2021 Vol. 20 No. 12 Previous Issue    Next Issue

    Crop Science
    Plant Protection
    Animal Science · Veterinary Medicine
    Agro-ecosystem & Environment
    Agricultural Economics and Management

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    Control of cotton pests and diseases by intercropping: A review
    CHI Bao-jie, ZHANG Dong-mei, DONG He-zhong
    2021, 20(12): 3089-3100.  DOI: 10.1016/S2095-3119(20)63318-4
    Abstract ( )   PDF in ScienceDirect  
    Cotton (Gossypium hirsutum L.) is a globally important crop that is often damaged by pests and diseases.  Current cotton pests and diseases management is dependent on chemical pesticides.  Although chemical pesticides are usually effective, long-term application of these pesticides often leads to increased insecticide resistance in the pests, fewer natural enemies, reduced natural control, and a degraded environment.  Because of increased environmental awareness and the need for sustainable cotton production, the control of cotton pests and diseases using biological means like intercropping is increasingly receiving attention.  Intercropping of cotton with other crops can often boost the total yield and output of the intercropping system and provide significant economic benefits without sacrificing cotton quality.  Intercropping also increases the number of natural enemies, and reduces the occurrence of cotton pests and diseases by altering the ecological structure and environmental conditions in the fields.  Cotton-based intercropping is an effective strategy to reduce the competition between cotton and grain or other economic crops for arable land.  It is also an important way to increase the populations of natural enemies in cotton fields for the management of pests and diseases.  However, inappropriate intercropping can also increase labor requirements and even result in inadequate control of pests and diseases.  This review focuses on the performance and the mechanisms of intercropping for reducing cotton pests and disease as well as on the effective management of intercropping systems.  The risks and limitations, as well as the study approaches needed and the prospects of intercropping for the control of cotton pests and diseases, are also discussed.  This information is intended to aid researchers and growers in designing economically viable and ecologically friendly pest and disease management strategies that will reduce the use of chemicals and the cost of cotton production.
    Crop Science
    Identification of genetic locus with resistance to take-all in the wheat-Psathyrostachys huashanica Keng introgression line H148
    BAI Sheng-sheng, ZHANG Han-bing, HAN Jing, WU Jian-hui, LI Jia-chuang, GENG Xing-xia, LÜ Bo-ya, XIE Song-feng, HAN De-jun, ZHAO Ji-xin, YANG Qun-hui, WU Jun, CHEN Xin-hong
    2021, 20(12): 3101-3113.  DOI: 10.1016/S2095-3119(20)63340-8
    Abstract ( )   PDF in ScienceDirect  
    Take-all is a devastating soil-borne disease of wheat (Triticum aestivum L.).  Cultivating resistant line is an important measure to control this disease.  Psathyrostachys huashanica Keng is a valuable germplasm resource with high resistance to take-all.  This study reported on a wheat-P. huashanica introgression line H148 with improved take-all resistance compared with its susceptible parent 7182.  To elucidate the genetic mechanism of resistance in H148, the F2 genetic segregating population of H148×XN585 was constructed.  The mixed genetic model analysis showed that the take-all resistance was controlled by two major genes with additive, dominant and epistasis effects.  Bulked segregant analysis combined with wheat axiom 660K genotyping array analysis showed the polymorphic SNPs with take-all resistance from P. huashanica alien introgression were mainly distributed on the chromosome 2A.  Genotyping of the F2 population using the KASP marker mapped a major QTL in an interval of 68.8–70.1 Mb on 2AS.  Sixty-two genes were found in the target interval of the Chinese Spring reference genome sequence.  According to the functional annotation of genes, two protein genes that can improve the systematic resistance of plant roots were predicted as candidate genes.  The development of wheat-P. huashanica introgression line H148 and the resistant QTL mapping information are expected to provide some valuable references for the fine mapping of disease-resistance gene and development of take-all resistant varieties through molecular marker-assisted selection.
