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    Crop Genetics · Breeding · Germplasm Resources
    Genetic Structure and Eco-Geographical Differentiation of Cultivated Keng Rice (Oryza sativa L. subsp. japonica) in China Revealed by Microsatellites
    ZHANG Dong-ling, WANG Mei-xing, QI Yong-wen, SUNJun-li , WANG Feng-mei, LI Jin-jie, ZHANG Hong-liang, and LI Zi-chao
    2012, 12(11): 1755-1766.  DOI: 10.1016/S1671-2927(00)8710
    Abstract ( )   PDF in ScienceDirect  
    China is one of the largest centers of genetic diversity of Oryza sativa L. and is the original centers of Oryza sativa L. subspecies japonica. Using a genetically representative core collection of 1 442 rice landraces of japonica in China, the genetic structure, differentiation, and geographic diversity were analyzed. The model-based structure analysis on varieties within three ecotypes revealed 16 eco-geographical types, which are partially accorded with some of the ecological zones in China. The differentiation of eco-geographical types contributed to the local ecological adaption and physical isolation, and maybe could be used to develop the heterotic groups of japonica. To facilitate the identification of different ecotypes and eco-geographical types, we provided the SSR character alleles of each ecotype or geographical eco-group and a rapid discriminated method based on these character alleles. Lastly, investigation on genetic diversity, genetic differentiation indicated that southwest region of China, including south of Yunnan Province, northwest of Guangxi Zhuang Autonomous Region, and southwest of Guizhou Province, possessed the highest genetic diversity and all the necessary conditions as a center of genetic diversity and should be the center of genetic diversity of rice landraces of japonica in China.
    Identification of Quantitative Trait Locus for Overwintering Germinability in Rice (Oryza sativa L.)
    ZHAO Zheng-wu, LUOAn-cai , LE Tao , LI Shi-gui
    2012, 12(11): 1767-1774.  DOI: 10.1016/S1671-2927(00)8711
    Abstract ( )   PDF in ScienceDirect  
    312 recombinant inbred lines (RILs) in F9 from a cross between a overwintering cold-tolerant germplasm resource Glutinous rice 89-1(Gr 89-1) and a cold-sensitive variety Shuhui 527 was used for quantitative trait locus (QTL) analysis. The scores of percent ratooning germinability (PRG) and overwintering germinability (POG) were evaluated. The overwintering germination rate of axillary buds was scored to represent the overwintering germinability. Two significant QTLs (qPRG-4 and qPRG-7) on chromosomes 4 and 7 were detected and explained 8.3 and 7.2% of the total phenotypic variation, respectively. Three significant QTLs (qPOG-2, qPOG-3 and qPOG-7) were identified and mapped on chromosomes 2, 3, and 7, respectively. These QTLs contributed 9.6, 6.7, and 17.8% of phenotypic variations, respectively. A comparative analysis using SSR markers closely linked to the three QTLs for the overwintering revealed cold-tolerant individuals, which harbour the Glutinous rice 89-1 alleles at RM7110, RM250, RM418, and RM232, had a high percent overwintering germinability, while cold-sensitive individuals, which carry Shuhui 527 alleles at these loci, had a low percent overwintering germinability in the F2 population of Shuhui 527/Glutinous rice 89-1. This study demonstrated the utility of these SSR markers for selection of overwintering germinability genotypes.
