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    Crop Genetics · Breeding · Germplasm Resources
    Fine Mapping of qTGW3-1, a QTL for 1000-Grain Weight on Chromosome 3 in Rice
    ZHANG Qiang, YAO Guo-xin, HU Guang-long, TANG Bo, ZHANG Hong-liang, LI Zi-chao
    2012, 12(6): 879-887.  DOI: 10.1016/S1671-2927(00)8610
    Abstract ( )   PDF in ScienceDirect  
    The QTL qTGW3-1 was located on chromosome 3 of rice (Oryza sativa L.) and associated with the 1 000-grain weight (TGW) according to the result of our earlier study. With the objective of fine mapping of this locus, we developed a F2 population consisting of 3 428 plants derived from the cross between TGW-related near isogenic line DL017 (BC3F4 generation of GSL156×Nipponbare) and the recurrent parent Nipponbare. Using six microsatellites, this QTL was delimited between RM5477 and RM6417. Markers MM1455 and MM1456 within this region were used for further mapping of this QTL. Finally, qTGW3-1 was fine-mapped into a 89-kb interval between RM5477 and MM1456, which locates in the BAC clone AC107226 harboring five putative candidate genes.
    Characterization of a Novel Chlorophyll-Deficient Mutant Mt6172 in Wheat
    GUO Hui-jun, ZHAO Hong-bing, GU Jia-yu, LI Jun-hui, LIU Qingchang, LIU Lu-xiang
    2012, 12(6): 888-897.  DOI: 10.1016/S1671-2927(00)8611
    Abstract ( )   PDF in ScienceDirect  
    Identification of new chlorophyll-deficient mutants will provide materials for studying signaling components and pathways between plastid and nucleus. A novel chlorophyll-deficient mutant, named Mt6172, was obtained by spaceflight environment induction. Genetic analysis showed that its inheritance was controlled by nuclear and cytoplamic genes. Leaf color of its self-fertilized progenies was albino, narrow-white striped, or green. Only a few cells with abnormal chloroplasts were observed in albino plants and white section of narrow-white striped plants. These chloroplasts had obvious flaws in inner structure, and granum lamellae was extremely disordered. The narrow-white striped plants were characterized with greenand- narrow-white striped leaves, and the width of stripes between different plants was even, their plant height, number of productive tillers, and 1 000-grain weight were lower than those of the wild type. The narrow-white striped plants and the wild type had significant difference in the value of potential activity of photosystem II at all tested stages. At elongation stage, which was impacted the most seriously, effective quantum yield significantly decreased, whereas the energy for photoprotection and photodamage significantly increased. Under different photosynthetic active radiation conditions, changes of electron transport rate, photochemical dissipation, and effective quantum yield were different, electron transport rate was more impacted than other parameters. Therefore, the leaf morphology and inheritance of mutant Mt6172 was different from the other reported mutants in wheat, and it was a novel mutant of chlorophyll deficiency.
    Cloning and Characterization of a Somatic Embryogenesis Receptor-Like Kinase Gene in Cotton (Gossypium hirsutum)
    SHI Ya-li, WU Xiao-ping, MENG Zhi-gang, GUO San-dui
    2012, 12(6): 898-909.  DOI: 10.1016/S1671-2927(00)8612
    Abstract ( )   PDF in ScienceDirect  
    A novel gene, GhSERK1, was identified in cotton. It encoded a protein belonging to the somatic embryogenesis receptorlike kinase (SERK) family. The genomic sequence of GhSERK1 was 6 920 bp in length, containing a predicted transcriptional start site (TSS). Its full-length cDNA was 2 502 bp, encoding a protein of 627 amino acids. Sequence analysis of GhSERK1 revealed high levels of similarity to other reported SERKs, as well as a conserved intron/exon structure that was unique to members of the SERK family. Expression analysis showed that GhSERK1 mRNA was present in all organs of cotton plants and at different developmental stages, but its transcripts were most abundant in reproductive organs. Compared with that of the male-fertile line, the level of GhSERK1 mRNA was lower in the anther of the male-sterile cotton line, in which the pollen development was defected. Taken together, these findings illustrated that the GhSERK1 play a critical role during the anther formation, and may also have a broad role in other aspects of plant development.
