Doctor of Philosophy / Department of Agronomy / Guihua Bai / Allan K. Fritz / Wheat pre-harvest sprouting (PHS), germination of physiologically matured grains in a wheat spike before harvesting, can cause significant reduction in grain yield and end-use quality. Many quantitative trait loci (QTL) for PHS resistance have been reported in different sources. To determine the genetic architecture of PHS resistance and its relationship with grain color (GC) in US hard winter wheat, a genome-wide association study (GWAS) on both PHS resistance and GC was conducted using in a panel of 185 U.S. elite breeding lines and cultivars and 90K wheat SNP arrrays. PHS resistance was assessed by evaluating sprouting rates in wheat spikes harvested from both greenhouse and field experiments. Thirteen QTLs for PHS resistance were identified on 11 chromosomes in at least two experiments, and the effects of these QTLs varied among different environments. The common QTLs for PHS resistance and GC were identified on the long arms of the chromosome 3A and 3D, indicating pleiotropic effect of the two QTLs. Significant QTLs were also detected on chromosome arms 3AS and 4AL, which were not related to GC, suggesting that it is possible to improve PHS resistance in white wheat. To identify markers closely linked to the 4AL QTL, genotyping-by-sequencing (GBS) technology was used to analyze a population of recombinant inbred lines (RILs) developed from a cross between two parents, “Tutoumai A” and “Siyang 936”, contrasting in 4AL QTL. Several closely linked GBS SNP markers to the 4AL QTL were identified and some of them were coverted to KASP for marker-assisted breeding. To investigate effects of the two non-GC related QTLs on 3AS and 4AL, both QTLs were transferered from “Tutoumai A” and “AUS1408” into a susceptible US hard winter wheat breeding line, NW97S186, through marker-assisted backcrossing using the gene marker TaPHS1 for 3AS QTL and a tightly linked KASP marker we developed for 4AL QTL. The 3AS QTL (TaPHS1) significantly interacted with environments and genetic backgrounds, whereas 4AL QTL (TaMKK3-A) interacted with environments only. The two QTLs showed additive effects on PHS resistance, indicating pyramiding these two QTLs can increase PHS resistance. To improve breeding selection efficiency, genomic prediction using genome-wide markers and marker-based prediction (MBP) using selected trait-linked markers were conducted in the association panel. Among the four genomic prediction methods evaluated, the ridge regression best linear unbiased prediction (rrBLUP) provides the best prediction among the tested methods (rrBLUP, BayesB, BayesC and BayesC0). However, MBP using 11 significant SNPs identified in the association study provides a better prediction than genomic prediction. Therefore, for traits that are controlled by a few major QTLs, MBP may be more effective than genomic selection.

Made available in DSpace on 2014-06-11T19:22:16Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-02-24Bitstream added on 2014-06-13T18:48:46Z : No. of bitstreams: 1 fioreze_sl_me_botfca.pdf: 515942 bytes, checksum: 36e6e68c9485cd45059afbe0dccf4ee9 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Melhorar o potencial produtivo de plantas cultivadas através de práticas de cultivo é um dos principais desafios da pesquisa frente à crescente demanda de alimentos em nível mundial. Assim, o presente estudo teve por objetivo investigar as alterações morfofisiológicas ocorridas no colmo principal e em perfilhos, bem como caracterizar os processos envolvidos com a plasticidade do desenvolvimento de plantas de trigo em função da densidade de semeadura e da aplicação de regulares vegetais. O experimento foi conduzido no ano agrícola de 2010 na Fazenda Experimental Lageado, Faculdade de Ciências Agronômicas, UNESP, em Botucatu (SP). O delineamento experimental utilizado foi o de blocos casualizados, em esquema de parcelas subdivididas. As parcelas foram formadas por quatro densidades de semeadura (30, 50, 70 e 90 plantas m-1), cultivar IAC 370, enquanto as subparcelas foram formadas pela aplicação de reguladores vegetais [controle, (Ax+GA+CK), Etil-Trinexapac e (Ax+GA+CK) + Etil-Trinexapac]. Foram avaliados a emissão de perfilhos, o acúmulo de matéria seca em perfilhos e no colmo principal, a altura de plantas, as trocas gasosas, características morfofisiológicas da folha bandeira e sua relações com a espiga, além dos componentes da produção para perfilhos e colmo principal e da produtividade final da cultura. Ao final do experimento foram determinadas a participação de perfilhos no desenvolvimento