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    Crop Genetics · Breeding · Germplasm Resources
    Genetic Analysis and Mapping of an Enclosed Panicle Mutant Locus esp1 in Rice (Oryza sativa L.)
    DUAN Yuan-lin, GUAN Hua-zhong, ZHUO Ming, CHEN Zhi-wei, LI Wen-tao, PAN Run-sen, MAO Da-mei, ZHOU Yuan-chang, WU Wei-ren
    2012, 12(12): 1933-1939.  DOI: 10.1016/S1671-2927(00)8729
    Abstract ( )   PDF in ScienceDirect  
    A mutant was isolated from the M2 of 60Co-g ray mutagenized male-fertility restorer line Zao-R974 in rice. The mutant showed pleiotropic phenotypes including dwarfism, delayed heading time, short and partially enclosed panicles, short uppermost internode, decreased grain and secondary branch numbers per panicle, and partially degenerated spikelets. The mutant was named as esp1 (enclosed shorter panicle 1). Genetic analysis indicated that the mutant phenotype was controlled by a recessive locus. Spraying exogenous GA3 did not rescue the panicle enclosure. Using an F2 and a BC1 population of the cross between esp1 and a japonica cultivar Nipponbare, we mapped the ESP1 locus to a region of ~260 kb on chromosome 11. This result provides a basis for further map-based cloning of the ESP1 locus.
    Selection of Submergence Tolerant Homozygous Line by STS Marker and Twice Submergence Stress
    LI Jin-jiang, XIAO You-lun, XIAO Guo-ying
    2012, 12(12): 1940-1947.  DOI: 10.1016/S1671-2927(00)8730
    Abstract ( )   PDF in ScienceDirect  
    One sequence tagged site marker Sub1-1 and twice submergence stress method were used in selection of submergence tolerant homozygous line from Sub-1BS, a submergence tolerant, bentazon sensitive and photoperiod-sensitive and/or thermo-sensitive genic male sterile line that developed by our laboratory. The results revealed that the original Sub-1BS was heterozygous in Sub1A-1 locus even though it was identical in almost all of agronomical traits and the segregation of Sub1A-1 was in accordance with Mendelian law based on chi-square test. And then the original Sub-1BS was divided into two groups: one was of Sub1A-1 introgression and the other was not; and the two groups were tested by twice submergence stress method. After the first submergence stress that lasted for 12 d, the average plant heights were significant difference at the 1% level between the two groups. After recovery for 10 d, the second submergence stress sustained for 18 d was carried on; and the group with Sub1A-1 gene was found apparently tolerant than the other group in submergence tolerance.
    Effects of Papain Hydrolysis on the Pasting Properties of Wheat Flour
    CHEN Jian-sheng, TIAN Ji-chun, DENG Zhi-ying, ZHANG Ying-xiang, FENG Shou-li, YAN Zuo-chen, ZHANG Xin-ye, YUAN Hui-qing
    2012, 12(12): 1948-1957.  DOI: 10.1016/S1671-2927(00)8731
    Abstract ( )   PDF in ScienceDirect  
    As one of the most effective enzymatic modification methods of protein, papain hydrolysis is applied widely in food production, accompanying starch pasting frequently in order to improve industrial quality. Effects of the papain hydrolysis on flour pasting properties were investigated in five papain/flour concentrations and five time-treatments. The structure of starch and protein networks in slurry was investigated under microscope before and after pasting. Results showed that papain hydrolysis influenced the pasting properties of wheat flour significantly through affecting structural characteristics, amylase activity and exothermic transition, especially during the early stage of hydrolysis. Peak viscosity, trough, final, integral area, and setback significantly decreased along with the increasing concentration of papain. Both hydrolysis time and concentration of papain had obviously effect on the breakdown. Pasting temperature and pasting time increased significantly with the enhancement of papain concentration. Hydrolysis time exerted minor effect on the pasting temperature and pasting time. The average peak time was slightly prolonged by lower concentration of papain, otherwise slightly shortened by higher concentration.
