs offers great potential in improving animal production traits.  Herein we comprehensively review the roles of enhancers in muscle formation and its potential function in skeletal muscle development.  This review will describe the future application of enhancers in skeletal muscle development and discuss the prospects that enhancer studies offer for agriculture, biotechnology, and animal breeding.
    Crop Science
    Identification and gene mapping of the starch accumulation and premature leaf senescence mutant ossac4 in rice
    ZHU Mao-di, CHEN Xin-long, ZHU Xiao-yan, XING Ya-di, DU Dan, ZHANG Ying-ying, LIU Ming-ming, ZHANG Qiu-li, LU Xin, PENG Sha-sha, HE Guang-hua, ZHANG Tian-quan
    2020, 19(9): 2150-2164.  DOI: 10.1016/S2095-3119(19)62814-5
    Abstract ( )   PDF in ScienceDirect  
    The rice mutant ossac4 (starch accumulating 4) was raised from seeds of the rice (Oryza sativa L.) indica maintainer line Xinong 1B treated with ethyl methanesulfonate.  The distal and medial portions of the second leaf displayed premature senescence in the ossac4 mutant at the four-leaf stage.  Physiological and biochemical analysis, and cytological examination revealed that the ossac4 mutant exhibited the premature leaf senescence phenotype.  At the four-leaf stage, the leaves of the ossac4 mutant exhibited significantly increased contents of starch compared with those of the wild type (WT).  Quantitative real-time PCR analysis showed that the expression levels of photosynthesis-associated genes were down-regulated and the expression levels of glucose metabolism-associated genes were abnormal.  Genetic analysis indicated that the ossac4 mutation was controlled by a single recessive nuclear gene.  The OsSAC4 gene was localized to a 322.7-kb interval between the simple-sequence repeat marker XYH11-90 and the single-nucleotide polymorphism marker SNP5300 on chromosome 11.  The target interval contained 20 annotated genes.  The present results demonstrated that ossac4 represents a novel starch accumulation and premature leaf senescence mutant, and lays the foundation for cloning and functional analysis of OsSAC4.
    Functional polymorphism among members of abscisic acid receptor family (ZmPYL) in maize
    LU Feng-zhong, YU Hao-qiang, LI Si, LI Wan-chen, ZHANG Zhi-yong, FU Feng-ling
    2020, 19(9): 2165-2176.  DOI: 10.1016/S2095-3119(19)62802-9
    Abstract ( )   PDF in ScienceDirect  
    Pyrabactin resistance 1-like proteins (PYLs) are direct receptors of abscisic acid (ABA).  For the redundant and polymorphic functions, some members of the PYL family interact with components of other signaling pathways.  Here, 253 positive colonies from a maize cDNA library were screened as interacting proteins with the members of ZmPYL family.  After sequencing and function annotation, 17 of 28 interaction combinations were verified by yeast two-hybrid (Y2H).  The germination potential, taproot length and proline content of a quartet mutant of Arabidopsis PYL genes were significantly deceased comparing to the wild type (WT) under alkaline stress (pH 8.5) and 100 μmol L–1 methyl jasmonate (MeJA) induction.  The malondialdehyde (MDA) content was significantly increased.  After germinating in darkness, the characteristics of dark morphogenesis of the quartet mutant seedlings were more obvious than those of the WT.  The differential expression of the related genes of photomorphogenesis in the mutant was much more than that in the WT.  Three light and two JA responsive cis-affecting elements were identified during the promoter sequences of the AtPYL1 and AtPYL2 genes.  These results suggested that functional polymorphism has evolved among the members of ZmPYL family.  In response to developmental and environmental stimuli, they not only function as direct ABA receptors but also interact with components of other signaling pathways mediated JA, brassinosteroid (BR), auxin, etc., and even directly regulate downstream stress-related proteins.  These signaling pathways can interact at various crosstalk points and different levels of gene expression within a sophisticated network.