e na produção de grãos, bem como o potencial produtivo de perfilhos em relação ao colmo principal. A aplicação de Etil- Trinexapac resultou em alterações morfofisiológicas em plantas de trigo, como altura de plantas, redução da distância entre fonte e dreno, teor de clorofila e comprimento da folha bandeira, não afetou a produtividade de grãos, tampouco as relações entre colmo principal e perfilhos de trigo. O aumento do número de plantas por unidade de área... / Improve on yield potential of plants by crop management is the main research challenge due to the growing of food demand worldwide. The objective of this work was to study morphological and physiological changes in main stem and tillers, and to characterize the processes involved on developmental plasticity of wheat plants affected by sowing densities under plant growth regulators application. The experiment was carried out at Faculdade de Ciencias Agronômicas – Universidade Estadual Paulista “Júlio de Mesquita Filho”, Botucatu (SP) in 2010 crop season. The experimental design was split-plot with four replications. The plots were consisted by four plant densities (30, 50 70 and 90 plants m-1) and the subplots were consisted by plant growth regulators [control, (Ax+GA+CK), Trinexapac- Ethyl e (Ax+GA+CK) + Trinexapac-Ethyl]. Tiller emission, main stem and tiller dry mass accumulation, plant height, gas exchange, morphological and physiological characteristics of flag leaf, main stem and tiller yield components and yield were determined. The contribution of main stem and tillers on grain yield and yield potential of tillers in relation to main stem were evaluated at the end of the crop cycle. Trinexapac-Ethyl application resulted in decreasing of plant height, source-sink distance, flag leaf length and chlorophyll content, however, the grain yield was not affected. The increase in the number of plants per unit area resulted in linear lower emission of tillers, dry matter accumulation and relationship between main stem and tillers, with direct relation to the yield. The increase in yield of the lower plant populations occurred due to the higher number of grain weight per spike, offsetting the decrease in the number of spikes per square meter. The competition for production factors resulted in decreasing in contribution of tillers on grain yield and yield potential... (Complete abstract click electronic access below)

Submitted by Maria Beatriz Vieira (mbeatriz.vieira@gmail.com) on 2017-03-28T11:54:55Z No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) dissertacao_fabio_andre_sanders.pdf: 1291888 bytes, checksum: bc9ad7bd484a37f895916a6034e588bf (MD5) / Approved for entry into archive by Aline Batista (alinehb.ufpel@gmail.com) on 2017-03-28T20:47:04Z (GMT) No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) dissertacao_fabio_andre_sanders.pdf: 1291888 bytes, checksum: bc9ad7bd484a37f895916a6034e588bf (MD5) / Approved for entry into archive by Aline Batista (alinehb.ufpel@gmail.com) on 2017-03-28T20:49:05Z (GMT) No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) dissertacao_fabio_andre_sanders.pdf: 1291888 bytes, checksum: bc9ad7bd484a37f895916a6034e588bf (MD5) / Made available in DSpace on 2017-03-28T20:49:14Z (GMT). No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) dissertacao_fabio_andre_sanders.pdf: 1291888 bytes, checksum: bc9ad7bd484a37f895916a6034e588bf (MD5) Previous issue date: 2015-03-04 / Sem bolsa / Esta dissertação tem por base um experimento conduzido em uma área de trigo, na localidade de Figueiras, município de Santa Bárbara do Sul, na safra 2013/2013. Tem por objetivo identificar a interferência da aplicação da mistura dos seguintes herbicidas: Glifosato (Roundup WG) + Saflufenacil (Heat) + Oleato de metilo e de Palmitato de metilo (Dasch), na qualidade fisiológica (germinação e vigor) das sementes, aplicados em pré-colheita na cultura do trigo (Triticum aestivum). Essa mistura de Roundup WG + Heat + Dasch realizou-se para controlar de forma eficiente a buva (Conyza bonariensis), planta daninha de difícil controle, que gera uma competição significativa com a cultura subsequente, a soja. No intuito de identificar a interferência dos herbicidas, conduziram-se doze tratamentos, seis deles sem a aplicação dos produtos (testemunha) e os outros seis com a aplicação dos herbicidas. Após a colheita do trigo, ocorreu a secagem das amostras, para não haver interferência da umidade nas sementes no período de armazenamento e efetivação das devidas análises de germinação, vigor e tetrazólio, que se estenderam bimestralmente por um período de 11 meses. Nestas condições, os