    Proteomic Identification of Rhythmic Proteins in Maize Seedling Leaves
    FENG Wan-jun, GUO Bao-jian, YAO Ying-yin, PENGHui-ru , SUN Qi-xin, NI Zhong-fu
    2012, 12(12): 1958-1967.  DOI: 10.1016/S1671-2927(00)8732
    Abstract ( )   PDF in ScienceDirect  
    Plant leaves respond to day/night cycling in a number of physiological ways. At the mRNA level, the expression of some genes changes during the 24 h period. To determine which proteins exhibited a rhythmic pattern of expression, proteomic profiles in maize seedling leaves were analyzed by high-throughput two-dimensional gel electrophoresis, combined with MALDI-TOF MS technology. Of the 464 proteins that were detected with silver staining in a pH range of 4-7, 17 (3.66%) showed clock rhythmicity in their abundance. These proteins belonged to diverse functional groups and proteins involved in photosynthesis and carbon metabolism were over-represented. These findings provide a new perspective on the relationship between the physiological functions of leaves and the clock rhythmic system.
    GeneticAnalysisofEarlinessTraits inShortSeasonCotton (Gossypiumhirsutum L.)
    SONG Mei-zhen, FAN Shu-li, YUAN Ri-hong, PANG Chao-you , YU Shu-xun
    2012, 12(12): 1968-1975.  DOI: 10.1016/S1671-2927(00)8733
    Abstract ( )   PDF in ScienceDirect  
    Inheritance and interrelationship of phenotype and genotype of earliness traits were evaluated in a diallel analysis involving six early-maturing parents. Date of first square (DFS), date of first flower (DFF), date of first open boll (DFOB), number of node first sympodial branch (NNFSB), and harvested rate before frost (HRBF) as earliness traits of six parents, 15 F1 hybrids and 15 F2 progenies were investigated from 2005 to 2008. The experiment design was a randomized complete block design with three replications. Additive, dominance and epistasis effects were analyzed with ADAA (additivedominance- epistasis) model. HRBF, DFF, and DFOB showed significant additive genetic variances. Heritability estimates ranged from 0.088 (HN, narrow sense) and 0.416 (HNE, environment interaction) for HRBF, to 0.103 (HN) and 0.524 (HNE) for DFF, and to 0.187 (HN) and 0.519 (HNE) for DFOB. Dominance genetic effects for DFS, DFF, DFOB, and NNSFB were stronger than additive effects. Additive-by-additive epistatic effects for DFS, DFOB, and NNSFB were detected and affected by environment. Correlation analysis showed generally that HRBF had a significant negative genetic and phenotypic correlation with DFS, DFOB, and NNFSB; DFS had significant positive genetic and phenotypic correlations with DFF, DFOB, and NNFSB; significant positive genetic and phenotypic correlations were also detected between DFF and DFOB, DFF and NNFSB, DFOB and NNFSB. The results showed that the lower the node to the first fruiting branch and the shorter the plant, the earlier was the onset of squaring, flowering, and boll opening, the higher was the harvest rate before frost. Heredity of earliness traits among parents and their hybrids were also detected and parents A1, A2, B1, B2, and B3 could be used to improve earliness traits of short season cotton cultivars.
    Identification of QTLsAssociated with Total SoyasaponinContent in Soybean (Glycine max (L.) Merr.)
    HUANG Shan-shan, HAN Ying-peng, LI Chang-suo, TIAN Jun, LI Wen-bin, WANG Ji-an
    2012, 12(12): 1976-1984.  DOI: 10.1016/S1671-2927(00)8734
    Abstract ( )   PDF in ScienceDirect  
    Soyasaponins are valuable compounds in certain drugs, industry, food additives and surfactants. Selecting cultivars with higher-soyasaponin content along with agronomic traits is a main goal for many soybean breeders. The aim of the present study was to identify the quantitative trait loci (QTLs) associated with total soyasaponin content through a F2 population, which was derived from a cross between Ha 91016 (higher soyasaponin content cultivar, 16.8 mg g-1) and N98-9445A (lower soyasaponin content, only 5.7 mg g-1). A genetic linkage map including a total of 162 simple sequence repeat markers was constructed, which covered the total length 2 735.5 cM, and the average distance between markers was 16.96 cM. Two QTLs associated with total soyasaponin content were identified. One, qSAP_1 (located in sat_044-satt102 of linkage group (LG) K), could explain 12.6% of phenotypic variance. The other, qSAP_2, was located between satt368 and sat_413 of LG D1a, which could explain 15.8% of phenotypic variance. It was concluded that the two QTLs would have some potential value for marker-assisted selection for high-soyasaponin content breeding in soybeans.
