Wheat Production In China Research Articles

Potential allelopathic effects of Xanthium italicum Moretti on wheat.

The allelopathic potential of invasive Xanthium italicum Moretti on seedling growth of wheat (Triticum aestivum Linn) was investigated. Aqueous (0.05 g/ml) and ethanol (1 mg/ml) extracts reduced root elongation of wheat seedlings by 71 and 87%, respectively; chloroform fraction of the ethanol extract exhibited the strongest phytotoxic effect as compared to other fractions, inhibiting root growth of wheat seedlings by 95% at 1 mg/ml. Incorporation of X. italicum plant residues (20, 50 and 100 g/kg soil) into soils affected not only photosynthetic pigment content, but also photosynthetic parameters of wheat seedlings. Chlorophyll a, b and carotenoid contents of wheat seedlings decreased significantly when plant residues were applied at 100 g/kg soil. Net photosynthetic rate (Pn), transpiration rate (Tr) and stomatal conductivity (gs) decreased greatly when seedlings were treated with plant residues at 20, 50 and 100 g/kg soil, whereas CO2 concentration (Ci) increased significantly at 50 and 100 g plant residue/kg soil. Shoot length, fresh and dry weight were also significantly affected starting from 20 g plant residue/kg soil treatment in a dose-dependent manner. Furthermore, our results indicated that soil conductivity, soil pH and soil nutrients were unlikely responsible for the aforementioned changes. Our results suggest that allelopathy might contribute to the invasion success of X. italicum, and its invasion could possibly pose potential threat to wheat production in China. Key words: Allelopathy, phytotoxin, wheat, Xanthium italicum.

Climate change impacts on regional winter wheat production in main wheat production regions of China

Wheat is the second primary crop in China. Wheat production in China is an important component for national food security. The combination of high-resolution Global Climate Model (GCM) and WheatGrow model was used to assess the effects of climate change on wheat yields in the main wheat production regions of China. With the application of many techniques including the downscaling of meteorological data, rasterizing of sowing date, parameterization of region cultivar and vectorization of soil data, the spatial data in study area is divided into homogeneous grids with the resolution of 0.1°×0.1°. The grid is taken as the basic simulation unit, and each grid has a complete set of input data (meteorological, soil, management and varieties). Regional productivities are simulated with WheatGrow for each grid cell under scenarios of climate-change. There is an advance in flowering date in future climate compare to 2000s, but with a more homogeneous pattern for the whole producing region. The changes in grain filling period are relatively stable. Under rain-fed conditions, wheat yield is reduced in the north regions of China in three future periods, while wheat yield increases in the south regions of China. Under full-irrigation conditions, irrigated wheat yields will increase in almost all regions of whole producing region. The spatial pattern of evapotranspiration change is quite similar to that of yield change under rain-fed and full-irrigation conditions. The correlation between wheat yield and evapotranspiration (ET) increases to 0.96 and 0.51 (p<0.01) under rain-fed and full-irrigation conditions, respectively. The irrigation water use efficiency (IWUE) will decrease under three time slices in 2030s, 2050s and 2070s in western Shandong, southern Sichuan, as well as northern Henan, Shanxi and Shaanxi, while IWUE will increase under scenarios of climate-change in other areas. The results revealed that the increase in effective irrigation in the future would help to increase the ET and further improve the wheat yield in the northern regions of China, and the limited water should be mad full use of in the regions with relatively high IWUE under scenarios of climate-change.

