The presented work provides the results of experiments with winter wheat during the growing season 2016/2017, which were established at the field research station of Mendel University in Žabčice. Eight winter wheat varieties were grown on two sites with different water regimes in the soil (optimal conditions - Obora/water-limited conditions - Písky). The varieties were evaluated for the number of spikes per area, thousand seed weight and grain number per spike. Then the grain yield per hectare and harvest index (which was calculated as the ratio of biomass and grain) were evaluated. In the water-limited conditions, there was a decrease in all monitored characters. The site had the largest influence on the number of spikes per area where the average number of spikes per area under water-limited conditions fell by 23 %. The second most affected was thousand seed weight which was decreased by 19 %, and the least affected character was grain number per spike, which was changed by 11 %. The harvest index was lower on water-limited field. The weight of biomass was reduced by 24 – 34 % and weight of grain was reduced by 50 % for evaluated varieties. The average yield at the site with optimal conditions was 10,4 t per ha and at water-limited conditions site it was 6,1 t per ha. According to the results of this harvest year 2017 varieties Patras, Gordian and Cimrmanova raná were found as suitable for worse conditions. On the other hand varieties Tobak and Hyfi seem to be unsuitable for stressful conditions.

Fusarium graminearum (Schwabe), causal organism of fusarium head blight (FHB), has become a major pathogen of wheat (Triticum aestivum L.) throughout North America. Since its discovery in the United States, the disease has spread south and east until at present it is an annual threat for growers of winter wheat in the Mid-Atlantic region. Yield losses for soft red winter (SRW) wheat averaged 908 kg ha-1 in the FHB outbreak of 1998 (Griffey et al., 1999). The economic loss from this single FHB epidemic was an estimated 8.5 million dollars. Environmental conditions favorable for FHB development, including above average rainfall and temperatures during anthesis, have become more common in the Upper-Midwestern wheat-growing region over the past decade, leading to substantial losses in wheat and barley crops. This, coupled with low prices being paid for wheat, has prompted research toward solving the problem of FHB across the nation. The majority of labor and financial resources devoted to FHB research are dedicated to incorporating FHB resistance into adapted wheat lines. While this is a prudent method of combating this disease, this process will take many years to complete. We have examined all FHB assessment parameters, which include FHB incidence, FHB severity, FHB index, percentage fusarium damaged kernels (percentage FDK), and 15-acetyl deoxynivalenol toxin (DON toxin) accumulation, to ascertain which assessment parameters best quantify FHB resistance levels in addition to grain yield and grain volume weight (GVW) losses. FHB index provides the most reliable in-field assessment of a genotype's resistance level, whereas percentage FDK provides a reliable measure of a genotype's resistance level post-harvest. FHB index and percentage FDK are also the most predictive assessment parameters with regard to grain yield and GVW loss. A wide range in both level and type of resistance was observed among genotypes examined in this study. The cultivars Agripro Patton, Ernie, INW9824, Roane, and the experimental line NY87048W-7388 consistently had lower scores for FHB assessment parameters and lower losses of grain yield and GVW. / Master of Science

Wheat is the most widely grown crop in the world and as such, is an essential source of energy and nutrition. The challenges that breeders presently face is to increase production to feed the rising population of the world, while also accounting for climate change, pollution, water and environmental stresses. As genetic uniformity of modern cultivars has increased vulnerability to pests and diseases, the wild relatives of wheat offer a rich source of genetic diversity and stress tolerance traits, that can be harnessed and transferred in to modern wheat. In this study, we used array-based genotyping to explore genetic diversity in 385 domesticated and non-domesticated lines of wheat and their wild relatives. Genetic characterization using the wheat 90K array, and subsequent filtering and validation mapped 9,570 single nucleotide polymorphic markers onto the wheat reference genome. Phylogenetic analyses illustrated four major clades, clearly separating the wild species from the domesticated, and the ancient Triticum turgidum species from modern T. turgidum cultivars. Using this diverse germplasm, a genome-wide association study (GWAS) was performed for leaf rust, the most widespread rust disease of wheat. Identification of novel sources of resistance is necessary to maintain disease resistance and stay ahead in the plant-pathogen evolutionary arms race. GWAS was conducted using eight statistical models for infection types against six leaf rust isolates and leaf rust severity rated in field trials for 3-4 years at 2-3 locations in Canada. Functional annotation of genes containing significant quantitative trait nucleotides (QTNs) identified 96 disease-related nucleotide associated with leaf rust resistance. A total of 21 QTNs were in haplotype blocks or within flanking markers of at least 16 known leaf rust (Lr) resistance genes. The remaining significant QTNs were considered loci that putatively harbor new Lr resistance genes. Future efforts to validate these loci will help understand their role in disease resistance and promote their utility for marker-assisted selection in pre-breeding.