    Impacts of soil fertility management on productivity and economics of rice and fodder intercropping systems under rainfed conditions in Odisha, India
    Dilip Kumar BASTIA, Subrat Kumar BEHERA, Manas Ranjan PANDA
    2021, 20(12): 3114-3126.  DOI: 10.1016/S2095-3119(20)63591-2
    Abstract ( )   PDF in ScienceDirect  
    Under small and marginal farm conditions, allocation of land exclusively for forages is not possible.  Hence, integration of forages in existing crop geometry can ensure production of grain and fodder, simultaneously under rainfed conditions.  A field experiment was conducted to study the effect of different nutrient management practices on rice and fodder intercropping systems under rainfed conditions during 2015–2017.  The intercropping system comprised (i) sole rice (R), (ii) rice and cowpea (5:2) (CP) and (iii) rice and ricebean (5:2) (RB) whereas the different nutrient management practices comprised (i) application of farm yard manure (FYM) at 5 t ha–1 (farmers’ practice) (N1), (ii) application of inorganic fertilizer (recommended dose of fertilizer (RDF) of rice, 60:30:30 kg ha–1 of N:P2O5:K2O) (N2) and (iii) application of both FYM at 5 t ha–1 and 50% of RDF inorganic fertilizer (N3).  The results of the experiment revealed that the growth attribute such as leaf area was influenced significantly when fodder crops were taken as intercrops because rice plant was getting more nitrogen from soil due to nitrogen fixation of leguminous fodder crops.  Among the nutrient management practices, significant differences in leaf area were found beween N2 and N1, and between N3 and N1 treatments.  However, regarding total number of effective tillers, significant differences were found neither between nutrient management practices nor between cropping systems.  The rice equivalent yield (REY) based on price (REYP) was found to be significantly lower in CP (2 615 kg ha–1; –6.4%) and RB intercropping systems (2 571 kg ha–1; –8.0%)  than in R monocropping system (2 794 kg ha–1).  However, the REY based on energy (REYE) of CP (2 999 kg ha–1; +7.3%) and RB (2 960 kg ha–1; +5.9%) were found to be significantly higher than that of R (2 794 kg ha–1) irrespective of nutrient management practices.  Between different nutrient management practices, the N3 treatment recorded the highest REYP and REYE which was at par with the N2 treatment and significantly higher than the N1 treatment irrespective of cropping systems.  The combined application of both organic and inorganic sources of nutrients helped to supply nutrients throughout the growing season, which led to improved growth parameters and rice yield.  The R monocropping system resulted in more income and rain water use efficiency (RWUE) closely followed by rice and fodder intercropping systems.  However, the REYE and energy use efficiency (EUE) of rice and fodder intercropping systems were higher than those of R.  Also, fodder helped to meet the requirement of cattle feeding in the off-season.  Hence, the intercropping system is advocated in the study zone.  Further study can be done on ecosystem services and carbon sequestration potential of the intercropping system, as well as the system’s coping ability in response to short drought through observing periodic soil moisture regime in root zone.  
    Drip irrigation incorporating water conservation measures: Effects on soil water–nitrogen utilization, root traits and grain production of spring maize in semi-arid areas
    WU Yang, BIAN Shao-feng, LIU Zhi-ming, WANG Li-chun, WANG Yong-jun, XU Wen-hua, ZHOU Yu
    2021, 20(12): 3127-3142.  DOI: 10.1016/S2095-3119(20)63314-7
    Abstract ( )   PDF in ScienceDirect  
    The Northeast Plain is the largest maize production area in China, and drip irrigation has recently been proposed to cope with the effects of frequent droughts and to improve water use efficiency (WUE).  In order to develop an efficient and environmentally friendly irrigation system, drip irrigation experiments were conducted in 2016–2018 incorporating different soil water conservation measures as follows: (1) drip irrigation under plastic film mulch (PI), (2) drip irrigation under biodegradable film mulch (BI), (3) drip irrigation incorporating straw returning (SI), and (4) drip irrigation with the tape buried at a shallow soil depth (OI); with furrow irrigation (FI) used as the control.  The results showed that PI and BI gave the highest maize yield, as well as the highest WUE and nitrogen use efficiency (NUE) because of the higher root length density (RLD) and better heat conditions during the vegetative stage.  But compared with BI, PI consumed more soil water in the 20–60 and 60–100 cm soil layers, and accelerated the progress of root and leaf senescence due to a larger root system in the top 0–20 cm soil layer and a higher soil temperature during the reproductive stage.  SI was effective in improving soil water and nitrate contents, and promoted RLD in deeper soil layers, thereby maintaining higher physiological activity during the reproductive stage.  FI resulted in higher nitrate levels in the deep 60–100 cm soil layer, which increased the risk of nitrogen losses by leaching compared with the drip irrigation treatments.  RLD in the 0–20 cm soil layer was highly positively correlated with yield, WUE and NUE (P<0.001), but it was negatively correlated with root nitrogen use efficiency (NRE) (P<0.05), and the correlation was weaker in deeper soil layers.  We concluded that BI had advantages in water–nitrogen utilization and yield stability response to drought stress, and thus is recommended for environmentally friendly and sustainable maize production in Northeast China.
    Hormonal changes play important roles in the key period of superior and inferior earshoot differentiation in maize
    DU Kang, ZHAO Wen-qing, ZHOU Zhi-guo, SHAO Jing-jing, HU Wei, KONG Ling-jie, WANG You-hua
    2021, 20(12): 3143-3155.  DOI: 10.1016/S2095-3119(20)63337-8
    Abstract ( )   PDF in ScienceDirect  
    The upper earshoots with higher superiority usually have higher yield potential and higher efficiency.  To determine the key period for the asynchronous differentiation of superior and inferior earshoots and how hormones are involved in this process, a two-year experiment was designed using two maize hybrids: Suyu 41 (S41, single-ear hybrid) and AN 101 (A101, double-ear hybrid).  The results showed that the lag of lower earshoot differentiation was not only caused by the delay of the differentiation starting time but also related to extension of the duration in spikelet differentiation (stage II) and sexual organ formation stage (stage IV).  From 12 days before silking (DBS), the contents of indole-3-acetic acid (IAA), zeatin riboside (ZR)+zeatin (ZT), and gibberellic acid (GA3) in both upper and lower earshoots of the two hybrids increased dramatically and then decreased quickly.  ABA slightly increased in the two hybrids and then decreased slowly in S41, while it was maintained at a high level in A101.  At 8 DBS, i.e., the transition period from floret differentiation to sexual organ formation stage, not only the growth of upper-to-lower earshoot difference (ULED), but also the values for ULED of IAA, ZR+ZT and GA3 were all significantly higher in S41 than in A101.  Furthermore, the upper-to-lower hormone ratios IAAU/IAAL and (ZR+ZT)U/(ZR+ZT)L were also much higher in the single-ear hybrid than in the double-ear hybrid, while the GA3U/GA3L and ABAU/ABAL had no significant differences.  In addition, the time course of ULEDhormone/ULEDearshoot growth rate also suggested that the hormones work in different ways in earshoot superiority/inferiority formation.  The delayed differentiation of lower ear shoots was conclusively related to the later initiation of differentiation and the longer durations of specific differentiation stages.  Compared with the regulating roles of IAA and ZR+ZT in the key period (8 DBS) of superiority/inferiority differentiation, GA3 seems to be affected earlier, while ABA contributes little to this process.