Molecular characterization of vernalization and response genes in bread wheat from the Yellow and Huai Valley of China

BackgroundFlowering time greatly influences the adaptation of wheat cultivars to diverse environmental conditions and is mainly controlled by vernalization and photoperiod genes. In wheat cultivars from the Yellow and Huai Valleys, which represent 60%-70% of the total wheat production in China, the large-scale genotyping of wheat germplasms has not yet been performed in terms of vernalization and photoperiod response alleles, limiting the use of Chinese wheat germplasms to a certain extent.ResultsIn this study, 173 winter wheat cultivars and 51 spring wheat cultivars from China were used to identify allelic variations of vernalization and photoperiod genes as well as copy number variations of Ppd-B1 and Vrn-A1. Two new co-dominant markers were developed in order to more precisely examine Vrn-A1b, Vrn-B1a, and Vrn-B1b. Two novel alleles at the Vrn-B3 locus were discovered and were designated Vrn-B3b and Vrn-B3c. Vrn-B3b had an 890-bp insertion in the promoter region of the recessive vrn-B3 allele, and Vrn-B3c allele had 2 deletions (a 20-bp deletion and a 4-bp deletion) in the promoter region of the dominant Vrn-B3a allele. Cultivar Hemai 26 lacked the Vrn-A1 gene. RT-PCR indicated that the 890-bp insertion in the Vrn-B3b allele significantly reduced the transcription of the Vrn-B3 gene. Cultivars Chadianhong with the Vrn-B3b allele and Hemai 26 with a Vrn-A1-null allele possessed relatively later heading and flowering times compared to those of Yanzhan 4110, which harbored recessive vrn-B3 and vrn-A1 alleles. Through identification of photoperiod genes, 2 new polymorphism combinations were found in 6 winter wheat cultivars and were designated Hapl-VII and Hapl-VIII, respectively. Distribution of the vernalization and photoperiod genes indicated that all recessive alleles at the 4 vernalization response loci, truncated “Chinese Spring” Ppd-B1 allele at Ppd-B1 locus and Hapl-I at the Ppd-D1 locus were predominant in Chinese winter wheat cultivars.ConclusionThis study illustrated the distribution of vernalization and photoperiod genes and identified 2 new Vrn-B3 alleles, 1 Vrn-A1-null allele, and two new Ppd-D1 polymorphism combinations, using developed functional markers. Results of this study have the potential to provide useful information for screening relatively superior wheat cultivars for better adaptability and maturity.

Estimating potential yield of wheat production in China based on cross-scale data-model fusion

The response of the agro-ecological system to the environment includes the response of individual crop's physiological process and the adaption of the crop community to the environment and its change. Observation and simulation at the single scale level cannot fully explain the above process. It is necessary to develop cross-scale agro-ecological models and study the interaction of agro-ecological processes across different scales. Two typical agro-ecological models (DSSAT and AEZ) are employed in this study and a framework for effective cross-scale data-model and model-model fusion is proposed and illustrated based on the application of DSSAT and AEZ models. The site-specific crop model is up-scaled by using this data-model fusion method, observed data from 36 different agricultural observation stations nationwide and historical weather stations observations (1962-1990) are employed and average crop productivity are estimated. Comparison of the estimation results shows the major consistency across the two models and also indicates specific directions for further improvement. This would help the future efforts in cross-scale crop model fusion.

Mapping and validation of quantitative trait loci associated with wheat yellow mosaic bymovirus resistance in bread wheat

