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    Special Focus: Developing sustainable bioenergy in Northwest China
    EDITORIAL- Developing sustainable bioenergy in Northwest China
    CHEN Shao-lin
    2017, 16(06): 1195-1196.  DOI: 10.1016/S2095-3119(17)61656-3
    Abstract ( )   PDF in ScienceDirect  
    This special focus on bioenergy is a product of 2014 and 2016 Yangling International Agri-science Forums held at the Northwest A&F University (NWAFU), Yangling, Shaanxi, China.  The forums brought together scientists over the world to address the challenges and opportunities of developing bioenergy and bio-based economy in China.  It was initiated for recognition of China’s need for developing sustainably produced energy crops in marginal lands and bioenergy and bio-based pro­ducts to support sustainable development.
    Section 1: Modeling of cellulosic bioenergy development
    Modeling the biomass of energy crops: Descriptions, strengths and prospective
    JIANG Rui, WANG Tong-tong, SHAO Jin, GUO Sheng, ZHU Wei, YU Ya-jun, CHEN Shao-lin, HATANO Ryusuke
    2017, 16(06): 1197-1210.  DOI: 10.1016/S2095-3119(16)61592-7
    Abstract ( )   PDF in ScienceDirect  
    The assessment of the biomass of energy crops has garnered widespread interest since renewable bioenergy may become a substantial proportion of the future energy supply, and modeling has been widely used for the simulation of energy crops yields.  A literature survey revealed that 23 models have been developed or adapted for simulating the biomass of energy crops, including Miscanthus, switchgrass, maize, poplar, willow, sugarcane, and Eucalyptus camaldulensis.  Three categories (radiation model, water-controlled crop model, and integrated model with biochemical and photosynthesis and respiration approaches) were addressed for the selected models according to different principles or approaches used to simulate biomass production processes.  EPIC, ALMANAC, APSIM, ISAM, MISCANMOD, MISCANFOR, SILVA, DAYCENT, APEX and SWAT are radiation models based on a radiation use efficiency approach (RUE) with few empirical and statistical parameters.  The AquaCrop model is a typical water-crop model that emphasizes crop water use, the expression of canopy cover, and the separation of evapotranspiration to soil evaporation and plant transpiration to drive crop growth.  CANEGRO, 3PG, CropSyst and DSSAT are integrated models that use photosynthesis and respiration approaches.  SECRETS, LPJmL, Agro-BGC, Agro-IBIS, and WIMOVAC/BioCro, DNDC, DRAINMOD-GRASS, and AgTEM are integrated models that use biochemical approaches.  Integrated models are mainly mechanistic models or combined with functional models, which are dynamic with spatial and temporal patterns but with complex parameters and large amounts of input data.  Energy crop models combined with process-based models, such as EPIC in SWAT and CANEGRO in DSSAT, provide good examples that consider the biophysical, socioeconomic, and environmental responses and address the sustainability and socioeconomic goals for energy crops.  The use of models for energy crop productivity is increasing rapidly and encouraging; however, relevant databases, such as climate, land use/land cover, soil, topography, and management databases, are scarce.  Model structure and design assumptions, as well as input parameters and observed data, remain a challenge for model development and validation.  Thus, a comprehensive framework, which includes a high-quality field database and an uncertainty evaluation system, needs to be established for modeling the biomass of energy crops.
    Section 2: Switchgrass in the Loess Plateau
    Switchgrass as a bioenergy crop in the Loess Plateau, China: Potential lignocellulosic feedstock production and environmental conservation
    Danielle Cooney, Hyemi Kim, Lauren Quinn, Moon-Sub Lee, Jia Guo, CHEN Shao-lin, XU Bing-cheng, D. K. Lee
    2017, 16(06): 1211-1226.  DOI: 10.1016/S2095-3119(16)61587-3
    Abstract ( )   PDF in ScienceDirect  
    A large portion of the Loess Plateau of China is characterized as “marginal” with serious land degradation and desertification problems.  Consequently, two policies, Grain for Green and Western Development Action were established by the Chinese government in response to the demand for ecological protection and economic development in the Loess Plateau.  These policies are designed to increase forest cover, expand farmlands, and enhance soil and water conservation, while creating sustainable vegetation restoration.  Perennial grasses have gained attention as bioenergy feedstocks due to their high biomass yields, low inputs, and greater ecosystem services compared to annual crops.  Moreover, perennial grasses limit nutrient runoff and reduce greenhouse gas emissions and soil losses while sequestering carbon.  Additionally, perennial grasses can generate economic returns for local farmers through producing bioenergy feedstock or forage on marginal lands.  Here, we suggest a United States model energy crop, switchgrass (Panicum virgatum L.) as a model crop to minimize land degradation and desertification and to generate biomass for energy on the Loess Plateau.