    QTLMapping forAdult-Plant Resistance to Stripe Rust in a CommonWheat RIL Population Derived from Chuanmai 32/Chuanyu 12
    WULing , XIAXian-chun , ZHENGYou-liang , ZHANGZheng-yu , ZHUHua-zhong , LIUYong-jian , YANG En-nian, LI Shi-zhao , HE Zhong-hu
    2012, 12(11): 1775-1782.  DOI: 10.1016/S1671-2927(00)8712
    Abstract ( )   PDF in ScienceDirect  
    Stripe rust, caused by Puccinia striiformis f. sp. tritici, is a devastating wheat disease worldwide. The Chinese wheat cultivar Chuanmai 32 has shown stable resistance to stripe rust for 10 yr in Sichuan Province, a hotspot for stripe rust epidemics. The objective of the present study was to map quantitative trait loci (QTL) for adult-plant resistance (APR) to stripe rust in a population of 140 recombinant inbred lines (RILs) derived from Chuanmai 32/Chuanyu 12. Field trials were conducted in Chengdu and Yaan, Sichuan, from 2005 to 2008, providing stripe rust reaction data for 6 environments. 797 simple sequence repeat (SSR) markers were screened for association with stripe rust reaction, initially through bulked segregant analysis (BSA). Based on the mean disease values averaged across environments, the broad-sense heritability of maximum disease severity (MDS) was 0.75. Two QTLs for stripe rust resistance were detected by composite interval mapping (CIM). They were designated QYr.caas-3BL and QYr.caas-3BS and explained from 6.6 to 20.1%, respectively, of the phenotypic variance across environments. QYr.caas-3BL came from Chuanmai 32; QYr.caas-3BS with lower effect was from the susceptible parent Chuanyu 12. Both QTLs appear to be new.
    Transcriptomic Analysis of the Highly Heterotic Maize Hybrid Zhengdan 958 and Its Parents During Spikelet and Floscule Differentiation
    LI Zhi-yong, ZHANG Ti-fu, WANG Shou-cai
    2012, 12(11): 1783-1793.  DOI: 10.1016/S1671-2927(00)8713
    Abstract ( )   PDF in ScienceDirect  
    Heterosis plays an important role in crop production and plant evolution. Although heterosis has been widely exploited by plant breeders, the underlying molecular mechanisms are not well understood. We analyzed gene expression of the highly heterotic maize hybrid Zhengdan 958 and its parents, Zheng 58 and Chang 7-2 during spikelet and floscule differentiation using the GeneChip® Maize Genome Array. Pairwise comparison among Zhengdan 958 and its parents at the two stages of immature ear development identfied 1 089 and 1 352 differentially expressed genes. Gene ontology (GO) functional analysis showed that these genes participate in many functional categories, and those encoding response to stress and transcription factor may play important roles in heterosis. Pathway analysis showed that the differentially expressed genes are involved in various metabolic processes, and those participating in lipid metabolism, signal transduction, transport, and catabolism may contribute to heterosis. A non-additive expression pattern was prevalent in genes that were differentially expressed between the hybrid and its parents during both spikelet and floscule differentiation. Because genes that are differentially expressed in a hybrid and its parents could underlie heterosis, nonadditive expression patterns might contribute to the manifestation of heterosis.
    GeneticStructureandDiversityofParentalCultivars Involved inChinaMainland Sugarcane Breeding Programs as Inferred from DNA Microsatellites
    QI Yong-wen, PANYong-bao , LAO Fang-ye, ZHANG Chui-ming, FAN Li-na, HE Hui-yi, LIU Rui, WANG Qin-nan, LIU Shao-mou, LIU Fu-ye, LI Qi-wei , DENG Hai-hua
    2012, 12(11): 1794-1803.  DOI: 10.1016/S1671-2927(00)8714
    Abstract ( )   PDF in ScienceDirect  
    To understand genetic structure and diversity of parental cultivars involved in China Mainland sugarcane breeding programs, 92 elite parents and 4 wild relatives were genotyped with 18 microsatellite DNA markers. The genetic similarity (GS) values among the cultivars ranged from 0.346 to 0.960 with an average of 0.533. Among the introduced cultivars, India accessions had the closest genetic distance to China Mainland accessions (0.447), while Australia accessions have the furthest distance (0.503). A comparison of allelic diversity among geographical origins showed that there were 22 China Mainland specific alleles, of which 28% were derived from native S. spontaneaum germplasm in China. Model-based genetic structure, clustering, and principal components analyses consistently revealed there were five groups within the 96 accessions. Groups 1, 2, 4, and 5 consisted of all cultivars and group 3 only contained wild germplasm. Group 2 was characterized as the Introduction group with 46 cultivars predominantly introduced from Australia, Taiwan of China, India, and USA. Groups 1, 4, and 5 consisted of cultivars mostly originated from China Mainland, defined as the Complex group, Yacheng lines group, and F134/CP72-1210 group, respectively, upon their pedigree. By understanding the genetic relationships among the parental cultivars, breeders can gain a rational basis for expanding the gene pool and select the best parental accessions for crossing.