El trigo candeal o trigo duro (Triticum turgidum L. ssp. durum) es una especie de trigo tetraploide (2n= 4x= 28 AABB) que se utiliza, principalmente, para la elaboración de pastas secas de calidad. El mejoramiento de esta especie está focalizado en la obtención de variedades de alta productividad con endosperma duro, vítreo, alto contenido proteico y pigmentos amarillos. Las variedades disponibles en Argentina son de hábito primaveral de ciclo corto a intermedio, y la siembra se realiza en el periodo comprendido entre junio y agosto. La principal zona de cultivo en nuestro país, es el sur de la provincia de Buenos Aires donde la ocurrencia de heladas entre abril y noviembre afecta al cultivo en estadio vegetativo y reproductivo. Los genes de desaturasas que introducen dobles enlaces en los ácidos grasos de cadena larga, se encuentran involucrados en la tolerancia a estrés por bajas temperaturas. La disponibilidad de secuencias de ADN, ARN y proteínas de desaturasas de gramíneas en las bases de datos públicas, permitió realizar un análisis in silico de las mismas, logrando caracterizar estructural y funcionalmente esta familia de proteínas. Se observó una distribución cromosómica dispersa y se predijo la localización subcelular más probable. Teniendo en cuenta que no existen secuencias de desaturasas caracterizadas de trigo candeal disponibles en GenBank (https://www.ncbi.nlm.nih.gov/), se realizó un análisis de la variabilidad genética en cinco genotipos, con diferencias en su grado de tolerancia a bajas temperaturas. Se detectó un bajo número de polimorfismos en la estearoil-ACP desaturasa (SAD) y ω- 3 lípido desaturasa (FAD3), mientras que ω- 6 lípido desaturasa (FAD2) mostró una mayor variabilidad. No se encontraron relaciones entre los polimorfismos en secuencia y el comportamiento frente a frío. El mapeo in silico de FAD2 permitió detectar la presencia de cuatro copias del gen localizadas en el cromosoma 6, incluyendo pseudogenes y un elemento transponible (TE, transponible element) insertado en la cuarta copia del genoma B. Las proteínas deducidas de las secuencias de trigo candeal fueron incluidas en el análisis in silico de gramíneas antes mencionado. Las regiones promotoras de los genes de desaturasas contienen sitios de unión a factores de transcripción de respuesta a estrés abiótico. Por otra parte, se realizó un estudio de respuesta a bajas temperaturas, en tres genotipos de trigo candeal, dos primaverales (BUCK AMBAR y CBW 0101) y uno invernal (MVTD 10- 98). Experimentos previos habían mostrado tolerancia a temperaturas bajo cero en cámara, de los genotipos MVTD 10-98 y CBW 0101 en estado vegetativo. El presente estudio incluyó el análisis de expresión del gen FAD2, la obtención del perfil de ácidos grasos y ensayos de conductividad eléctrica. Los ácidos grasos insaturados oleico (18:1), linoleico (18:2) y linolénico (18:3) fueron los que presentaron mayor nivel de cambios frente a bajas temperaturas. Se observó que las líneas CBW 0101 y MVTD 10-98, presentaron similares incrementos de 18:1 y 18:2 ante el tratamiento con frío y perfiles de expresión de FAD2 concordantes con los niveles de su producto 18:2. Las evaluaciones de integridad de membrana también estuvieron de acuerdo con las diferencias fenotípicas en la tolerancia. Además, se realizaron ensayos de rendimiento a campo en tres fechas de siembra (mayojunio- julio), durante dos años consecutivos en la Estación Experimental Agropecuaria Integrada Barrow - INTA (EEAI). Las variables evaluadas fueron: duración del ciclo a antesis, periodo de llenado de granos, rendimiento y medidas relacionadas (peso de granos, número de granos y sus subcomponentes, biomasa en antesis y madurez fisiológica, índice de cosecha y altura de planta), contenido de proteína en grano y peso hectolítrico. Se encontraron diferencias significativas entre años, fechas y genotipos en todas las variables. El primer año presentó un rendimiento promedio menor que el segundo (57 %), atribuido principalmente a las diferentes condiciones ambientales en relación a precipitaciones, suelo y temperaturas, mientras que el contenido de proteína en grano fue menor en el segundo año (22,25 %). En cuanto al momento de siembra, el rendimiento promedio fue mayor en fechas más tempranas en ambos años. La determinación de los periodos desde emergencia a antesis y de llenado de granos, combinados con diferentes fechas de siembra, permitieron explicar variaciones en el rendimiento. Además, los valores promedio de biomasa aérea total, peso de las espigas alcanzado en el periodo de llenado de granos (PEAT-MF) y peso promedio de granos por unidad de superficie (PG), fueron superiores en las fechas más tempranas. El peso de los granos por unidad de superficie, fue el principal componente numérico del rendimiento. Del análisis de componentes principales entre rendimiento y las variables asociadas, se deduce que el índice de cosecha, PG y PEAT-MF fueron las variables que mejor explicaron cambios en el rendimiento en todos los ensayos. Se evaluó, además, el daño por heladas en etapa de floración en el año 2016. Se identificaron tres formas de daño en espiga (deformada, por zonas y blanca) y el porcentaje promedio total varió entre genotipos desde 0,25 a 9,47 %. En general, los materiales menos afectados por heladas, fueron los de ciclo más largo, aunque también se observaron algunas diferencias en el nivel de daño entre genotipos de fenología