    Transformation of Upland Cotton (Gossypium hirsutum L.) with gfp Gene as a Visual Marker
    JIN Shuang-xia, LIU Guan-ze, ZHU Hua-guo, YANG Xi-yan, ZHANG Xian-long
    2012, 12(6): 910-919.  DOI: 10.1016/S1671-2927(00)8613
    Abstract ( )   PDF in ScienceDirect  
    The green-fluorescent protein (gfp) gene was evaluated as a screening marker during cotton (Gossypium hirsutum L.) transforming and plant regeneration. High expression of GFP (green-fluorescent protein) was observed in transgenic cells as early as 42 h after co-culture with Agrobacterium. Most of the stable transformation events were detected in the cells of primary vascular tissue. GFP transient expression could be detected on all the explants after co-culturing for 4 d, however, the highest GFP stable expression was recorded when the explants were co-cultured for 3 d. We believe the transient and stable expression of a foreign gene in genetic transformation were two relative but different events, because high transient expression did not surely lead to high stable transformation. Under the same conditions of in vitro culture, transgenic and non-transgenic calli exhibited different morphological characters on different stages of development. High concentration of plant growth regulators (PGRs) was efficient for somatic embryogenesis of the transgenic calli, which means that the transgenic calli need relatively higher dose of hormone for further growth and somatic embryogenesis than non-transgenic ones. Strong GFP-expression was observed in leaf, stem, petioles, floral tissues, and seedlings of T1 progeny. Segregation ratios of eight transgenic lines were scored for expression of GFP in the T1 progeny that providing further evidence of stable transformation. These results proved that GFP is a powerful reporter gene for protocol optimization, selection, and monitioring in whole transformation events.
    Root Morphology and Physiology in Relation to the Yield Formation of Rice
    YANG Jian-chang, ZHANG Hao, ZHANG Jian-hua
    2012, 12(6): 920-926.  DOI: 10.1016/S1671-2927(00)8614
    Abstract ( )   PDF in ScienceDirect  
    Root system is a vital part of plant and regulates many aspects of shoot growth and development. This paper reviews how some traits of root morphology and physiology are related to the formation of grain yield in rice (Oryza sativa L.). Higher root biomass, root oxidation activity, and cytokinin contents in roots are required for achieving more panicle number, more spikelets per panicle, greater grain-filling percentage, and higher grain yield. However, these root traits are not linearly correlated with yield components. When these traits reach very high levels, grain filling and grain yield are not necessarily enhanced. High numbers of mitochondria, Golgi bodies, and amyloplasts in root tip cells benefit root and shoot growth and yield formation. Proper crop management, such as an alternate wetting and moderate soil drying irrigation, can significantly improve ultra-structure of root tip cells, increase root length density and concentration of cytokinins in root bleedings, and consequently, increase grain-filling percentage, grain yield, and water use efficiency. Further studies are needed to investigate the mechanism underlying root-shoot and root-soil interactions for high grain yield, the roles of root-sourced hormones in regulating crop growth and development and the effects of soil moisture and nutrient management on the root architecture and physiology.