resultados da aplicação da mistura dos herbicidas, em pré-colheita na cultura do trigo, não apresentam efeitos prejudiciais a qualidade fisiológica das sementes no momento da colheita e no armazenamento. / This thesis has as a base an experiment carried out in a wheat field, in Figueiras, Santa Bárbara do Sul/RS, in the crop year of 2013/2013. It aimed to identify the interference of the application of the following herbicides: Glifosato (Roundup WG) +Saflufenacil (Heat) +Oleato de metilo and Palmitato de Metilo (Dasch), in the physiological quality (germination and vigor) of the seeds, preharvest applied at pre harvesting on the wheat cultivation (Triticum aestivum. The Roundup WG + Heat + Dasch compound was done to effectively control the “Buva” (Conyza bonariensis), a very difficult weed to controll, which generates a competition against the following crop, the soybean. In order to identify the herbicides influence, led to twelve treatments, six of them without the application of the products (evidence) and the other six with herbicide application. After harvesting the wheat, the samples were dried, in order to remove excess moisture of the seed. The seed were stored for 11 months and every two the following analysis were done:germination analysis, vigor and tetrazolium. Based on the results it was concluded that herbicides application in the wheat cultivation do not present effect on the physiological quality of the seeds at harvesting and during storage.

Submitted by Maria Beatriz Vieira (mbeatriz.vieira@gmail.com) on 2017-03-30T11:46:45Z No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) dissertacao_patricia_bressan.pdf: 1051408 bytes, checksum: 8a217e84712a4c8d9fe535bdca1679c2 (MD5) / Approved for entry into archive by Aline Batista (alinehb.ufpel@gmail.com) on 2017-04-05T17:58:57Z (GMT) No. of bitstreams: 2 dissertacao_patricia_bressan.pdf: 1051408 bytes, checksum: 8a217e84712a4c8d9fe535bdca1679c2 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Aline Batista (alinehb.ufpel@gmail.com) on 2017-04-05T17:59:56Z (GMT) No. of bitstreams: 2 dissertacao_patricia_bressan.pdf: 1051408 bytes, checksum: 8a217e84712a4c8d9fe535bdca1679c2 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2017-04-05T18:00:06Z (GMT). No. of bitstreams: 2 dissertacao_patricia_bressan.pdf: 1051408 bytes, checksum: 8a217e84712a4c8d9fe535bdca1679c2 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2015-08-04 / Sem bolsa / O presente estudo de caso objetivou avaliar aspectos da produção de sementes de trigo na Cooperativa Agrícola Mista São Cristóvão Ltda., durante os anos agrícolas de 2010 a 2014. As informações foram coletadas a partir de sistema informatizado, com autorização da administração da Cooperativa. Em cada ano agrícola, foi analisada a participação de cada cultivar de trigo na região de atuação da Cooperativa para as classes de semente certificada de primeira geração e certificada de segunda geração. O levantamento de dados considerou os seguintes aspectos: a) área inscrita para a produção de sementes junto ao Ministério da Agricultura, sendo os dados expressos em hectares (ha); b) produção bruta recebida, em quilogramas (Kg); c) produção de sementes beneficiada em quilogramas (kg); d) quebra no beneficiamento (%); e) produção aprovada em sacos de 40 Kg e, produção comercializada, expressa em quilogramas (kg). A cooperativa produz diferentes cultivares de trigo com quebras variáveis no beneficiamento conforme a cultivar, ano agrícola e categoria de semente. Estes são fatores que afetam a disponibilidade de sementes de trigo para a comercialização. / This case study aimed evaluating aspects of wheat seed production in Cooperativa Agrícola Mista São Cristóvão Ltda., farm during the years 2010 – 2014. The information was collected from computerized system, with authorization management of cooperative. In each crop year, it analyzed the participation of each wheat cultivar in the Cooperative operating region for seed certified classes of first generation and second generation certified. The data collection considered the following issues: a) area registered for seed production with the Ministry of Agriculture, and the data expressed in hectares (ha); b) gross production received in kilograms (Kg); c) benefited seed production in kilograms; d) break in processing (%); e) production approved in bags of 40 Kg and, commercialized production in kilograms (Kg). The cooperative produces different wheat cultivars with breaks in processing variables as to cultivate, growing season and seed category. These are factors affecting availability wheat seed for commercialization.