    Evaluation of drought tolerance in ZmVPP1-overexpressing transgenic inbred maize lines and their hybrids
    JIA Teng-jiao, LI Jing-jing, WANG Li-feng, CAO Yan-yong, MA Juan, WANG Hao, ZHANG Deng-feng, LI Hui-yong
    2020, 19(9): 2177-2187.  DOI: 10.1016/S2095-3119(19)62828-5
    Abstract ( )   PDF in ScienceDirect  
    The vacuolar proton-pumping pyrophosphatase gene (VPP) is often used to enhance plant drought tolerance via genetic engineering.  In this study, the drought tolerance of four transgenic inbred maize lines overexpressing ZmVPP1 (PH4CV-T, PH6WC-T, Chang7-2-T, and Zheng58-T) and their transgenic hybrids was evaluated at various stages.  Under normal and drought conditions, the height and fresh weight were greater for the four transgenic inbred maize lines than for the wild-type (WT) controls at the germination and seedling stages.  Additionally, the transgenic plants exhibited enhanced photosynthetic efficiency at the seedling stage.  In irrigated and non-irrigated fields, the four transgenic lines grew normally, but with increased ear weight and yield compared with the WT plants.  Moreover, the ear weight and yield of the transgenic hybrids resulting from the PH4CV-T×PH6WC-W and Chang7-2-T×Zheng58-W crosses increased in the non-irrigated field.  Our results demonstrated that the growth and drought tolerance of four transgenic inbred maize lines with improved photosynthesis were enhanced by the overexpression of ZmVPP1.  Moreover, the Chang7-2 and PH4CV transgenic lines may be useful for future genetic improvements of maize hybrids to increase drought tolerance.
    Quantifying key model parameters for wheat leaf gas exchange under different environmental conditions
    ZHAO Fu-nian, ZHOU Shuang-xi, WANG Run-yuan, ZHANG Kai, WANG He-ling, YU Qiang
    2020, 19(9): 2188-2205.  DOI: 10.1016/S2095-3119(19)62796-6
    Abstract ( )   PDF in ScienceDirect  
    The maximum carboxylation rate of Rubisco (Vcmax) and maximum rate of electron transport (Jmax) for the biochemical photosynthetic model, and the slope (m) of the Ball-Berry stomatal conductance model influence gas exchange estimates between plants and the atmosphere.  However, there is limited data on the variation of these three parameters for annual crops under different environmental conditions.  Gas exchange measurements of light and CO2 response curves on leaves of winter wheat and spring wheat were conducted during the wheat growing season under different environmental conditions.  There were no significant differences for Vcmax, Jmax or m between the two wheat types.  The seasonal variation of Vcmax, Jmax and m for spring wheat was not pronounced, except a rapid decrease for Vcmax and Jmax at the end of growing season.  Vcmax and Jmax show no significant changes during soil drying until light saturated stomatal conductance (gssat) was smaller than 0.15 mol m–2 s–1.  Meanwhile, there was a significant difference in m during two different water supply conditions separated  by gssat at 0.15 mol m–2 s–1.  Furthermore, the misestimation of Vcmax and Jmax had great impacts on the net photosynthesis rate simulation, whereas, the underestimation of m resulted in underestimated stomatal conductance and transpiration rate and an overestimation of water use efficiency.  Our work demonstrates that the impact of severe environmental conditions and specific growing stages on the variation of key model parameters should be taken into account for simulating gas exchange between plants and the atmosphere.  Meanwhile, modification of m and Vcmax (and Jmax) successively based on water stress severity might be adopted to simulate gas exchange between plants and the atmosphere under drought.
    Calibration and validation of SiBcrop Model for simulating LAI and surface heat fluxes of winter wheat in the North China Plain
    CHEN Ying, LIU Feng-shan, TAO Fu-lu, GE Quan-sheng, JIANG Min, WANG Meng, ZHAO Feng-hua
    2020, 19(9): 2206-2215.  DOI: 10.1016/S2095-3119(20)63178-1
    Abstract ( )   PDF in ScienceDirect  
    The accurate representation of surface characteristic is an important process to simulate surface energy and water flux in land-atmosphere boundary layer.  Coupling crop growth model in land surface model is an important method to accurately express the surface characteristics and biophysical processes in farmland.  However, the previous work mainly focused on crops in single cropping system, less work was done in multiple cropping systems.  This article described how to modify the sub-model in the SiBcrop to realize the accuracy simulation of leaf area index (LAI), latent heat flux (LHF) and sensible heat flux (SHF) of winter wheat growing in double cropping system in the North China Plain (NCP).  The seeding date of winter wheat was firstly reset according to the actual growing environment in the NCP.  The phenophases, LAI and heat fluxes in 2004–2006 at Yucheng Station, Shandong Province, China were used to calibrate the model.  The validations of LHF and SHF were based on the measurements at Yucheng Station in 2007–2010 and at Guantao Station, Hebei Province, China in 2009–2010.  The results showed the significant accuracy of the calibrated model in simulating these variables, with which the R2, root mean square error (RMSE) and index of agreement (IOA) between simulated and observed variables were obviously improved than the original code.  The sensitivities of the above variables to seeding date were also displayed to further explain the simulation error of the SiBcrop Model.  Overall, the research results indicated the modified SiBcrop Model can be applied to simulate the growth and flux process of winter wheat growing in double cropping system in the NCP. 