    Factors Influencing Glucoraphanin and Sulforaphane Formation in Brassica Plants: AReview
    GU Zhen-xin, GUO Qiang-hui, GU Ying-juan
    2012, 12(11): 1804-1816.  DOI: 10.1016/S1671-2927(00)8715
    Abstract ( )   PDF in ScienceDirect  
    Sulforaphane is a type of sulfur-containing isothiocyanates hydrolyzed from glucosinolates by myrosinase found in Brassica plants. Sulforaphane is a naturally occurring inducer of phase II enzymes in human and animal bodies to detoxify cancer-causing chemicals. Glucoraphanin is the precursor of sulforaphane and its content is greatly influenced by plant species and genotype, plant organs, pre-harvest factors, and post-harvest processing, thus sulforaphane formation is also directly influenced. Here, we review the formation mechanism of sulforaphane and the factors influencing sulforaphane formation. In the end, the future directions are also discussed.
    UsingPhospholipid FattyAcid Technique toAnalysis theRhizosphere Specific Microbial Community of Seven Hybrid Rice Cultivars
    ZHUYu-jing , HU Gui-ping, LIU Bo, XIE Hua-an, ZHENGXue-fang , ZHANG Jian-fu
    2012, 12(11): 1817-1827.  DOI: 10.1016/S1671-2927(00)8716
    Abstract ( )   PDF in ScienceDirect  
    To analyze the intrinsic relationship between rhizosphere microbial community structure and variety of rice, the microbial community structures in rhizosphere of different hybrid rice cultivars were determined with phospholipid fatty acids (PLFA) analysis. Three series of new-breeding hybrid rice cultivars in China were tested in the experiment, IIyouming 86 (II-32A/Minghui 86), IIyouhang 1 (II-32A/Hang 1), and IIyouhang 2 (II-32A/Hang 2) with II-32A as female parent, XinyouHK02 (XinA/HK02) and YiyouHK02 (YXA/HK02) with HK02 as male parent, Chuanyou 167 (ChuanxiangA/MR167) and 44you167 (Hunan44A/MR167) with MR167 as male parent. The results showed that the microbial community in rhizosphere of the hybrid rice comprised bacteria, fungi, actinomycetes, and protozoa, according to the 40 PLFA biomarkers detected. Bacteria were more abundant than fungi and actinomycetes in rhizosphere of the hybrid rice tested. Both sulfate-reducing and methane-oxidizing bacteria were found to exist in the hybrid rice rhizosphere. It was also found that the characteristics of PLFA biomarkers had correlation with the biological traits of rice. The cluster analysis suggested that microbial community structure and activity in rhizosphere were associated with genetic background of the rice cultivar.
    Influence of Diazotrophic Bacteria on Antioxidant Enzymes and Some Biochemical Characteristics of Soybean Subjected to Water Stress
    Hamed Zakikhani, Mohammad RezaArdakani, Farhad Rejali, Majid Gholamhoseini, Aydin Khodaei Joghan
    2012, 12(11): 1828-1835.  DOI: 10.1016/S1671-2927(00)8717
    Abstract ( )   PDF in ScienceDirect  
    Drought stress is an abiotic stress that imposes serious constraints on plants. The present investigation was carried out to determine the inter-relationship between some physiological attributes of soybeans affected by drought stress and pure isolates of Azotobacter and Azospirillum. Drought stress and bacterial application increased catalase and glutathione peroxidase activity, whereas drought stress increased superoxide dismutase activity during the pod-filling stage. Abscisic acid and proline levels increased due to drought stress and bacterial application during the flowering stage, whereas total plant nitrogen was enhanced under well-watered conditions when plants were inoculated with bacteria. The close relationship between enzyme activity and drought stress with bacteria indicated that antioxidant enzymes play an important role in alleviating the detrimental effects of water stress. In addition, the enhancement of abscisic acid and proline could be positively linked with drought stress, and drought-induced abscisic acid could induce proline accumulation and the expression of antioxidant enzyme genes.
