Posts Tagged ‘wheat’

Physiological factors underpinning grain yield improvements of synthetic derived wheat in South Western China

Posted by Carelia Juarez on , in Journal Articles

Published in Crop Science, 2014

Yonglu TangRosewarne, G.M.Chaosu LiXiaoli WuWuyun YangChun Wu.

Synthetic hexaploid wheat (SHW) is a valuable source of genetic diversity for germplasm enrichment in wheat breeding. In China, SHW derived material has shown significant yield increases. A three year field experiment at Guanghan and Jiangyou in the Sichuan Basin of China was conducted to characterize the potential of three SHW-derived cultivars (SDCs) with five local elite non-synthetic derived cultivars as checks (NSCs). SDCs showed on average an 11.5% or 951 kg ha-1 yield increase as compared to NSCs. This yield gain was mainly attributed to increases in both grain number m-2 (5.7%) and thousand kernel weight (5.9%). A higher rate of above-ground dry matter accumulation, especially in the early growth stages, was observed in the SDCs. The SDCs also had better partitioning to the grain, as evidenced through an increased harvest index (HI). The SDCs had a relatively compact and erect plant type with medium and upper leaves having a mean EC45° increase of 8.4% over the NSCs at 20 d after flowering. Correlations between grain yield components and physiological traits were analyzed. We concluded that the use of SHW has the potential to significantly increase wheat yield grown under rain-fed environments with low photosynthetically active radiation.

Measuring the impact of agricultural research: The case of new wheat varieties in Turkey

Posted by Carelia Juarez on , in Journal Articles

Published in Experimental Agriculture, 2014

Mazid, A.Keser, M.;Amegbeto, K.N.Morgounov, A.I.Bagci, A.Peker, K.Akin, M.kucukcongar, M.Kan, M.Semerci, A.Karabak, S.Altikat, A.;Yaktubay, S.

This paper summarizes a study initiated by the Turkish General Directorate of Agricultural Research and ICARDA/CIMMYT Wheat Improvement Program on the adoption of five new winter and spring wheat varieties developed and released by the Turkish national breeding program and through international collaboration in the past 10 years. The study results are based on a survey of 781 households selected randomly in the Adana, Ankara, Diyarbakir, Edirne, and Konya provinces of Turkey. The five new wheat varieties are compared to old improved varieties released prior to 1995 that are also still grown by farmers. Technical and biological indicators of impacts including crop productivity are measured to determine the impact of these varieties. Yield stability is assessed by comparing average yields in normal, good and dry years and by comparing the coefficients of variation of yields by variety. Profitability is measured by the gross margin generated per unit of land. Household income from wheat and for all economic activities are estimated and compared between adopters and non-adopters. Adopters of the new varieties have higher per-capita income than non-adopters as compared to the same group using old varieties. However, the overall impact of the improved varieties is generally low, mainly due to their low adoption levels. Farmers’ knowledge and perception of certain variety characteristics and unavailability of adequate and timely seed are the main reasons. Increasing adoption has the potential to improve household income and this requires revising wheat impact pathway to achieve the expected impact.

Genetic analysis of resistance to leaf rust and stripe rust in wheat cultivar Francolin#1

Posted by Carelia Juarez on , in Journal Articles

Published in Plant Disease 98 (9) : 1227-1234, 2014

Caixia LanSingh, R.P.;Calvo-Salazar, V.Herrera-Foessel, S.A.

Leaf rust and stripe rust are important diseases of wheat and can be controlled by growing resistant varieties. We investigated the genetic basis of resistance to both rusts in 198 F5 recombinant inbred lines derived from a cross between ‘Avocet’ and ‘Francolin#1’. The population was phenotyped in greenhouse and field, and genotyped with known gene-associated molecular markers. Seedling resistance of Francolin#1 to leaf and stripe rusts was attributed to the loosely linked genes Lr16 and YrF, respectively, with a recombination frequency of 0.36. Field segregation indicated that adult plant resistance (APR) to leaf and stripe rusts was conferred by three and five additive genes, respectively. Among them, Lr46/Yr29 was associated with resistance to both rusts in Francolin#1, Lr16 reduced field leaf rust severity by 8 to 9%, and YrF contributed to 10 to 25% reductions in stripe rust severity. The Lr16 region was also associated with a 5 to 16% reduction in stripe rust severity, which is likely due to its linkage with YrF or another unidentified stripe rust APR gene. Significant additive effects on stripe rust were detected between YrF and Yr29. We conclude that APR in Francolin#1 to leaf and stripe rusts involves a combination of seedling and APR genes.