    Effects of post-silking water deficit on the leaf photosynthesis and senescence of waxy maize
    YE Yu-xiu, WEN Zhang-rong, YANG Huan, LU Wei-ping, LU Da-lei
    2020, 19(9): 2216-2228.  DOI: 10.1016/S2095-3119(20)63158-6
    Abstract ( )   PDF in ScienceDirect  
    Waxy maize is widely cultivated under rainfed conditions and frequently suffers water shortage during the late growth stage.  In this study, a pot trial was conducted to examine the effects of post-silking drought on leaf photosynthesis and senescence and its influence on grain yield.  Two waxy maize hybrids, Suyunuo 5 (SYN5) and Yunuo 7 (YN7), were grown under the control and drought (soil moisture content was 70–80% and 50–60%, respectively) conditions after silking in 2016 and 2017.  The decrease in yield was 11.1 and 15.4% for YN7 and SYN5, respectively, owing to the decreased grain weight and number.  Post-silking dry matter accumulation was reduced by 27.2% in YN7 and 26.3% in SYN5.  The contribution rate of pre-silking photoassimilates transferred to grain yield was increased by 15.6% in YN7 and 10.2% in SYN5, respectively.  Post-silking drought increased the malondialdehyde content, but decreased the contents of water, soluble protein, chlorophyll, and carotenoid in the leaves.  The weakened activities of enzymes involved in photosynthesis (ribulose-1,5-bisphosphate carboxylase and phosphoenolpyruvate carboxylase) and antioxidant system (catalase, superoxide dismutase and peroxidase) reduced the photosynthetic rate (Pn) and accelerated leaf senescence.  The correlation results indicated that reduced Pn and catalase activity and increased malondialdehyde content under drought conditions induced the decrease of post-silking photoassimilates deposition, ultimately resulted in the grain yield loss.
    Utilizing comprehensive decision analysis methods to determine an optimal planting pattern and nitrogen application for winter oilseed rape
    DU Ya-dan, CUI Bing-jing, ZHANG Qian, SUN Jun, WANG Zhen, NIU Wen-quan
    2020, 19(9): 2229-2238.  DOI: 10.1016/S2095-3119(19)62870-4
    Abstract ( )   PDF in ScienceDirect  
    Oilseed rape is one of the most important oil crops globally.  Attaining the appropriate cultivation method (planting pattern and nitrogen level) is necessary to achieve high yield, quality and resource utilization efficiency.  However, the optimal method for oilseed rape varies across countries and regions.  The objective of the present study was to determine an appropriate cultivation method, including planting pattern and nitrogen application, for winter oilseed rape in northwestern China.  Two planting patterns: ridge film mulching and furrow planting (RFMF) and flat planting (FP), and six nitrogen (N) amounts: 0 (N0), 60 (N60), 120 (N120), 180 (N180), 240 (N240), and 300 (N300) kg N ha–1 were applied across three growing seasons (2014–2017).  Three comprehensive decision analysis methods: principal component analysis, grey correlation degree analysis and the combined entropy weight and dynamic technique for order preference by similarity to ideal solution method were used to evaluate the growth and physiological indicators, nutrient uptake, yield, quality, evapotranspiration, and water use efficiency of winter oilseed rape.  Planting pattern, nitrogen amount and their interaction significantly affected the indicators aforementioned.  The RFMF pattern significantly increased all indicators over the FP pattern.  Application of N also markedly increased all the indicators except for seed oil content, but the yield, oil production and water use efficiency were decreased when N fertilizer exceeded 180 kg N ha–1 under FP and 240 kg N ha–1 under RFFM.  The evaluation results of the three comprehensive decision analysis methods indicated that RFMF planting pattern with 240 kg N ha–1 is an appropriate cultivation method for winter oilseed rape in northwestern China.  These findings are of vital significance to maximize yield, optimize quality and improve resource use efficiencies of winter oilseed rape.