    Effects of Extreme Air Temperature and Humidity on the Insecticidal Expression Level of Bt Cotton
    CHEN Yuan, WEN Yu-jin, CHENYuan , John Tom Cothren, ZHANG Xiang, WANG Yong-hui, William A
    2012, 12(11): 1836-1844.  DOI: 10.1016/S1671-2927(00)8718
    Abstract ( )   PDF in ScienceDirect  
    The higher survival rates of Helicoverpa amigera larvae were usually observed after adverse climate which was related to extreme temperature (T) and relative humidity (RH) stresses in transgenic Bacillus thuringiensis (Bt) cotton. The unstable resistance of Bt cotton to bollworms has been correlated with the reduced expression of CryIAc d-endotoxin. The objective of this study was to investigate the effects of combined temperature and relative humidity stresses on the leaf CryIAc insecticidal protein expression during critical developmental stages. The study was undertaken on two transgenic cotton cultivars that share same parental background, Sikang 1 (a conventional cultivar) and Sikang 3 (a hybrid cultivar), during the 2007 and 2008 growing seasons at the Yangzhou University Farm, Yangzhou, China. The study was arranged with two factors that consisted of temperature (two levels) and relative humidity (three levels). The six T/RH treatments were 37°C/95%, 37°C/70%, 37°C/50%, 18°C/95%, 18°C/70%, and 18°C/50%. In 2007, the six treatments were imposed to the plants at peak flowering stage for 24 h; in 2008, the six treatments were applied to the plants at peak square, peak flowering, and peak boll stages for 48 h. The results of the study indicated that the leaf insecticidal protein expression in CryIAc was significantly affected by extreme temperature only at peak flowering stage, and by both extreme temperature and relative humidity during boll filling stage. The greatest reductions were observed when the stresses were applied at peak boll stage. In 2008, after 48 h stress treatment, the leaf Bt endotoxin expression reduced by 25.9-36.7 and 23.6-40.5% at peak boll stage, but only by 14.9-26.5 and 12.8-24.0% at peak flowering stage for Sikang 1 and Sikang 3, respectively. The greatest reduction was found under the low temperature combined with low relative humidity condition for both years. It is believed that the temperature and relative humidity stresses may be attributed to the reduced efficacy of Bt cotton in growing conditions in China, where extreme temperatures often increase up to 35-40°C and/or decrease down to 15-20°C, and relative humidity may reach to 85-95% and/or reduce to 40-55% during the cotton growing season.
    Comparative Analysis of Cry1Ac Toxin Oligomerization and Pore Formation Between Bt-Susceptible and Bt-Resistant Helicoverpa armigera Larvae
    LI Yi-ping, WUJun-xiang , LIU Chen-xi, YUAN Xiang-qun, WU Kong-ming, LIANG Ge-mei, GUO Yu-yuan
    2012, 12(11): 1845-1851.  DOI: 10.1016/S1671-2927(00)8719
    Abstract ( )   PDF in ScienceDirect  
    With the long-term use of Bacillus thuringiensis (Bt) insecticide and expansion of Cry1A-expressing transgenic plants, some insect pests have developed resistance to Bt in open fields, greenhouses, and in the laboratory. Bt resistance is complex and there appear to be different ways for resistance development. Understanding the Bt resistance mechanisms is critical to prolong its usefulness. In this article, Bt receptors, the cadherin and aminopeptidase N (APN), in brush border membrane vesicles (BBMV) of Helicoverpa armigera were examined in both Cry1Ac-susceptible (96S) and Cry1Acresistant (LF120) strains, to compare Cry1Ac toxin oligomerization and pore formation in these two strains. Cry1Ac toxin oligomerization and pore formation in these two strains were compared. Results showed that cadherin and aminopeptidase N proteins could express normally in both susceptible and resistant H. armigera strains. The ability to form Cry1Ac oligomers and ion channels on BBMVs was also not significantly different between these two strains.