    Effects of RNAi Silencing of SSIII Gene on Phosphorus Content and Characteristics of Starch in Potato Tubers
    DU Hong-hui, YANG Tao, MA Cong-yu, FENG Dan, ZHANG Ning, SI Huai-jun, WANG Di
    2012, 12(12): 1985-1992.  DOI: 10.1016/S1671-2927(00)8735
    Abstract ( )   PDF in ScienceDirect  
    The sense and antisense fragments of the soluble starch synthase (SSIII) gene and the intron fragment of somatic embryogenesis receptor-like kinase (SERK1) gene were cloned from potato using PCR techniques. The RNAi plant expression vectors pBI-SSIII-RNAi and pBIC-SSIII-RNAi were constructed which containing fusion fragment of “sense fragment-intron-antisense fragment” driven by the constitutive expression promoter CaMV 35S and the tuber-specific expression promoter CIPP, respectively. The putative transgenic plants of potato cultivars Kexin-1 and Kexin-4 were obtained using Agrobacterium-mediated transformation method. PCR assay showed that the interference fragment of SSIII gene was integrated into potato genome. The RT-PCR analysis showed that the expression of SSIII gene was repressed apparently on the transcription level. Starch granules of the transgenic potato plants were different in morphology and became cracked in starch granule centre compared with the non-transgenic control plants. The amylose content of starch was increased by 2.68-29.05%, amylopectin to amylose ratio of starch had declined significantly, and the phosphorus content of the starch of the transgenic plants was reduced 9.94-58.36% compared with control plants. The results could provide certain foundation for improvement of potato starch quality.
    Effects of N Management on Yield and N Uptake of Rice in Central China
    PANSheng-gang , HUANG Sheng-qi, ZHAI Jing, WANG Jing-ping, CAO Cou-gui, CAI Ming-li, ZHAN Ming , TANG Xiang-ru
    2012, 12(12): 1993-2000.  DOI: 10.1016/S1671-2927(00)8736
    Abstract ( )   PDF in ScienceDirect  
    Efficient N fertilizer management is critical for the economic production of rice and the long-term protection of environmental quality. A field experiment was designed to study the effects of N fertilizer management practices on grain yield and N uptake of rice. The experiment was laid out in the randomized complete block design with four replications in Central China during 2008 and 2009. Five N treatments denoted as N0, N150A, N150B, N240A, and N240B, respectively, were studied. N0 represented no N application and served as a control, N150A and N150B indicated the total N application of 150 kg N ha-1 but with two different application schedules (A and B) across the early stage of rice growth. Schedule A was applied as follows: 40% basal, 30% at 10 d after transplanting (DAT) and 30% at 36 DAT (nearly at the panicle initiation stage), while schedule B was as follows: 30% at basal, 20% at 10 DAT, and 50% at 36 DAT. Similarly, N240A and N240B indicated the total N application of 240 kg N ha-1 with schedules A and B as described above. To quantify N uptake from fertilizer and soil, a 15N experiment was also conducted within the main experimental field, with micro-plots. Grain yields were significantly increased as N rates increased from 0 to 240 kg N ha-1. At the same rate, splitting N application as schedule B significantly increased the grain yield, spikelets per panicle, percentage of ripened grain, and 1 000-grain weight, compared with the N application according to schedule A. Mean rice recovery of N fertilizer by 15N tracing method ranged from 25.39% at N240A to 34.89% at N150B, however, N fertilizer residual rate in the soil ranged from 12.40% at N240A to 16.61% at N150B. About 31.5 and 28.5% of total uptake of 15N derived from basal fertilizer was absorbed at panicle initiation and heading stages, respectively. However, 65.6-92.5% of total uptake of 15N derived from topdressing fertilizer was absorbed at the heading stage. Based on yield and nitrogen recovery efficiency, splitting N application according to schedule B at the rate of 240 kg N ha-1 will be more profitable among the tested five N treatments in Central China.