Wheat yellow mosaic (WYM) caused by wheat yellow mosaic bymovirus (WYMV) has been growing as one of the most serious diseases affecting wheat production in China. In this study, the association of quantitative trait loci (QTLs) governing WYMV resistance with molecular markers was established using 164 recombinant inbred lines (RILs) derived from 'Xifeng Wheat' (highly resistant)×'Zhen 9523' (highly susceptible). Phenotypic data of WYMV resistance of the RILs were collected from 4-year, two-location replicated field trials. A molecular marker-based linkage map, which was comprised of 273 non-redundant loci and represented all the 21 wheat chromosomes, was constructed with the JoinMap 4.0 software. Using the Windows QTL Cartographer V2.5 software, three QTLs associated with WYMV resistance, QYm.njau-3B.1, QYm.njau-5A.1 and QYm.njau-7B.1, were detected on chromosomes 3BS, 5AL, and 7BS, respectively. The favorable allele effects were all contributed by 'Xifeng Wheat'. Among the three QTLs, QYm.njau-3B.1 and QYm.njau-5A.1 were detected in all the four trials and the overall mean, and could explain 3.3-10.2% and 25.9-53.7% of the phenotypic variation, respectively, while QYm.njau-7B.1 was detected in one trial and the overall mean and explained 4.9 and 3.3% of the phenotypic variation, respectively. A large portion of the variability for WYMV response was explained by a major QTL, QYm.njau-5A.1. The relationship of the molecular markers linked with QYm.njau-5A.1 and the WYMV resistance was further validated using a secondary F(2) population. The results showed that three markers, i.e., Xwmc415.1, CINAU152, and CINAU153, were closely linked to QYm.njau-5A.1 with the genetic distances of 0.0, 0.0, and 0.1cM, respectively, indicating they should be useful in marker-assisted selection (MAS) wheat breeding for WYMV resistance. A panel of germplasm collection consisting of 46 wheat varieties with known WYMV response phenotypes was further used to validate the presence and effects of QYm.njau-5A.1 and the above three markers. It was found that QYm.njau-5A.1 was present in 12 of the 34 WYMV-resistant varieties.

Molecular mapping of resistance gene to English grain aphid (Sitobion avenae F.) in Triticum durum wheat line C273

The English grain aphid, Sitobion avenae (Fabricius), is one of the most important insect pests causing substantial yield losses in wheat production in China and other grain-growing areas in the world. The efficient utilization of wheat genes for resistance to English grain aphid (EGA) provides an efficient, economic and environmentally sound approach to reduce the yield losses. In the present study, the wheat line C273 (Triticum durum AABB, 2n=4x=28), is resistant to EGA in greenhouse and field tests. To identify the resistance gene, designated RA-1 temporarily, C273 was crossed with susceptible genotype Poland 305 (T. polonicum, AABB, 2n=4x=28). The F(1), F(2) and F(2:3) lines were tested with EGA in the field and greenhouse. The results indicated that RA-1 is a single dominant gene, closely linked to the microsatellite markers (SSR) Xwmc179, Xwmc553 and Xwmc201 on chromosome 6AL at genetic distances of 3.47, 4.73 and 7.57cM, respectively. The three SSR markers will be valuable in marker-assisted selection for resistance to EGA as well as for cloning this gene in the future.

Spatial distribution and temporal variation of the winter wheat late frost disaster in Henan, China

The winter wheat late frost disaster (WFD) occurs mainly in the Yellow and Huaihe River area, of which Henan Province covers the most part. Henan is the major area of wheat production in China, but it is severely hit by the WFD. In this study, we construct a WFD index based on the minimum temperature and the winter wheat development period (WDP). The WFD degrees and days at 30 agrometeorological stations in Henan Province during the period of 1981–2004 are calculated. For the large-scale temporal variation analysis of WFD, the 24-yr WDP observation series is relatively short, so it is expanded by using the relation between the turning green date of winter wheat and the 5-day running mean temperature and that between the stem elongation phase and the effective cumulative temperature above a critical value of 2.5°C. The WFD data are also expanded for the last 50 years and are analyzed by using the empirical orthogonal function (EOF) and the Morlet wavelet methods. Characteristics in the spatial distribution and temporal variation of WFD are revealed. The results show that the frequency of WFD is generally high, exceeding 40% in parts of Henan, and exhibits a rising trend in the period of 1970–1990. The variation trend of WFD degrees is similar to that of WFD days, and the areas with higher WFD degrees coincide the areas with more WFD days. Moreover, the WFD degree has a greater impact on the winter wheat yield than the WFD days. The areas with high WFD degrees lie in the southeast and southwest of Henan, and the areas with low WFD degrees lie in the south of the Huaihe River and parts of western Henan. Temporal variations of the first and second EOF modes of the WFD degree display 16- and quasi-22-yr periodicities, respectively. The areas of high (low) WFD frequency are distributed in the northern Henan and the southwest border of Henan (the northeast Henan and the middle part of southwest Henan). The temporal variation of the first (second) EOF mode of WFD days exhibits a periodicity (periodicities) of quasi-4 yr (quasi-3 and quasi-6-7 yr).