Association of digital photo parameters and NDVI with winter wheat grain yield in variable environments

Posted by Carelia Juarez on , in Journal Articles

Published in Turkish Journal of Agriculture and Forestry  38 (5) : 624-632, 2014

Morgounov, A.I.Gummadov, N.Belen, S.Kaya, Y.Keser, M.Mursalova, J.

The normalized difference vegetation index (NDVI) is gaining popularity as a complementary selection tool, even though it requires an instrument not readily available in the developing world. We evaluated several parameters (originating from the analysis of digital photos using BreedPix software) as potential selection criteria in 23 winter wheat yield trials grown over 4 years at 2 sites. NDVI and digital photos were taken at key development stages from stem elongation to maturity. The correlations between digital photo parameters a and u and grain yield, as well as correlations between NDVI and grain yield within individual trials, varied depending on crop stage, moisture availability, and germplasm composition. NDVI, photo-a, and photo-u parameters had equal power in distinguishing high- and low-yielding genotypes in the trials and were significantly associated with yield in approximately 50% of all observations. The association of vegetative indices with grain yield can be improved by evaluating germplasm with a similar maturity range. An important challenge is in utilizing these tools in unreplicated small plots, including head rows where selection efficiency is low.

Accessing Spelt Gene Pool to Develop Well-Adapted Zinc- and Iron-Rich Bread Wheat

Posted by Carelia Juarez on , in Journal Articles

Published in Crop Science, 2014

Srinivasa, J.Arun, B.Mishra, V.K.Chand, R.Sharma, D.Bhardwaj, S.C.Joshi, A.K.

Breeding for higher Zn and Fe content in the wheat grain can be justified in the context of malnutrition. This breeding study set out to gauge the potential of crosses between spelt (Triticum aestivum ssp. spelta) and bread wheat (Triticum aestivum L. em. Thell) for enhancing the Zn and Fe content of wheat cultivars adapted to the northeastern plains zone (NEPZ) of India. BC1F8 populations were developed from two spelt × bread wheat combinations: H+ 35 × HUW 468 and H+ 15 × HUW 234. Their performance was evaluated at three locations in NEPZ. Around four genes were found to control inheritance of grain Zn concentration. Grain Zn and Fe concentration varied among the lines, as did other yield-related traits. Significant positive correlations were recorded between the grain content of Zn, Fe, and protein, but also negative correlations between them and the important agronomic characteristics plant height, grain yield, and thousand grain weight (TGW). Some of the derived lines showed increased mineral concentration without any decrease in grain size. The best ten selections in each population were all significantly superior to their respective bread wheat parent with respect to grain Zn and Fe content as well as some of the agronomic traits, which included resistance to spot blotch, stem rust, and leaf rust.

 

On-farm economic and environmental impact of zero-tillage wheat: a case of North-West India

Posted by Carelia Juarez on , in Journal Articles

Published in Experimental Agriculture, 2014

Aryal, J.P.;Sapkota, T.B.Jat, M.L.Bishnoi, D.K.