    Common Spectral Bands and Optimum Vegetation Indices for Monitoring Leaf Nitrogen Accumulation in Rice andWheat
    WANG Wei, YAO Xia, TIAN Yong-chao, LIU Xiao-jun, NI Jun, CAO Wei-xing , ZHU Yan
    2012, 12(12): 2001-2012.  DOI: 10.1016/S1671-2927(00)8737
    Abstract ( )   PDF in ScienceDirect  
    Real-time monitoring of nitrogen status in rice and wheat plant is of significant importance for nitrogen diagnosis, fertilization recommendation, and productivity prediction. With 11 field experiments involving different cultivars, nitrogen rates, and water regimes, time-course measurements were taken of canopy hyperspectral reflectance between 350-2 500 nm and leaf nitrogen accumulation (LNA) in rice and wheat. A new spectral analysis method through the consideration of characteristics of canopy components and plant growth status varied with phenological growth stages was designed to explore the common central bands in rice and wheat. Comprehensive analyses were made on the quantitative relationships of LNA to soil adjusted vegetation index (SAVI) and ratio vegetation index (RVI) composed of any two bands between 350-2 500 nm in rice and wheat. The results showed that the ranges of indicative spectral reflectance were largely located in 770-913 and 729-742 nm in both rice and wheat. The optimum spectral vegetation index for estimating LNA was SAVI (R822,R738) during the early-mid period (from jointing to booting), and it was RVI (R822,R738) during the mid-late period (from heading to filling) with the common central bands of 822 and 738 nm in rice and wheat. Comparison of the present spectral vegetation indices with previously reported vegetation indices gave a satisfactory performance in estimating LNA. It is concluded that the spectral bands of 822 and 738 nm can be used as common reflectance indicators for monitoring leaf nitrogen accumulation in rice and wheat.
    Relationship Between the N Concentration of the Leaf Subtending Boll and the Cotton Fiber Quality
    WANG You-hua, ZHAO Xin-hua, CHEN Bing-lin, GAO Xiang-bin , ZHOU Zhi-guo
    2012, 12(12): 2013-2019.  DOI: 10.1016/S1671-2927(00)8738
    Abstract ( )   PDF in ScienceDirect  
    This experiments were conducted in Nanjing (118º50´E, 32º02´N) and Xuzhou (117°11´E, 34°15´N), Jiangsu Province, China, to study the response of fiber quality to the N concentration of the leaf subtending boll in cotton (Gossypium hirsutum L.). Results suggested that the N dilution curve of the leaf subtending boll can accurately indicate the stagespecific plant N status for fiber development. Fiber strength is likely to be the most variable fiber quality index responding to the leaf N variation which is different in cultivars. Fiber length was the most stable index among strength, length, micronaire, and elongation. There existed an optimum leaf N concentration for fiber strength development in each stage. The optimum leaf N regression curve was very close to the N dilution curve in the middle positional fruiting branches under the 240 kg N ha-1 soil N application rate.
    Genomic Analysis of the Natural Population of Wheat dwarf virus inWheat fromChina and Hungary
    LIU Yan, WANG Biao, Gyula Vida, Mónika Cséplo-Károlyi, WU Bei-lei, WU Yuan-hua, WANG Xifeng
    2012, 12(12): 2020-2027.  DOI: 10.1016/S1671-2927(00)8739
    Abstract ( )   PDF in ScienceDirect  
    During the last decade, the leafhopper transmitted Wheat dwarf virus (WDV) has become a serious problem both in northwestern China and Hungary. In order to study the molecular diversity and population structure of WDV in these two countries, 39 Chinese isolates and 16 Hungarian isolates were collected from different regions of China and Hungary, and their genomes were sequenced. All isolates belonged to the wheat strain of WDV and showed limited genetic diversity. The highest and lowest nucleotide sequence identities among isolates from China and Hungary were 99.9 and 90%, respectively. In all isolates, the lowest nucleotide sequence identity was 89.5% between MO10-1 and KP10-5, which were collected from Martonvásár and Kompolt, Hungary. Phylogenetic analyses showed the genome sequences of 55 WDV isolates belong to two big clades, but no clear correlation to geographical location. Population difference analyses indicated that the Chinese and Hungarian WDV populations have no significant difference. The regions in WDV genome with relatively low nucleotide diversities represented protein coding regions suggested that these regions evolved under negative selection, and might be one of the causes restricting the number of genetic variants.