    Photosynthetic performance of switchgrass and its relation to field productivity: A three-year experimental appraisal in semiarid Loess Plateau
    GAO Zhi-juan, LIU Jin-biao, AN Qin-qin, WANG Zhi, CHEN Shao-lin, XU Bing-cheng
    2017, 16(06): 1227-1235.  DOI: 10.1016/S2095-3119(16)61397-7
    Abstract ( )   PDF in ScienceDirect  
    To reveal photosynthetic characteristics and biomass yield is important for evaluating introduced species adaptation to local environments.  A field experiment was conducted over three consecutive years (2011–2013) to evaluate photosynthetic characteristics, soil water content, aboveground biomass accumulation, and water use efficiency (WUE) in switchgrass (Panicum virgatum L.) populations exposed to three row spacing (20, 40 and 60 cm) treatments in two growth months (June and August) on the semiarid Loess Plateau of China.  Results indicated that net photosynthetic rate (Pn), transpiration rate (Tr), instantaneous water use efficiency (WUEi) and plant height of switchgrass showed an increased trend, but aboveground biomass production and WUE showed an decreased trend with enlarged row spacings over the three years.  The maximum daily mean Pn values (17.9, 18.4 and 19.7 µmol CO2 m–2 s–1) were observed in 2011, and the highest aboveground biomass production (67 771.8, 6 976.8 and 6 609.2 kg ha–1) were recorded in 2012 for 20, 40 and 60 cm, respectively.  A close correlation between tiller numbers and aboveground biomass production (r=0.907) was observed.  Pn was positively and significantly correlated with biomass per tiller, but it showed a negative correlation with aboveground biomass production.  Our results confirm that wide row spacing is beneficial for single plant development, while narrow row spacing favors biomass production and water use of switchgrass in the region.  It also implies that single leaf growth and performance could explain the switchgrass community density differences, while fails to account for the aboveground biomass production.
    Section 3: Improvement of energy crops for arid and semi-lands
    Sweet sorghum and Miscanthus: Two potential dedicated bioenergy crops in China
    HU Shi-wei, WU Lei-ming, Staffan Persson, PENG Liang-cai, FENG Sheng-qiu
    2017, 16(06): 1236-1243.  DOI: 10.1016/S2095-3119(15)61181-9
    Abstract ( )   PDF in ScienceDirect  
    Among the potential non-food energy crops, the sugar-rich C4 grass sweet sorghum and the biomass-rich Miscanthus are increasingly considered as two leading candidates.  Here, we outline the biological traits of these energy crops for large-scale production in China.  We also review recent progress on understanding of plant cell wall composition and wall polymer features of both plant species from large populations that affect both biomass enzymatic digestibility and ethanol conversion rates under various pretreatment conditions.  We finally propose genetic approaches to enhance biomass production, enzymatic digestibility and sugar-ethanol conversion efficiency of the energy crops.
    The molecular mechanism of shade avoidance in crops- How data from Arabidopsis can help to identify targets for increasing yield and biomass production
    TANG Yun-jia, Johannes Liesche
    2017, 16(06): 1244-1255.  DOI: 10.1016/S2095-3119(16)61434-X
    Abstract ( )   PDF in ScienceDirect  
    In order to prevent or counteract shading, plants enact a complex set of growth and developmental adaptations when they sense a change in light quality caused by other plants in their vicinity.  This shade avoidance response (SAR) typically includes increased stem elongation at the expense of plant fitness and yield, making it an undesirable trait in an agricultural context.  Manipulating the molecular factors involved in SAR can potentially improve productivity by increasing tolerance to higher planting density.  However, most of the investigations of the molecular mechanism of SAR have been carried out in Arabidopsis thaliana, and it is presently unclear in how far results of these investigations apply to crop plants.  In this review, current data on SAR in crop plants, especially from members of the Solanaceae and Poaceae families, are integrated with data from Arabidopsis, in order to identify the most promising targets for biotechnological approaches.  Phytochromes, which detect the change in light caused by neighboring plants, and early signaling components can be targeted to increase plant productivity.  However, they control various photomorphogenic processes not necessarily related to shade avoidance.  Transcription factors involved in SAR signaling could be better targets to specifically enhance or suppress SAR.  Knowledge integration from Arabidopsis and crop plants also indicates factors that could facilitate the control of specific aspects of SAR.  Candidates are provided for the regulation of plant architecture, flowering induction and carbohydrate allocation.  Yet to-be-elucidated factors that control SAR-dependent changes in biotic resistance and cell wall composition are pointed out.  This review also includes an analysis of publicly available gene expression data for maize to augment the sparse molecular data available for this important species.
    Section 4: Analysis of cellulosic ciomass
    The application of Fourier transform mid-infrared (FTIR) spectroscopy to identify variation in cell wall composition of Setaria italica ecotypes
    Christopher Brown, Antony P. Martin, Christopher P. L. Grof
    2017, 16(06): 1256-1267.  DOI: 10.1016/S2095-3119(16)61574-5
    Abstract ( )   PDF in ScienceDirect  
    Cell wall composition in monocotyledonous grasses has been identified as a key area of research for developing better feedstocks for forage and biofuel production.  Setaria viridis and its close domesticated relative Setaria italica have been chosen as suitable monocotyledonous models for plants possessing the C4 pathway of photosynthesis including sorghum, maize, sugarcane, switchgrass and Miscanthus×giganteus.  Accurate partial least squares regression (PLSR) models to predict S. italica stem composition have been generated, based upon Fourier transform mid-infrared (FTIR) spectra and calibrated with wet chemistry determinations of ground S. italica stem material measured using a modified version of the US National Renewable Energy Laboratory (NREL) acid hydrolysis protocol.  The models facilitated a high-throughput screening analysis for glucan, xylan, Klason lignin and acid soluble lignin (ASL) in a collection of 183 natural S. italica variants and clustered them into classes, some possessing unique chemotypes.  The predictive models provide a highly efficient screening tool for large scale breeding programs aimed at identifying lines or mutants possessing unique cell wall chemotypes.  Genes encoding key catalytic enzymes of the lignin biosynthesis pathway exhibit a high level of conservation with matching expression profiles, measured by RT-qPCR, among accessions of S. italica, which closely mirror profiles observed in the different developmental regions of an elongating internode of S. viridis by RNASeq.