Detection of wheat dwarf virus (WDV) in wheat and vector leafhopper ( Psammotettix alienus Dahlb.) by real-time PCR

Wheat dwarf virus (WDV) is a newly emerging pathogen affecting wheat production in China. A real-time PCR method using the TaqMan probe is described for quantitative detection of WDV in wheat tissues and in leafhopper ( Psammotettix alienus Dahlb.). Primers and probes for specific detection of WDV were designed within the conserved region of the coat protein (CP) gene sequence. A sensitivity assay showed the detection limit of the assay was 30 copies, and the standard curve was linear over range 30–3 × 10 6 copies, with good reproducibility. Simultaneously, this real-time PCR assay could be used to detect WDV CP genes in viruliferous leafhoppers. As determined by an end-point dilution comparison, real-time PCR was close to 10 4-fold more sensitive than the indirect enzyme-linked immunosorbent assay for WDV detection. Field samples of wheat and leafhopper collected from different regions of China were detected by both real-time PCR and gel-based PCR. The results showed more positive samples could be identified by real-time PCR than by gel-based PCR. This quantitative detection assay provides a valuable tool for diagnosis and molecular studies of WDV biology.

Assessment on Typical Drought Risk for Wheat Production in China Based on Natural Vulnerability

Food security is the base of human survival and national stability.,of which food supply-demand balance variation and its induced food price fluctuation are the two major concerns.Global food production has been kept on increase since 2000,though in a slow pace,which should be able to meet the basic diet requirement.According to the 4th IPCC report,however,from the end of 2007,the worldwide food supply problem has been paid great attention to due to a sky rocket of food price.The earth is getting warmer and the frequency of drought is increased. Consequently,the intensification of water stress to crops,resulted from both the long term climate change and increase of extreme weather events,may lead to the reduction of crop yield and the increase of drought disasters. To understand the mechanism of crop drought disaster process is the key to the understanding of food security and hence a possible solution to the problem.In the past researches,the concepts of physical vulnerability and social vulnerability are not always yet explicitly distinguished or separated regarding to agricultural drought disaster risk assessment,which restricts the understanding of process-based mechanism of disaster risk dramatically.The major focuses of studies on drought disaster risk assessment range from statistical analysis and probability analysis to prediction of drought hazard or disaster losses,whilst few attached importance to the quantitative separation of physical and social vulnerabilities. The goals of this paper are to explore and quantify the physical vulnerability and drought hazard and risk.The detailed process is as follows:Firstly,agricultural drought disaster risk assessment model is developed based on the physical vulnerability of crops.This model covers agricultural drought hazard possibility distribution estimation, physical vulnerability curve estimation,land use-based exposure assessment,coping capacity integration and risk assessment.Secondly,a case study on two typical wheat species in China is carried out,and a quantitative physical vulnerability to agricultural drought hazards is analyzed using a physical-process based crop growth model and Erosion Productivity Impact Calculator(EPIC).At the beginning,the one-dimension(point scale) crop growth model EPIC with a capability of depicting water stress and temperature stress is extended to a two-dimension(area scale) model,and the Spatial Erosion Productivity Impact Calculator(S-EPIC) can be used to simulate crop yield under different intensity scenarios of drought.Two extreme scenarios for crop growth and yield simulation were investigated. Finally,the maps of drought risk occurring every 2,5,10 and 20 years were charted separately based on the calculated probable distribution of drought hazard and the vulnerability curve.The results reveal that the wheat yield loss caused by drought is decreased from the northwestern part to the southeastern part of China.

