Quantifying major sources of uncertainty in projecting the impact of climate change on wheat grain yield in dryland environments

Modelling the impact of climate change on cropping systems is crucial to support policy-making for farmers and stakeholders.Nevertheless,there exists inherent uncertainty in such cases.General Circulation Models(GCMs)and future climate change scenarios(different Representative Concentration Pathways(RCPs)in different future time periods)are among the major sources of uncertainty in projecting the impact of climate change on crop grain yield.This study quantified the different sources of uncertainty associated with future climate change impact on wheat grain yield in dryland environments(Shiraz,Hamedan,Sanandaj,Kermanshah and Khorramabad)in eastern and southern Iran.These five representative locations can be categorized into three climate classes:arid cold(Shiraz),semi-arid cold(Hamedan and Sanandaj)and semi-arid cool(Kermanshah and Khorramabad).Accordingly,the downscaled daily outputs of 29 GCMs under two RCPs(RCP4.5 and RCP8.5)in the near future(2030s),middle future(2050s)and far future(2080s)were used as inputs for the Agricultural Production Systems sIMulator(APSIM)-wheat model.Analysis of variance(ANOVA)was employed to quantify the sources of uncertainty in projecting the impact of climate change on wheat grain yield.Years from 1980 to 2009 were regarded as the baseline period.The projection results indicated that wheat grain yield was expected to increase by 12.30%,17.10%,and 17.70%in the near future(2030s),middle future(2050s)and far future(2080s),respectively.The increases differed under different RCPs in different future time periods,ranging from 11.70%(under RCP4.5 in the 2030s)to 20.20%(under RCP8.5 in the 2080s)by averaging all GCMs and locations,implying that future wheat grain yield depended largely upon the rising CO2 concentrations.ANOVA results revealed that more than 97.22% of the variance in future wheat grain yield was explained by locations,followed by scenarios,GCMs,and their interactions.Specifically,at the semi-arid climate locations(Hamedan,Sanandaj,Kermanshah and Khorramabad),most of the variations arose from the scenarios(77.25%),while at the arid climate location(Shiraz),GCMs(54.00%)accounted for the greatest variation.Overall,the ensemble use of a wide range of GCMs should be given priority to narrow the uncertainty when projecting wheat grain yield under changing climate conditions,particularly in dryland environments characterized by large fluctuations in rainfall and temperature.Moreover,the current research suggested some GCMs(e.g.,the IPSL-CM5B-LR,CCSM4,and BNU-ESM)that made moderate effects in projecting the impact of climate change on wheat grain yield to be used to project future climate conditions in similar environments worldwide.

Detection and enumeration of wheat grains based on a deep learning method under various scenarios and scales

Grain number is crucial for analysis of yield components and assessment of effects of cultivation measures.The grain number per spike and thousand-grain weight can be measured by counting grains manually,but it is time-consuming,tedious and error-prone.Previous image processing algorithms cannot work well with different backgrounds and different sizes.This study used deep learning methods to resolve the limitations of traditional image processing algorithms.Wheat grain image datasets were collected in the scenarios of three varieties,six background and two image acquisition devices with different heights,angles and grain numbers,1748 images in total.All images were processed through color space conversion,image flipping and rotation.The grain was manually annotated,and the datasets were divided into training set,validation set and test set.We used the TensorFlow framework to construct the Faster Region-based Convolutional Neural Network Model.Using the transfer learning method,we optimized the wheat grain detection and enumeration model.The total loss of the model was less than 0.5 and the mean average precision was 0.91.Compared with previous grain counting algorithms,the grain counting error rate of this model was less than 3%and the running time was less than 2 s.The model can be effectively applied under a variety of backgrounds,image sizes,grain sizes,shooting angles,and shooting heights,as well as different levels of grain crowding.It constitutes an effective detection and enumeration tool for wheat grain.This study provides a reference for further grain testing and enumeration applications.