Conducting farmers participatory field trials at 40 sites for 3 consecutive years in four rice-wheat system dominated districts of Haryana state of India, this paper tested the hypothesis that zero tillage (ZT) based crop production emits less greenhouse gases and yet provide adequate economic benefits to farmers compared to the conventional tillage (CT). In each farmer’s field, ZT and CT based wheat production were compared side by side for three consecutive years from 2009–10 to 2011–12. In assessing the mitigation potential of ZT, we examined the differences in input use and crop management, especially those contributing to GHGs emissions, between ZT wheat and CT wheat. We employed Cool Farm Tool (CFT) to estimate emission of GHGs from various wheat production activities. In order to assess economic benefits, we examined the difference in input costs, net returns and cost-benefit analysis of wheat production under CT and ZT. Results show that farmers can save approximately USD 79 ha−1 in terms of total production costs and increase net revenue of about USD 97.5 ha−1 under ZT compared to CT. Similarly, benefit-cost ratio under ZT is 1.43 against 1.31 under CT. Our estimate shows that shifting from CT to ZT based wheat production reduces GHG emission by 1.5 Mg CO2-eq ha−1 season−1. Overall, ZT has both climate change mitigation and economic benefits, implying the win-win outcome of better agricultural practices.

Genome-wide association for grain morphology in synthetic hexaploid wheats using digital imaging analysis

Posted by Carelia Juarez on , in Journal Articles

Published in BMC Plant Biology 14 (128) : 21, 2014

Awais Rasheed, A.Xianchun XiaOgbonnaya, F.Mahmood, T.Zongwen ZhangMujeeb-Kazi, A.He Zhonghu

Background: Grain size and shape greatly influence grain weight which ultimately enhances grain yield in wheat. Digital imaging (DI) based phenomic characterization can capture the three dimensional variation in grain size and shape than has hitherto been possible. In this study, we report the results from using digital imaging of grain size and shape to understand the relationship among different components of this trait, their contribution to enhance grain weight, and to identify genomic regions (QTLs) controlling grain morphology using genome wide association mapping with high density diversity array technology (DArT) and allele-specific markers.

Results: Significant positive correlations were observed between grain weight and grain size measurements such as grain length (r = 0.43), width, thickness (r = 0.64) and factor from density (FFD) (r = 0.69). A total of 231 synthetic hexaploid wheats (SHWs) were grouped into five different sub-clusters by Bayesian structure analysis using unlinked DArT markers. Linkage disequilibrium (LD) decay was observed among DArT loci > 10 cM distance and approximately 28% marker pairs were in significant LD. In total, 197 loci over 60 chromosomal regions and 79 loci over 31 chromosomal regions were associated with grain morphology by genome wide analysis using general linear model (GLM) and mixed linear model (MLM) approaches, respectively. They were mainly distributed on homoeologous group 2, 3, 6 and 7 chromosomes. Twenty eight marker-trait associations (MTAs) on the D genome chromosomes 2D, 3D and 6D may carry novel alleles with potential to enhance grain weight due to the use of untapped wild accessions of Aegilops tauschii. Statistical simulations showed that favorable alleles for thousand kernel weight (TKW), grain length, width and thickness have additive genetic effects. Allelic variations for known genes controlling grain size and weight, viz. TaCwi-2ATaSus-2BTaCKX6-3D and TaGw2-6A, were also associated with TKW, grain width and thickness. In silico functional analysis predicted a range of biological functions for 32 DArT loci and receptor like kinase, known to affect plant development, appeared to be common protein family encoded by several loci responsible for grain size and shape.

Conclusion: Conclusively, we demonstrated the application and integration of multiple approaches including high throughput phenotyping using DI, genome wide association studies (GWAS) and in silicofunctional analysis of candidate loci to analyze target traits, and identify candidate genomic regions underlying these traits. These approaches provided great opportunity to understand the breeding value of SHWs for improving grain weight and enhanced our deep understanding on molecular genetics of grain weight in wheat.

 

 

Effective resistance to wheat stripe rust in a region with high disease pressure

Posted by Carelia Juarez on , in Journal Articles

Published in Plant Disease 98 (7) : 891-897, 2014

Bai, B.Du, J.Y.Lu, Q.L.He, C.Y.Zhang, L.J.Zhou, G.Xia, X.C.He ZhonghuWang, C.S.