    Overexpression of StCYS1 gene enhances tolerance to salt stress in the transgenic potato (Solanum tuberosum L.) plant
    LIU Min-min, LI Ya-lun, LI Guang-cun, DONG Tian-tian, LIU Shi-yang, LIU Pei, WANG Qing-guo
    2020, 19(9): 2239-2246.  DOI: 10.1016/S2095-3119(20)63262-2
    Abstract ( )   PDF in ScienceDirect  
    Salt stress seriously restricts the growth and yield of potatoes.  Plant cystatins are vital players in biotic stress and development, however, their roles in salt stress resistance remain elusive.  Here, we report that StCYS1 positively regulates salt tolerance in potato plants.  An in vitro biochemical test demonstrated that StCYS1 is a bona fide cystatin.  Overexpression of StCYS1 in both Escherichia coli and potato plants significantly increased their resistance to high salinity.  Further analysis revealed that the transgenic plants accumulated more proline and chlorophyll under salt stress conditions.  Moreover, the transgenic plants displayed higher H2O2 scavenging capability and cell membrane integrity compared with wild-type potato.  These results demonstrate that StCYS1 is closely correlated with salt stress and its overaccumulation can substantially enhance salt stress resistance.
    Endogenous phytohormones and the expression of flowering genes synergistically induce flowering in loquat
    CHI Zhuo-heng, WANG Yong-qing, DENG Qun-xian, ZHANG Hui, PAN Cui-ping, YANG Zhi-wu
    2020, 19(9): 2247-2256.  DOI: 10.1016/S2095-3119(20)63246-4
    Abstract ( )   PDF in ScienceDirect  
    Flowering is an important process for the reproduction of higher plants.  Up to this point, the studies on flowering have mostly focused on the model plant Arabidopsis thaliana, and the flowering mechanism of fruit trees remains mostly unknown.  The diversity of the flowering time of loquat (Eriobotrya japonica Lindl.) makes it an ideal material to study the regulation of flowering.  In this study, we first observed the inflorescence bud differentiation in two varieties of loquat that had different blooming times (cv. Dawuxing (E. japonica), that blooms in the fall and cv. Chunhua (E. japonica×Eriobotrya bengalensis Hook. f.) that blooms in the spring) and found that the starting time of inflorescence bud differentiation and the speed of inflorescence development were responsible for the difference in blooming times.  The determination of endogenous phytohormones by high performance liquid chromatography (HPLC) indicated that abscisic acid (ABA), zeatin (ZT), and gibberellin (GA3) promoted flowering in loquat, while indole-3-acetic acid (IAA) was mainly involved in inflorescence bud differentiation in Chunhua.  A transcription level analysis illustrated that multiple flowering-related genes could respond to different signals, integrate to the TFL1, AP1 and FT genes, and then synergistically regulate flowering in loquat.  Thus, this study provides a new insight into flowering regulation mechanisms in loquat.
    Plant Protection
    Diversity in metagenomic sequences reveals new pathogenic fungus associated with smut in Job’s tears
    LI Xiang-dong, SHI Ming, PAN Hong, LU Xiu-juan, WEI Xin-yuan, LU Ping, LIAN Qi-xian, FU Yu-hua
    2020, 19(9): 2257-2264.  DOI: 10.1016/S2095-3119(20)63164-1
    Abstract ( )   PDF in ScienceDirect  
    Smut is a serious disease in Job’s tears, also known as adlay, and contributes to the reduction of crop yield in agricultural fields.  In this study, the key pathogenic fungi in adlay smut disease were first identified by internal transcribed spacer region (ITS) high-throughput sequencing and then used to elucidate the composition and diversity of the fungal community in adlay smut.  Results indicate that an abundance of operational taxonomic units (OTUs) were detected in the infected involucres of flowering plants and the OTUs were classified to nine phyla, 20 classes, 45 orders, 90 families and 119 genera.  A total of 4 986 OTUs clustered together, sharing six core OTUs in all samples, while 145 OTUs were shared among four geographical groups.  The Shannon and Simpson indices ranged from 0.137–1.629 and 0.357–0.970, respectively.  Community diversity ranked as Anshun (AS)>Qinglong (QL)>Xingren (XR)>Xingyi (XY) among the four geographical groups by Shannon and Simpson indices, exhibiting complex community diversities among accessions and geographical groups.  The richness and diversity data imply a weak relationship between the accession community richness and geographical origins of samples.  Two closely related fungal genera, Sporisorium and Ustilago, were implicated as causes of smut disease.  The genus Sporisorium appears to be more commonly found among accessions and thus is more likely to be the fungal pathogen causing smut in adlay.  This work can facilitate strategies to control and prevent smut infection to improve adlay yield.