    Maize grain yield and water use efficiency in relation to climatic factors and plant population in northern China
    LIU Yue-e, HOU Peng, HUANG Gui-rong, ZHONG Xiu-li, LI Hao-ru, ZHAO Jiu-ran, LI Shao-kun, MEI Xu-rong
    2021, 20(12): 3156-3169.  DOI: 10.1016/S2095-3119(20)63428-1
    Abstract ( )   PDF in ScienceDirect  
    Water scarcity has become a limiting factor for increasing crop production.  Finding ways to improve water use efficiency (WUE) has become an urgent task for Chinese agriculture.  To understand the response of different maize populations to changes in precipitation and the effects of changes in maize populations on WUE, this study conducted maize population experiments using maize hybrids with different plant types (compact and semi compact) and different planting densities at 25 locations across China.  It was found that, as precipitation increased across different locations, maize grain yield first increased and then decreased, while WUE decreased significantly.  Analyzing the relationship between WUE and the main climatic factors, this study found that WUE was significantly and negatively correlated with precipitation (R (daily mean precipitation) and R (accumulated precipitation)) and was positively correlated with temperature (TM (daily mean maximum temperature), TM–m (Tm, daily mean minimum temperature) and GDD (growing degree days)) and solar radiation (Ra (daily mean solar radiation) and Ra (accumulated solar radiation)) over different growth periods.  Significant differences in maize grain yield, WUE and precipitation were found at different planting densities.  The population densities were ranked as follows according to maize grain yield and WUE based on the multi-site experiment data: 60 000 plants ha–1 (P2)>90 000 plants ha–1 (P3)>30 000 plants ha–1 (P1).  Further analysis showed that, as maize population increased, water consumption increased significantly while soil evaporation decreased significantly.  Significant differences were found between the WUE of ZD958 (compact type) and that of LD981 (semi-compact type), as well as among the WUE values at different planting densities.  In addition, choosing the optimum hybrid and planting density increased WUE by 21.70 and 14.92%, respectively, which showed that the hybrid played a more significant role than the planting density in improving WUE.  Therefore, choosing drought-resistant hybrids could be more effective than increasing the planting density to increase maize grain yield and WUE in northern China.  Comprehensive consideration of climatic impacts, drought-resistant hybrids (e.g., ZD958) and planting density (e.g., 60 000 plants ha–1) is an effective way to increase maize grain yield and WUE across different regions of China.
    Overexpression of the MADS-box gene SlMBP21 alters leaf morphology and affects reproductive development in tomato
    WANG Yun-shu, GUO Peng-yu, ZHANG Jian-ling, XIE Qiao-li, SHEN Hui, HU Zong-li, CHEN Guo-ping
    2021, 20(12): 3170-3185.  DOI: 10.1016/S2095-3119(21)63638-9
    Abstract ( )   PDF in ScienceDirect  
    Fruit yield is the most important horticultural trait of tomato.  SlMBP21, a SEPALLATA subclass MADS-box gene has been reported to have functions in regulating pedicel abscission zone identity and development and controlling sepal size in tomato.  However, we generated transgenic tomato plants which overexpress SlMBP21 and found the transformants displayed curly leaves, abnormally shaped flowers with twisted and opened stamens, reduced yield parameters, and small and light seeds.  Our studies on the gain-of-function phenotype and gene expression level showed that its novel aspects played important roles in determining leaf morphology, flower and inflorescence architecture, and seed size, as well as the fruit yield.  Overexpression of SlMBP21 in tomato resulted in curly leaves with fewer leaflets due to the regulation of the critical leaf polarity genes that cause an imbalance between the midvein adaxial–abaxial cell growth.  Defects in the architecture of flowers and inflorescences resulted in reduced fruit set.  Furthermore, we demonstrated that SlMBP21 plays its role through inhibiting the expression of the genes involved in the determination of seed development in tomato and SlMBP21 protein can interact with other MADS-box protein (SlAGL11, TAGL1 and SlMBP3) to control seed size.  Thus, these results suggest that overexpression of SlMBP21 causes multiple types of damage to plant growth and development, especially fruit yield, in tomato.