    Leaf Gas Exchange, Chlorophyll Fluorescence, and Fruit Yield in Hot Pepper (Capsicum anmuum L.) Grown Under Different Shade and Soil Moisture During the Fruit Growth Stage
    ZHUJuan-juan , LIANGYin-li , WUXing , HAOWang-lin
    2012, 12(6): 927-937.  DOI: 10.1016/S1671-2927(00)8615
    Abstract ( )   PDF in ScienceDirect  
    Relative leaf chlorophyll (Chl.) content, leaf gas exchange, Chl. fluorescence, plant biological biomass, and fruit yield were evaluated in growing hot pepper (Capsicum annuum L.) during the fruit-growing stages in hot summer under three shade levels (un-shade, 30% shade, and 70% shade) and four soil water contents (SWC) of 40-55%, 55-70%, 70-85%, and 85- 100% of field moisture capacity (FMC). Hot pepper crops were more affected by light irradiance than by soil moisture and by their interaction during the whole observed periods. Hot pepper attained greatest relative leaf Chl. content (expressed as SPAD value) and photosynthetic activity when cultivated with 30% shade, resulting in the highest plant biological biomass and fruit yield. Although 70% shade improved leaf photosynthetic efficiency (expressed as Fv/Fm or Fv´/Fm´), crops obtained the lowest photosynthetic rate, photochemical quenching coefficient (qP), and non-photochemical quenching coefficient (NPQ). This showed that light irradiance was insufficiency in S70% (70% shade) treatment. The leaf net photosynthetic rates (PN), Fv/Fm, and fruit yield increased gradually as SWC levels increased from 40-55% to 70- 85% FMC, but decreased as SWC was higher than 70-85% FMC. The water consumption increased progressively with SWC levels, but water-use efficiency (WUE) was the highest when soil moisture was 55-70% FMC. Interaction of shade and soil moisture had significant effects on PN and Fv/Fm, but not on other parameters. Under drought stress (40-55% and 55-70% FMC), 30% shade could relieve the droughty damage of crops and improve photosynthetic capacity and WUE, but 70% shade could not, oppositely, aggravate the damage. The positive correlation (r2 =0.72) between leaf PN and fruit yield was existent. This indicated that improvement of leaf photosynthesis would increase potentially marketable yield in hot pepper crops during the full fruit-growing stages. For agricultural purposes, approximately S30% (30% shade) with 70- 85% FMC is suggested to cultivate hot pepper during the fruit growth stage in hot summer months.
    Responses of Aerobic Rice (Oryza sativa L.) to Iron Deficiency
    SHI Rong-li, FAN Xiao-yun, ZHANG Fu-suo, ZOU Chun-qin
    2012, 12(6): 938-945.  DOI: 10.1016/S1671-2927(00)8616
    Abstract ( )   PDF in ScienceDirect  
    Aerobic rice has the advantage of saving water. Most published work has focused on improving its yield, while few reported on its micronutrient status. In fact, Fe deficiency is a common nutritional problem in the production of aerobic rice. Shortterm hydroponic culture experiments were conducted to study the response of aerobic rice to Fe deficiency and the effect of root exudates from Fe-deficient wheat on its Fe uptake ability. The results indicate that the amount of phytosiderophores (PS) released from aerobic rice did not increase under Fe deficient conditions. The Fe(III) reducing capacity of Fe-deficient aerobic rice did not increase and the solution pH did not decrease significantly. What’s more, no obvious swelling was observed in the root tips. Aerobic rice did not show special responses to improve their Fe nutrition under Fe deficiency as both strategy I and II plants though they were very sensitive to Fe deficiency. This may be a reason which causes Fe deficiency problem in aerobic rice. However, root exudates from Fe-deficient wheat (PSw) could improve its Fe nutrition in the presence of insoluble Fe(OH)3. This suggests that aerobic rice could utilize Fe activated by PSw.