similar. Este estudio aporta información de Triticum turgidum L. ssp. durum relacionada con su genoma, respuesta a estrés abiótico y efecto de fecha de siembra en el sudoeste de Buenos Aires. / Durum wheat, also called pasta wheat, (Triticum turgidum L. ssp. durum) is a tetraploid species of wheat (2n= 4x= 28 AABB), mainly produced for the elaboration of high quality dry pasta. Breeding of this species is focused on the obtention of high yield varieties, with hard and glassy endosperm, high protein contents, and yellow pigmentation. Available varieties in Argentina are spring-habit, short to intermediate cycle, with a sowing period that spans from June to August. The main cultivation area in our country is in the South of the Buenos Aires province, where frost occurrences (which may happen between April and November) negatively affect the crops during vegetative and reproductive stages. Fatty acid desaturase genes, which introduce double bonds in long-chain fatty acids, are related to low temperature stress tolerance. Availability of ADN, ARN, and desaturase sequences of grasses in public databases enabled in silico analyses, which in turn allowed to structurally and functionally characterize this protein family. A sparse chromosome distribution was observed, and a most likely sub-cellular location was predicted. Taking into account that there are no featured durum wheat desaturase sequences available in GenBank (https://www.ncbi.nlm.nih.gov/), a genetic variability analysis was performed in five different genotypes, each with different low temperature tolerance degrees. A low number of polymorphisms in the estearoil-ACP desaturase (SAD) and in the ω-3 desaturase (FAD3) where detected, while the ω-6 desaturase (FAD2) exhibited higher variability. No relationships between sequence polymorphisms and low temperature tolerance were detected. In silico mapping of FAD2 enabled to detect four copies of the gen, located in chromosome 6, including pseudogenes and a transponible element (TE) inserted in the fourth copy of the B genome. Proteins deduced from durum wheat sequences were included in the in silico gramineae analyses mentioned above. The promoting regions in the desaturase genes contain sites with bonding to transcription factors related to abiotic stress response. On the other hand, an analysis of low temperature response was performed on three genotypes of durum wheat, two spring-like (BUCK AMBAR and CBW 0101) and one wintry (MVTD 10-98). Previous experiments showed below-zero chamber temperature tolerance in genotypes MVTD 10-98 and CBW 0101 in vegetative state. The present study includes the expression analysis of the gene FAD2, the obtention of the fatty acid profile, and electric conductivity studies. The insaturated fatty acids oleic (18:1), linoleic (18:2), and linolenic (18:3), presented greater change levels under low temperatures. The lines CBW 0101 and MVTD 10-98, presented similar increments in 18:1 y 18:2 upon low temperature exposure, and FAD2 expression profiles in accordance with its product 18:2. Membrane 8 integrity evaluations were also in accordance with phenotypic differences in low temperature tolerance. In addition, field yield tests were performed in the Barrow Integrated Experimental Farming Station (Estación Experimental Agropecuaria Integrada, EEAI Barrow) of the National Agricultural Technology Institute (INTA), during three different sowing dates (May, June and July) along two consecutive years. The evaluated variables were: cycle length up to anthesis, grain filling period length, yield, and related mesures (grain weight, number of grains and their subcomponents, biomass during anthesis and physiological maturity, harvest index, and plant height), the protein contents in grain, and the hectolitre weight. Meaningful differences were found among years, sowing dates, and genotypes in all the evaluated variables. The first year presented an average yield 57 % lower than the second, which can be attributed to environmental conditions related to precipitation, soil, and temperatures, while the average protein contents in the grain was 22.25 % lower during the second year. Regarding the sowing date, average yield was higher in earlier dates in both years. Period determination from emergency to anthesis, and grain fill, combined with different sowing dates, are able to explain these yield differences. In addition, average total aerial biomass, spikes weight achieved during the grain filling period (PEAT-MF), and average grain weight per surface unit (PG), were all higher in earlier sowing dates. From Principal Component Analyisis between yield and the associate variables, it can be established that PG was the most important component of the yield, while PG and PEATMF were the variables that best explained yield changes in all the trials. In addition, the frost related damage during the flowering period was evaluated during 2016. Three different damage forms were identified (deformed, by zones, and white), where the average percentage varied between 0.25 and 9.47 %. In general, the genotypes less affected by frost were the ones of longest cycles, even though some differences were observed in the damage level among genotypes of similar phenology. This study provides information related to the genome and abiotic stress response of Triticum turgidum L. ssp. durum, and the effects of sowing date in the Southwest of Buenos Aires.