Global sensitivity analysis of wheat grain yield and quality and the related process variables from the DSSAT-CERES model based on the extended Fourier Amplitude Sensitivity Test method

A crop growth model,integrating genotype,environment,and management factor,was developed to serve as an analytical tool to study the influence of these factors on crop growth,production,and agricultural planning.A major challenge of model application is the optimization and calibration of a considerable number of parameters.Sensitivity analysis(SA) has become an effective method to identify the importance of various parameters.In this study,the extended Fourier Amplitude Sensitivity Test(EFAST) approach was used to evaluate the sensitivity of the DSSAT-CERES model output responses of interest to 39 crop genotype parameters and six soil parameters.The outputs for the SA included grain yield and quality(take grain protein content(GPC) as an indicator) at maturity stage,as well as leaf area index,aboveground biomass,and aboveground nitrogen accumulation at the critical process variables.The key results showed that:(1) the influence of parameter bounds on the sensitivity results was slight and less than the impacts from the significance of the parameters themselves;(2) the sensitivity parameters of grain yield and GPC were different,and the sensitivity of the interactions between parameters to GPC was greater than those between the parameters to grain yield;and(3) the sensitivity analyses of some process variables,including leaf area index,aboveground biomass,and aboveground nitrogen accumulation,should be performed differently.Finally,some parameters,which improve the model’s structure and the accuracy of the process simulation,should not be ignored when maturity output as an objective variable is studied.

Transcriptome analysis reveals key differentially expressed genes involved in wheat grain development

Wheat seed development is an important physiological process of seed maturation and directly affects wheat yield and quality. In this study, we performed dynamic transcriptome microarray analysis of an elite Chinese bread wheat cultivar(Jimai 20) during grain development using the Gene Chip Wheat Genome Array. Grain morphology and scanning electron microscope observations showed that the period of 11–15 days post-anthesis(DPA) was a key stage for the synthesis and accumulation of seed starch. Genome-wide transcriptional profiling and significance analysis of microarrays revealed that the period from 11 to 15 DPA was more important than the 15–20 DPA stage for the synthesis and accumulation of nutritive reserves.Series test of cluster analysis of differential genes revealed five statistically significant gene expression profiles. Gene ontology annotation and enrichment analysis gave further information about differentially expressed genes, and Map Man analysis revealed expression changes within functional groups during seed development. Metabolic pathway network analysis showed that major and minor metabolic pathways regulate one another to ensure regular seed development and nutritive reserve accumulation. We performed gene co-expression network analysis to identify genes that play vital roles in seed development and identified several key genes involved in important metabolic pathways. The transcriptional expression of eight key genes involved in starch and protein synthesis and stress defense was further validated by q RT-PCR. Our results provide new insight into the molecular mechanisms of wheat seed development and the determinants of yield and quality.

Monitoring Protein and Starch Accumulation in Wheat Grains with Leaf SPAD and Canopy Spectral Reflectance

The research was conducted to determine the relationships of protein and starch accumulation dynamics in grains of wheat to post-heading leaf SPAD values and canopy spectral reflectance. The results showed that leaf nitrogen accumulation was exponentially related to leaf SPAD values and linearly related to canopy spectral reflectance, and that there was negative linear relationship between leaf nitrogen accumulation and grain protein accumulation, but positive linear relationship between post-heading leaf nitrogen transloca-tion and grain protein accumulation at maturity. In addition, leaf SPAD values were parabolically related with and ratio indices R(l 500,610)and R(l 220,560)were exponentially related with protein and starch accumulation in grains. These results indicate that leaf SPAD values and canopy spectral reflectance should be good indicators of quality formation dynamics in wheat grains.

Accumulation of glycolipids in wheat grain and their role in hardness during grain development

Grain hardness is an important parameter for wheat quality. To understand the role of glycolipids in the formation of grain hardness, the glycolipid contents in wholegrain wheat flour and the starch granule surfaces of oven-dried and freeze-dried hard and soft wheat grain were analyzed. Changes in endosperm structure and amyloplast membrane integrity during grain development were also examined by electron microscopy. The monogalactosyldigylcerol(MGDG) and digalactosyldigylcerol(DGDG) contents of the starch surface were significantly higher in soft wheat than in hard wheat, regardless of the drying method or developmental stage. Throughout grain development, MGDG content was significantly higher in the starch surface of freeze-dried hard wheat than in the starch surface of oven-dried hard wheat. In contrast, the MGDG content of the starch surface was significantly higher in freeze-dried soft grain at 14 and 35 days after anthesis. No significant difference was observed in puroindoline protein(PIN) accumulation in wholegrain flour from wheat that was dried using the two methods, whereas PIN accumulation on the starch surface of freeze-dried grain was lower than that on the starch surface of oven-dried grain.The gap between the amyloplast membrane and starch granules was larger in hard wheat than in soft wheat, as shown by transmission electron microscopy. For the same wheat cultivar, this gap was larger for oven-dried than for freeze-dried grain. The content of polar lipids in the starch surface was closely related to grain hardness, and the breakdown of the amyloplast membrane may determine the location of polar lipids on the starch surface.