    Integrated Weed Management Through Tillage and Herbicides for Wheat Production in Rice-Wheat Cropping System in Northwestern Pakistan
    Khalid Usman, Said Mir Khan, Said Ghulam, Muhammad Anwar Khan
    2012, 12(6): 946-953.  DOI: 10.1016/S1671-2927(00)8617
    Abstract ( )   PDF in ScienceDirect  
    Conservational tillage (CT) in combination with broad spectrum herbicide may be more efficient and economical in controlling weeds, reducing cost of cultivation, and enhancing wheat yield. Field experiments were carried out to evaluate the effect of tillage and herbicides on weeds and wheat yield under rice-wheat cropping system (RWCS). The results indicated that broad spectrum herbicides particularly, carfentrazone ethyl ester + isoproturon (Affinity 50 WDG) reduced weeds density by 93 and 95% compared to control and also produced the maximum grain yield (6 818 and 6 996 kg ha-1) and HI (harvest index, 44.7 and 44.6%) in 2007-2008 and 2008-2009 growing seasons, respectively. The maximum weeds infestation and the lowest yield were recorded in control. Tillage methods significantly influenced grain yield and HI, while no significant effect on all other parameters. The overall mean yield was significantly higher in zero tillage (5 575 kg ha-1) and reduced tillage (5 584 kg ha-1) compared to CT (5 479 kg ha-1). Besides increasing wheat yield, Affinity 50 WDG and zero tillage are important weed management practices that can be integrated into wheat production in RWCS. However, in case of perennial weeds or insect pests’ infestation, CT in combination with Affinity 50 WDG would be more productive than conservation tillage.
    Evolution of Xanthomonas Gene Content: Gene Gain/Loss History and Species Divergence
    JIN Gu-lei, ZHANG Guo-qing, ZHU Jun, ZHOU Xue-ping, SUN Guo-chang, LI Bin, ZHU Bo
    2012, 12(6): 954-961.  DOI: 10.1016/S1671-2927(00)8618
    Abstract ( )   PDF in ScienceDirect  
    Horizontal gene transfer (HGT) plays key roles in the evolution of pathogenetic bacteria, especially in pathogenetic associated genes. In this study, the evolutionary dynamics of Xanthomonas at species level were determined by the comparative analysis of the complete genomes of 15 Xanthomonas strains. A concatenated multiprotein phyletic pattern and a dataset with Xanthomonas clusters of orthologous genes were constructed. Mathematical extrapolation estimates that the core genome will reach a minimum of about 1 547 genes while the pan-genome will increase up to 22 624 genes when sequencing 1 000 genomes. The HGT extent in this genus was assessed by using a Markov-based probabilistic method. The reconstructed gene gain/loss history, which contained several features consistent with biological observations, showed that nearly 60% of the Xanthomonas genes were acquired by HGT. A large fraction of variability was in the clade ancestor nodes and “leaves of the tree”. Coexpression analysis suggested that the pathogenic and metabolic variation between Xanthomonas oryzae pv. oryzicola and Xanthomonas oryzae pv. oryzae might due to recently-transferred genes. Our results strongly supported that the gene gain/loss may play an important role in divergence and pathogenicity variation of Xanthomonas species.
    Identification of a Resistance Gene bls1 to Bacterial Leaf Streak in Wild Rice Oryza rufipogon Griff.
    HE Wen-ai, HUANG Da-hui, LI Rong-bai, YANG Hai-ning, HUANG Yue-yue, LIU Chi, MA Zeng-feng, YANG Yong
    2012, 12(6): 962-969.  DOI: 10.1016/S1671-2927(00)8619
    Abstract ( )   PDF in ScienceDirect  
    Bacterial leaf streak (BLS) of rice, caused by Xanthomonas oryzae pv. oryzicola (Xoc) is a worldwide destructive disease. Development of resistant varieties is considered to be one of the most effective and eco-friendly ways to control the disease. However, only a few genes/QTLs having resistance to BLS have been identified in rice until now. In the present study, we have identified and primarily mapped a BLS-resistance gene, bls1, from a rice line DP3, derived from the wild rice species Oryza rufipogon Griff. A BC2F2 (9311/DP3//9311) population was constructed to map BLS-resistance gene in the rice line DP3. The segregation of the resistant and susceptible plants in BC2F2 in 1:3 ratio (χ2=0.009, χ2 0.05, 1=3.84, P>0.05), suggested that a recessive gene confers BLS resistance in DP3. In bulked segregant analysis (BSA), two SSR markers RM8116 and RM584 were identified to be polymorphic in resistant and susceptible DNA bulks. For further mapping the resistance gene, six polymorphic markers around the target region were applied to analyze the genotypes of the BC2F2 individuals. As a result, the BLS-resistant gene, designated as bls1, was mapped in a 4.0-cM region flanked by RM587 and RM510 on chromosome 6.