    Evaluation of the Resistance of Different Tea Cultivars to TeaAphids by EPG Technique
    LIANG Li-yun, LIU Li-fang, YU Xiao-ping , HAN Bao-yu
    2012, 12(12): 2028-2034.  DOI: 10.1016/S1671-2927(00)8740
    Abstract ( )   PDF in ScienceDirect  
    In order to investigate the resistance of tea plant to tea aphid, the feeding behavior of tea aphids on six different tea cultivars was monitored by (EPG) technique. The result showed that the duration of E1, E2 as well as (E1+E2) which was feeding waveforms of Toxoptera aurantii (Boyer) in tea phloem was significantly different by variance analysis (P<0.05) and so did the duration of the probing of T. aurantii in all the tea tissues. And the six tea cultivars were classified into three groups with cluster analysis, based on the six major parameters which were durations of np, C, E1, E2, F, and G waveforms, then the six major parameters of these three groups were detected by variance analysis, and the rank of six different tea cultivars’ resistance to T. aurantii from strong to weak was Zhongcha 108, Sucha 1, Anjibaicha, Longjing 43, Xicha 5, and Sucha 120. As this result was in accord with the investigation into the tea field, we concluded that EPG technique was one of the most important means to examine tea plant resistance to T. aurantii and the durations of waveform E1, E2 and (E1+E2) were important parameters for evaluating resistance of tea plants to tea aphids.
    Attenuation of Virulent PorcineReproductive andRespiratorySyndrome Virus Strain CH-1a and Genetic Variation of ORF5 Gene
    CAI Xue-hui, WUGuo-jun , LIU Yong-gang, LIU Guang-qing, SHI Wen-da, WANG Shu-jie, MA Ping, LI Cheng-jun , HAN Wen-yu
    2012, 12(12): 2035-2042.  DOI: 10.1016/S1671-2927(00)8741
    Abstract ( )   PDF in ScienceDirect  
    To develop a modified live vaccine (MLV) against porcine reproductive and respiratory syndrome virus (PRRSV), virulent CH-1a strain was attenuated by serial passages up to 130 passage (P130) in Marc-145 cells. The virulence and immune efficacy of the attenuated CH-1a were evaluated in pigs. The results showed that animals inoculated with P130 did not develop any clinical sign of the disease, but produced rapid and effective humoral immune responses against PRRSV challenge, indicating that attenuated CH-1a P130 is the candidate as the effective vaccine against PRRSV. To define the potential mutations in the attenuated CH-1a genome, we sequenced and analyzed the ORF5 gene of CH-1a strain of different passages (P39, P55, P65, P70, P85, P100, P115, P120, P125, and P130) and found that three mutations (C5Y, H38Q and L146Q) which may be related with the attenuation of CH-1a. In addition, we also found a unique restriction enzyme site (TspEI) in the ORF5 gene of attenuated CH-1a, which can be used as a genetic marker to distinguish original and attenuated CH-1a.
    Effect of Semen vaccariae and Taraxacumogono on CellAdhesion of Bovine Mammary Epithelial Cells
    TONG Jin-jin, LI Ye, LIU Rong, GAO Xue-jun , LI Qing-zhang
    2012, 12(12): 2043-2050.  DOI: 10.1016/S1671-2927(00)8742
    Abstract ( )   PDF in ScienceDirect  
    The aim of this study is to reveal the regulation mechanism of the effect of Semen vaccariae and Taraxacu mogono on the cell-cell adhersion molecule, E-cadherin and b-catenin on the proliferation role and secretion function of bovine mammary epithelial cells cultured in vitro. Firstly, the epithelial character of bovine mammary epithelial cells was authenticated using immunofluorescence, then the cell grow curve was observed and investigated after S. vaccariae and T. mogono treatment. On the effect of S. vaccariae and T. mogono, cell adhesion molecules E-cadherin, b-catenin and CycinD1 mRNA and protein were detected by qRT-PCR and Western blotting, respectively. The results showed that the cellular keratin 18 expressed positively and proliferated vigorously after S. vaccariae and T. mogono treament. The mRNA and protein levels of E-cadherin and CycinD1 were remarkably higher (P<0.05) in 36 h after S. vaccariae and T. mogono treatment. The cell proliferation at 36 h was increased significantly (P<0.05). In conclusion, S. vaccariae and T. mogono have a positive impact on the cell proliferation and an effect on the adhesion molecules E-cadherin, b-catenin and CycinD1 in the Wnt signaling pathway.