Stripe rust resistance in Aegilops tauschii and its genetic analysis

Aegilops tauschii Coss., the D-genome progenitor of common wheat (Triticum aestivum L.) includes two subspecies, tauschii and strangulata (Eig) Tzvel. Subspecies tauschii has a wide geographic distribution spreading westwards to Turkey and eastwards to Afghanistan and China, while ssp. strangulata has a narrower distribution occurring only in two disjoined regions, southeastern Caspian Iran and Transcaucasia. A collection of 56 Ae. tauschii accessions was screened at adult stage against a mixture of pathotypes of stripe rust prevalent in the current wheat production in China. The results for three crop seasons indicated that among the 38 ssp. tauschii accessions, 37 were susceptible and only one was resistant, while all the 18 ssp. strangulata accessions were resistant. These results indicated that stripe rust resistance was related to taxonomic origin. Further genetic analysis revealed the resistance of stripe rust in ssp. strangulata accession AS2388 was conferred by a single dominant gene.

Effect of wheat cultivar mixtures on wheat yield and stripe rust

用“繁19”、“引11-12”、“川麦107”、“靖麦10号”、“青春55”、“46548-3”和“安96-8”7个不同小麦品种, 组合成6个品种混种的群体, 于2003～2004年、2004～2005年、2005～2006年在云南省曲靖市对其产量效应进行了多年多点试验, 并在自然发病条件下, 调查了6个品种混种群体对小麦条锈病发生程度的影响。结果表明, 小麦品种混种的产量效应平均为+3.9%; 小麦品种混种在产量上的正效应、0效应、负效应所出现的频率分别为69.4%、8.3%、22.3%; 年份、地点等具体环境条件会影响小麦品种混种的产量效应。在小麦条锈病发病强度相对较高的年份, 品种混种可降低条锈病病情指数。因此, 品种混种在我国一些小麦产区有利用价值。

Evaluation of CERES‐Wheat simulation of Wheat Production in China

Crop models have been used extensively to assess the impacts of environmental change, but few studies have evaluated their performance at the regional scale. Here, we evaluate the performance of CERES‐Wheat (Triticum aestivum L.) in simulating regional spatial and temporal characteristics of wheat production in China. The model uses genetic coefficients of representative cultivars within relatively homogeneous Agro Ecological Zones on a 50‐ by 50‐km grid resolution with supported soil and daily weather inputs. Simulated maturity dates and yields are compared with observations (1998–2000) at 141 experimental agricultural stations, and with county‐scale census yields (1980–2000). The model is evaluated with respect to its ability to capture the regional and temporal patterns of yield, measured by statistics including relative root mean square error (RMSE) and the index of agreement (d). Results show that the model captures the spatial patterns of yield variability reasonably well when compared to observed field data (RMSE% = 22.8% and d = 0.85) and census data (RMSE% = 27.0% and d = 0.76). Simulation of interannual variability in national production is very good (RMSE% = 8.2%, and d = 0.85). In spatial terms, simulation of variability varies considerably; good results are achieved in some of the main wheat planting areas, but not in others. The paper ends with a discussion of likely reasons for these differences in performance.

Genetic Analysis and Molecular Tagging a Novel Yellow Rust Resistance Gene Derived from Synthetic Hexaploid Wheat Germplasm M08

Yellow rust of wheat (caused by Puccinia striiformis Westend. f. sp. tritici Eriks.) has been periodically epidemic and severely damaged wheat production in China. The development of resistant cultivars could be an effective way to reduce yield losses of wheat caused by yellow rust. Rust reaction tests and genetic analysis indicated that M08, the synthetic hexaploid wheat derived from hybridization between Triticum durum (2n = 6X = 28; genome AABB) and Aegilops tauschii (2n = 2X = 14; genome DD), showed resistance to current prevailing yellow rust races at seedling stage, which was controlled by a single dominant gene, designated as YrAm. Bulked segregant analysis was used to identify microsatellite markers linked to gene YrAm in an F 2 population derived from cross M08 (resistant) × Jinan 17 (susceptible). Three microsatellite marker loci Xgwm77, Xgwm285, and Xgwm131 located on chromosome 3B were mapped to the YrAm locus. Xgwm131 was the closest marker locus and showed a linkage distance of 7.8 cM to the resistance locus. Thus, it is assumed that YrAm for resistance to yellow rust may be derived from Triticum durum and is located on the long arm of chromosome 3B.