Stripe rust is a major fungal disease of wheat. It frequently becomes epidemic in southeastern Gansu province, a stripe rust hot spot in China. Evaluations of wheat germplasm response are crucial for developing cultivars to control the disease. In total, 57 wheat cultivars and lines from Europe and other countries, comprising 36 cultivars with documented stripe rust resistance genes and 21 with unknown genes, were tested annually with multiple races of Puccinia striiformis f. sp.tritici in the field at Tianshui in Gansu province from 1993 to 2013. Seven wheat lines were highly resistant, with infection type (IT) 0 during the entire period; 16 were moderately resistant (IT 0;-2); and 26 were moderately susceptible (IT 0;-4), with low maximum disease severity compared with the susceptible control Huixianhong. ‘Strampelli’ and ‘Libellula’, with three and five quantitative trait loci, respectively, for stripe rust resistance have displayed durable resistance in this region for four decades. Ten cultivars, including ‘Lantian 15’, ‘Lantian 26’, and ‘Lantian 31’, with stripe rust resistance derived from European lines, were developed in our breeding program and have made a significant impact on controlling stripe rust in southeastern Gansu. Breeding resistant cultivars with multiple adult-plant resistance genes seems to be a promising strategy in wheat breeding for managing stripe rust in this region and other hot spots.

Genetic control of grain yield and grain physical characteristics in a bread wheat population grown under a range of environmental conditions

Posted by Carelia Juarez on , in Journal Articles

Published in Theoretical and Applied Genetics, 2014

Maphosa, L.Langridge, P.Taylor, H.Parent, B.Emebiri, L.C.Kuchel, H.Reynolds, M.P.;Chalmers, K.J.Okada, A.Edwards, J.Mather, D.E. 

Environmental conditions such as moisture deficit and high temperatures during the growing period affect the grain yield and grain characteristics of bread wheat (Triticum aestivum L.). The aim of this study was to map quantitative trait loci (QTL) for grain yield and grain quality traits using a Drysdale/Gladius bread wheat mapping population grown under a range of environmental conditions in Australia and Mexico. In general, yield and grain quality were reduced in environments exposed to drought and/or heat stress. Despite large effects of known photoperiod-sensitivity loci (PpdB1 andPpdD1) on crop development, grain yield and grain quality traits, it was possible to detect QTL elsewhere in the genome. Some of these QTL were detected consistently across environments. A locus on chromosome 6A (TaGW2) that is known to be associated with grain development was associated with grain width, thickness and roundness. The grain hardness (Ha) locus on chromosome 5D was associated with particle size index and flour extraction and a region on chromosome 3B was associated with grain width, thickness, thousand grain weight and yield. The genetic control of grain length appeared to be largely independent of the genetic control of the other grain dimensions. As expected, effects on grain yield were detected at loci that also affected yield components. Some QTL displayed QTL-by-environment interactions, with some having effects only in environments subject to water limitation and/or heat stress.

A consensus map for Ug99 stem rust resistance loci in wheat

Posted by Carelia Juarez on , in Journal Articles

Published in Theoretical and Applied Genetics, 2014

Long-Xi YuBarbier, H.Rouse, M.N.Sukhwinder SinghSingh, R.P.Bhavani, S.Huerta-Espino, J.Sorrells, M.E. 

The global effort to identify new sources of resistance to wheat stem rust, caused by Pucciniagraminis f. sp. tritici race group Ug99 has resulted in numerous studies reporting both qualitative genes and quantitative trait loci. The purpose of our study was to assemble all available information on loci associated with stem rust resistance from 21 recent studies on Triticum aestivum L. (bread wheat) and Triticum turgidum subsp. durum desf. (durum wheat). The software LPmerge was used to construct a stem rust resistance loci consensus wheat map with 1,433 markers incorporating Single Nucleotide Polymorphism, Diversity Arrays Technology, Genotyping-by-Sequencing as well as Simple Sequence Repeat marker information. Most of the markers associated with stem rust resistance have been identified in more than one population. Several loci identified in these populations map to the same regions with known Sr genes including Sr2SrND643Sr25 and Sr57(Lr34/Yr18/Pm38), while other significant markers were located in chromosome regions where no Srgenes have been previously reported. This consensus map provides a comprehensive source of information on 141 stem rust resistance loci conferring resistance to stem rust Ug99 as well as linked markers for use in marker-assisted selection.