    Effects of the Residues of Cuscuta campestris and Mikania micrantha on Subsequent Plant Germination and Early Growth
    LI Feng-lan, LI Ming-guang, ZAN Qi-jie, GUO Qiang, ZHANG Wei-yin, WU Zhi, WANG Yong-jun
    2012, 12(11): 1852-1860.  DOI: 10.1016/S1671-2927(00)8720
    Abstract ( )   PDF in ScienceDirect  
    Cuscuta campestris, a dodder, can parasitize and suppress a scrambling herbaceous to semi-woody perennial vine, Mikania micrantha, one of the most destructive weeds in the world. To assess the effects of the mixed residue of C. campestris and M. micrantha on the subsequent plant community, we conducted a one-year experiment on the germination and seedling growth of subsequent plant community after the application of C. campestris. Seven treatments of varying proportions of C. campestris and M. micrantha residue on 21 subject trees and shrubs, which were commonly found in South China, resulted in a germination rate of 35.3% for all 8715 seeds from 18 species, ranging from 5.7 to 81.9%; the remaining 3 species failed to germinate. ANOVA analysis showed that the residue did not affect the germination, growth, or mortality of the trees and shrubs. The germinated C. campestris seeds from the residue coiled the seedlings of most of the species, but less than 4% host death caused by C. campestris. In addition, the residue did not affect the germination of the herbaceous seedlings originating from the loam, and the similarity coefficients of the germinated seedlings between the treatments were very high. These results suggested that the residue had no negative impact on the germination and early seedling stages of the tree, shrub and grass species of the subsequent plant community. The use of C. campestris residue had a positive effect on the growth of M. micrantha, but it did not change the trend of M. micrantha being suppressed because re-parasitization occurred soon after the growth restarted. No negative effect was detected on the other species as a result of the parasitization of C. campestris or by the use of the mixed residue. This suggests that C. campestris is likely to be an effective and promising ecologically safe native herbaceous agent for controlling M. micrantha.
    Determination of Pesticide Residue Cartap Using a Sensitive Fluorescent Probe
    JING Xu, DU Li-ming, WU Hao, WU Wen-ying , CHANG Yin-xia
    2012, 12(11): 1861-1870.  DOI: 10.1016/S1671-2927(00)8721
    Abstract ( )   PDF in ScienceDirect  
    The insecticide cartap (CP) is non-fluorescent in aqueous solutions. This property makes its determination through direct fluorescent method difficult. In acidic medium and at room temperature, palmatine (PAL) can react with cucurbit[7]uril (CB[7]) to form stable complexes, and the fluorescence intensity of the complex is greatly enhanced. Significant quenching of the fluorescence intensity of the CB[7]-PAL complex was observed with the addition of cartap. Based on the significant quenching of the supramolecular complex fluorescence intensity, a new spectrofluorimetric method with high sensitivity and selectivity was developed to determine cartap in aqueous solution. The fluorescence quenching values (DF) showed good linear relationship with cartap concentrations from 0.009 to 2.4 μg mL-1 with a detection limit 0.0029 μg mL-1. The proposed method had been successfully applied to the determination of cartap residues in grain and vegetable with recoveries of 87.4-103%. In addition, the association constants of the complexes formed between the host and the guest were determined. The competing reaction and the supramolecular interaction mechanisms between the cartap and PAL as they fight for occupancy of the CB[7] cavity were studied using spectrofluorimetry, 1H NMR and molecular modeling calculations.