    Ultrastructural Changes of Sphaerotheca fuliginea (Schlechtend.:Fr.) Pollacci in Cucumber After Treated by Chrysophanol
    REN Hong-min, FAN Fan, CAO Ke-qiang
    2012, 12(6): 970-977.  DOI: 10.1016/S1671-2927(00)8620
    Abstract ( )   PDF in ScienceDirect  
    Chrysophanol (1,8-dihydroxy-3-methylanthraquinone) is a free anthraquinone compound and a secondary metabolite of medicinal plant rhubarb. Chrysophanol has been reported to have both protective and curative activity against Sphaerotheca fuliginea (Schlechtend.:Fr.) Pollacci, the causal agent of cucumber powdery mildew. In this paper the ultrastructure of powdery mildew on cucumber leaves was studied using electron microscopy after the leaves were treated with chrysophanol. Results showed that preventive treatments with chrysophanol affected fungal development, including spore germination, appressorial formation, and penetration. In the curative treatment, chrysophanol affected fungal survival, resulting in broken cell wall of germ tubes, swelling and collapse of hyphal tips, hyphal malformation, delayed and reduced sporulation. The morphological changes induced by chrysophanol at the ultrastructural level were reflected by haustorium deformation, vacuolization, abortion, and necrosis. Host cell walls infected or adjacent to haustoria were thickened. All these morphological changes of S. fuliginea further confirmed the fungicidal activity of chrysophanol on powdery mildew of cucumber.
    An Insect Imaging System to Automate Rice Light-Trap Pest Identification
    YAO Qing, LIU Qing-jie, YANG Bao-jun, CHEN Hong-ming, TANG Jian
    2012, 12(6): 978-985.  DOI: 10.1016/S1671-2927(00)8621
    Abstract ( )   PDF in ScienceDirect  
    Identification and counting of rice light-trap pests are important to monitor rice pest population dynamics and make pest forecast. Identification and counting of rice light-trap pests manually is time-consuming, and leads to fatigue and an increase in the error rate. A rice light-trap insect imaging system is developed to automate rice pest identification. This system can capture the top and bottom images of each insect by two cameras to obtain more image features. A method is proposed for removing the background by color difference of two images with pests and non-pests. 156 features including color, shape and texture features of each pest are extracted into an support vector machine (SVM) classifier with radial basis kernel function. The seven-fold cross-validation is used to improve the accurate rate of pest identification. Four species of Lepidoptera rice pests are tested and achieved 97.5% average accurate rate.
    Identification and Promoter Activity Analysis of Porcine miR-181 and miR-1
    ZHANG Hai-xin, LIU Yi-nan, ZHAO Yan-he, REN Zhu-qing, XIONG Yuan-zhu
    2012, 12(6): 986-992.  DOI: 10.1016/S1671-2927(00)8622
    Abstract ( )   PDF in ScienceDirect  
    Since its discovery a decade ago, microRNA has been identified as one of the major regulatory gene families in eukaryotic cells. Many functions of microRNAs have been revealed both in flora and fauna in recent years, but the transcriptional regulation of microRNA genes is not well-understood. In the present study, a series of primers were designed in the 2 000 nt upstream regions of porcine miR-181 and miR-1 and then the sequences were cloned into pGL3-basic vector to test their transcriptional activity. Dual-luciferase reporter assays showed that, the activity of 5´-flanking sequence of miR-181 started on construct -51, decreasing with the length of the fragment up to -444. The upstream 590 bp confer maximal transcriptional activity and the basal promoter activity is located within the -82 to +16 bp region. For miR-1, the activity starts on construct -50, decreasing with the length of the fragment up to -1 254 in despite of a bit of fluctuation, and the basal promoter activity is located within the -50 to +47 bp region. Furthermore, some putative regulation elements of both miR-181 and miR-1 were located. In addition, tissue distribution revealed that miR-181 is expressed at a relatively low level.
