Posts Tagged ‘Wheats’

Climate variability and yield risk in South Asia’s rice–wheat systems : emerging evidence from Pakistan

Posted by gabrielamartinez on , in Journal Articles

57981Authors: Muhammad Arshad.; Amjath-Babu, T.S.; Krupnik, T.J.; Aravindakshan, S.; Abbas, A.; Kachele, H.; Muller, K.

Published in: Paddy Water Environment, In press.


Rice and wheat are the principal calorie sources for over a billion people in South Asia, although each crop is particularly sensitive to the climatic and agronomic management conditions under which they are grown. Season-long heat stress can reduce photosynthesis and accelerate senescence; if extreme heat stress is experienced during flowering, both rice and wheat may also experience decreased pollen viability and stigma deposition, leading to increased grain sterility. Where farmers are unable to implement within-season management adaptations, significant deviations from expected climatic conditions would affect crop growth, yield, and therefore have important implications for food security. The influence of climatic conditions on crop growth have been widely studied in growth chamber, greenhouse, and research station trials, although empirical evidence of the link between climatic variability and yield risk in farmers’ fields is comparatively scarce. Using data from 240 farm households, this paper responds to this gap and isolates the effects of agronomic management from climatic variability on rice and wheat yield risks in eight of Pakistan’s twelve agroecological zones. Using Just and Pope production functions, we tested for the effects of crop management practices and climatic conditions on yield and yield variability for each crop. Our results highlight important risks to farmers’ ability to obtain reliable yield levels for both crops. Despite variability in input use and crop management, we found evidence for the negative effect of both season-long and terminal heat stress, measured as the cumulative number of days during which crop growth occurred above critical thresholds, though wheat was considerably more sensitive than rice. Comparing variation in observed climatic parameters in the year of study to medium-term patterns, rice, and wheat yields were both negatively affected, indicative of production risk and of farmers’ limited capacity for within-season adaptation. Our findings suggest the importance of reviewing existing climate change adaptation policies that aim to increase cereal farmers’ resilience in Pakistan, and more broadly in South Asia. Potential agronomic and extension strategies are proposed for further investigation.

Baseline simulation for global wheat production with CIMMYT mega-environment specific cultivars

Posted by gabrielamartinez on , in Journal Articles

57984Authors: Gbegbelegbe, S.D.; Cammarano, D.; Asseng, S.; Robertson, R.; Chung, U.; Adam, M.; Abdalla, O.; Payne, T.S.; Reynolds, M.P.; Sonder, K.; Shiferaw, B.; Nelson, G.

Published in: Field Crops Research, In press.


Climate change is expected to impact global food supply and food security by affecting growing conditions for agricultural production. Process-based dynamic growth models are important tools to estimate crop yields based on minimum inputs of climate, soil, crop management, and crop cultivar parameters. Using region-specific cultivar parameters is critical when applying crop models at a global scale because cultivars vary in response to climate conditions, soils, and crop management. In this study, parameters were developed for modern cultivars representing all 17 CIMMYT wheat Mega Environments (MEs) using field experimental data and genetic cultivar relationships for the CROPSIM-CERES model in DSSAT v 4.5 (Decision-Support System for Agrotechnology Transfer). Cultivar performance was tested with independent CIMMYT breeding trial field experiments across several locations. Then crop simulations were carried out at 0.5 × 0.5 ° pixels for global wheat-growing areas, using cultivars representing MEs, soil information, region-specific crop management, and initial soil conditions. Aggregated simulated wheat yields and production were compared to reported country yields and production from Food and Agriculture Organization (FAO) statistics, resulting in a Root Mean Square Error (RMSE) of 1.3 t/ha for yield and 2.2 M t/country for country production. Some of the simulated errors are relatively large at country level because of uncertainties in pixel information for climate, soil, and crop management input and partly because of crop model uncertainties. In addition, FAO yield statistics have uncertainties because of incomplete farm reports or poor estimates. Nevertheless, this new cultivar-specific, partially-validated global baseline simulation enables new studies on issues of food security, agricultural technology, and breeding advancement impacts combined with climate change at a global scale.