    Effects of protein and lignin on cellulose and xylan anaylses of lignocellulosic biomass
    James MacLellan, Rui Chen, Zhengbo Yue, Robert Kraemer, Yan Liu, Wei Liao
    2017, 16(06): 1268-1275.  DOI: 10.1016/S2095-3119(15)61142-X
    Abstract ( )   PDF in ScienceDirect  
    Interactions of lignocellulosic components during fiber analysis were investigated using the highly adopted compositional analysis procedure from the National Renewable Energy Laboratory (NREL), USA.  Synthetic feedstock samples were used to study the effects of lignin/protein, cellulose/protein, and xylan/protein interaction on carbohydrate analysis.  Disregarding structural influence in the synthetic samples, lignin and protein components were the most significant (P<0.05) factors on cellulose analysis.  Measured xylan was consistent and unaffected by content variation throughout the synthetic analysis.  Validation of the observed relationships from synthetic feedstocks was fulfilled using real lignocellulosic feedstocks: corn stover, poplar, and alfalfa, in which similar results have been obtained, excluding cellulose analysis of poplar under higher protein content and xylan analysis of alfalfa under higher protein content.  The results elucidated that according to their protein and lignin contents of different lignocellulosic materials, accuracy of the NREL method on cellulose and xylan analyses could be improved by applying a stronger extraction step to replace water/ethanol extraction.
    Section 5: Bioconversion and bioprocess
    In-depth observations of fermentative hydrogen production from liquid swine manure using an anaerobic sequencing batch reactor
    Xiao Wu, Jun Zhu, Hongjian Lin
    2017, 16(06): 1276-1285.  DOI: 10.1016/S2095-3119(15)61108-X
    Abstract ( )   PDF in ScienceDirect  
    In this study, experiments were designed to reveal in-depth information of the effect of pH and hydraulic retention time (HRT) on biohydrogen fermentation from liquid swine manure supplemented with glucose using an Anaerobic Sequencing Batch Reactor (ASBR) System.  Five values of HRT (8, 12, 16, 20, and 24 h) were first tested and the best HRT determined was further studied at five pH levels (4.4, 4.7, 5.0, 5.3, and 5.6).  The results showed that for HRT 24 h, there was a dividing H2 content (around 37%) related to the total biogas production rate for the ASBR System running at pH 5.0.  When the H2 content went beyond 37%, an appreciable decline in biogas production rate was observed, implying that there might exist an H2 content limit in the biogas.  For other HRTs (8 through 20 h), an average H2 content of 42% could be achieved.  In the second experiment (HRT 12 h), the highest H2 content (35%) in the biogas was found to be associated with pH 5.0.  The upswing of pH from 5.0 to 5.6 had a significantly more impact on biogas H2 content than the downswing of pH from 5.0 to 4.3.  The results also indicated good linear relationships of biogas and H2 production rates with HRT (r=0.9971 and 0.9967, respectively).  Since the optimal ASBR operating conditions were different for the biogas/H2 production rates and the H2 yield, a compromised combination of the running parameters was determined to be HRT 12 h and pH 5.0 in order to achieve good biogas/H2 productions.  
    Crop Genetics · Breeding · Germplasm Resources
    BRITTLE CULM16 (BRITTLE NODE) is required for the formation of secondary cell walls in rice nodes
    WANG Ying, REN Yu-long, CHEN Sai-hua, XU Yang, ZHOU Kun-neng, ZHANG Long, MING Ming, WU Fu-qing, LIN Qi-bing, WANG Jiu-lin, GUO Xiu-ping, ZHANG Xin, LEI Cai-lin, CHENG Zhi-jun, WAN Jian-min
    2017, 16(06): 1286-1293.  DOI: 10.1016/S2095-3119(16)61536-8
    Abstract ( )   PDF in ScienceDirect  
    Plant cell walls constitute the skeletal structures of plant bodies, and thus confer lodging resistance for grain crops.  While the basic cell wall synthesis machinery is relatively well established now, our understanding of how the process is regulated remains limited and fragmented.  In this study, we report the identification and characterization of the novel rice (Oryza sativa L.) brittle culm16 (brittle node; bc16) mutant.  The brittle node phenotype of the bc16 mutant appears exclusively at nodes, and resembles the previously reported bc5 mutant.  Combined histochemical staining and electron microscopy assays revealed that in the bc16 mutant, the secondary cell wall formation and thickening of node sclerenchyma tissues are seriously affected after heading.  Furthermore, cell wall composition assays revealed that the bc16 mutation led to a significant reduction in cellulose and lignin contents.  Using a map-based cloning approach, the bc16 locus is mapped to an approximately 1.7-Mb region of chromosome 4.  Together, our findings strengthen evidence for discretely spatial differences in the secondary cell wall formation within plant bodies.