    StimulationStudyofGenePyramiding inAnimals byMarker-AssistedSelection
    ZHAO Fu-ping, , ZHANG Qin
    2012, 12(11): 1871-1876.  DOI: 10.1016/S1671-2927(00)8722
    Abstract ( )   PDF in ScienceDirect  
    This gene pyramiding strategy is based on the idea of efficiently pyramiding genes of interest by crosses and selection to obtain a population with favorable alleles from different breeds or lines, which is called an ideal population. We investigate impacts of some factors on the pyramiding efficiencies by simulation. These factors include selection strategies (the breeding value selection, the molecular scores selection and the index selection), proportion selected (2, 10 and 20%), recombination rates between adjacent target genes (0.1, 0.3 and 0.5) and different mating types (the random mating and the positive assortative mating avoiding sib mating). The results show that: (1) The more recombination rate and the lower proportion male selected, the better pyramiding efficiency; (2) the ideal population is obtained via various selection strategies, while different selection strategies are suitable for different breeding objectives. From the perspective of pyramiding target genes merely, the molecular scores selection is the best one, for the purpose of pyramiding target genes and recovering genetic background of the target trait, the index selection is the best one, while from the saving cost point of view, the breeding value selection is the best one; (3) the positive assortative mating is more efficient for gene pyramiding compared with the random mating in the terms of the number of generations of intercross for getting the ideal population.
    Development of a Porcine cDNA Microarray: Analysis of Clenbuterol Responding Genes in Pig (Sus scrofa) Internal Organs
    ZHANG Jin, GUO Wei, SHEN Liang-cai, LIU Qiu-yue, DENG Xue-mei, HU Xiao-xiang , LI Ning
    2012, 12(11): 1877-1883.  DOI: 10.1016/S1671-2927(00)8723
    Abstract ( )   PDF in ScienceDirect  
    Pig (Sus scrofa) fat accumulation can be reduced by feeding with high dosages of clenbuterol, but the molecular mechanism has not yet been explained. In our study, a porcine cDNA microarray representing 3 358 pig genes was successfully developed. This microarray is the first porcine DNA microarray in China and its false positive rate is 0.98%, which means the microarray platform is reliable. The microarray can be used to study gene expression profiles in multiple pig tissues because the present genes percentage of adipose, skeletal muscle, heart, liver, lung, kidney, and spleen were all more than 60%. This microarray was used to identify the genes responding to clenbuterol stimulation in pig internal organs, including heart, liver, lung, spleen, and kidney. Many genes were identified including enzymes involved in lipids metabolism (lipoprotein lipase up-regulated in liver, heart and lung, ATP-citrate lyase and carnitine palmitoyltransferase II precursor up-regulated in liver, succinyl-CoA up-regulated in lung, mitochondrial malate dehydrogenase down-regulated in spleen), and signaling pathway genes (cAMP-protein kinase A signaling pathway was found up-regulated in liver, heart, lung, and kidney as reported previously, while transforming growth factor was found down-regulated in heart and lung). However, no common gene responding to clenbuterol administration was found in all tissues. The expression levels of 14 genes were analyzed using real-time PCR with 82.1% of them induced to express similar magnitudes as in the microarray analyses. This work offers some understanding of how clenbuterol so effectively reduces pig adipose accumulation on the molecular level.
    Bzw2 Promotes Proliferation and Lactation of Mammary Epithelial Cell in Dairy Goat
    SUN Rui-qiu, LI Qing-zhang, YAN Hong-bo, ZHAO Jing, GAO Xue-jun
    2012, 12(11): 1884-1891.  DOI: 10.1016/S1671-2927(00)8724
    Abstract ( )   PDF in ScienceDirect  
    Mitosis of mammary epithelial cell is foundation of mammal lactation. We developed a strategy of combined application of generation of longer cDNA fragments from the serial analysis of gene expression (SAGE) tags for gene identification (GLGI) to screen and identify genes influencing lactating ability of mammary epithelial cell in dairy goat. GLGI as a new tag identification technique was brought about with SAGE. Bzw2 was found as a candidate gene related to lactation by screening Long-SAGE library of mammary gland in dairy goat. Bzw2 cDNA was synthesized by switching mechanism at 5´-end of RNA transcript (SMART) technology. The mRNA level of Bzw2 was relatively higher in early lactation than in other development stages of mammary gland. The proliferation of mammary epithelial cell was inhibited by transfecting specific shRNA of Bzw2. The mRNA levels of Stat5, Csn2 and Prlr were also down-regulated, suggesting the lactating ability of mammary epithelial cell was attenuated after Bzw2 RNAi. The reduction of mammary epithelial cell growth and lactation by Bzw2 RNAi was rescued through over-expression of Bzw2. These results revealed that Bzw2 might play an important role in lactation though the molecular mechanism was still unclear.