    Effects of different rotation patterns on the occurrence of clubroot disease and diversity of rhizosphere microbes
    YANG Xiao-xiang, HUANG Xiao-qin, WU Wen-xian, XIANG Yun-jia, DU Lei, ZHANG Lei, LIU Yong
    2020, 19(9): 2265-2273.  DOI: 10.1016/S2095-3119(20)63186-0
    Abstract ( )   PDF in ScienceDirect  
    Clubroot disease, caused by Plasmodiophora brassicae, is one of the most destructive soil-borne diseases in cruciferous crops worldwide.  New strategies are urgently needed to control this disease, as no effective disease-resistant varieties or chemical control agents exist.  Previously, we found that the incidence rate and disease index of clubroot in oilseed rape decreased by 50 and 40%, respectively, when oilseed rape was planted after soybean.  In order to understand how different rotation patterns affect the occurrence of clubroot in oilseed rape, high-throughput sequencing was used to analyze the rhizosphere microbial community of oilseed rape planted after leguminous (soybean, clover), gramineous (rice, maize) and cruciferous (oilseed rape, Chinese cabbage) crops.  Results showed that planting soybeans before oilseed rape significantly increased the population density of microbes that could inhibit P. brassicae (e.g., Sphingomonas, Bacillus, Streptomyces and Trichoderma).  Conversely, consecutive cultivation of cruciferous crops significantly accumulated plant pathogens, including P. brassicae, Olpidium and Colletotrichum (P<0.05).  These results will help to develop the most effective rotation pattern for reducing clubroot damage.
    Two farnesyl pyrophosphate synthases, GhFPS1–2, in Gossypium hirsutum are involved in the biosynthesis of farnesol to attract parasitoid wasps
    ZHANG Hong, HUANG Xin-zheng, JING Wei-xia, LIU Dan-feng, Khalid Hussain DHILOO, HAO Zhi-min, ZHANG Yong-jun
    2020, 19(9): 2274-2285.  DOI: 10.1016/S2095-3119(20)63203-8
    Abstract ( )   PDF in ScienceDirect  
    Sesquiterpenoids play an import role in the direct or indirect defense of plants.  Farnesyl pyrophosphate synthases (FPSs) catalyze the biosynthesis of farnesyl pyrophosphate, which is a key precursor of farnesol and (E)-β-farnesene.  In the current study, two FPS genes in Gossypium hirsutum, GhFPS1 and GhFPS2, were heterologously cloned and functionally characterized in a greenhouse setting.  The open reading frames for full-length GhFPS1 and GhFPS2 were each 1 029 nucleotides, and encoded two proteins of 342 amino acids with molecular weights of 39.4 kDa.  The deduced amino acid sequences of GhFPS1–2 showed high identity to FPSs of other plants.  Quantitative real-time PCR analysis revealed that GhFPS1 and GhFPS2 were highly expressed in G. hirsutum leaves, and were upregulated in methyl jasmonate (MeJA)-, methyl salicylate (MeSA)- and aphid infestation-treated cotton plants.  The recombinant proteins of either GhFPS1 or GhFPS2 plus calf intestinal alkaline phosphatase could convert geranyl diphosphate (GPP) or isopentenyl diphosphate (IPP) to one major product, farnesol.  Moreover, in electrophysiological response and Y-tube olfactometer assays, farnesol showed obvious attractiveness to female Aphidius gifuensis, which is an important parasitic wasp of aphids.  Our findings suggest that two GhFPSs are involved in farnesol biosynthesis and they play a crucial role in indirect defense of cotton against aphid infestation.