    The allelic distribution and variation analysis of the NAM-B1 gene in Chinese wheat cultivars
    CHEN Xue-yan, SONG Guo-qi, ZHANG Shu-juan, LI Yu-lian, GAO Jie, Islam Shahidul, MA Wu-jun, LI Gen-ying, JI Wan-quan
    2017, 16(06): 1294-1303.  DOI: 10.1016/S2095-3119(16)61459-4
    Abstract ( )   PDF in ScienceDirect  
    The NAM-B1 gene is a member of the NAC (NAM, ATAF, and CUC) transcription factor family and plays an important role in regulating wheat grain protein content (GPC).  The ancestral NAM-B1 allele has been discovered in many tetraploid wild emmer (Triticum turgidum ssp. dicoccoides) accessions and few domesticated emmer accessions (T. turgidum ssp. dicoccum), however, it is rarely found in hexaploid bread wheat (Triticum aestivum L.).  There are no systematic reports on the distribution of NAM-B1 alleles in Chinese wheat cultivars.  In this study, the NAM-B1 alleles in 218 Chinese cultivars were investigated.  The cultivars were collected from five major wheat regions (12 provinces), covering most of the winter wheat growing regions in China.  The results showed that the NAM-B1 gene is present in 53 (24.3%) cultivars and absent in the remaining 165 (75.7%) cultivars.  Further analysis revealed that in contrast to the wild-type allele, the NAM-B1 gene in Chinese wheat cultivars contained a 1-bp insertion in the coding region.  This caused a frame-shift mutation and introduced a stop codon in the middle of the gene, rendering it non-functional.  Polymorphisms were detected in DNA sequences of 21 cultivars among these 53 cultivars.  However, cDNA sequence analysis suggested that these variations in the exon region were not able to restore NAM-B1 gene (1-bp insertion) function.  Thus, exploring the distribution of NAM-B1 gene variations (1-bp insertion and deletion) can provide some information for improving the quality of winter wheat in China and other countries.
    Agronomic characterization and genetic analysis of the supernume­r­ary spikelet in tetraploid wheat (Triticum turgidum L.)
    ZHANG Rui-qi, HOU Fu, CHEN Juan, CHEN Shu-lin, XING Li-ping, FENG Yi-gao, CAO Ai-zhong
    2017, 16(06): 1304-1311.  DOI: 10.1016/S2095-3119(16)61469-7
    Abstract ( )   PDF in ScienceDirect  
    The supernumerary spikelets (SS) characters of tetraploid wheat (Triticum turgidum L.) resulting in more spikelets and kernels per spike, thus enhancing sink capacity may contribute to potential wheat yield improvement.  In order to investigate the effect of different SS types on agronomic characters and understand the genetic base of SS phenotype in tetraploid wheat, near isogenic lines (NILs), bh-50 with normal spikelets (NS), bh-51 with four-rowed spikelets (FRS), bh-52 with short-ramified spikelets (SRS), and bh-53 with long-ramified spikelets (LRS) in a Triticum durum cv. ZY1286 genetic background were developed by continuous backcrossing.  Agronomic characters showed that the SS phenotype lines, bh-51, bh-52 and bh-53 have significant increase in the number of spikelets and grains per spike compared with the NS phenotype line bh-50 (P<0.05), and bh-53 line showed much more increase than those of bh-51 and bh-52.  However, bh-53 had the lowest grain weight and the longest spike development stage than those of other spike phenotypes.  These results indicated that the different SS types have different effects on the agronomic and spike characters.  Genetic analysis through bh-50/bh-51 and bh-51/bh-53 F2 populations showed that a recessive major gene controlled the spike architecture to transform from NS to FRS, and a dominant major gene determined the change of spike phenotype from FRS to RS.  DNA sequences of TtBH/WFZP ortholog on chromosome 2AS revealed that a single nucleotide polymorphism (SNP) substitution happened in the open reading frame (ORF) region of all the SS tetraploid wheat accessions, which may lead to the generation of lateral meristems between glume and lemma during the immature spike development.  While the fates of the lateral meristems, developing into lateral spikelets or branched spikelets, may be determined by another major gene.  Our results presented here may advance our understanding and knowledge of the genes and genetic pathways determining the spike architecture development in wheat.