Yes / The Mesolithic-to-Neolithic transition marked the time when a hunter-gatherer economy gave way to agriculture, coinciding with rising sea levels. Bouldnor Cliff, is a submarine archaeological site off the Isle of Wight in the United Kingdom that has a well-preserved Mesolithic paleosol dated to 8000 years before the present. We analyzed a core obtained from sealed sediments, combining evidence from microgeomorphology and microfossils with sedimentary ancient DNA (sedaDNA) analyses to reconstruct floral and faunal changes during the occupation of this site, before it was submerged. In agreement with palynological analyses, the sedaDNA sequences suggest a mixed habitat of oak forest and herbaceous plants. However, they also provide evidence of wheat 2000 years earlier than mainland Britain and 400 years earlier than proximate European sites. These results suggest that sophisticated social networks linked the Neolithic front in southern Europe to the Mesolithic peoples of northern Europe.

Master of Science / Genetics Interdepartmental Program / Bikram S. Gill / TILLING (Targeting Induced Local Lesions IN Genomes) is a high-throughput, reverse genetics strategy for scanning mutagenized populations for point mutations in loci of interest. Originally, TILLING was used to investigate gene function in Arabidopsis and has since been similarly applied for gene functional analysis in other organisms. TILLING also allows the generation of novel genetic variation in specific genotypes and, thus, has been implemented as a tool for crop improvement. Ethyl methanesulfonate (EMS) is a widely used mutagen to induce point mutations in most TILLING protocols. M1 plants are then self-pollinated and M2 seed harvested. A single seed is grown from each M2 progeny and tissue taken for DNA isolation. M3 seed is cataloged. DNA is pooled to increase the efficiency and aid in mutation detection. Polymerase chain reaction (PCR) is used to amplify a locus of interest using the M2 DNA pools as a template. The PCR products are digested with an endonuclease that cleaves mismatched, mutant DNA, and the digested products are visualized. The pools for which PCR products are positive for a mutation are deconvoluted to determine which individual plant of the pool was responsible for the mutation. DNA from the positive individual is sequenced to determine the type of mutation (missense, nonsense, synonymous). Individuals with mutations that are more likely to disrupt gene function (nonsense and certain missense) are studied further by growing the corresponding M3 generation. In bread wheat, Triticum aestivum, TILLING is complicated by polyploidy: genes that have homoeologs require that the functionality of each be studied. If functional homoeologs are present for all three genomes, mutants must be identified for each homoeolog, followed by successive intercrossing to produce a triple mutant plant. As a model for wheat genetics, we propose TILLING in diploid wheat. EMS mutant populations were created in diploid wheat (Triticum monococcum ssp. monococcum) and the hexaploid bread wheat cultivar ‘Jagger’. The diploid and hexaploid wheat populations were screened for mutations at the waxy locus, GBSS1, as a validation of our population and for comparative analysis of mutation rates in 2x and 6x wheat. For diploid wheat, GBSSI was screened in 716 M2 plants, and one mutant was found for 1.9 Mb screened. 3 For hexaploid wheat, GBSSI was screened in 518 M2 plants, and 30 mutants were identified within a total of 657 Kb screened, giving a mutation frequency of one mutation per 22 Kb. The reasons for this vast difference in mutation frequency between diploid and hexaploid wheat are discussed. The diploid wheat population was further examined by screening for mutations within four lignin biosynthesis candidate genes, for a total of 2 Mb screened. A single mutant was discovered for both of the lignin genes PAL6 and HCT, giving a mutation frequency of one mutation per 1 Mb screened.