    Influence of PPV, PRV and PRRSV on Efficacy of the Lapinized Hog Cholera Vaccine and Pathogenicity of Classical swine fever virus
    NING Yi-bao, ZHAO Yun, WANG Qin, FAN Xue-zheng, QIN Yu-ming, ZHANG Guang-chuan, XU Lu, QIU Hui-shen, WANG Zai-shi, SONG Li, SHEN Qing-chun, ZHAO Qi-zu
    2012, 12(11): 1892-1897.  DOI: 10.1016/S1671-2927(00)8725
    Abstract ( )   PDF in ScienceDirect  
    Classical swine fever caused by Classical swine fever virus (CSFV) is a serious problem for swine industries in developing countries, which successful control of the disease have been relying on vaccination. However, classical swine fever still occurs in some immunized swine herds for various reasons. In this study, we conducted animal experiments to examine the influence of single or mixed infection with Porcine parvo virus (PPV), Pseudorabies virus (PRV) and Porcine reproductive and respiratory syndrome virus (PRRSV) on the protective immunity induced by the Lapinized hog cholera virus (HCLV) vaccine and the pathogenicity of CSFV. In experiment 1, pigs were first inoculated with PPV, PRV or PRRSV, then immunized with HCLV, and finally challenged with a highly virulent CSFV Shimen strain. All of the pigs immunized with HCLV survived after the challenge, while all of the pigs in the non-immunized control group died after the challenge. The pigs in the group immunized with HCLV did not show any clinical symptoms of classical swine fever and were negative with CSFV after the challenge. The pigs infected with the non-CSFV before HCLV immunization did not display any clinical symptoms after the challenge with CSFV Shiman strain, but 11 of the 12 pigs were positive with CSFV. In experiment 2, pre-infections with PPV, PRV, and PRRSV were followed by inoculation with a low-virulence CSFV strain (CSFV 39), and then the pigs were challenged with the CSFV Shimen strain. Infections by either PPV, PRV or PRRSV did not enhance the virulence of CSFV-39, but pigs infected by a mixture of the 3 viruses developed clinical symptoms after inoculation with CSFV-39. The mixed infection also increased mortality caused by the challenge with the CSFV Shimen strain. Together, these results showed PPV, PRV and PRRSV infections in pigs can reduce the efficacy of the HCLV vaccine and enhance the pathogenicity of CSFV, which may partly explain the immunization failure against CSFV in some swine herds.