    Relationship between population competitive intensity and yield in maize cultivars
    ZHAI Li-chao, XIE Rui-zhi, LI Shao-kun, FAN Pan-pan
    2017, 16(06): 1312-1321.  DOI: 10.1016/S2095-3119(16)61541-1
    Abstract ( )   PDF in ScienceDirect  
    Competition is a common phenomenon in agriculture production.  Research on the relationship between competitive ability and crop yield is extensive, but the results have been inconsistent.  Few studies have focused on the relationship between population competitive intensity and yield of maize (Zea mays L.) cultivars.  The main objective of this study was to determine if a consistent relationship exists between maize yield and competitive ability.  A two-year field experiment was conducted, employing a de Wit replacement series design.  When two maize cultivars were grown in a mixture, yield was reduced for the modern cultivar and increased for the older cultivar.  In each replacement series, per plant level yield of each cultivar, and population level yield of the mixture, decreased with increasing proportion of the older cultivar.  Competitive ratio (CR) reflected differences in competitive ability of the three maize cultivars.  In each replacement series, population competition pressure (PCP) increased with increasing proportion of the older cultivar, indicating that the older cultivar was a strong competitor.  Biomass yield, grain yield, harvest index, thousand-kernel weight, and kernel number per plant, were negatively correlated with PCP.  Our results demonstrated that inter-cultivar competition affects maize productivity, and increasing PCP will decrease translocation of assimilates to grain and, ultimately, reduce yield.  Therefore, there is a negative correlation between population competitive intensity and yield performance in maize, breeders should develop a communal ideotype that would not perform well in competition in future. 
    The effects of sowing date on cottonseed properties at different fruiting-branch positions
    HU Wei, CHEN Mei-li, ZHAO Wen-qing, CHEN Bing-lin, WANG You-hua, WANG Shan-shan, MENG Ya-li, ZHOU Zhi-guo
    2017, 16(06): 1322-1330.  DOI: 10.1016/S2095-3119(16)61537-X
    Abstract ( )   PDF in ScienceDirect  
    A two-year field experiment was conducted to illustrate the effects of sowing date on cottonseed properties at different fruiting-branch positions (FBPs).  Two cotton cultivars (Kemian 1 and Sumian 15) were sowed on 25 April, 25 May, and 10 June in 2010 and 2011, respectively.  The boll maturation period increased with the delaying of sowing date.  Normal sowing treatment (25 April) had higher seed weight, embryo weight, embryo oil content and protein content than late sowing treatments (25 May and 10 June).  The flowering date, seed weight, embryo weight, embryo oil and protein contents, and the dynamic changes of embryo oil and protein contents were altered by different FBPs.  A significant interaction of sowing date×FBP was observed on embryo weight, embryo oil content, embryo protein content and the dynamic changes of embryo oil and protein contents, but was not observed on seed weight.  Seed weight, embryo weight, embryo oil and protein content had significant positive correlations with the mean daily temperature (MDT), mean daily maximum temperature (MDTmax), mean daily minimum temperature (MDTmin), and mean daily solar radiation (MDSR), indicating that temperature and light resources were the main reasons for different sowing dates affecting the cottonseed properties at different FBPs.  Moreover, the difference in MDT was the main difference in climatic factors among different sowing dates.
    Shade adaptive response and yield analysis of different soybean genotypes in relay intercropping systems
    WU Yu-shan, YANG Feng, GONG Wan-zhuo, Shoaib Ahmed, FAN Yuan-fang, WU Xiao-ling, YONG Tai-wen, LIU Wei-guo, SHU Kai, LIU Jiang, DU Jun-bo, YANG Wen-yu
    2017, 16(06): 1331-1340.  DOI: 10.1016/S2095-3119(16)61525-3
    Abstract ( )   PDF in ScienceDirect  
    Soybean is one of the major oil seed crops, which is usually intercropped with other crops to increase soybean production area and yield.  However, soybean is highly sensitive to shading.  It is unclear if soybean morphology responds to shading (i.e., shade tolerance or avoidance) and which features may be suitable as screening materials in relay strip intercropping.  Therefore, in this study, various agronomic characteristics of different soybean genotypes were analyzed under relay intercropping conditions.  The soybean materials used in this study exhibited genetic diversity, and the coefficient of variations of the agronomic parameters ranged from 13.84 to 72.08% during the shade period and from 6.44 to 52.49% during the maturity period.  The ratios of shading to full irradiance in stem mass fraction (SMF) were almost greater than 1, whereas opposite results were found in the leaves.  Compared with full irradiance, the average stem length (SL), leaf area ratio (LAR) and specific leaf area (SLA) for the two years (2013 and 2014) increased by 0.78, 0.47 and 0.65 under shady conditions, respectively.  However, the stem diameter (SD), total biomass (TB), leaf area (LA), number of nodes (NN) on the main stem, and number of branches (BN) all decreased.  During the shady period, the SL and SMF exhibited a significant negative correlation with yield, and the SD exhibited a significant positive correlation with yield.  The correlation between the soybean yield and agronomic parameters during the mature period, except for SL, the first pod height (FPH), 100-seed weight (100-SW), and reproductive growth period (RGP), were significant (P<0.01), especially for seed weight per branch (SWB), pods per plant (PP), BN, and vegetative growth period (VGP).  These results provide an insight into screening the shade tolerance of soybean varieties and can be useful in targeted breeding programs of relay intercropped soybeans.  