O trigo é um alimento básico da humanidade cuja demanda cresce proporcionalmente ao aumento populacional. Existe carência de pesquisas sobre o efeito da nutrição da planta doadora na resposta androgenética. Este trabalho teve por objetivo avaliar a influência de cinco concentrações de nitrogênio e de boro (25%, 50%, 100%, 150% e 200%) a partir da solução de Sarruge modificada, no cultivo de plantas de trigo doadoras de anteras visando à obtenção de estruturas embriogênicas androgenéticas. Para tanto, foram avaliados os componentes do rendimento (número de colmos, diâmetro e comprimento do colmo principal; comprimento, largura e área da folha bandeira; teor de clorofila da folha bandeira, distância entre a folha bandeira e o último nó e comprimento da espiga); o acúmulo de graus dias e duração do ciclo da semeadura até a coleta das espigas para a cultura de anteras; a formação de estruturas embriogênicas androgenéticas e o desenvolvimento dos micrósporos (tétrade, mononucleado central, mononucleado periférico, binucleado e pólen P). Constatou-se que as concentrações de nitrogênio afetaram significativamente os componentes do rendimento, a formação de estruturas embriogênicas androgenéticas e o desenvolvimento dos micrósporos. A duração do ciclo das plantas cultivadas na concentração de 25% de nitrogênio foi menor que nas demais doses, apresentando diferença de até 3,3 dias quando comparada às plantas submetidas a doses mais elevadas. Houve aumento linear na produção de estruturas embriogênicas androgenéticas em função das doses crescentes de nitrogênio utilizadas no cultivo das plantas doadoras das anteras. As doses de nitrogênio interferiram também no estádio de desenvolvimento dos micrósporos, para todas as variáveis estudadas. Essa influência no desenvolvimento dos micrósporos foi efetiva enquanto a folha bandeira menos um encontrava-se no primeiro terço de deslocamento em relação à distância total entre a folha bandeira e o último nó do colmo. As concentrações de boro utilizadas nas soluções de cultivo das plantas de trigo doadoras de anteras não influenciaram nos componentes do rendimento, na formação de estruturas embriogênicas, na duração do ciclo da planta e na maioria das variáveis estudadas com relação ao desenvolvimento dos micrósporos. O desenvolvimento dos micrósporos na espiga seguiu o padrão normal descrito para a espécie, independentemente dos nutrientes estudados. Concluiuse que as concentrações de nitrogênio influenciaram positivamente nos componentes do rendimento (exceto no comprimento da espiga), na formação de estruturas embriogênicas e na distância entre a folha bandeira e o último nó do colmo (marcador morfológico da coleta das espigas para cultura de anteras), enquanto que as concentrações de boro utilizadas no cultivo das plantas doadoras de anteras não apresentaram esse efeito. / Wheat is the staple food of humanity whose demand grows in proportion to the population growth. There is lack of research about the effect of the nutrition of the donor plant in the androgenetic response. This work aim for evaluate the influence of five concentrations of nitrogen and boron (25%, 50%, 100%, 150% and 200%) from the solution of Sarruge modified, in the cultivation of wheat plants donors of anthers aiming the obtainment of androgenetics embryogenic structures. Both for, were evaluated the yield components (number stalks, diameter and length of the main stem; length, width and area of flag leaf; chlorophyll content of flag leaf, distance between flag leaf and the last node and ear length); the accumulation of degree-days and cycle duration of sowing until collection of ears to the anther´s culture; the formation of androgenetics embryogenic structures and the development of microporous (determination of the number of cells in stages: tetrad, central mononucleate, peripheral mononucleate and binucleated and occurrence of pollen P). It was found that the concentrations of nitrogen significantly affected the yield components, the formation of androgenetics embryogenic structures and the development of microspores. The duration of the cycle of the cultivated plants in the concentration of 25% of nitrogen was lower than in other doses, presenting difference of up to 3.3 days when compared to plants subjected to higher doses. There was a linear increase in the production of androgenetics embryogenic structures in function of increasing doses of nitrogen used in cultivation of donor plants of the anthers. The doses of nitrogen interfered also at the stage of development of microspores, for all variables studied. This influence on the development of microspores was effective while the flag leaf less one was in the first third of displacement in relation to the total distance between the flag leaf and the last node of the culm. The concentrations of boron used in solutions of cultivation of wheat donors plants of anthers did not affect the income components, in the formation of embryogenic structures, on the duration of the cycle of the plant and in the majority of the variables studied in relation to the development of the microspores. The development of microspores in spike followed the normal pattern described for the species, regardless of the nutrients studied. It was concluded that the concentrations of nitrogen positively influenced in yield components (except the length of the ear), the formation of embryogenic structures on and the distance between the flag leaf and the last node of the culm (morphological marker of collection of ears to anther culture), while the concentrations of boron used for the cultivation of plants donated anthers did not have this effect.