Linkage analysis and map construction in genetic populations of clonal F1 and double cross

Posted by gabrielamartinez on , in Journal Articles

57985Authors: Manickavelu, A.; Joukhadar, R.; Jighly, A.; Caixia Lan; Huerta-Espino, J.; Ahmad Shah Stanikzai; Kilian, A.; Singh, R.P.; Ban, T.

Published in: Plant Science, 2016, vol.252, p.222-229


Mining of new genetic resources is of paramount importance to combat the alarming spread of stripe rustdisease and breakdown of major resistance genes in wheat. We conducted a genome wide associationstudy on 352 un-utilized Afghan wheat landraces against stripe rust resistance in eight locations. Highlevel of disease variation was observed among locations and a core-set of germplasm showed consis-tence performance. Linkage disequilibrium (LD) decayed rapidly (R2≈ 0.16 at 0 cM) due to germplasmpeerless diversity. The mixed linear model resulted in ten marker-trait associations (MTAs) across allenvironments representing five QTL. The extensively short LD blocks required us to repeat the analysiswith less diverse subset of 220 landraces in which R2decayed below 0.2 at 0.3 cM. The subset GWASresulted in 36 MTAs clustered in nine QTL. The subset analysis validated three QTL previously detectedin the full list analysis. Overall, the study revealed that stripe rust epidemics in the geographical originof this germplasm through time have permitted for selecting novel resistance loci.

Yield gain due to fungicide application in varieties of winter wheat (Triticum aestivum) resistant and susceptible to leaf rust

Posted by gabrielamartinez on , in Journal Articles

56912Authors: Morgounov, A.I.; Akin, B.; Demir, L.; Keser, M.; Kokhmetova, A.; Martynov, S.; Orhan, S.; Ozdemir, F.; Ozseven, I.; Sapakhova, Z.; Yessimbekova, M.

Published in: Crop and Pasture Science 2015, vol. 66, no.7, p. 649-659


 

In three independent experiments in Turkey and Kazakhstan, winter wheat germplasm with variable degrees of resistance to leaf rust was subjected to fungicide protection. The yield loss of genotypes susceptible to leaf rust varied from 30% to 60% depending on the environment and severity of infection. Genotypes completely or moderately resistant to leaf rust also responded positively to fungicide protection, with average yield increases in the range 10–30%. This increase was observed even in one season without leaf rust infection. The main character affected by fungicide was 1000-kernel weight. There was stable expression of the magnitude of yield gain in resistant genotypes in different seasons, confirming genetic variation for this trait. Possible mechanisms of yield gain from fungicide protection in resistant genotypes are related to a positive physiological effect of the chemical used as well as a possible ‘cost of resistance’ to wheat plants. The magnitude of yield gain by resistant germplasm justifies its capture in breeding programs to develop varieties resistant to diseases and with greater benefits from the fungicide protection.

Compendium of deliverables of the conservation agriculture course 2014

Posted by Carelia Juarez on , in CIMMYT Publications

Compendium of deliverables of the conservation agriculture course 2014. 2014. Verhulst, N.; Mulvaney, M.J.; Cox, R.; Van Loon, J.; Nichols, V. (eds.). Mexico, DF (Mexico): CIMMYT iv, 43 p.

99448.pdfThis book is the result of the hard work of 5 CIMMYT trainees who work on sustainable practices in India, Ethiopia and Zimbabwe, and participated in the 2014 visiting scientist program “Conservation agriculture: Laying the groundwork for sustainable and productive cropping systems”. Over 5 weeks the scientists received an intense training program that combined mentoring and problem solving approaches. They actively participated in the ongoing cropping systems management activities of CIMMYT’s Global Conservation Agriculture Program, Latin-America, at the experimental stations near Mexico City at El Batán and Toluca, and in nearby farmers? fields. Emphasis was given to conservation agriculturebased technologies for both irrigated and rainfed conditions: reduced tillage, using alternative crop residue management strategies and crop rotation.Wheat and maize were the main crops under study.