    Plant Protection
    Effect of acid phosphatase produced by Trichoderma asperellum Q1 on growth of Arabidopsis under salt stress
    ZHAO Lei, LIU Qun, ZHANG Ya-qing, CUI Qing-yu, LIANG Yuan-cun
    2017, 16(06): 1341-1346.  DOI: 10.1016/S2095-3119(16)61490-9
    Abstract ( )   PDF in ScienceDirect  
    Salt stress is a major environmental factor that inhibits crop growth.  Trichoderma spp. are the most efficient biocontrol fungi and some of the strains can stimulate plant growth.  Phosphate solubilization is known as one of the main mechanisms in promoting plant growth, but the underlying mechanisms of phosphate solubilization in the salinity still need to be explored.  The Trichoderma asperellum Q1 isolated and identified in our lab is a beneficial rhizosphere biocontrol fungus with a high phosphate solubilization activity.  It could produce acid and alkaline phosphatases when using insoluble organic phosphorus as the sole phosphorus source, the salt stress increased the phosphorus-solubilization ability of the strain and the activities of the two enzymes.  Furthermore, an acid phosphatase was purified from the fermentation broth by ammonium sulphate precipitation, ion-exchange, and gel filtration chromatography.  Its molecular weight was 55 kDa as determined by SDS-PAGE.  The purified acid phosphatase was used to investigate growth performance of Arabidopsis thaliana by plate assay and the result showed that it contributed to Arabidopsis growth by transforming organic phosphate into a soluble inorganic form under salt stress.  To our knowledge, this is the first report on acid phosphatase purification from T. asperellum and its function in regulation of plant growth under salt stress.
    Field evaluation of Streptomyces rubrogriseus HDZ-9-47 for biocontrol of Meloidogyne incognita on tomato
    JIN Na, XUE Hui* LI Wen-jing, WANG Xue-yan, LIU Qian, LIU Shu-sen, LIU Pei, ZHAO Jian-long, JIAN Heng
    2017, 16(06): 1347-1357.  DOI: 10.1016/S2095-3119(16)61553-8
    Abstract ( )   PDF in ScienceDirect  
    Streptomyces rubrogriseus HDZ-9-47, isolated from eggs of Meloidogyne spp., was evaluated as a potential biocontrol agent of Meloidogyne incognita under in vitro and protective field.  Microscopic observations showed that HDZ-9-47 parasitized eggs of M. incognita within 7 days.  In vitro, the culture filtrate of HDZ-9-47 caused 97.0% mortality of second-stage juveniles (J2s) of M. incognita and inhibited more than 50% egg hatching.  In the field, compared with the control, the root-knot index and J2s density in the treatment of drench the broth contained 1012 HDZ-9-47 spores were respectively reduced by 51.1 and 80.7% at 90 days post transplantation, which were better than that in other application doses and methods.  In addition, reduction rates of root-knot index and J2s density of the treatment of combined application of HDZ-9-47 with biofumigation was 87.1 and 91.0%, respectively, better than either of HDZ-9-47 or biofumigation used alone or fosthiazate treatment.  And tomato yield also increased by 16.1%.  Together, our results suggest that HDZ-9-47 could be an effective biocontrol agent of M. incognita, and that application of HDZ-9-47 combined with cabbage residue biofumigation was a promising and sustainable option for M. incognita control.
    High-level expression and purification of Plutella xylostella acetylcholinesterase in Pichia pastoris and its potential application
    LIU Niu, CHE Jun, LAI Duo, WEN Jin-jun, XU Han-hong
    2017, 16(06): 1358-1366.  DOI: 10.1016/S2095-3119(16)61508-3
    Abstract ( )   PDF in ScienceDirect  
    The acetylcholinesterase 2 (AChE2) cloned from Plutella xylostella was first successfully expressed in methylotrophic yeast Pichia pastoris GS115.  One transformant with high-level expression of the recombinant AChE (rAChE, 23.2 U mL–1 in supernatant) was selected by plating on increasing concentrations of antibiotic G418 and by using a simple and specific chromogenic reaction with indoxyl acetate as a substrate.  The maximum production of rAChE reached about 11.8 mg of the enzyme protein per liter of culture.  The rAChE was ?rst precipitated with ammonium sulfate (50% saturation) and then puri?ed with procainamide af?nity column chromatography.  The enzyme was puri?ed 12.1-fold with a yield of 22.8% and a high speci?c activity of 448.3 U mg–1.  It was sensitive to inhibition by methamidophos and pirimicarb, the calculated 50% inhibitory concentration (IC50) values of the two pesticides were 0.357 and 0.888 mg L–1, respectively, and the calculated 70% inhibitory concentration (IC70) values were 0.521 and 0.839 mg L–1, respectively.  The results suggested that it has a potential application in the detection of pesticide residues.