Made available in DSpace on 2017-07-25T19:29:37Z (GMT). No. of bitstreams: 1 melissa.pdf: 22685399 bytes, checksum: 52613e711bdb2207d8ee610ea5bcd520 (MD5) Previous issue date: 2006-08-10 / Trinexapac-ethyl is a growth reducer used in winter cereals that promote height plant reduction, preventing the lodging. With the aim of determine the rate and the time of ethyltrinexapac (Moddus) application in wheat cultivars of different lodging answers an experiment was established at the UEPG School Farm in Ponta Grossa, PR, in 2005, in a clay soil. The experimental design was complete randomized blocks, in a factorial design 2 x 2 x 6, with three repetitions for four wheat cultivars. The treatments consisted of two nitrogen rates (50 and 240 kg/ha), two times of trinexapac-ethyl application (between 1º and 2º knot and between 2º and 3º perceivable knot) and six trinexapac-ethyl rates (0; 31,2; 62,5; 93,7; 125,0 and 156,2 g/ha), applied in four wheat cultivars of different answers to the lodging (CD-104 - resistant), (Vanguarda - moderately resistant), (Supera - moderately susceptible) and (CEP-24 - susceptible). It evaluated agronomicals characteristics, diseases severity, yield components and yield. The nitrogen rate affected some plant characteristics and the yield for CEP-24. The application time of trinexapac-ethyl affect the yield of CD-104; the plant height that was lesser how much more delayed was the application in cultivars CEP-24 and CD-104; trinexapac-ethyl reduced the plants height of all the cultivars with changeable intensity with the port of the same ones. For all the cultivars the adjustment equation of the yield in relation to the trinexapac-ethyl rates was quadratic, occurring an increase of the yield with the increase of the reducer rate, until a changeable limit with the cultivar. However, for all cultivars occurred increase of the yield with the trinexapac-ethyl application. For the cultivar majority it had reduction of rust severity, head blight and foliar spots with the increase of the trinexapac-ethyl rate. / O trinexapac-ethyl é um redutor de crescimento utilizado em cereais de inverno que promove redução na altura das plantas, evitando o acamamento. Visando determinar a dose e a época de aplicação de trinexapac-ethyl (Moddus) em cultivares de trigo de diferentes respostas ao acamamento realizou-se um experimento na Fazenda Escola da Universidade Estadual de Ponta Grossa (UEPG), no ano de 2005, em um Cambissolo distrófico de textura argilosa. O delineamento experimental foi de blocos ao acaso, em esquema fatorial 2 x 2 x 6 com três repetições para quatro cultivares de trigo. Os tratamentos constaram de duas doses de nitrogênio (50 e 240 kg/ha), duas épocas de aplicação de trinexapac-ethyl (entre o 1º e o 2º nó e entre o 2º e o 3º nó perceptível) e de seis doses de trinexapac-ethyl (0; 31,2; 62,5; 93,7; 125,0 e 156,2 g/ha), aplicadas em quatro cultivares de trigo de diferentes respostas ao acamamento (CD-104 – resistente), (Vanguarda – moderadamente resistente), (Supera – moderadamente suscetível) e (CEP-24 – suscetível). Avaliou-se características agronômicas, severidade de doenças, componentes da produção e produtividade. As doses de nitrogênio afetaram algumas características da planta e a produtividade de apenas da cultivar CEP-24. A época de aplicação do trinexapac-ethyl afetou de forma substancial a produtividade apenas na CD-104; a altura das plantas foi menor quanto mais tardia foi a aplicação do redutor nas cultivares CEP-24 e CD-104; o trinexapac-ethyl reduziu a altura das plantas de todas as cultivares com intensidade variável com o porte das mesmas. Para todas as cultivares a equação de ajuste da produtividade em relação às doses de trinexapac-ethyl foi quadrática ocorrendo um aumento da produção com o aumento da dose do redutor, até um limite variável com a cultivar. No entanto, para todas as cultivares ocorreu aumento da produtividade com a aplicação do trinexapac-ethyl, e para a maioria delas houve redução da severidade de giberela e manchas foliares com o aumento da dose de trinexapac-ethyl.