iTRAQ-based quantitative proteome characterization of wheat grains during filling stages

Using isobaric tags for relative and absolute quantification （iTRAQ） and associated analytic technologies, we have cataloged and compared 7 069 unique wheat proteins expressed during four substages of the filling stage. Among them, 859 are differentially expressed, showing at least a 2-fold difference in concentration across substages. Differentially expressed proteins （DEPs） includind high-molecular weight giutenin subunit （W5AIU1）, low-molecular weight glutenin subunit （QSW3V4）, gliadin/avenin-like seed protein （D2KFG9）, and avenin-like protein （W5DVL2）, all of which have previously been identified as important for nutritional quality and bread-making properties, and all of which were found to increase at the latter stages of development. We have applied statistical techniques to group the proteins into hierarchical clusters, and have consulted databases to infer functional and other relationships among the identified proteins.

Mechanical strength of wheat grain varieties influenced by moisture content and loading rate

Mechanical shear resistance of wheat grain is a significant concern for the designers and researchers related to the design of threshing,handling and processing machinery of the field crops.The grain mechanical properties directly affect the machine geometry and its operational parameters.The present study was carried out to determine the shear resistance of five wheat varieties(Locally names;TD-02,Sindhu-1105,Benazir,China and SKD-118)influenced by moisture content(16.7%,18.7%and 19.5%)and loading rate(3 mm/s,6 mm/s and 9 mm/s).However,some physio-dimensional properties(length,width,thickness,slenderness ratio,surface area and sphericity)were obtained at different moisture contents.The results showed that the shear resistance reduced by increasing the moisture content and loading rate.The average shear resistance decreased from 10.45 N to 3.74 N for 3-9 mm/s loading rate at moisture content of 16.7%to 19.5%.Thus,the maximum correlation(r=0.905)of shear resistance obtained at 16.7%,whereas minimum correlation(r=0.692)obtained at 19.5%.The shear resistance of wheat grain was highly significant(p<0.05)at 9 mm/s for 19.5%.Shear resistance decreased with an increase in the moisture content in the grain whereas deformation is increasing with the increase of moisture content.However,the maximum bulk density of wheat grain obtained at 19.5%for SKD-118,while the minimum obtained at 16.7%for TD-02.It is recommended that the design and modification of wheat grain processing equipment should be executed on the physio-mechanical properties of grain varieties.

The Effect of Plastic-Covered Ridge and Furrow Planting on the Grain Filling and Hormonal Changes of Winter Wheat

Although plastic-covered ridge and furrow planting（RF） has been reported to produce substantial increases in the grain weight of winter wheat,the underlying mechanism is not yet understood.The present study used two cultivars,Xinong 538 and Zhoumai 18,and RF and traditional flatten planting（TF,control） with the objective of investigating the effect of RF on wheat grain filling and the possible relationship of hormonal changes in the wheat grains under RF to grain filling.The results indicated that RF significantly increased the grain weight,although the effects on grain filling were different： RF significantly increased the grain-filling rate and grain weight of inferior grains,whereas RF had no significant effect on grainfilling rate and grain weight of superior grains.The final grain weight of inferior grains under RF was 39.1 and 50.7 mg for Xinong 538 and Zhoumai 18,respectively,3.6 and 3.4 mg higher than the values under TF.However,the final grain weight of superior grains under RF was only 0.6 and 0.8 mg higher than under TF for Xinong 538 and Zhoumai 18,respectively.RF significantly decreased the ethylene and gibberellic acid content in the inferior grains and increased the indole-3-acetic acid,abscisic acid and zeatin ＋ zeatin riboside content in the inferior grains;however,no significant difference between RF and TF was observed for the hormonal content in the superior grains.Based on these results,we concluded that RF significantly modulated hormonal changes in the inferior grains and,thus,affected the grain filling and grain weight of the inferior grains;in contrast,RF had no significant effect on grain filling,grain weight and hormonal changes in the superior wheat grains.