    Animal Science · Veterinary Science
    Molecular characterization and tissue expression profile of the Dnmts gene family in pig
    LUO Zong-gang, ZHANG Kai, CHEN Lei, YANG Yuan-xin, FU Peng-hui, WANG Ke-tian, WANG Ling, LI Ming-zhou, LI Xue-wei, ZUO Fu-yuan, WANG Jin-yong
    2017, 16(06): 1367-1374.  DOI: 10.1016/S2095-3119(16)61512-5
    Abstract ( )   PDF in ScienceDirect  
    DNA methyltransferases (Dnmts) comprise a family of proteins which involved in the establishment and maintenance of DNA methylation patterns.  In pig, the molecular characterization and tissue expression profile of Dnmt gene family are not clear.  To solve this problem, reverse transcriptase PCR and rapid amplification of cDNA ends were used to clone the sequences of the porcine Dnmt2 and Dnmt3b genes.  Furthermore, the mRNA expression profiles of Dnmt1, Dnmt2, Dnmt3a and Dnmt3b genes from 54 adult tissues and 2 entire fetuses of Rongchang pig were analyzed by quantitative real-time PCR (qRT-PCR).  As a result, the lengths of porcine Dnmt2 and Dnmt3b gene cDNAs were 1 227 and 2 559 bp with cytosine-C5 specific DNA methylase domain, respectively.  The four Dnmt genes were highly expressed in longissimus dorsi muscle (P<0.01).  Dnmt1 is highly expressed in heart (P<0.01) and Dnmt 2 shows its preference in liver and seminal vesicle tissue (P<0.01).  Dnmt3a and Dnmt3b are highly expressed in the two fetus stages (P<0.01).  All these results suggested that each gene has its specific expression profile, and deeper study is required to dig more details between the methylation level and Dnmt family mRNA expressions in different tissues.
    Effects of different feeding methods and space allowance on the growth performance, individual and social behaviors of Holstein calves
    DONG Li-feng, XU Xian-cha, ZHANG Nai-feng, TU Yan, DIAO Qi-yu
    2017, 16(06): 1375-1382.  DOI: 10.1016/S2095-3119(16)61484-3
    Abstract ( )   PDF in ScienceDirect  
    The importance of nutrient provisions and weaning methods for calves has been well established over the past few years, while as increasing interest has focused on contribution of animal behavior and their overall performance in production regimes.  The present study investigated the effects of feeding methods and space allowance on growth performance, individual and social behaviors in Holstein calves.  Twenty-four Chinese Holstein male and female calves were allocated to either an individual or group of 6 and fed either with a bucket or a teat.  Milk replacer, calf starter, and Chinese wildrye were offered during the experiment.  A fecal index used in the present study was defined as the total fecal scores/total number of calves in each treatment.  The results showed that there was no significant difference among the 4 treatments in terms of feed intake, body weight, average daily gain, and fecal index.  For the feeding behaviors, the ingesting milk time and ingesting milk rate were significantly affected by space allowance, while the feeding methods showed a significant influence on the bunting behavior of the calves.  There was no significant difference among the 4 treatments in terms of licking fixtures, self-grooming, and lying down behaviors, irrespective of the feeding method or space allowance.  However, sucking an empty bucket or the teat was significantly affected by the feeding method.  Several selected group behaviors were examined in the present study, and similar values for sniffing the other calves, social grooming, and cross-sucking behaviors were observed.  Overall, the present study demonstrated that different feeding methods and space allowances had a significant effect on the feeding behavior of calves, while the feed intake, growth performance, health condition, individual and group social behaviors were not significantly influenced.  Furthermore, under intensified production systems, Holstein calves raised in a group may obtain a similar production performance, thus reducing management input and profitability compared with those kept individually.  However, there may be competition during the feeding period.
    Effects of different proportions of two Bacillus sp. on the growth performance, small intestinal morphology, caecal microbiota and plasma biochemical profile of Chinese Huainan Partridge Shank chickens
    YANG Jia-jun, QIAN Kun, WU Dong, ZHANG Wei, WU Yi-jing, XU Ya-yuan
    2017, 16(06): 1383-1392.  DOI: 10.1016/S2095-3119(16)61510-1
    Abstract ( )   PDF in ScienceDirect  
    A total of 900 one-d-old Chinese Huainan Partridge Shank chickens were randomly allocated into nine groups with five replicates of 20 each.  Birds were fed with basal diet, basal diet supplemented with 150 mg kg–1 aureomycin, basal diet supplemented with different proportions of Bacillus licheniformis and Bacillus subtilis, which was 0:1.0×106, 2.5×105:7.5×105, 3.3×105:6.6×105, 5.0×105:5.0×105, 6.6×105:3.3×105, 7.5×105:2.5×105 and 1.0×106:0, respectively.  The duration of the experiment was 56 d.  The results indicated that dietary supplementation of 6.6×105:3.3×105 of B. lichenifornis:B. subtilis improved final body weight, increased the average daily gain, and reduced feed/gain ratio (P<0.05).  The numbers of total Lactobacillus and Bifidobacterium sp. in the caecum significantly increased, and the numbers of Escherichia coli and Salmonella sp. significantly declined compared to that of the control (P<0.05).  Intestinal villous height and villous height to crypt depth ratio of the duodenum, jejunum, and ileum were significantly higher than that of the control, and intestinal crypt depth of the duodenum and ileum was significantly lower (P<0.05).  The total antioxidant capacity, total superoxide dismutase, and glutathione peroxidase ability in plasma significantly improved, while the malondialdehyde concentration in plasma decreased (P<0.05).  Compared to the control, plasma concentrations of ammonia, uric acid and urea nitrogen and the activity of xanthine oxidase were reduced (P<0.05).  In conclusion, an inclusion of 6.6×105:3.3×105 of B. licheniformis: B. subtilis to the diet improved the growth performance, caecal microbiota, plasma biochemical profile, and significantly improved the small intestine morphology, while reducing the mortality rate. 