Made available in DSpace on 2017-07-25T19:29:42Z (GMT). No. of bitstreams: 1 Hellen Aparecida Arantes.pdf: 691625 bytes, checksum: a3ecb17b706b52a2674dc29e0a5e82cc (MD5) Previous issue date: 2008-12-15 / The development and grain yield of the crop of wheat are influenced by several factors, among which is the interference caused by pathogens present in crops. Currently, the main tool for controlling these pathogens in crops is the use of constant application of fungicides. However, this practice is causing pathogens resistant to these groups of fungicides used, as well as encouraging the expression of the mutagenic character of these populations. In an attempt to provide more tools to control the diseases of wheat to the farmer, this study aimed to: a) assess the effect of timing of implementation and sources of phosphite and acibenzolar-S-methyl alone and combined with the fungicide pyraclostrobin + epoxiconazole in control the powdery mildew (Blumeria graminis f. sp. tritici) and the leaf rust (Puccinia triticina), b) assess the effect of different rates, sources of phosphite and acibenzolar-S-methyl isolated and associated to the fungicide pyraclostrobin + epoxiconazole in control of the spots brown (Bipolaris sorokiniana) and yellow (Drechslera tritici-repentis); c) and in vitro effect of different concentrations of phosphite and pyraclostrobin + epoxiconazole on the mycelial growth and germination of conidia of Bipolaris sorokiniana. About the control of powdery mildew and rust can be concluded that the phosphites have no effect on these pathogens and do not change their productivity. It is also clear that there is no difference between the different sources of phosphites to control the powdery mildew and leaf rust, which occurs on powdery mildew and leaf rust's only when the phosphite associated with the fungicide is applied. About the control of yellow and brown stains concluded that the dose of 1048 g i.a. ha-1 potassium phosphite reduces the severity of leaf spots and can be used as a tool in the management of leaf spots. In in vitro tests concluded that the phosphites have direct action on Bipolaris sorokiniana. / O desenvolvimento e o rendimento de grãos da cultura do trigo são influenciados por diversos fatores, entre os quais se encontram a interferência causada por patógenos presentes nas lavouras. Atualmente, a principal ferramenta de controle destes patógenos nas lavouras é o uso de constantes aplicações de fungicidas. Contudo, essa prática vem ocasionando resistência destes patógenos aos grupos de fungicidas utilizados, bem como favorecendo a expressão do caráter mutagênico destas populações. Na tentativa de disponibilizar mais uma ferramenta de controle às doenças do trigo ao agricultor, este trabalho objetivou: a) avaliar o efeito de épocas de aplicação e de fontes de fosfito e acibenzolar-S-metil isolados e combinados com o fungicida epoxiconazole + piraclostrobina no controle do oídio (Blumeria graminis f. sp. tritici) e da ferrugem da folha (Puccinia triticina); b) avaliar o efeito de diferentes doses, fontes de fosfito e acibenzolar-S-metil isolados e associados ao fungicida epoxiconazole + piraclostrobina no controle das manchas marrom (Bipolaris sorokiniana) e mancha amarela (Drechslera tritici-repentis); c) e efeito in vitro de diferentes concentrações de fosfito e epoxiconazole + piraclostrobina sobre o crescimento micelial e a germinação de conídios de Bipolaris sorokiniana. Sobre o controle de oídio e ferrugem pode-se constatar que os fosfitos não possuem efeito sobre estes patógenos e não alteram a produtividade. Concluiu-se ainda que não existe diferença entre as diferentes fontes de fosfitos no controle de oídio e ferrugem da folha, que ocorre efeito sobre o oídio e a ferrugem da folha apenas quando o fosfito é aplicado associado ao fungicida. Sobre o controle das manchas amarela e marrom conclui-se que a dose de 1048 g i.a. ha-1 de fosfito potássico reduz a severidade das manchas foliares, podendo ser utilizado como uma ferramenta no manejo das manchas foliares. Nos testes in vitro conclui-se que os fosfitos possuem ação direta sobre Bipolaris sorokiniana.