Polycyclic aromatic hydrocarbons in ambient air,surface soil and wheat grain near a large steel-smelting manufacturer in northern China

The total concentrations and component profiles of polycyclic aromatic hydrocarbons（PAHs） in ambient air,surface soil and wheat grain collected from wheat fields near a large steel-smelting manufacturer in Northern China were determined.Based on the specific isomeric ratios of paired species in ambient air,principle component analysis and multivariate linear regression,the main emission source of local PAHs was identified as a mixture of industrial and domestic coal combustion,biomass burning and traffic exhaust.The total organic carbon（TOC） fraction was considerably correlated with the total and individual PAH concentrations in surface soil.The total concentrations of PAHs in wheat grain were relatively low,with dominant low molecular weight constituents,and the compositional profile was more similar to that in ambient air than in topsoil.Combined with more significant results from partial correlation and linear regression models,the contribution from air PAHs to grain PAHs may be greater than that from soil PAHs.

Comparison of FT-NIR and NIR for evaluation of phyisco-chemical properties of stored wheat grains

Objectives:Storage studies were carried out in wheat grains with different moisture contents,level of infestation,and storage days.Material and Methods:Wheat grain samples were infested with Rhyzopertha dominica and stored for up to 90 days under ambient conditions.Every 45 days,samples of wheat were collected and evaluated for protein,fat,ash,1000 kernel weight,and hardness.Results:The physicochemical parameters,namely,protein,1000 kernel weight,and hardness decreased while fat and ash content increased with the storage.Methodology for identification of infested samples was developed in Fourier transform near infrared(FT-NIR)and near infrared(NIR)using infested wheat and control samples.The linear regression plots for different quality parameters gave an R2 value of 82.04%and 97.15%via FT-NIR and 81.61%and 98.07%via NIR.The RMSEP values by NIR were in the range of 0.03 to 0.7,whereas the RMSECV values of FT-NIR were in the range of 0.03 to 1.2.Conclusions:Both the models performed well for the cross validation studies;hence,they can be used in future for the rapid assessment of storage quality of wheat grains.

Transcriptome analysis of wheat grain using RNA-Seq

With the increase in consumer demand,wheat grain quality improvement has become a focus in China and worldwide.Transcriptome analysis is a powerful approach to research grain traits and elucidate their genetic regulation.In this study,two cDNA libraries from the developing grain and leaf-stem components of bread wheat cultivar,Nongda211,were sequenced using Roche/454 technology.There were 1061274 and 1516564 clean reads generated from grain and leaf-stem,respectively.A total of 61393 high-quality unigenes were obtained with an average length of 1456 bp after de novo assembly.The analysis of the 61393 unigenes involved in the biological processes of the grain showed that there were 7355 differentially expressed genes upregulated in the grain library.Gene ontology enrichment and the Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis showed that many transcription products and transcription factors associated with carbohydrate and protein metabolism were abundantly expressed in the grain.These results contribute to excavate genes associated with wheat quality and further study how they interact.

Grain yield and water use of winter wheat as affected by water and sulfur supply in the North China Plain

Water shortage has threatened sustainable development of agriculture globally as well as in the North China Plain（NCP）.Irrigation,as the most effective way to increase food production in dry land,may not be readily available in the situation of drought.One of the alternatives is to supply plants with enough nutrients so that they can be more sustainable to the water stress.The objective of this study was to explore effects of irrigation and sulphur（S）application on water consumption,dry matter accumulation（DMA）,and grain yield of winter wheat in NCP.Three irrigation regimes including no irrigation（rainfed,I0）during the whole growth period,once irrigation only at jointing stage（90 mm,I1）,and twice respective irrigation at jointing and anthesis stages（90 mm plus 90 mm,I2）,and two levels of S application including 0S0and 60 kg ha^–1（S60）were designed in the field experiment in NCP.Results showed that increasing irrigation times significantly increased mean grain yield of wheat by 12.5–23.7%and nitrogen partial factor productivity（NPFP）by 21.2–45.0%in two wheat seasons,but markedly decreased crop water use efficiency（YWUE）.Furthermore,S supply 60 kg ha^–1 significantly increased mean grain yield,YWUE,IWUE and NPFP by 5.6,6.1,23.2,and 5.6%（across two wheat seasons）,respectively.However,we also found that role of soil moisture prior to S application was one of important greater factors on improving the absorption and utilization of storage water and nutrients of soil.Thus,water supply is still the most important factor to restrict the growth of wheat in the present case of NCP,supplying 60 kg ha^–1 S with once irrigation 90 mm at the jointing stage is a relatively appropriate recommended combination to improve grain yield and WUE of wheat when saving water resources is be considered in irrigated wheat farmlands of NCP.