    Animal Science · Veterinary Medicine
    A novel method to improve sow reproductive performance: Combination of pre-weaning immunization against inhibin and post-insemination hCG treatment
    GUO Ri-hong, He Pei-yuan, Mai Yan-long, DAI Zi-cun, CHEN Fang, SHI Zhen-dan
    2020, 19(9): 2286-2293.  DOI: 10.1016/S2095-3119(20)63225-7
    Abstract ( )   PDF in ScienceDirect  
    The feasibility of a novel method to improve sow reproductive performance by combining inhibin immunization and hCG treatment was tested using in vivo and in vitro experiments.  In the in vivo experiment, 106 sows were administered an inhibin immunogen on day 7 prior to weaning, and 56 non-treated sows served as the controls.  Sows exhibiting oestrous behaviour on day 5 after weaning were artificially inseminated.  On day 5 post-insemination, a subset of 50 inhibin-immunized sows received an injection of 1 000 IU human chorionic gonadotropin (hCG).  Our results showed that pre-weaning immunization against inhibin marginally improved (P=0.068) total litter size and significantly increased (P=0.044) the live litter size.  The overall differences in farrowing rates and live litter size tended toward significance (P=0.10) in the three groups, and the differences in total litter size were not significant (P=0.18).  In the in vitro experiment, activin and hCG dose-dependently suppressed (P<0.001) and stimulated (P<0.001) progesterone (P4) secretion in cultured pig granulosa cells (GCs), respectively, and the suppression effect of activin was reversed (P<0.001) by hCG.  Activin suppressed P4 secretion mainly by downregulating (P<0.001) the expression of StAR, Cyp11a1, and 3β-HSDII, whereas hCG prevented (P<0.001) the suppression effects.  These results indicate that the combination of pre-weaning immunization against inhibin and post-insemination hCG treatment provides a novel method for improving sow reproductive performance.
    Protective efficacy of an H5/H7 trivalent inactivated vaccine produced from Re-11, Re-12, and H7-Re2 strains against challenge with different H5 and H7 viruses in chickens
    ZENG Xian-ying, CHEN Xiao-han, MA Shu-jie, WU Jiao-jiao, BAO Hong-mei, PAN Shu-xin, LIU Yan-jing, DENG Guo-hua, SHI Jian-zhong, CHEN Pu-cheng, JIANG Yong-ping, LI Yan-bing, HU Jing-lei, LU Tong, MAO Sheng-gang, GUO Xing-fu, LIU Jing-li, TIAN Guo-bin, CHEN Hua-lan
    2020, 19(9): 2294-2300.  DOI: 10.1016/S2095-3119(20)63301-9
    Abstract ( )   PDF in ScienceDirect  
    We developed an H5/H7 trivalent inactivated vaccine by using Re-11, Re-12, and H7-Re2 vaccine seed viruses, which were generated by reverse genetics and derived their HA genes from A/duck/Guizhou/S4184/2017(H5N6) (DK/GZ/S4184/17) (a clade virus), A/chicken/Liaoning/SD007/2017(H5N1) (CK/LN/SD007/17) (a clade virus), and A/chicken/Guangxi/SD098/2017(H7N9) (CK/GX/SD098/17), respectively.  The protective efficacy of this novel vaccine and that of the recently used H5/H7 bivalent inactivated vaccine against different H5 and H7N9 viruses was evaluated in chickens.  We found that the H5/H7 bivalent vaccine provided solid protection against the H7N9 virus CK/GX/SD098/17, but only 50–60% protection against different H5 viruses.  In contrast, the novel H5/H7 trivalent vaccine provided complete protection against the H5 and H7 viruses tested.  Our study underscores the importance of timely updating of vaccines for avian influenza control.
    Agro-ecosystem & Environment
    Phosphorus fertilization alters complexity of paddy soil dissolved organic matter
    ZHANG Zhi-jian, WANG Xian-zhe, LIANG Lu-yi, HUANG En, TAO Xing-hua
    2020, 19(9): 2301-2312.  DOI: 10.1016/S2095-3119(20)63215-4
    Abstract ( )   PDF in ScienceDirect  
    The structural complexity of soil dissolved organic matter (DOM) may reflect soil biogeochemical processes due to its spectral characteristics.  However, the features of DOM structural complexity in paddy soil amended with long-term chemical P fertilization are still unclear, which may limit understanding of nutrient-related soil C cycle.  We collected soil samples from field experiments receiving application of 0, 30, 60, and 90 kg P ha–1 yr–1 to assess the effect of exogenous P on the complexity of soil DOM structure.  Three-dimensional excitation-emission matrix fluorescence analysis and enzymatic activity assay were used to determine the features of soil DOM molecular structure and the associated microbial reactions.  The results showed that P input increased the biodegradability of DOM, indicating by the increased lower molecular weight components and decreased humic degree in the DOM.  P input also reduced the structural complexity of DOM with blue shifts of fluorescent signals.  The fluorescence index and β/α index of DOM increased with increasing P application by 4–5% and 3–11%, respectively, while humification index decreased by 8–13%.  The P input increased the abundance of bacteria and fungi by 34–167% and 159–964%, respectively, while 29–54% increments were found for the β-1,4-glucosidase activities.  These results implicated that P fertilization accelerated the soil DOM cycle, although the structural complexity of DOM declined, which potentially benefits soil C sequestration in paddy fields and may be a C sequestration mechanism in the P-dependent paddy. 