    Analysis of genetic diversity and structure across a wide range of germplasm reveals genetic relationships among seventeen species of Malus Mill. native to China 
    GAO Yuan, WANG Da-jiang, WANG Kun, CONG Pei-hua, LI Lian-wen, PIAO Ji-cheng
    2021, 20(12): 3186-3198.  DOI: 10.1016/S2095-3119(20)63421-9
    Abstract ( )   PDF in ScienceDirect  
    China is a center of diversity for Malus Mill. with 27 native species including 21 wild species and six domesticated species.  We applied a set of 19 simple sequence repeat markers to genotype 798 accessions of 17 species (12 wild species and five cultivated species) of Malus originating from 14 provinces in China.  A total of 500 alleles were detected.  Diversity statistics indicated a high level of genetic variation as quantified by the average values of the effective allele number (Ne), expected heterozygosity (He), and Shannon’s Information Index (I) (10.309, 0.886, and 2.545, respectively).  Malus sieversii (MSR; He=0.814, I=2.041, Ne=6.054), M. baccata (MBB; He=0.848, I=2.350, Ne=8.652), M. toringoides (MTH; He=0.663, I=1.355, Ne=3.332), and M. hupehensis (MHR; He=0.539, I=0.912, Ne=0.579) showed a higher level of genetic diversity in this study than the previous studies.  MSR and MBB contributed to the origin and evolution of some accessions of M. domestica subsp. chinensis (MDC).  However, other accessions of MDC showed a closer genetic distance with MBB and cultivated species, especially M. robusta (MRB), M. asiatica (MAN), and M. prunifolia (MPB).  Not all accessions of MDC were descended from MSR in Xinjiang Uygur Autonomous Region of China.  This research provides novel insights into the genetic relationships of Malus native to China, which will be useful for genetic association studies, germplasm conservation, and breeding programs.
    Transcriptome analysis of the influence of CPPU application for fruit setting on melon volatile content
    CHENG Jin-tao, CHEN Hai-wen, DING Xiao-chen, SHEN Tai, PENG Zhao-wen, KONG Qiu-sheng, HUANG Yuan, BIE Zhi-long
    2021, 20(12): 3199-3208.  DOI: 10.1016/S2095-3119(21)63639-0
    Abstract ( )   PDF in ScienceDirect  
    In fruit production, the application of the plant growth regulator 1-(2-chloro-4-pyridyl)-3-phenylurea (CPPU) dulls the fruit aroma.  Gas chromatography–mass spectrometry and transcriptome analyses were performed on CPPU-treated and pollinated fruits to determine how CPPU affects the production of aroma in melon fruit.  The results showed that the contents of two important esters (benzyl acetate and phenethyl acetate) in the CPPU-treated fruits were significantly lower than those in the pollinated fruits.  Transcriptome sequencing data revealed that most differentially expressed genes were involved in “phenylalanine metabolism” pathway, and their expression was significantly decreased in the CPPU-treated fruits.  Further analysis showed that the phenylalanine content in the CPPU-treated fruits was significantly higher than that in the pollinated fruits.  In summary, CPPU application interferes with phenylalanine metabolism in melon fruits and affects the production of aromatic esters. 
    Plant Protection
    Identification of proteins associated with Fusarium crown rot resistance in wheat using label-free quantification analysis  
    JIN Jing-jing, DUAN Shuo-nan, QI Yong-zhi, ZHEN Wen-chao, MA Jun
    2021, 20(12): 3209-3221.  DOI: 10.1016/S2095-3119(20)63573-0
    Abstract ( )   PDF in ScienceDirect  
    Fusarium crown rot (FCR), typically caused by Fusarium pseudograminearum, is a severe soil-borne disease that, in recent years, has become an emerging threat to Chinese wheat crops.  For the first time in this study, we investigated and compared the proteomic characteristics of two Chinese wheat varieties (04 Zhong 36 and Xinmai 26) at 24, 48, and 72 h post-inoculation using label-free quantitative proteomic analysis.  A total of 9 234 proteins were successfully quantified, of which 783 were differentially expressed after inoculation.  These proteins were mainly involved in metabolic, single-organism, and cellular processes.  Thirty-three proteins associated with defense, cell wall formation, photosynthesis, etc., showed consistently different expression between the two genotypes at multiple time points.  In particular, chitinase, which degrades chitin in the fungal cell wall and limits fungal growth, was exclusively and consistently upregulated in 04 Zhong 36 across the three time points.  Other proteins such as flavonoid O-methyltransferase, glycosyltransferase, and peroxidase were only upregulated in 04 Zhong 36, and proteins, including the berberine bridge enzyme and rubisco large subunit-binding protein, were specifically downregulated in Xinmai 26.  The expression of transcripts encoding eight selected proteins through qRT-PCR analysis supported the proteomic profiles.  Overall, the results of this study allow us to understand FCR resistance in wheat at the protein level.  Some proteins and their corresponding genes may be useful resources for the genetic improvement of FCR resistance in wheat. 