Contribution of ear photosynthesis to grain yield under rainfed and irrigation conditions for winter wheat cultivars released in the past 30 years in North China Plain

To understand the contribution of ear photosynthesis to grain yield and its response to water supply in the improvement of winter wheat, 15 cultivars released from 1980 to 2012 in North China Plain（NCP） were planted under rainfed and irrigated conditions from 2011 to 2013, and the ear photosynthesis was tested by ear shading. During the past 30 years, grain yield significantly increased, the flag leaf area slightly increased under irrigated condition but decreased significantly under rainfed condition, the ratio of grain weight：leaf area significantly increased, and the contribution of ear photosynthesis to grain yield changed from 33.6 to 64.5% and from 32.2 to 57.2% under rainfed and irrigated conditions, respectively. Grain yield, yield components, and ratio of grain weight：leaf area were positively related with contribution of ear photosynthesis. The increase in grain yield in winter wheat was related with improvement in ear photosynthesis contribution in NCP, especially under rainfed condition.

Distribution of Grain Hardness in Chinese Wheats and Genetic Analysis

A hundred winter wheat and 41 spring wheat cultivars and advanced lines were used to investigate the distribution of grain hardness in Chinese wheats and correlations between grain hardness and other kernel traits. P1, P2, F1 , F2 and F3 from three crosses, i. e. , Liken2/Yumai2, 85Zhong33/Wenmai6 and 85Zhong33/95Zhong459 were sown to study the genetics of grain hardness. Significant correlation was observed between hardness measured by Single Kernel Characteristic System 4100 (SKCS 4100) and Near Infrared (NIR) Spectroscopy, r ranging from 0.85 to 0.94. Chinese wheat is a mixed population in terms of hardness, ranging from very soft to very hard. For autumn-sown wheat, on average, grain hardness decreases from north to south and spring-sown wheat is dominant with hard type. Hardness is negatively associated with flour color, and its associations with flour yield and ash content differ in winter and spring wheats. Grain hardness is controlled by a major gene and several minor genes with additive effect mostly, but dominant effect is also observed, with heritability of 0.78.

Inheritance and Availability of High Grain Number Per Spike in Two Wheat Germplasm Lines

Grain number per spike （GNPS） is a major factor in wheat yield breeding. The development of high GNPS germplasm is widely emphasized in wheat-yield breeding. This paper reported two high GNPS wheat germplasm lines, Pubing 3228 and Pubing 3504, which had a stable and wide adaptability to different ecological regions. By exploring a nested cross design with reciprocals using Pubing 3228 or Pubing 3504 as a common parent and investigating the GNPS phenotypes of F1 hybrids in 2007-2008 and F2 populations in 2008-2009 of different cross combinations, the narrow-sense GNPS heritability was up to 49.58 and 52.23%, respectively. Genetic model analysis predictions suggested that GNPS in Pubing 3228 and Pubing 3504 was mainly controlled by additive genetic effects. Correlation analysis results between GNPS and 1 000- kernel weight （TKW） of F2 populations showed that TKW was not influenced with the increase of GNPS. The good coordination among three yield components of spike number per plant （SNPP）, GNPS, and TKW in the F2 segregating population implied that selection of good candidate individuals in breeding programs would be relatively straightforward. Overall, our results indicated that Pubing 3228 and Pubing 3504 are two potential germplasm lines for yield improvement of GNPS in pedigree selection of wheat breeding.