Microsatellite marker for yellow rust resistance gene Yr5 in wheat introgressed from spelt wheat

AbstractYellow rust of wheat caused by Puccinia striiformis f sp. tritici has been periodically epidemic and severely damaged wheat production in China and throughout the world. Breeding for resistant cultivars has been proved to be an effective way to resolve the problem. A yellow rust resistance gene, Yr5, derived from Triticum spelta shows immunity or high resistance to the most popular isolates Tiaozhong 30 and 31 in China. Establishment of DNA markers for the Yr5 gene will facilitate marker‐assisted selection and gene pyramiding in the breeding programme. Since the Yr5 gene was cytologically located on the long arm of chromosome 2B, By33, the donor of Yr5, was crossed and backcrossed with the susceptible line 441, and BC3F2 and BC3F3 segregating populations were screened for polymorphism by using 11 microsatellite primers mapped on chromosome 2B. A marker, Xgwm501‐195 bp/160 bp, was found to be linked to Yr5, with a genetic distance of 10.5‐13.3 cM.

Comparative advantage and food grain imports in China

AbstractOne of the significant features of Chinese economic development in the 1980s was that grain imports increased sharply, while the whole economy experienced rapid growth and reform. This paper attempts to measure the domestic resources costs (DRC) of rice and wheat production in China (two of the most important grains in the Chinese grain sector) during the period 1981–87 and to examine the questions of whether, or to what extent, the level of comparative advantage in grain production can explain the performance of China's grain trade. Substantial comparative advantage in China's rice production and considerable comparative disadvantage in wheat production have been found by the measurement. These preliminary results suggest that the relative costs incurred by China's domestic grain sector were likely to have played some role in determining both the structure of its grain trade and its large scale of net wheat importation in the 1980s.

Statistical model to study the relationship between the wheat variety composition and the race composition of wheat stripe rust

In the study of the relationship between wheat cultivar and race of wheat stripe rust, a lot of the work done was based on experimental data. Since the spores of this pathogen can be disseminated over a long distance in the wheat ecosystem, the experimental results from a local region can not be used as a general law in making the variety deployment decision in the whole wheat ecosystem to protect the wheat from wheat stripe rust. In this paper, we use statistical methods to study this problem. Since we get a clear quantitative relation between the wheat cultivar composition and the race composition of wheat stripe rust, possibly our tentative model can be used for making the variety deployment decision in wheat production in China.

Potential Effects of Global Climate Change on Winter Wheat Production in China

The potential impact of climate changes on winter wheat production in China was evaluated using an approach liking the CERES-Wheat model to both the local current weather data and the doubled CO2 climate change scenario generated by the GISS GCM. Changes in overall output of winter wheat in China were also estimated, using a statistical model. Several agroclimatic indices were finally adopted to analyze possible changes in moisture condition, northern limits, varietal disposition, and cropping systems for winter wheat throughout the country.

The climatic resources for wheat production in China

In China, wheat is second to rice among the food grains. In the 1970's seasonal multiple cropping was implemented in some areas. The growing of winter wheat further north resulted in extensive freeze injury while wheat planted in other areas, deficient in water supply, resulted in low and highly variable annual production. The geographic areas for growing winter wheat vs. spring wheat in China are set out. These suitable wheat-growing areas are based on climatic resources that include seasonal temperature and water balance considerations. The climatic potential for growing wheat in many areas of northern and western China is based on an analysis of seasonal temperature and crop-water sufficiency during the principal growing stages that influence grain yields. Potential wheat yields are discussed, including the climatic potential for crop yields vs. actual yields under rain-fed cropping practices.