    Horizontal gene transfer of a syp homolog contributes to the virulence of Burkholderia glumae
    WANG Sai, WANG Pei-hong, NIE Wen-han, CUI Zhou-qi, LI Hong-yu, WU Yan, Ayizekeranmu YIMING, FU Luo-yi, Iftikhar AHMAD, CHEN Gong-you, ZHU Bo
    2021, 20(12): 3222-3229.  DOI: 10.1016/S2095-3119(20)63553-5
    Abstract ( )   PDF in ScienceDirect  
    Horizontal gene transfer (HGT) has been proved a major driving force in prokaryotic evolution.  However, the molecular functions of these transferred genes in pathogenic bacteria especially plant pathogenic bacteria are still not fully investigated.  In this study, the whole-genome in silico analysis was performed and found a syringopeptin synthetase (syp) homolog in Burkholderia glumae, which can cause bacterial panicle blight in rice, was predicted to be horizontally transferred from Pseudomonas ancestor with solid confidence by phylogenetic analysis.  The comprehensive molecular experiments were performed to study the potential role of this gene in B. glumae.  Inoculation of rice panicles with the syp mutant resulted in 60% lower disease index compared with the wild type (WT) parent strain, suggesting the requirement of syp for the full virulence of B. glumae.  Chromatography analysis of exudates from B. glumae showed suppression of synthesis of metabolites analogous to syringopeptin in the mutants.  All these data raise the possibility of HGT phenomenon in shaping the virulence and adaptation of B. glumae over evolutionary time.
    Effect of Aspergillus niger NBC001 on the soybean rhizosphere microbial community in a soybean cyst nematode-infested field
    JIN Na, LIU Shi-ming, PENG Huan, HUANG Wen-kun, KONG Ling-an, PENG De-liang
    2021, 20(12): 3230-3239.  DOI: 10.1016/S2095-3119(20)63467-0
    Abstract ( )   PDF in ScienceDirect  
    Soybean cyst nematode (SCN, Heterodera glycines Ichinohe) is one of the most important pests causing considerable damage to soybean (Glycine max (L.) Merr.) around the world.  Biocontrol provides a strategy for sustainable nematode control.  Previously, Aspergillus niger NBC001 was isolated from the cysts of Heterodera spp. and able to control H. glycines and promote the growth of soybean in a pot experiment.  In this study, the effects of NBC001 on H. glycines density and on the soybean rhizosphere microbial community in a soybean cyst nematode-infested field were studied.  The results showed that NBC001 could suppress H. glycines by 31.7% in the field.  High-throughput sequencing analysis showed that NBC001 had no significant influence on soybean rhizosphere microbial community structure, indicating that seed coat-dressing with the concentrated culture filtrate of NBC001 was safe for the soil ecological environment.  In addition, high-throughput sequencing results demonstrated that at 10 days post transplantation, NBC001 increased the abundances of Actinobacteria and Acidobacteria, but decreased the abundances of Bacteroidetes and Gemmatimonadetes at the phylum level.  Meanwhile, the abundances of Phyllobacterium, Ralstonia and H16 were increased, while the abundances of Adhaeribacter, Gemmatimonas, Sphingomonas, Flavisolibacter were suppressed by application of NBC001.  However, at 90 days post transplantation, NBC001 only increased the abundances of Aeromicrobium and RB41 whereas it decreased the abundance of H16.  The results indicated that application of NBC001 increased the relative abundances of the beneficial microorganisms such as Actinobacteria, Acidobacteria, Aeromicrobium and Phyllobacterium in the soil.  In summary, NBC001 is an eco-friendly biocontrol agent for H. glycines control. 
    Functional identification of C-type lectin in the diamondback moth, Plutella xylostella (L.) innate immunity
    LI Jin-yang, LIN Jun-han, G. Mandela FERNáNDEZ-GRANDON, ZHANG Jia-yu, YOU Min-sheng, XIA Xiao-feng
    2021, 20(12): 3240-3255.  DOI: 10.1016/S2095-3119(21)63650-X
    Abstract ( )   PDF in ScienceDirect  
    C-type lectins (CTLs) are a superfamily of Ca2+-dependent carbohydrate-recognition proteins, and an important pattern recognition receptor (PRR) in insect innate immunity which can mediate humoral and cellular immunity in insects.  In this study, we report a novel dual carbohydrate-recognition domain (CRD) CTL from Plutella xylostella which we designate PxIML.  PxIML is a protein with a 969 bp open reading frame (ORF) encoding 322 amino acids, containing a signal peptide and a dual-CRD with EPN (Glu124-Pro125-Asn126) and QPD (Gln274-Pro275-Asp276) motifs.  The expression of PxIML mRNA in the fat body was significantly higher than in hemocytes and midgut.  The relative expression levels of PxIML in the whole insect and the fat body were significantly inhibited after infection with Bacillus thuringiensis 8010 (Bt8010) at 18 h, while they were significantly upregulated after infection with Serratia marcescens IAE6 or Pichia pastoris.  The recombinant PxIML (rPxIML) protein could bind to the tested pathogen-associated molecular patterns (PAMPs), and the bacteria of Enterobacter sp. IAE5, S. marcescens IAE6, Staphylococcus aureus, Escherichia coli BL21, and Bt8010 in a Ca2+-dependent manner, however, it showed limited binding to the fungus, P. pastoris.  The rPxIML exhibited strong activity in the presence of Ca2+ to agglutinate Bt8010, Enterobacter sp. IAE5 and S. aureus, but it only weakly agglutinated with E. coli BL21, and could not agglutinate with S. marcescens IAE6 or P. pastoris.  Furthermore, the rPxIML could bind to hemocytes, promote the adsorption of hemocytes to beads, and enhance the phenoloxidase (PO) activity and melanization of P. xylostella.  Our results suggest that PxIML plays an important role in pathogen recognition and in mediating subsequent humoral and cellular immunity of P. xylostella.