Activities of the Enzymes Involved in Starch Synthesis and Starch Accumulation in the Grains of Wheat Cultivars, GC8901 and SN1391

Two wheat cultivars, GC8901 (hard winter wheat) and SN1391 (soft winter wheat), were used for investigating the changes of enzyme activities for sucrose metabolism and starch biosynthesis and the accumulation character of starch composition. The result showed that activities of sucrose (SS), sucrose-phosphate synthase (SPS), adenosine diphosphorate glucose pyrophrylase (AGPase) and soluble starch syntheses (SSS) of 1391, which have more starch, were significant higher than those of 8901, that with low starch content. But the changing of granule-bound starch synthase (GBSS) activity was consistent with the amylose content, which indicated that amylose contents in grain were determined by GBSS activity, especially the activity at later grain filling stages. Simulating with Richards equation showed that it was initiating time and accumulation rate, but not accumulation duration that determined the content of starch composition. Furthermore, changing of sucrose transport capacity was consistent with SSS and GBSS activities, starch accumulation rate was accordant to AGPase and SS/SPS ration, not SS, SPS, SSS or GBSS activities. The results suggested that there was no inevitable relation of starch accumulating rate and starch composition contents with the activity of single enzyme such as SS, SPS, SSS or GBSS, but closely related to AGPase activity and SS/SPS ratio, and it was SPS and AGPase that play a vital role in the biosynthetic pathway. Later polymerization reactions catalyzed by SSS and GBSS don’t seem to control the rate of starch accumulation, but do affect starch structure.

Use of a post-production fractionation process improves the nutritional value of wheat distillers grains with solubles for young broiler chicks

Background： Post-production fractionation of wheat distillers grains with solubles（DDGS） increases their crude protein content and reduces their fiber content.This experiment was conducted to determine the effects of fractionation of wheat DDGS on apparent total tract digestibility（ATTD） and performance when fed to broiler chicks（0–21 d）.Methods： A total of 150,day-old,male broiler chicks（Ross-308 line;Lilydale Hatchery,Wynyard,Saskatchewan） weighing an average of 49.6 ± 0.8 g were assigned to one of five dietary treatments in a completely randomized design.The control diet was based on wheat and soybean meal and contained 20% regular wheat DDGS.The experimental diets contained 5,10,15 or 20% fractionated wheat DDGS added at the expense of regular wheat DDGS.Results： The ATTD of dry matter and gross energy were linearly increased（P 0.01） as the level of fractionated wheat DDGS in the diet increased.Nitrogen retention was unaffected by level of fractionated wheat DDGS（P 0.05）.Weight gain increased linearly（P = 0.05） as the level of fractionated wheat DDGS in the diet increased.Feed intake,feed conversion and mortality were unaffected by level of fractionated wheat DDGS in the diet（P 0.05）.Conclusions： Post-production fractionation of wheat DDGS improves their nutritional value by lowering their fiber content and increasing their content of crude protein and energy.These changes in chemical composition supported increased weight gain of broilers fed wheat DDGS.

Effects of exogenous ABA application on post-anthesis dry matter redistribution and grain starch accumulation of winter wheat with different staygreen characteristics

The objective of this study was to investigate whether and how exogenous abscisic acid(ABA)is involved in mediating starch accumulation in the grain and redistribution of carbohydrates during grain filling of two wheat cultivars with different staygreen characteristics.At blooming stage,plants of Wennong 6(a staygreen cultivar)and Jimai 20(control)were sprayed with10 mg L-1abscisic acid(ABA)for 3 days.The application of ABA significantly(P<0.05)increased grain filling rate,starch accumulation rate and content,remobilization of dry matters to kernels,and 1000-grain weight of the two cultivars.Exogenous ABA markedly(P<0.05)increased grain yield at maturity,and Wennong 6 and Jiami 20 showed 14.14%and 4.86%higher compared yield than the control.Dry matter accumulation after anthesis of Wennong 6 was also significantly(P<0.05)influenced by exogenous ABA,whereas that of Jimai 20 was unchanged.Application of ABA increased endogenous zeatin riboside(ZR)content 7 days after anthesis(DAA),and spraying ABA significantly increased endogenous indole-3-acetic acid(IAA)and ABA contents from 7 to 21 DAA and decreased gibberellin(GA3)content at 14 DAA,but increased GA3content from 21 to 35 DAA.The results suggested that increased yield of staygreen was due to greater starch assimilation owing to a higher filling rate and longer grain-filling duration.