    Improving Geese Production Performance in “Goose-Fish” Production System by Competitive Reduction of Pathogenic Bacteria in Pond Water
    YANG Xi-wen, JIANG Dan-li, SUN Ai-dong, SHI Zhen-dan
    2012, 12(6): 993-1001.  DOI: 10.1016/S1671-2927(00)8623
    Abstract ( )   PDF in ScienceDirect  
    This study investigated whether competitive reduction of pathogenic bacteria growth in pond water alleviates lipopolysaccharide (LPS) contamination and improves geese production performances in the “goose-fish” production system, thereby providing the potential for an improved technique for ecological water fowl production. In the first experiment, 240 Magang goslings of 15-d age were randomly and equally allocated into 16 “yard and pond” pens using a 2×2 factorial design with 4 replications per treatment. In the 55-d experimental period, the goslings received 2 main treatments: supplementation of Bacillus subtilis spores in the feed and addition of photosynthetic bacteria (PSB) to the pond water. Both B. subtilis spores and PSB treatments significantly suppressed water counts of Gram-negative bacteria Escherichia coli, Salmonella and Shigella, and LPS concentrations in pond water and in gosling blood (P<0.05). As the result, the two treatments significantly improved gosling weight gain and carcass quality, marked by enhanced breast and leg muscle percentages and reduced subcutaneous fat proportions (P<0.05). Moreover, the improved effects of B. subtilis spores and PSB treatments were additive. In the second experiment, 1 160 adult geese were induced to start egg laying from May throughout the summer months. The geese were separated equally into control and experimental flocks to fit into 2 integration production units, with a density of 1 bird m-2 meter on pond water. Experimental flock geese were treated with B. subtilis spores in feed and PSB in the pond water for the duration of the study. Such treatment combination significantly depressed the growth of E. coli, Salmonella and Shigella in the pond water and reduced LPS concentrations both in pond water and in geese blood (P<0.01). As a result, egg fertility, fertile and set egg hatchabilities were all improved in the treated flock. Results from both growing goslings and breeding geese demonstrated that water bacteria pollution can be competitively reduced by supplementation with B. subtilis spores via the feed and addition of PSB in pond water, each of which reduces LPS contamination to geese and improves production performances. Microecological agents such as B. subtilis spores and PSB improve water quality and provide a simple ecological technique for the “water fowl-fish” integrative production system.
    Immune BlotAnalysis on Expression of the Mammalian Target of Rapamycin in Goat Fetal Fibroblasts with Recombinant Polyclonal Antibody
    LIANGYan , WANGXiao-jing , YANGJiao-fu , HAOXi-yan , BAYin-ma , CHENXian-wei WANGZhi-gang
    2012, 12(6): 1002-1008.  DOI: 10.1016/S1671-2927(00)8624
    Abstract ( )   PDF in ScienceDirect  
    To detect the mammalian target of rapamycin (mTOR) expressed in Cashmere goat fetal fibroblasts (GFb), mTOR gene was cloned from Inner Mongolia Cashmere goat (Capra hircus) and expressed in Escherichia coli followed by immunizing mice with the purified recombinant protein as an immunogen to produce the anti-goat mTOR recombinant polyclonal antibody. Antiserum was collected from the immunized mice after the fifth immunization and its titer was determined with enzyme-linked immunosorbent assay (ELISA). The results showed that the recombinant polyclonal antibody had a titer 1:200 000 and could react with the mTOR expressed in GFb cells with a specific and sensitive affinity. Western blot showed that mTOR expression and phospho-mTOR (Ser 2448) activity were inhibited when GFb cells were treated with CCI-779, an mTOR specific inhibitor.