    Fosfomycin Resistance in Avian Pathogenic Escherichia coli Isolates
    JIN Wen-jie, ZHENG Zhi-ming, WANG Qian-qian, QIN Ai-jian, SHAO Hong-xia , QIAN Kun
    2012, 12(12): 2051-2057.  DOI: 10.1016/S1671-2927(00)8743
    Abstract ( )   PDF in ScienceDirect  
    Fosfomycin, a broad-spectrum antibiotic against both Gram-positive and Gram-negative bacteria, is very important in the clinic but many fosfomycin-resistant bacteria have been isolated from patients. In this study, the resistance mechanism of three fosfomycin-resistant avian pathogenic Escherichia coli (APEC) strains (JE1, IF7 and CD11) isolated from septicemic chickens were analyzed. The results showed that their fosfomycin-resistance mechanisms were different. An alteration in the glpT transport system was the main reason of the fosfomycin-resistance mechanisms of strain IF7. Compared with the control stain BL21, the capacity of fosfomycin-uptake was low in all these three stains (JE1>IF7>CD11). Sequence results of murA showed that there were more than 10 sites of nucleotide mutation, but only one amino acid mutation T116A showed in CD11. Real-time detection test showed that the expression level of the murA gene of the three stains was significantly increased (four times increase in strain CD11 and two times increase in strains JE1 and IF7). The transformation and recombinant test showed that the recombinant bacteria with the murA of JE1 and CD11 showed high minimal inhibitory concentration (MIC) against fosfomycin. From the results of this research, it showed that most of the fosfomycinresistance mechanisms once showed in patient bacteria have appeared in the APEC strains and the fosfomycin-resistance mechanism of the three APEC isolates was different.
    Induction ofApoptosis in the ImmatureMouse Testes by aMixture ofMelamine and CyanuricAcid
    YOU Hua, ZHU Jin-feng, SHE Rui-ping, CHANG Ling-ling, SHI Rui-han, DING Ye, CHI Li-juan, LIUBin , YUE Zhuo, TIAN Ji-jing, MAO Jing-jing , SU Li-fang
    2012, 12(12): 2058-2066.  DOI: 10.1016/S1671-2927(00)8744
    Abstract ( )   PDF in ScienceDirect  
    The toxicity of melamine has attracted much attention since the recent outbreaks of renal injury in pets and infants. Previous studies indicated that melamine by itself had low toxicity, whereas a mixture of melamine and cyanuric acid (M+CA) could cause serious renal damage. At present, most researches on the toxicity of M+CA are focused on the kidney. However, little is known about the adverse effects of this mixture on the reproductive system. In the present study, the toxicity of M+CA to testes was investigated. Immature male mice were orally dosed with 0, 0.6, 3, and 15 mg kg-1 d-1 of a 1:1 M+CA for 28 d. Pathological changes occurred in germ cells, such as loose arrangement, reduced numbers and karyopyknosis, indicating that this mixture was toxic to spermatogenesis. Compared with the control group, the TUNELpositive germ cells increased significantly and the ratio of Bcl-2 to Bax, total antioxidant capacity and superoxide dismutase activity decreased significantly in the 3 and 15 mg kg-1 d-1 M+CA treated group, while the activities of caspase-3, caspase- 8 and caspase-9 remained unchanged. The results suggest that M+CA can induce apoptosis in the mice testes. The downregulation of Bcl-2/Bax and oxidative stress may play a pivotal role in the induction of apoptosis by M+CA in mice testes.