    Animal Science · Veterinary Medicine
    Effects of dietary amylose to amylopectin ratio on growth performance, carcass quality characteristics and meat fatty acids in Chinese Qinchuan cattle
    PIAO Min-yu, HU Feng-ming, KONG Fan-lin, LIU Yun-long, WANG Shuo, CUI Kai, SUN Tao, DIAO Qi-yu, TU Yan
    2021, 20(12): 3256-2169.  DOI: 10.1016/S2095-3119(20)63576-6
    Abstract ( )   PDF in ScienceDirect  
    This study evaluated the effects of the dietary starch amylose/amylopectin ratio on growth performance, rumen fermentation and blood parameters, carcass characteristics and marbling score, and meat fatty acid profiles and transcriptional changes in the genes involved in the gluconeogenesis pathway in Chinese Qinchuan cattle.  Forty-five cattle were randomly divided into three groups.  The bulls were fed a control diet (middle amylose/amylopectin ratio=0.47) or diets with either waxy corn starch (WS) inclusion (low amylose/amylopectin ratio=0.23) or pea starch (PS) inclusion (high amylose/amylopectin ratio=0.60) for 90 days.  The bulls were individually allowed to receive the diets at the daily amount of at least 2.1% of their individual BW twice daily.  The bulls were weighed at 45-day intervals, and blood and rumen fluid samples were also collected at 45-day intervals.  The bulls were slaughtered and longissimus thoracis (LT) samples were collected for meat quality measurements.  Compared with PS, the average daily gain (ADG) and feed efficiency in control and WS were increased (P<0.05) during d 0 to 45.  However, the feed efficiency in PS was increased (P<0.05) compared with the control and WS during d 46 to 90.  During the whole feeding trial, the ADG in control and WS showed trends that were higher (0.05<P<0.1) than that of PS, while other growth performance measures and feed intake did not differ (P>0.05) among the three groups.  Compared with PS, the serum insulin concentration in WS was increased (P<0.05) at d 45, but not at d 90.  Compared with control and WS, the serum SOD and T-AOC concentrations in PS were increased (P<0.05) at d 45, but not at d 90.  Compared with control, the rumen microbial crude protein contents in WS and PS were increased (P<0.05) at d 0, while those of control and WS were higher (P<0.05) than that of PS at d 45, but not at d 90.  Compared with PS, the backfat thickness in control and WS were increased (P<0.05), however, the marbling score and expression of genes related to the gluconeogenesis pathway in liver of the three groups did not differ (P>0.05).  Chemical and physio-chemical compositions of LT did not differ (P>0.05) among the three groups.  In conclusion, diets with low or middle amylose/amylopectin ratios increased the backfat thickness, and tended to improve ADG, but had no effect on other carcass characteristics, fat content in the LT, or the expression of hepatic genes related to the gluconeogenesis pathway in Chinese Qinchuan cattle. 
    Detection and characterization of Hepatitis E virus from commercial rabbit livers in Hebei, China
    XIAO Peng, TIAN Ji-jing, MAO Jing-jing, GUO Zhao-jie, ZHAO Yue, LIU Tian-long, CHEN Jian, WANG Tong-tong, MA Long-huan, SHE Rui-ping
    2021, 20(12): 3270-3276.  DOI: 10.1016/S2095-3119(21)63632-8
    Abstract ( )   PDF in ScienceDirect  

    Rabbit hepatitis E virus (HEV) has been reported for years and is thought to have the potential for zoonotic transmission from rabbits to humans.  As reported, HEV genotype 3 (gt3) is the most prevalent form of HEV in rabbits.  To determine the prevalence of HEV in commercial rabbit livers, 176 liver samples were collected from an abattoir in Hebei Province, China.  Three (1.7%) samples tested positive for RNA of HEV-ORF2 (open reading frames-2).  Sequence analysis showed that the three isolates shared high identities with each other (94.08–98.85%).  Further analysis showed that all the rabbit strains clustered together in the branch of HEV gt3.  Further study by immunohistochemistry (IHC) assays showed that 131 (74.4%) liver samples were positive for HEV ORF2 protein.  Pathological changes including cell degeneration, inflammatory cell infiltration and bile duct epithelial cell hyperplasia were observed under microscopy.  These findings indicated the presence of HEV in commercial livers of rabbits.  Additional studies should be conducted to investigate the infectivity of rabbit HEV (rHEV) and the potential risks of zoonotic transmission of rHEV from rabbits to human beings.