    Optimizing Parameters of CSM-CERES-Maize Model to Improve Simulation Performance of Maize Growth and Nitrogen Uptake in Northeast China
    LIU Hai-long, YANG Jing-yi, HE Ping, BAI You-lu, JINJi-yun , Craig FDrury, ZHUYe-ping , YANG Xue-ming, LI Wen-juan, XIE Jia-gui, YANGJing-min , Gerrit Hoogen boom
    2012, 12(11): 1898-1913.  DOI: 10.1016/S1671-2927(00)8726
    Abstract ( )   PDF in ScienceDirect  
    Crop models can be useful tools for optimizing fertilizer management for a targeted crop yield while minimizing nutrient losses. In this paper, the parameters of the decision support system for agrotechnology transfer (DSSAT)-CERES-Maize were optimized using a new method to provide a better simulation of maize (Zea mays L.) growth and N uptake in response to different nitrogen application rates. Field data were collected from a 5 yr field experiment (2006-2010) on a Black soil (Typic hapludoll) in Gongzhuling, Jilin Province, Northeast China. After cultivar calibration, the CERES-Maize model was able to simulate aboveground biomass and crop yield of in the evaluation data set (n-RMSE=5.0-14.6%), but the model still over-estimated aboveground N uptake (i.e., with E values from -4.4 to -21.3 kg N ha-1). By analyzing DSSAT equation, N stress coefficient for changes in concentration with growth stage (CTCNP2) is related to N uptake. Further sensitivity analysis of the CTCNP2 showed that the DSSAT model simulated maize nitrogen uptake more precisely after the CTCNP2 coefficient was adjusted to the field site condition. The results indicated that in addition to calibrating 6 coefficients of maize cultivars, radiation use efficiency (RUE), growing degree days for emergence (GDDE), N stress coefficient, CTCNP2, and soil fertility factor (SLPF) also need to be calibrated in order to simulate aboveground biomass, yield and N uptake correctly. Independent validation was conducted using 2008-2010 experiments and the good agreement between the simulated and the measured results indicates that the DSSAT CERES-Maize model could be a useful tool for predicting maize production in Northeast China.
    Cropping Pattern Modifications Change Water Resource Demands in the Beijing Metropolitan Area
    HUANG Jing, Bradley GRidoutt, XU Chang-chun, ZHANG Hai-lin , CHEN Fu
    2012, 12(11): 1914-1923.  DOI: 10.1016/S1671-2927(00)8727
    Abstract ( )   PDF in ScienceDirect  
    Adequate freshwater supply has become an issue of increasing local and international concern. Reducing water use in agriculture, which is the largest water using sector of the economy, is both important and urgent. The aim of this paper was to quantify how recent cropping pattern changes have influenced water resources in the great Beijing metropolitan area, an expanding megacity which also includes rural counties. Crop production affects blue water use through water consumption and water pollution, the latter assessed here using a critical dilution method. From 1990 to 2010, the total blue water used by crop production declined due to a decrease in overall cropped area, initially in response to local government policies favouring urban development. However, the average blue water use per hectare increased from 2 112 m3 ha-1 yr-1 in 1990 to 2 764 m3 ha-1 yr-1 in 2003, largely as the result of a transition from cereal to vegetable crops, and in particular an increase in intensively managed plastic and glass covered vegetable production systems. Current policies aim to conserve agricultural land, in the interests of food security, and to stimulate cereal production systems with higher ecosystem services provision. As such, in 2010 the average blue water use was 2 425 m3 ha-1 yr-1. These results demonstrate that cropping pattern changes in peri-urban regions and rural communities surrounding the Beijing metropolitan area can have a substantial impact on water resources. They also highlight the tradeoffs between food production and urban and industrial water supply and the need for integrated policy development.
    Comparison of Two Dripper Line Designs to Assess Cotton Yield, Water Use, and Net Return in Northwest China
    WANG Ruo-shui, WAN Shu-qin, KANG Yue-hu , LIU Shi-ping
    2012, 12(11): 1924-1932.  DOI: 10.1016/S1671-2927(00)8728
    Abstract ( )   PDF in ScienceDirect  
    This study aimed to compare the effects of two types of drip irrigation line design on cotton yield, water use, and net returns. The experiments were carried out in the arid region of Xinjiang, Northwest China, during 2009-2010 growing years. The two types of lateral placement are commonly used by the local farmers in the area: double lines (two laterals controlling four rows) and single line designs (one lateral controlling four rows). The results indicated that less irrigation water was applied by single line compared with double lines design. This implies that more irrigation water could be saved using single line, by reducing the water consumption of cotton. The emergence rates for double lines were 2 and 6% higher than those for single line design in 2009 and 2010. The seed cotton yields for double lines design were 5.76 and 6.41 Mg ha-1 which were 13 and 9% higher than for single line design in 2009 and 2010, respectively. Single lines could however lower the investment cost compared to double lines, which produced 10 and 7% more net income in 2009 and 2010, respectively. By contrast, the double lines was more profitable and suitable for the farmers in Northwest China than single line design.