CIMMYT Annual Report 2013: Agricultural research for development to improve food and nutritional security

Posted by Carelia Juarez on , in CIMMYT Publications

CIMMYT Annual Report 2013: Agricultural research for development to improve food and nutritional security. 2014. CIMMYT, Int.. : 136 p.. Mexico, DF (Mexico). CIMMYT. Series: CIMMYT Annual Report

99444.pdfThrough research, development, training and capacity building, CIMMYT works with partners to sustainably increase the productivity of maize- and wheat-based cropping systems. Focused on improving food and nutritional security and improving livelihoods in the developing world, CIMMYT is a member of CGIAR and leads the MAIZE and WHEAT CGIAR Research Programs (CRPs)..

 

An innovation systems approach to enhanced farmer adoption of climate-ready germplasm and agronomic practices.

Posted by Carelia Juarez on , in Journal Articles

Published in CAPRi Working Paper. No. 116, 2014

Hellin, J.; Beuchelt, T.; Camacho, C.; Badstue, L.; Govaerts, B.; Donnet, L.; Riis-Jacobsen, J.

By 2050, climate change is likely to reduce maize production globally by 3–10 percent and wheat production in developing countries by 29–34 percent. Even without climate change, the real costs of wheat and maize will increase by 60 percent between 2000 and 2050; climate change could make the figure substantially greater. Food security, despite the above, may be possible if agricultural systems are transformed through improved seed, fertilizer, land use, and governance.

 

Population- and genome-specific patterns of linkage disequilibrium and SNP variation in spring and winter wheat (Triticum aestivum L.)

Posted by Carelia Juarez on , in Journal Articles

Published in BMC Genomics  11: 727, 2010

Population- and genome-specific patterns of linkage disequilibrium and SNP variation in spring and winter wheat (Triticum aestivum L.)

 Shiaoman Chao, Jorge Dubcovsky, Jan Dvorak, Ming-Cheng Luo, Stephen P. Baenziger, Rustam Matnyazov, Dale R. Clark, Luther E. Talbert, James A. Anderson, Susanne Dreisigacker, Karl Glover, Jianli Chen, Kim Campbell, Phil L. Bruckner, Jackie C. Rudd, Scott Haley, Brett F. Carver, Sid Perry, Mark E. Sorrells and Eduard D. Akhunov

Background: Single nucleotide polymorphisms (SNPs) are ideally suited for the construction of high-resolution genetic maps, studying population evolutionary history and performing genome-wide association mapping experiments. Here, we used a genome-wide set of 1536 SNPs to study linkage disequilibrium (LD) and population structure in a panel of 478 spring and winter wheat cultivars (Triticum aestivum) from 17 populations across the United States and Mexico.

Results: Most of the wheat oligo pool assay (OPA) SNPs that were polymorphic within the complete set of 478 cultivars were also polymorphic in all subpopulations. Higher levels of genetic differentiation were observed among wheat lines within populations than among populations. A total of nine genetically distinct clusters were identified, suggesting that some of the pre-defined populations shared significant proportion of genetic ancestry. Estimates of population structure (FST) at individual loci showed a high level of heterogeneity across the genome. In addition, seven genomic regions with elevated FST were detected between the spring and winter wheat populations. Some of these regions overlapped with previously mapped flowering time QTL. Across all populations, the highest extent of significant LD was observed in the wheat D-genome, followed by lower LD in the A- and B-genomes. The differences in the extent of LD among populations and genomes were mostly driven by differences in long-range LD ( > 10 cM).

Conclusions: Genome- and population-specific patterns of genetic differentiation and LD were discovered in the populations of wheat cultivars from different geographic regions. Our study demonstrated that the estimates of population structure between spring and winter wheat lines can identify genomic regions harboring candidate genes involved in the regulation of growth habit. Variation in LD suggests that breeding and selection had a different impact on each wheat genome both within and among populations. The higher extent of LD in the wheat D-genome versus the A- and B-genomes likely reflects the episodes of recent introgression and population bottleneck accompanying the origin of hexaploid wheat. The assessment of LD and population structure in this assembled panel of diverse lines provides critical information for the development of genetic resources for genome-wide association mapping of agronomically important traits in wheat.