    Spatial variability of soil properties in red soil and its implications for site-specific fertilizer management
    SONG Fang-fang, XU Ming-gang, DUAN Ying-hua, CAI Ze-jiang, WEN Shi-lin, CHEN Xian-ni, SHI Wei-qi, Gilles COLINET
    2020, 19(9): 2313-2325.  DOI: 10.1016/S2095-3119(20)63221-X
    Abstract ( )   PDF in ScienceDirect  
    Assessing spatial variability and mapping of soil properties constitute important prerequisites for soil and crop management in agricultural areas.  To explore the relationship between soil spatial variability and land management, 256 samples were randomly collected at two depths (surface layer 0–20 cm and subsurface layer 20–40 cm) under different land use types and soil parent materials in Yujiang County, Jiangxi Province, a red soil region of China.  The pH, soil organic matter (SOM), total nitrogen (TN), cation exchange capacity (CEC), and base saturation (BS) of the soil samples were examined and mapped.  The results indicated that soils in Yujiang were acidified, with an average pH of 4.87 (4.03–6.46) in the surface layer and 4.99 (4.03–6.24) in the subsurface layer.  SOM and TN were significantly higher in the surface layer (27.6 and 1.50 g kg–1, respectively) than in the subsurface layer (12.1 and 0.70 g kg–1, respectively), while both CEC and BS were low (9.0 and 8.0 cmol kg–1, 29 and 38% for surface and subsurface layers, respectively).  Paddy soil had higher pH (mean 4.99) than upland and forest soils, while soil derived from river alluvial deposits (RAD) had higher pH (mean 5.05) than the other three parent materials in both layers.  Geostatistical analysis revealed that the best fit models were exponential for pH and TN, and spherical for BS in both layers, while spherical and Gaussian were the best fitted for SOM and CEC in the surface and subsurface layers.  Spatial dependency varied from weak to strong for the different soil properties in both soil layers.  The maps produced by selecting the best predictive variables showed that SOM, TN, and CEC had moderate levels in most parts of the study area.  This study highlights the importance of site-specific agricultural management and suggests guidelines for appropriate land management decisions.
    Effects of water application uniformity using a center pivot on winter wheat yield, water and nitrogen use efficiency in the North China Plain
    CAI Dong-yu, YAN Hai-jun, LI Lian-hao
    2020, 19(9): 2326-2339.  DOI: 10.1016/S2095-3119(19)62877-7
    Abstract ( )   PDF in ScienceDirect  
    In recent years, the use of fertigation technology with center pivot irrigation systems has increased rapidly in the North China Plain (NCP).  The combined effects of water and nitrogen application uniformity on the grain yield, water use efficiency (WUE) and nitrogen use efficiency (NUE) have become a research hotspot.  In this study, a two-year field experiment was conducted during the winter wheat growing season in 2016–2018 to evaluate the water application uniformity of a center pivot with two low pressure sprinklers (the R3000 sprinklers were installed in the first span, the corresponding treatment was RS; the D3000 sprinklers were installed in the second span, the corresponding treatment was DS) and a P85A impact sprinkler as the end gun (the corresponding treatment was EG), and to analyze its effects on grain yield, WUE and NUE.  The results showed that the water application uniformity coefficients of R3000, D3000 and P85A along the radial direction of the pivot (CUH) were 87.5, 79.5 and 65%, respectively.  While the uniformity coefficients along the traveling direction of the pivot (CUC) were all higher than 85%.  The effects of water application uniformity of the R3000 and D3000 sprinklers on grain yield were not significant (P>0.05); however, the average grain yield of EG was significantly lower (P<0.05) than those of RS and DS, by 9.4 and 11.1% during two growing seasons, respectively.  The coefficients of variation (CV) of the grain yield had a negative correlation with the uniformity coefficient.  The CV of WUE was more strongly affected by the water application uniformity, compared with the WUE value, among the three treatments.  The NUE of RS was higher than those of DS and EG by about 6.1 and 4.8%, respectively, but there were no significant differences in NUE among the three treatments during the two growing seasons.  Although the CUH of the D3000 sprinklers was lower than that of the R3000, it had only limited effects on the grain yield, WUE and NUE.  However, the cost of D3000 sprinklers is lower than that of R3000 sprinklers.  Therefore, the D3000 sprinklers are recommended for winter wheat irrigation and fertigation in the NCP. 