    Estimates of N2O Emissions and Mitigation Potential from a Spring Maize Field Based on DNDC Model
    LI Hu, QIU Jian-jun, WANG Li-gang, XU Ming-yi, LIU Zhi-qiang, WANG Wei
    2012, 12(12): 2067-2078.  DOI: 10.1016/S1671-2927(00)8745
    Abstract ( )   PDF in ScienceDirect  
    Agricultural production plays an important role in affecting atmospheric nitrous oxide (N2O) concentrations. Field measurements were conducted in Dalian City, Liaoning Province in Northeast China from two consecutive years (2009 and 2010) to estimate N2O emissions from a spring maize field, a main cropping system across the Chinese agricultural regions. The observed flux data in conjunction with the local climate, soil and management information were utilized to test a process-based model, DeNitrification-DeComposition (DNDC), for its applicability for the cropping system. The validated DNDC was then used for exploring strategies to reduce N2O emissions from the target field. The results showed that the major N2O pulse emissions occurred with duration of about 3-5 d after fertilizer application in both years 2009 and 2010, which on average accounted for about 60% of the total N2O emissions each year. Rainfall and fertilizer application were the major factors influencing the N2O emissions from spring maize field. The average N2O fluxes from the CK (control plot, without fertilization) and FP (traditional chemical N fertilizer) treatments were 23.1 and 60.6 μg m-2 h-1 in 2009, respectively, and 21.5 and 64.3 μg m-2 h-1 in 2010, respectively. The emission factors (EFs) of the applied N fertilizer (270 kg N ha-1) as N2ON were 0.62% in 2009 and 0.77% in 2010, respectively. The comparison of modeled daily N2O emission fluxes against observations indicated that the DNDC model had a good performance even if without adjusting the internal parameters. The modeled results showed that management practices such as no-till, changing timing or rate of fertilizer application, increasing residue incorporation, and other technically applicable measures could effectively reduce N2O emissions from the tested fields. Our study indicated that avoiding application of N fertilizers at heavy rainfall events or splitting the fertilizer into more applications would be the most feasible approaches to reduce N2O emissions from spring maize production in Northeast China.
    Biomass Components and Environmental Controls in Ningxia Grasslands
    WANG Kai-bo, LI Jian-ping , SHANGGUAN Zhou-ping
    2012, 12(12): 2079-2087.  DOI: 10.1016/S1671-2927(00)8746
    Abstract ( )   PDF in ScienceDirect  
    Grassland plays an important role in the global carbon cycle and climate regulation. However, there are still large uncertainties in grassland carbon pool and also its role in global carbon cycle due to the lack of measured grassland biomass at regional scale or global scale with a unified survey method, particular for below-ground biomass. The present study, based on a total of 44 grassland sampling plots with 220 quadrats across Ningxia, investigated the characteristics of above-ground biomass (AGB), below-ground biomass (BGB), litter biomass (LB), total biomass (TB) and root:shoot ratios (R:S) for six predominantly grassland types, and their relationships with climatic factors. AGB, BGB, LB and TB varied markedly across different grassland types, the median value ranging from 28.2-692.6 g m-2 forAGB, 130.4-2036.6 g m-2 for BGB, 9.2-82.3 g m-2 for LB, and 168.0-2 681.3 g m-2 for TB. R:S showed less variation with median values from 3.2 to 5.3 (excluding marshy meadow). The different grassland types showed similar patterns of biomass allocation, with more than 70% BGB for all types. There is evidence of strong positive effects associated with mean annual precipitation (MAP) and negative effects associated with mean annual temperature (MAT) on AGB, BGB, and LB, although both factors have the opposite effect on R:S.
    Toxicological Evaluation of Chicken-Breast Meat with High-Dose Irradiation
    ZHU Jia-ting, FENG Min, YAN Jian-min, LIU Chun-quan, HA Yi-ming, GAO Mei-xu, YANG Ping, WANG Zhi-dong, WANG De-ning, LI Shu-rong, GU Gui-qiang
    2012, 12(12): 2088-2096.  DOI: 10.1016/S1671-2927(00)8747
    Abstract ( )   PDF in ScienceDirect  
    In this paper, toxicity and safety of high-dose irradiated chicken-breast meat were evaluated. For assays of acute toxicity, genetic toxicity, and sub-chronic toxicity, ames test, mice bone marrow erythrocyte micronucleus, and mice sperm abnormality were performed. The results showed that, in the acute oral toxicity tests, median lethal dose (more than 10 000 mg kg-1) in male and female ICR mice showed no toxicological signs. For subacute 30-d oral toxicology of irradiated chicken-breast meat with dose of 10, 15 and 25 kGy in both male and female SD rats, no noticeable toxicological effects were observed. It is concluded that chicken-breast meat with high-dose irradiation has no acute toxicity and no genotoxicity, nor harmful effects on the animal body at the tested dosage range. Therefore, high-dose irradiated chicken-breast meat is safe for pet consumption.