    Effect of Methionine Deficiency on the Thymus and the Subsets and Proliferation of Peripheral Blood T-Cell, and Serum IL-2 Contents in Broilers
    WU Bang-yuan, CUI Heng-min, PENG Xi, FANG Jing, CUI Wei
    2012, 12(6): 1009-1019.  DOI: 10.1016/S1671-2927(00)8625
    Abstract ( )   PDF in ScienceDirect  
    The purpose of this study was to investigate the effects of methionine deficiency on cellular immune function by determining morphological and ultrastructural changes of thymus, thymic cell cycle and apoptosis, peripheral blood T-cell subsets, Tcell proliferation function and the serum interleukin-2 (IL-2) contents. 120 1-d-old broilers were randomly divided into two groups (6 replicates in each group and 10 broilers in each replicate) and fed on a control diet or methionine deficient diet for 42 d. Lesions were observed in experiment. Histopathologically, lymphopenia and congestion were observed in the medulla of thymic lobule. Ultrastructurally, there were more apoptosis lymphocytes, and the mitochondria of lymphocytes were swelled in thymus of methionine deficiency. The G0/G1 phase of the cell cycle of the thymus was much higher (P<0.01), and the S, G2+M phases and proliferating index (PI) were lower (P<0.01) in methionine deficiency than in control group. And the percentage of apoptotic cells in the thymus was significantly increased in methionine deficiency (P<0.01). The percentage of CD4+ and CD8+ T-cells was decreased in methionine deficiency compared with control group. Meanwhile, the proliferation function of peripheral blood T-cell was decreased in methionine deficiency. Also, the serum IL-2 contents were decreased in methionine deficiency. It was concluded that methionine deficiency could cause pathological and ultrastructural changes of thymus, reduce the T-cell population, serum IL-2 contents and the proliferation function of Tcells, and induce increased percentage of apoptotic cells. The cellular immune function was finally impaired in broilers.
    Effects of Nitrogen Management on the Yield of WinterWheat in Cold Area of Northeastern China
    LI Lian-peng, LUO Sheng-guo, PENG Xian-long
    2012, 12(6): 1020-1025.  DOI: 10.1016/S1671-2927(00)8626
    Abstract ( )   PDF in ScienceDirect  
    A plot experiment including four treatments, CK (N 105 kg ha-1 as urea, including a basal N application of 35 kg ha-1 and a topdressing N 70 kg ha-1 at turned green stage) and optimized N management (OPT1, OPT2 and OPT3, applied two-thirds, one-third and two-fifths N at jointing stage, respectively, total N 60 kg ha-1), was conducted to evaluate the effects of nitrogen management on growth and N uptake of winter wheat (Triticum aestivum), Dongnong 1, which is the first highly cold tolerant winter wheat in China. Index of population quality, N uptake and yield were determined. The ear-bearing tiller rate was increased by above 12%, and the leaf area index, biomass and N uptake were significantly decreased (P<0.05) at jointing stage. OPT treatments increased the grain to leaf area ratio at heading stage, the dry matter weight and N uptake after heading by 14.3-27.9%, 11.6-28.7% and 118.1-161.8 %, respectively. The yield of the OPT treatments was increased by 14.2-37.5% compared with CK, and there was a significant difference (P<0.05) between CK and OPT1 treatments. Harvest index and N partial factor productivity (PFP, kg grain yield per kg N applied) was clearly enhanced from 0.4 and 35.6 kg, respectively for CK to an average of 0.48 (P<0.05) and 77.6 kg (P<0.05) in the OPT treatments. These results indicated that the optimized N management increased the harvest index, yield and N use efficiency by decreasing the N application rate and postponing N application time, improved wheat population quality, controlled excessive growth in the vegetative stages and increased dry matter and N accumulation rates after heading.