    Agro-ecosystem & Environment
    Distribution and accumulation of zinc and nitrogen in wheat grain pearling fractions in response to foliar zinc and soil nitrogen applications
    ZHANG Pan-pan, CHEN Yu-lu, WANG Chen-yang, MA Geng, LÜ Jun-jie, LIU Jing-bao, GUO Tian-cai
    2021, 20(12): 3277-3288.  DOI: 10.1016/S2095-3119(20)63491-8
    Abstract ( )   PDF in ScienceDirect  
    Increasing zinc (Zn) concentration in wheat grain is important to minimize human dietary Zn deficiency.  This study aimed to investigate the effect of foliar Zn and soil nitrogen (N) applications on the accumulation and distribution of N and Zn in grain pearling fractions, N remobilization, and the relationships between nutrient concentration in the vegetative tissues and grain or its fractions in two cropping years in the North China Plain.  The results showed a progressive decrease in N and Zn concentrations from the outer to the inner parts of grain, with most of the accumulation in the core endosperm.  Foliar Zn application significantly increased N concentration in the pericarp, and soil N application increased N concentration in each grain fraction.  Both treatments significantly increased core endosperm Zn concentration.  Foliar Zn had no effect on grain N and Zn distribution.  Soil N application made N concentrated in the aleurone, promoted Zn translocation to the core endosperm and also increased N remobilization and its efficiency from the shoot to the grain, but no improved contribution to grain was found.  N concentration in grain and its fractions were positively correlated with N in vegetative organs at anthesis and maturity, while positive correlations were obtained between N concentration in the pericarp and progressive central area of the endosperm and Zn concentration in the core endosperm.  Thus, foliar Zn and soil N applications effectively increased yield and N and Zn concentrations in the wheat grain, particularly in the endosperm, and could be promising strategies to address Zn deficiency.
    Characteristics of maize residue decomposition and succession in the bacterial community during decomposition in Northeast China
    ZHAO Shi-cheng, Ignacio A. CIAMPITTI, QIU Shao-jun, XU Xin-peng, HE Ping
    2021, 20(12): 3289-3298.  DOI: 10.1016/S2095-3119(20)63570-5
    Abstract ( )   PDF in ScienceDirect  
    Microbes are decomposers of crop residues, and climatic factors and residue composition are known to influence microbial growth and community composition, which in turn regulate residue decomposition.  However, the succession of the bacterial community during residue decomposition in Northeast China is not well understood.  To clarify the property of bacterial community succession and the corresponding factors regulating this succession, bags containing maize residue were buried in soil in Northeast China in October, and then at different intervals over the next 2 years, samples were analyzed for residue mass and bacterial community composition.  After residue burial in the soil, the cumulative residue mass loss rates were 18, 69, and 77% after 5, 12, and 24 months, respectively.  The release of residue nitrogen, phosphorus, and carbon followed a similar pattern as mass loss, but 79% of residue potassium was released after only 1 month.  The abundance, richness, and community diversity of bacteria in the residue increased rapidly and peaked after 9 or 20 months.  Residue decomposition was mainly influenced by temperature and chemical composition in the early stage, and was influenced by chemical composition in the later stage.  Phyla Actinobacteria, Bacteroidetes, and Firmicutes dominated the bacterial community composition in residue in the early stage, and the abundances of phyla Chloroflexi, Acidobacteria, and Saccharibacteria gradually increased in the later stage of decomposition.  In conclusion, maize residue decomposition in soil was greatly influenced by temperature and residue composition in Northeast China, and the bacterial community shifted from dominance of copiotrophic populations in the early stage to an increase in oligotrophic populations in the later stage. 
    Assembly and co-occurrence patterns of rare and abundant bacterial sub-communities in rice rhizosphere soil under short-term nitrogen deep placement
    LI Gui-long, WU Meng, LI Peng-fa, WEI Shi-ping, LIU Jia, JIANG Chun-yu, LIU Ming, LI Zhong-pei
    2021, 20(12): 3299-3311.  DOI: 10.1016/S2095-3119(20)63462-1
    Abstract ( )   PDF in ScienceDirect  
    Nitrogen (N) deep placement has been found to reduce N leaching and increase N use efficiency in paddy fields.  However, relatively little is known how bacterial consortia, especially abundant and rare taxa, respond to N deep placement, which is critical for understanding the biodiversity and function of agricultural ecosystem.  In this study, Illumina sequencing and ecological models were conducted to examine the diversity patterns and underlying assembly mechanisms of abundant and rare taxa in rice rhizosphere soil under different N fertilization regimes at four rice growth stages in paddy fields.  The results showed that abundant and rare bacteria had distinct distribution patterns in rhizosphere samples.  Abundant bacteria showed ubiquitous distribution; while rare taxa exhibited uneven distribution across all samples.  Stochastic processes dominated community assembly of both abundant and rare bacteria, with dispersal limitation playing a more vital role in abundant bacteria, and undominated processes playing a more important role in rare bacteria.  The N deep placement was associated with a greater influence of dispersal limitation than the broadcast N fertilizer (BN) and no N fertilizer (NN) treatments in abundant and rare taxa of rhizosphere soil; while greater contributions from homogenizing dispersal were observed for BN and NN in rare taxa.  Network analysis indicated that abundant taxa with closer relationships were  usually more likely to occupy the central position of the network than rare taxa.  Nevertheless, most of the keystone species were rare taxa and might have played essential roles in maintaining the network stability.  Overall, these findings highlighted that the ecological mechanisms and co-occurrence patterns of abundant and rare bacteria in rhizosphere soil under N deep placement.