Submitted by Gabriela Lopes (gmachadolopesufpel@gmail.com) on 2017-09-22T14:46:47Z No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) DISSERTAÇÃO_BRUNA_RIGTH_CORRIGIDA+Catalog.pdf: 1361981 bytes, checksum: 172bb73af16db094ed298ba7457443d2 (MD5) / Approved for entry into archive by Aline Batista (alinehb.ufpel@gmail.com) on 2017-09-25T19:40:41Z (GMT) No. of bitstreams: 2 DISSERTAÇÃO_BRUNA_RIGTH_CORRIGIDA+Catalog.pdf: 1361981 bytes, checksum: 172bb73af16db094ed298ba7457443d2 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2017-09-25T19:40:41Z (GMT). No. of bitstreams: 2 DISSERTAÇÃO_BRUNA_RIGTH_CORRIGIDA+Catalog.pdf: 1361981 bytes, checksum: 172bb73af16db094ed298ba7457443d2 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2017-07-18 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / O trigo (Triticum aestivum L.) está entre os cereais mais produzidos no mundo devido a sua capacidade de adaptação a diferentes condições edafoclimáticas, além do valor nutritivo do grão. Aumentar a qualidade e a produtividade do trigo no Brasil tem sido um desafio para todos os segmentos envolvidos no processo produtivo. Nas últimas décadas, ocorreram avanços na produtividade, porém, a quantidade do trigo produzida no país ainda é inferior à necessária para o abastecimento interno. Para isto, é necessário incrementar o potencial de rendimento em condições de lavoura, onde os cultivares precisam interagir de forma benéfica com diferentes situações de ambiente e de manejo. Diferentes estratégias são utilizadas para composição do rendimento de grãos em cultivares de trigo. Dessa forma, o presente trabalho objetivou estudar diferentes cruzamentos entre genótipos de trigo e seu potencial para rendimento de grãos. O experimento foi conduzido junto ao campo experimental do Centro de Genômica e Fitomelhoramento (CGF), que está localizado no Centro Agropecuário da Palma, pertencente à Universidade Federal de Pelotas, no município de Capão do Leão, Rio Grande do Sul. O delineamento experimental foi em blocos casualizados, com três repetições. A unidade experimental utilizada para avaliação foi de 1m² para os anos de 2015 e 2016. Foram avaliados 51 genótipos de trigo na geração F6 e F7, além de cinco testemunhas comerciais, onde avaliou-se altura da planta (AP) e calculada a média de vários pontos da unidade experimental e número de afilhos férteis (AF). Após, foram coletadas 10 espigas de cada parcela, nas quais foram avaliados os seguintes caracteres do rendimento dos genótipos em estudo: massa da espiga (ME), número de grãos por espiga (NGE), massa de grãos da espiga (MGE), número de espiguetas (NE), comprimento da espiga (CE), medida do diâmetro (DG) e comprimento do grão (CG), massa de mil grãos (MMG) e massa da parcela inteira para avaliação do rendimento por área (MP). A análise da variância apresentou diferenças significativas entre os caracteres avaliados. Através de análises de dissimilaridade genética, houve formação de grupos distintos para os dois anos de estudo onde os genótipos 12 (ITAIPÚ/BRS 220) e 21 (MARFIM/FRONTANA) são genótipos promissores para serem utilizados em cruzamentos dirigidos entre si, tendo em vista sua superioridade para os caracteres comprimento de espiga e massa de grãos por espiga. As correlações obtidas entre os caracteres evidenciaram a importância das mesmas para seleção de genótipos superiores onde os caracteres MGE, NGE e ME apresentam as maiores correlações nos dois anos de cultivo. Através das análises de médias entre os anos, podemos observar que as variações climáticas tem forte influência sobre os caracteres que compõe o rendimento de grãos. O cruzamento FRONTANA x BRS 220 apresentou o maior potencial para incremento no rendimento de grãos. Dessa maneira, este estudo mostrou diferenças genéticas entre os genótipos avaliados e a importância e contribuição dos caracteres envolvidos no rendimento de grãos. / Wheat (Triticum aestivum L.) is one of the most produced cereals in the world due to its ability to adapt to different soil and climatic conditions, as well as the nutritive value of the grain. Increasing yield and quality of wheat in Brazil has been a challenge for all segments involved in the production process. In the last decades, there have been advances in yield, however, a quantity of wheat produced in the country is still lower than the domestic demand. Therefore, it is necessary to increase yield potential in the crop systems, where cultivars need to positively interact with different environmental and management conditions. The cultivars of wheat use different strategies for the composition of grain yield. Thus, the present work aimed to study different crosses between wheat genotypes and their potential for grain yield. The experiment was carried out at the Experimental Field of the Centro de Genômica e Fitomelhoramento (CGF), which is located at the Centro Agropecuário da Palma, of the Federal University of Pelotas, in the municipality of Capão do Leão, Rio Grande do Sul State. The experimental design used was random blocks with three replications. The experimental unit used for evaluation was 1m² for the years 2015 and 2016. In this experiment, the following characters were evaluated: plant height (AP) and calculated on average of several points of the experimental unit and number of fertile tiller (AF). Then, ten ears of each plot were collected for the measurement of yield components as follows: ear mass (ME), number of grains per ear (NGE), ear grain mass (MGE), number of spikelets (NE), ear length (CE), grain diameter (DG), grain length (CG), mass of a thousand grains (MMG) and mass of the whole plot (MP) for yield per area evaluation. An analysis of variance showed significant differences among the evaluated charcaters. Through genetic dissimilarity analyses, distinct groups were formed for the two years of study, where genotypes 12 (ITAIPÚ / BRS 220) and 21 (MARFIM / FRONTANA) are promising to be used in crosses directed towards each other, aiming at superiority for the characters of ear length and mass of grains per ear. The correlations obtained between the characters evidenced an importance for the selection of superior genotypes where MGE, NGE and ME presented the highest correlations in the two years of cultivation. Moreover, means analyzes between both years demonstrates that the climatic variations deeply influence the yield grains traits. The FRONTANA x BRS 220 cross showed the greatest potential for increment of grain yield. Thus, this study showed genetic differences among the studied genotypes and the importance and contribution of the characters involved in grain yield.

Raphanus raphanistrum L. (wild radish) is a widespread and economically problematic weed of winter crops including wheat (Triticum aestivum L.) in southern Australia. Management of the weed is achieved by a range of non-chemical and chemical techniques. Current management is failing to contain the weed, which is increasing in abundance and distribution. The characteristics of staggered recruitment, dormancy, rapid growth, competitive ability and high levels of seed production contribute to its persistence. The literature review concludes that weeds formed the basis for perpetuation of R. raphanistrum, a claim further investigated by simulation modeling. The effective management of R. raphanistrum should aim to achieve declining populations and this requires the integration of all factors that regulate seed production. Reducing seed production of R. raphanistrum in wheat can be achieved by applying herbicides at reproductive stages of development. This technique has been demonstrated to be an effective, safe and practical method of reducing seed production of R. raphanistrum in wheat. Reducing seed production of R. raphanistrum by herbicides applied at reproductive stages of development is a technique that can be incorporated into an integrated weed management program to improve control / Doctor of Philosophy (PhD)

Dans l'optique d'une agriculture plus durable, l'agriculture biologique offre l'opportunité d'une production agricole plus respectueuse de l'environnement. Néanmoins, en agriculture biologique, les niveaux de production sont inférieurs à ceux de l'agriculture conventionnelle. Le rendement et la teneur en protéines du blé biologique sont très variables et limités par de nombreux facteurs. Les faibles teneurs en protéines posent des difficultés de commercialisation car elles sont généralement inférieures au seuil de 10,5% que les organismes de collecte exigent pour les débouchés de panification. Afin d'améliorer les performances du blé biologique, dans un premier temps, les facteurs limitants et les pratiques agricoles expliquant ces performances ont été identifiés et hiérarchisés à l'aide d'un diagnostic agronomique réalisé en région Rhône-Alpes. Ce diagnostic a été réalisé à l'aide d'une méthode statistique innovante de mélange de modèles. Puis, des modèles permettant de prédire la distribution du rendement et de la densité d'une population d'adventices tardive à partir d'une densité précoce dans des parcelles de blé biologique, ont été mis au point à l'aide de la méthode de régression quantile. Ils permettent d'aider au raisonnement des pratiques de désherbage et de fertilisation. Enfin, une analyse des pratiques des agriculteurs a permis de prendre en compte la manière dont les agriculteurs prélèvent des informations sur leurs parcelles pour déclencher leurs pratiques. Des propositions sont ensuite discutées pour valoriser les résultats de ce travail dans la construction d'un outil d'aide à la décision destiné à raisonner les pratiques de désherbage et de fertilisation.