    Price Transmission in China’s Swine Industry with an Application of MCM
    XU Shi-wei, LI Zhe-min, CUI Li-guo, DONG Xiao-xia, KONG Fan-tao, LI Gan-qiong
    2012, 12(12): 2097-2106.  DOI: 10.1016/S1671-2927(00)8748
    Abstract ( )   PDF in ScienceDirect  
    The paper studies the relationship, adjustment ability, path, efficiency and intensity of price transmission in the swine industry chain in China, which consists of the prices of corn, compound feed for fattening pig, piglet, pig and pork. Monthly prices covering a period of 18 yr (1994-2011) are analyzed using a Market-Chain Cooperated Model (MCM). The empirical results show that there exists a stable long-term cointegration and short-term dynamic relationship in the price system. First, the adjustment speed of each price series is very slow and the transmission path is top-down and one-way significantly. Second, the price from upstream to downstream lags about 2 mon, while there is no lag in price transmission from midstream to downstream. Third, in terms of price transmission intensity, the price of pig impacted greatly on pork price, not only in the current period but also through the whole period. Besides, the price of corn has the largest lagged effects on pork price. According to the above empirical results, we suggest that government should strengthen monitoring and early warning of the swine industry chain, especially the upstream and midstream, attach great importance to the timely adjustment of feed prices and perfect the measures of price subsidy.
    Farmer’s Knowledge on GM Technology and Pesticide Use: Evidence from Papaya Production in China
    HOU Lin-ke, HUANG Ji-kun, WANG Xiao-bing, HU Rui-fa, XUE Chun-ling
    2012, 12(12): 2107-2115.  DOI: 10.1016/S1671-2927(00)8749
    Abstract ( )   PDF in ScienceDirect  
    Genetically modified (GM) technology can significantly reduce pesticide use and increase yield in crop production. However, the benefit from reducing pesticide use varies substantially among farmers. The overall goal of this paper is to understand the relationship between farmers’ knowledge of GM technology and pesticide use in genetically modified papaya (GMP) production. Based on a survey of 223 farms in three main papaya production provinces in 2010, the data show that almost all papaya planted in 2009 was genetically modified. However, only 28% of papaya farmers knew that they planted GMP, and 55% of them did not know GMP is resistant to papaya ringspot virus (PRSV). Further analyses using the general least squares (GLS) method show that farmers’ knowledge of GMP significantly affects their pesticide use, and potential gain from GM technology is far below its full potential. The paper concludes with policy implications.
    TheAbundance andPopulationDynamics of Leptocybe invasa (Hymenoptera: Eulophidae) Galls on Eucalyptus spp. in China
    ZHU Fang-li, REN Shun-xiang, QIU Bao-li, HUANG Zhen , PENG Zheng-qiang
    2012, 12(12): 2116-2123.  DOI: 10.1016/S1671-2927(00)8750
    Abstract ( )   PDF in ScienceDirect  
    The blue gum chalcid, Leptocybe invasa Fisher & La Salle, invaded China in 2007 and has subsequently caused substantial damage to eucalyptus trees. In the current paper, we investigated the susceptibility of 10 Eucalyptus spp. and Eucahetus dunnii to L. invasa in the field, determined the density of galls as well as the gall volume on these tree species, and monitored the population dynamics of wasps in Hainan and Guangdong provinces of China. The order of susceptibility to L. invasa was Eucalyptus urophylla×Eucalyptus camaldulensis>E. urophylla (coppices)>Eucalyptus exserta> Eucalyptus grandis×E. urophylla in Hainan, and Eucalyptus propinqua>Eucalyptus saligna>E. exserta>Eucalyptus microcorys>Eucahetus dunnii>E. camaldulensis>Eucalyptus tereticornis>Eucalyptus robust in Guangdong, China. Although L. invasa generally damages the midribs and petioles of young leaves and the tender bark of twigs of eucalyptus, galls were not observed on leaves of E. microcorys, E. camaldulensis, or E. dunnii. Gall volume significantly differed among the tree species, and gall volume and wasp number were positively correlated. In Dongfang, Hainan Province, the overwintering period of L. invasa emergencing through the year was from the end of December to March of the next year, and the number of population was the greatest on E. urophylla×E. camaldulensis, and the smallest on E. grandis×E. urophylla. In Guangzhou, Guangdong Province, L. invasa hardly emerged in winter from December to June of the next year, and the population was the greatest on E. propinqua, and the smallest on E. microcorys.