    Fertility and biochemical activity in sodic soils 17 years after reclamation with flue gas desulfurization gypsum
    ZHAO Yong-gan, WANG Shu-juan, LIU Jia, ZHUO Yu-qun, LI Yan, ZHANG Wen-chao
    2021, 20(12): 3312-3321.  DOI: 10.1016/S2095-3119(20)63446-3
    Abstract ( )   PDF in ScienceDirect  
    Previous studies have mainly focused on changes in soil physical and chemical properties to evaluate the reclamation of sodic soils using flue gas desulfurization (FGD) gypsum.  However, information on the effects of this reclamation method on microbial-based indicators of soil quality is limited, particularly after many years of FGD gypsum application.  This study aimed to investigate the long-term effects of FGD gypsum on soil organic carbon (SOC), nutrients, microbial biomass and enzyme activity.  Data were collected from soils of three exchangeable sodium percentage (ESP) classes (i.e., low-, middle- and high-ESP classes of 6.1–20, 20–30 and 30–78.4%, respectively) 17 years after FGD gypsum treatment in Inner Mongolia, China.  Averaged across the three ESP classes, FGD gypsum application increased the SOC contents at the 0–20 and 20–40-cm soil depths by 18 and 35%, respectively, and increased available potassium at the 0–20-cm soil depth by 51% compared with the no-gypsum controls.  The microbial biomass carbon and microbial biomass nitrogen contents at the 20–40-cm soil depth increased by 69 and 194%, respectively, under FGD gypsum.  Except in the high-ESP class, urease activities in the 0–40 cm soil profile were significantly higher in the FGD gypsum treatments than in the controls.  A significant increase in alkaline phosphatase activity was concentrated in the 20–40 cm soil layer; few classes showed significant increases in catalase and invertase activities in the 0–20 cm soil layer.  Pearson correlation analysis showed that increases in soil fertility and biological activity could be attributed to reductions in electrical conductivity, pH and ESP caused by FGD gypsum application.  These results confirm that FGD gypsum application is a viable strategy for reclaiming sodic soils due to its positive effects on soil fertility and biochemistry and that it may contribute to soil ecosystem sustainability.
    Agricultural Economics and Management
    The impact of farmers’ assessments of risk management strategies on their adoption willingness
    SHANG Yan, XIONG Tao
    2021, 20(12): 3323-3338.  DOI: 10.1016/S2095-3119(21)63749-8
    Abstract ( )   PDF in ScienceDirect  
    Farmers’ assessments of risk management strategies and how the assessments influence their willingness to adopt these strategies are poorly understood.  This study conducts a structured survey of 469 farmers to investigate how farmers assess both crop insurance and crop price insurance, the impact of the assessments on their adoption willingness, and in particular, the differences in assessments and adoption willingness between crop insurance and crop price insurance.  Empirical results show that farmers’ assessments on crop insurance can be significantly improved through communication and experience.  The most effective way to improve farmers’ assessments on crop price insurance is providing adequate information about the insurance products.  Furthermore, farmers’ adoption willingness would be enhanced by improved assessment of both crop yield and crop price insurance.  This study provides the first empirical evidence that farmers have limited information to assess insurance, which significantly influences their willingness to adopt.  This finding reflects that the dissemination of insurance policies, the effectiveness of insurance, and the availability of insurance services significantly enable farmers’ ability to assess risk management strategies, which potentially increases farmers’ willingness to adopt insurance.  
    Scale and scope economies in small household rice farming in Vietnam
    Viet-Ngu HOANG, Trung Thanh NGUYEN, Clevo WILSON, Thong Quoc HO, Uttam KHANAL
    2021, 20(12): 3339-3351.  DOI: 10.1016/S2095-3119(21)63612-2
    Abstract ( )   PDF in ScienceDirect  
    The Vietnamese agricultural sector has experienced a dramatic structural change based on increased specialization in rice cultivation.  However, small-scale rice-farmers have continued to grow multiple crops, especially in less developed provinces.  While the literature advocates crop diversification for reasons of both economic and ecological sustainability, there lacks empirical evidence as to whether crop diversification brings efficiency and productivity gains to small farms.  The present study is the first applications of the input-oriented stochastic distance function approach in estimating scale and scope economies using data of multi-crop farming households in Vietnam.  We find strong evidence of product-specific economies of scale.  Scope economies are also present for rice, vegetable, and other annual crop production.  This suggests that crop diversification enhances efficiency and productivity.  However, there still exists significant technical inefficiency in crop production, indicating opportunities to expand farm output at the existing level of inputs and technologies.  More specifically, our empirical results indicate that it is desirable to expand vegetable and other annual crop production in mountainous areas while rice cultivation can be further expanded in delta and coastal regions.