The aim of this study was to identify QTLs associated with the maintenance of grain quality following post-anthesis heat stress. A population of 64 F6Halberd X Cutter recombinant inbred lines (RILs) was exposed to either heat stress or control conditions in the greenhouse, starting ten days after anthesis. Grain quality was determined using the sodium dodecyl sulfate (SDS) sedimentation test, a significant predictor of bread baking quality. The percent change in SDS sedimentation test scores between the heat and control populations was used to identify QTLs associated with quality stability. Four QTLs were identified, located one each on chromosomes 1B, 1D, 4A, and 7A. Three of the QTLs, those on 1B, 1D, and 4A, were associated with variations in SDS sedimentation level. The QTL on chromosome 7A was associated with the percent change in SDS sedimentation scores between heat-stressed and control conditions. This indicated a relationship between the identified QTL and quality stability. To confirm the detected QTLs, eighty advanced lines grown at three Texas nurseries were genotyped and tested for relationships between QTL-associated markers, quality traits, and stability of the quality traits. Quality trait stability was estimated using the coefficient of variability (CV%) of quality traits between growing sites. Quality characters analyzed in the advanced lines included kernel hardness, mixograph peak time, kernel weight, flour yield, SDS sedimentation, and grain yield. The analysis showed support for the effect of the QTLs on chromosomes 1B, 1D, and 4A. Further analysis will be needed to confirm the QTL on 7A, in particular. The mapping of additional markers will be necessary. However, the potential importance of this QTL and the abundance of other QTLs detected in this region make it worth investigating.

The use of exotic resistance quantitative trait loci (QTL) provides one strategy for breeding wheat cultivars resistant to Fusarium Head Blight (FHB), a devastating disease of wheat. The objective of this study was to evaluate the effectiveness of two QTL, Fhb1 and QFhs.nau-2DL, in diverse genetic backgrounds and to evaluate their effects on agronomic and quality traits. Five populations from crosses between FHB susceptible parents (26R58, KY97C-0574-01, 25R54, KY97C, KY97C-0554-02, 25R78 and KY93C-1238-17-1) and FHB-resistant VA01W-476, were evaluated in the FHB nursery at Lexington, KY in 2010 and 2011. The populations were also grown in yield trials at Lexington (2010 and 2011) and Princeton (2011), KY, to measure agronomic and quality traits. Fhb1 reduced Fusarium damaged kernels (FDK) by 32% and the toxin, deoxynivalenol (DON) by 20%. QFhs.nau-2DL significantly reduced mean FDK by 29% in two of five populations and DON by 24% in four of five populations. While the effects of these QTL on agronomic and quality traits were significant, the impact was small. One cycle of either direct or indirect simulated phenotypic selection was effective at reducing DON levels and the frequency of Fhb1-homozygous resistant lines among the selects was higher than the frequency of QFhs.nau-2DL-homozygous resistant lines.

Fusarium Head Blight (FHB) is a destructive disease caused by Fusarium graminearum that affects wheat (Triticum aestivum L.) worldwide. Breeding for resistance to FHB is arguably the best way to combat this disease. However, FHB resistance is highly complex and phenotypic screening is difficult. Molecular markers are a promising tool but breeding programs face the challenge of allocating resources in such a way that the optimum balance between phenotypic and genotypic selection is reached. An F2:3 population derived from a resistant x susceptible cross was subjected to phenotypic and genotypic selection. For phenotyping, a novel air separation method was used to measure percentage of damaged kernels (FDK). Heritability estimates were remarkably high, which was attributed to the type of cross and the quality of phenotyping. Genotypic selection was done by selecting resistance alleles at quantitative trait loci (QTL) on the 3BS (Fhb1) and the 2DL chromosomes. Fhb1 conferred a moderate but stable FHB resistance while the 2DL QTL conferred a surprisingly high level of resistance but with significant interaction with the environment. Phenotypic selection conferred higher or lower genetic gains than genotypic selection, depending on the selection intensity. Based on these results, different selection strategies are discussed.