    Xanthium Suppression Under Maize||Sunflower Intercropping System
    CHEN Yuan-quan, LUAN Chen, SHI Xue-peng
    2012, 12(6): 1026-1037.  DOI: 10.1016/S1671-2927(00)8627
    Abstract ( )   PDF in ScienceDirect  
    Weed control is one of the major constraint factors in crop production around the world. Field experiments were conducted during 2008-2009 under intercropping systems involving alfalfa (Medicago sativa L.), sweet potato (Ipomoea batatas [L.] Lam.), peanut (Arachis hypogaea L.), and sunflower (Helianthus annuus L.) in maize (Zea mays L.) without any weeds control methods taken. The results demonstrate that maize||sunflower is most effective on weed suppression and that it also has a more competitively inhibitory effect on Xanthium compared with the other patterns by evaluating the Xanthium density and dry weight under different intercropping systems with maize. Maize||peanut, maize||alfalfa and maize||sweet potato intercrops have no apparent inhibitory effect on weeds. To further investigate the effect of maize||sunflower on weed control, indoor pot experiments were conducted by determining the effect of extractions on germination rate (GR), root vigor, MDA (malondialdehyde), SOD (superoxide dismutase) and POD (peroxidase) content of Xanthium. The results better prove that maize||sunflower extractions have more significant inhibitory effect on GR and young root vigor of Xanthium than maize monocrop extractions.
    Study on Environmental Risk and Economic Benefits of Rotation Systems in Farmland of Erhai Lake Basin
    TANG Qiu-xiang, Wilko Schweers, LEI Bao-kun, LIN Tao, ZHANG Gui-long
    2012, 12(6): 1038-1047.  DOI: 10.1016/S1671-2927(00)8628
    Abstract ( )   PDF in ScienceDirect  
    This study was designed to find out an optimised planting system of reducing non-point (source) pollution by analyzing the reasons and the factors of influence non-point pollution in farmland of Erhai Lake basin. The results showed that incomes, residual nitrogen in soil, and the loss of nitrogen in surface water in rice-garlic system were higher than those in rice-fava bean system. There were positive correlations between the nitrogen loss of farmland, nitrogen inputs, residual nitrogen in soil, and incomes of farmland. Economic benefits and environment benefits are both appropriate, if the area of rice-garlic system would be reduced to 53% and the area of rice-fava bean system increased to 36% of total cropping area in the investigated watershed. Adjustment of planting structure and introduction of reasonable rotation systems is considered an effective measure of controlling agricultural non-point pollution in watersheds of Erhai Lake.
    The Monitoring Analysis for the Drought in China by Using an Improved MPI Method
    MAO Ke-biao, XIA Lang, TANG Hua-jun, HAN Li-juan
    2012, 12(6): 1048-1058.  DOI: 10.1016/S1671-2927(00)8629
    Abstract ( )   PDF in ScienceDirect  
    MPI (microwave polarization index) method can use different frequencies at vertical polarization to retrieve soil moisture from TMI (tropical microwave imager) data, which is mainly suitable for bare soil. This paper makes an improvement for MPI method which makes it suitable for surface covered by vegetation. The MPI by using single frequency at different polarizations is used to discriminate the bare soil and vegetation which overcomes the difficulty in previous algorithms by using optical remote sensing data, and then the revision is made according to the different land surface types. The validation by using ground measurement data indicates that revision for different land surface types can improve the retrieval accuracy. The average error is about 24.5% by using the ground truth data obtained from ground observation stations, and the retrieval error is about 13.7% after making a revision by using ground measurement data from local observation stations for different surface types. The improved MPI method and precipitation are used to analyze the drought in Southwest China, and the analysis indicates the soil moisture retrieved by improved MPI method can be used to monitor the drought.