O fungo Magnaporthe oryzae, agente causal da brusone em trigo e em várias outras gramíneas, desde o seu primeiro relato no Brasil tem sido alvo de inúmeras pesquisas. O entendimento da morfologia, fisiologia e parâmetros bioquímicos deste ascomiceto é o primeiro passo para a adoção de medidas eficientes de controle da doença. Os objetivos deste trabalho foram avaliar os aspectos morfológicos, fisiológicos e bioquímicos relativos à patogenicidade do fungo M. oryzae em trigo, além de determinar in vitro as condições ótimas de temperatura e fotoperíodo para o crescimento e esporulação dos isolados testados, quantificar a pressão de turgor exercida pelo apressório no momento da penetração do substrato, verificar a presença de enzimas extracelulares produzidas pelo patógeno e o papel de cada uma delas na degradação da parede celular e, também, demonstrar a possível produção e ação de metabólitos tóxicos do fungo em plântulas de trigo. Dois isolados do fungo, Py5003 e Py6017, foram repicados para os meios de cultivo cenoura, milho-cenoura, batata-dextrose-ágar (BDA), aveia e V8, incubados, de maneira independente, sob luz contínua, escuro contínuo e fotoperíodo de 12h, por 20 dias, sendo avaliados periodicamente quanto ao crescimento micelial total e esporulação do patógeno. Em seguida, conídios germinados e com apressórios formados foram submetidos a diferentes concentrações de PEG-8000 para a mensuração da pressão de turgor apressorial. Além disso, o teor de proteínas totais foi mensurado e a atividade celulolítica determinada, por espectrofotometria indireta para os isolados cultivados em meio Merlin-Norkrans Modificado (MNM), a partir das enzimas exo e endo-?-1,4-glucanase e ?-glicosidase. A produção de metabólitos tóxicos foi determinada por condutivimetria, após o cultivo dos isolados por 5 e 10 dias em batata-dextrose (BD) e obtenção dos filtrados após esse período, sendo que, a ação destes, foi observada em plântulas de trigo com 25 dias de idade. Os resultados evidenciaram melhor crescimento micelial e esporulação dos isolados em meio de cultivo composto de aveia, incubado a 25 °C e fotoperíodo de 12 h. A pressão de turgor apressorial, tanto para Py5003 quanto para Py6017, concentrouse na faixa dos 7,5 MPa. Não houve diferença estatística entre os teores de proteínas totais apresentados pelo isolados. Os dois isolados exibiram alta atividade celulolítica, com diminuição da atividade observada para endo-?-1,4-glucanase e ?- glicosidase na presença de glicose e celobiose, respectivamente. A exposição de plântulas de trigo aos filtrados dos isolados do fungo M. oryzae provocou alta liberação de eletrólitos, sendo, em termos absolutos, Py5003 maior do que Py6017. Plântulas expostas ao filtrado, autoclavado ou não, e ao extrato bruto obtido a partir da separação dos metabólitos tóxicos em acetato de etila, apresentaram-se cloróticas e/ou necróticas. Os resultados sugerem um mecanismo de parasitismo desenvolvido por M. oryzae no desenvolvimento da brusone em trigo, indo desde a fase de pré-penetração, passando pelo estabelecimento das relações parasitárias estáveis e o aparecimento de sintomas e sinais na planta hospedeira. / The fungus Magnaporthe oryzae, causal agent of blast in wheat and several other grasses, since its first occurrence in Brazil has been the subject of extensive research. The understanding of the morphology, physiology and biochemical parameters of this ascomycete is the first step for the adoption of efficient measures to control the disease. The objectives of this study were to evaluate the morphological, physiological and biochemical aspects related to the pathogenicity of the fungus M. oryzae on wheat. Thus, it were determined in vitro the optimal conditions of temperature and photoperiod for growth and sporulation of the isolates tested, quantified the pressure exerted by appressorium at the time of substrate penetration, verified the presence of extracellular enzymes produced by the pathogen and their role in the degradation of cell wall and also demonstrated the possible production and action of toxic metabolites of the fungus in wheat seedlings. Two isolates of the fungus, Py5003 and Py6017, were grown on carrot, maize-carrot, PDA, oat and V8 media and measure periodically for 20 days and after that period, being evaluated the total mycelia growth and sporulation of the pathogen. Then, germinated conidia and appressoria were subjected to different concentrations of PEG-8000 for the measurement of appressorial turgor pressure. In addition, the concentration of total proteins was measured and enzyme activity (exo and endo-?- 1,4-glucanase, ?-glucosidase) was determined by indirect spectrophotometry, for the isolates grown in Modified Melin-Nokrans (MMN) medium. The production of toxic metabolites was determined after growing the isolates for 5 and 10 days in potatodextrose medium (PD) and obtaining the filtrate. The toxic action was evaluated in wheat seedlings (25 days old) by measuring electrolyte leakage. The results showed better mycelial growth and sporulation of the isolates in oat medium incubated at 25 °C and under a photoperiod of 12 h. Appressorial turgor pressure for both isolates were at the range of 7.5 MPa.There were no statistical differences between the levels of total protein presented by the isolates. The two isolates showed high cellulolytic activity, with decreased activity observed for endo-?-1,4-glucanase and ?- glucosidase in the presence of glucose and celobiose, respectively. The exposure of wheat seedlings to the filtrates of the fungus M. oryzae caused high electrolyte release, being, in absolute terms, Py5003 greater than Py6017. Seedlings exposed to the filtrate, autoclaved or not, and the crude extract obtained from the separation of the toxic metabolites in ethyl acetate, exibited clorotic and/or necrotic. These results suggest a mechanism of parasitism developed by M. oryzae on wheat, ranging from pre-penetration through the establishment of stable parasitic relationships and the appearance of symptoms and signals in the host plant.