    Agricultural Economics And Management
    Modeling the effects of urbanization on grain production and consumption in China
    LU Wen-cong, Chen Ning-lu, Qian Wen-xin
    2017, 16(06): 1393-1405.  DOI: 10.1016/S2095-3119(16)61602-7
    Abstract ( )   PDF in ScienceDirect  
    The impact of rapid urbanization on food security of China has received considerable attention.  It is not clear whether China can strike a balance between urbanization and food security, especially grain security.  There have been numerous studies examining the effects of urbanization on grain production or consumption, but few studies have yet analyzed grain balances.  Based on the Chinese World Agricultural Regional Market Equilibrium Model (CWARMEM), this paper explores the impacts of urbanization on national and regional grain balances through different scenarios.  The CWARMEM is a global partial equilibrium multimarket model which captures the differences between urban and rural residents as well as the effects of globalization.  The results show that urbanization has a small negative effect on maintaining grain self-sufficiency.  Despite of that, China is able to achieve the objective of grain security set by its policymakers.  Moreover, urbanization changes regional grain balances across China: The position of Northeast China and North China, as two dominant grain suppliers of China, will be weaken; Central China and East China will increase dependence on other grain suppliers; the grain surplus of Northwest China will increase slightly.  Besides, in terms of grain category, urbanization helps China achieve self-sufficiency in food grain (rice and wheat), while expands deficit of feed grain (maize).
    Factors influencing farmers’ participation in crop intensification program in Rwanda
    Alphonse Nahayo, Morris O. Omondi, ZHANG Xu-hui, LI Lian-qing, PAN Gen-xing, Stephen Joseph
    2017, 16(06): 1406-1416.  DOI: 10.1016/S2095-3119(16)61555-1
    Abstract ( )   PDF in ScienceDirect  
    The crop intensification program (CIP) was introduced in Rwanda in 2007 by the Ministry of Agriculture and Animal Resources (MINAGRI), Rwanda, as a solution to the land fragmentation, low use of agricultural inputs and low access to extension services.  However, due to the voluntary nature of farmers’ participation and their reluctance to participate, this study aimed at assessing the factors that influence their participation.  Data were collected from 340 respondents through a household survey in Mayange and Rusarabuye sectors.  Descriptive statistics and binary logistic regression model were used to analyze the data.  Results show that the factors that significantly influenced the farmers’ participation in the CIP include gender, non-farm income, farmland size, farming experience, land acquisition means, market access, trust and agro-ecological conditions.  In fact, the non-farm income significantly increased the farmers’ decisions to participate in the CIP (P<0.001) as it eases the financial capital needed to invest in the CIP activities.  On the land acquisition means, the farmers who inherited or bought the land positively and significantly participated in the CIP (P<0.05) because they had the land tenure security.  However, the participation in the CIP was hindered by inadequate irrigation and mechanization facilities, lack of farmers’ participation in the CIP planning process, inadequate extension services, inadequate agricultural inputs and inadequate post-harvest technologies.  Closer collaboration between farmers, local leaders, extension agents and agricultural service providers as well as the farmers’ practical skills in irrigation and mechanization could enhance the participation to the program.  Therefore, there is a need on the part of policymakers to empower farmers with adequate knowledge on better cropping practices and agricultural technologies through appropriate extension services and bottom-up based program.
    Short Communication
    Analysis of fig tree virus type and distribution in China
    Mahmut Mijit HE Zhen, HONG Jian, LU Mei-guang, LI Shi-fang, ZHANG Zhi-xiang
    2017, 16(06): 1417-1421.  DOI: 10.1016/S2095-3119(16)61551-4
    Abstract ( )   PDF in ScienceDirect  
    The common fig (Ficus carica L.) was one of the earliest horticultural crops to be domesticated.  A number of different viruses can infect fig trees including Fig mosaic virus (FMV) that has been detected in several commercial fig trees in Xinjiang, China.  However, the distribution of FMV and other fig-infecting viruses in China remains unknown.  In the present study, a sample from an ancient fig tree growing in Xinjiang was investigated by electron microscopy (EM) followed by PCR/RT-PCR, and FMV, Fig badnavirus 1 (FBV-1) and Fig leaf mottle-associated virus 1 (FLMaV-1) were detected.  Fig leaf samples (252) from commercial orchards across China were subjected to PCR/RT-PCR, and FMV, FBV-1 and Fig fleck-associated virus (FFkaV) were relatively abundant (44.4, 48.4 and 44%, respectively), while FLMaV-1 and Fig mild mottle-associated virus (FMMaV) were much scarcer (5.6 and 0.4%, respectively), and FLMaV-2, Fig cryptic virus (FCV), and Fig latent virus (FLV) were not detected.  The presence of disease-causing viruses in fig trees presents a significant challenge for fig producers in China.  This study may help to promote actions aimed at controlling fig viruses, especially FMV.