    Food Science
    An optimized industry processing technology of peanut tofu and the novel prediction model for suitable peanut varieties
    CHEN Bing-yu, LI Qi-zhai, HU Hui, MENG Shi, Faisal SHAH, WANG Qiang, LIU Hong-zhi
    2020, 19(9): 2340-2351.  DOI: 10.1016/S2095-3119(20)63249-X
    Abstract ( )   PDF in ScienceDirect  
    Peanut protein is easily digested and absorbed by the human body, and peanut tofu does not contain flatulence factors and beany flour.  However, at present, there is no industrial preparation process of peanut tofu, whereas the quality of tofu prepared by different peanut varieties is quite different.  This study established an industrial feasible production process of peanut tofu and optimized the key process that regulates its quality.  Compared with the existing method, the production time is reduced by 53.80%, therefore the daily production output is increased by 183.33%.  The chemical properties of 26 peanut varieties and the quality characteristics of tofu prepared from these 26 varieties were determined.  The peanut varieties were classified based on the quality characteristics of tofu using the hierarchical cluster analysis (HCA) method, out of which 7 varieties were screened out which were suitable for preparing peanut tofu.  An evaluation standard was founded based on peanut tofu qualities.  Six chemical trait indexes were correlated with peanut tofu qualities (P<0.05).  A logistic regressive model was developed to predict suitable peanut varieties and this prediction model was verified.  This study may help broaden the peanut protein utilization, and provide guidance for breeding experts to select certain varieties for product specific cultivation of peanut.
    Evaluation of sugar and organic acid composition and their levels in highbush blueberries from two regions of China
    ZHANG Jia, NIE Ji-yun, LI Jing, ZHANG Hui, LI Ye, Saqib FAROOQ, Syed Asim Shah BACHA, WANG Jie
    2020, 19(9): 2352-2361.  DOI: 10.1016/S2095-3119(20)63236-1
    Abstract ( )   PDF in ScienceDirect  
    Sweet and sour are the most important taste of blueberries, and they are produced by sugar and acid, respectively.  Their contributions to the taste depend not only on the levels of sugar and acid, but also on the types and relative proportions of sugar and acid.  Therefore, it is very important to evaluate the composition and levels of sugar and acid in blueberries.  Regional differences and variety diversity also affect the sugar and acid characteristics of fruits.  Therefore, this study selected two main producing regions in northern China (Weihai and Yingkou) to examine the sugar and acid characteristics of 11 common blueberry cultivars.  The indexes measured included soluble sugars, organic acids, soluble solid content and titratable acidity.  The results showed that glucose and fructose were the major sugars, and citric acid and quinic acid were the major organic acids.  Correlation analysis showed that glucose, fructose, and sucrose were positively correlated with total sugar content; the citric acid content was positively correlated with the titratable acidity and total organic acids.  Titratable acidity, glucose, fructose, sucrose, total sugar content, citric acid, shikimic acid and total acid content of the blueberries varied significantly between regions (P<0.05).  In general, compared with Weihai blueberries, Yingkou blueberries had higher sugar content and lower acid content.  The results of this study may provide useful references for the evaluation of sweet and sour flavors and cultivar selection of blueberries.
    Reducing environmental risk of nitrogen by popularizing mechanically dense transplanting for rice production in China
    HUANG Min, ZOU Ying-bin
    2020, 19(9): 2362-2366.  DOI: 10.1016/S2095-3119(20)63155-0
    Abstract ( )   PDF in ScienceDirect