Spelling suggestions: "subject:"triticum aestivum"" "subject:"triticum estivum""
141 |
Identification des critères du grain de blé (Triticum aestivum L.) favorables à la production de bioéthanol par l'étude d'un ensemble de cultivars et par l'analyse protéomique de lignées isogéniques waxyDebiton, Clément 17 November 2010 (has links) (PDF)
Dans le but d'identifier des critères de sélection du blé (T. aestivum L.) destiné à la production de bioéthanol, les objectifs de cette thèse étaient (1) de mettre en évidence les caractéristiques physico-chimiques du grain associées aux rendements en glucose et éthanol, et (2), d'étudier par approche protéomique l'effet de variants génétiques affectant la quantité d'amylose sur le métabolisme des sucres et de l'amidon. L'analyse de trente variétés implantées dans un essai multilocal pluriannuel a mis en évidence l'importance du taux de protéines, de la dureté et de la distribution des granules d'amidon sur les rendements en glucose et éthanol. Dans une moindre mesure, la composition allélique des protéines de réserves et la viscosité des arabinoxylanes ont également un effet lors de l'étape de transformation de l'amidon en sucres fermentescibles. Huit lignées isogéniques waxy de trois variétés françaises ont été implantées dans un essai multilocal. Les lignées dépourvues d'amylose ont produit moins de glucose et d'éthanol que les variétés normales. Les analyses protéomiques des protéines de l'albumen (albumines, globulines et amphiphiles) ainsi que des protéines associées aux granules d'amidon des grains matures des lignées isogéniques de la variété Trémie ont mis en évidence : (1) une relation entre le volume spécifique des GBSS et la quantité d'amylose et (2) une modification de l'expression d'enzymes impliquées dans le métabolisme des sucres et de l'amidon (Susy, AGPase, fructose biphosphate aldolase) mais aussi de protéines de stress et de défense (serpines et HSP). Ces observations suggèrent un développement du grain incomplet pour la lignée dépourvue d'amylose.
|
142 |
The Dof transcription factor family in Triticum aestivumLindsay Shaw Unknown Date (has links)
Abstract Transcription factors (TFs) play an indispensable role in cell biology as they are responsible for regulating gene activity. TFs act by binding to specific DNA sequences in a gene promoter resulting in either activation or repression of transcription of the target gene. TFs interact with target genes through a DNA binding domain which is often highly conserved and can be used to classify TFs into families. Dof (DNA binding with one finger) TFs are classified by the presence of a highly conserved bi-functional Dof domain. Characterisation of various Dof proteins has identified essential regulatory roles in plant-specific processes. This includes roles in carbon metabolism in maize, seed development and germination in Arabidopsis and cereal crops and circadian responses in Arabidopsis and rice. Despite the important role of Dof proteins in plant growth and development, this family has been studied to a limited extent in wheat with only two Dof proteins reported to date. Therefore, the aim of this thesis is to identify and initiate characterisation of the Dof TF family in wheat (Triticum aestivum) and investigate the potential role of members of this family in wheat productivity-associated physiological processes. Thirty-one Dof genes were identified after extensive searching of available Triticum aestivum ESTs and contig assembly. Phylogenetic analysis grouped these 31 genes into four clades. Extensive gene expression profiling of the TaDof family was undertaken and revealed that the majority of TaDof members were constitutively expressed in major vegetative organs with a few displaying a grain-predominant expression pattern. The TaDof family appears to be enriched with light-responsive or drought down-regulated members, suggesting that the role of this family is predominantly in growth-related processes. To further investigate their role in growth-related physiological processes, two Dof genes, TaDof4 and TaDof5, were selected for more detailed characterisation. TaDof5 was identified to be similar to the Cycling Dof Factors from Arabidopsis and the recently identified rice Dof daily fluctuations genes which are involved in the photoperiodic regulation of flowering time. TaDof5 gene expression was diurnally regulated, had strong expression in the stem and head and a peak in expression level at anthesis. Using publicly available Affymetrix data, correlation analysis suggested co-expression of TaDof5 with a number of circadian-regulated genes associated with flowering. Extensive analysis of the DNA-binding specificity of TaDof5 revealed a preferred binding motif of 5’GAAAAAGTGC. The binding of TaDof5 to DNA requires two (A/T)AAAG(T/C) core motifs in adjacent positions. The binding sequence of TaDof5 was identified in the promoter of one of the TaDof5 co-expressed genes in wheat and subsequent analysis showed that TaDof5 was capable of binding to this promoter region with high affinity. These data suggest that TaDof5 may be involved in photoperiod responses associated with flowering time. TaDof4 was among a large number of previously identified growth-related genes expressed at significantly higher levels in wheat cultivars and progeny lines with high transpiration efficiency (TE) (the amount of biomass produced per unit of water transpired). Field trials were undertaken with the parents and progeny from a cross between Quarrion (high TE) and Genaro 81 (low TE) and demonstrated that the high TE progeny lines had improved early vegetative growth. TaDof4 was therefore characterised further for a role related to biomass production and/or contribution to the TE trait. Expression profiling showed that TaDof4 was consistently expressed at higher levels in the lines with high TE, constitutively expressed in major vegetative organs, drought down-regulated and sucrose up-regulated. Over-expression of TaDof4 identified one line with significantly improved biomass. DNA binding specificity analysis demonstrated that TaDof4 binds to the AAAG(T/C) core target motif essential for Dof DNA binding. These results suggest that TaDof4 is potentially associated with growth-related processes in wheat. In conclusion this study has made the following achievements: (1) identified 31 TaDof family members in Triticum aestivum, (2) used phylogenetic analysis and expression profiling to infer potential functional roles for wheat TaDof family members, (3) further characterised TaDof5 to reveal a potential role in photoperiod responses associated with flowering and elucidated its DNA-binding specificity, (4) further characterised TaDof4 to suggest a potential role in growth-related processes. These results provide fundamental molecular information that increases our understanding of the diverse biological roles of the TaDof family, particularly in growth-related physiological processes in wheat.
|
143 |
Perennial clovers and ryegrasses as understorey crops in cereals /Bergkvist, Göran, January 2003 (has links) (PDF)
Diss. (sammanfattning). Uppsala : Sveriges lantbruksuniv., 2003. / Härtill 4 uppsatser.
|
144 |
Broadening of mildew resistance in wheat /Forsström, Per-Olov, January 2002 (has links) (PDF)
Diss. (sammanfattning) Alnarp : Sveriges lantbruksuniv., 2002. / Härtill 4 uppsatser.
|
145 |
Genetic variability of Wheat dwarf virus /Ramsell, Jon, January 2007 (has links) (PDF)
Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniv., 2007. / Härtill 4 uppsatser.
|
146 |
Gene silencing in bread wheat (Triticum aestivum L.) following a biolistics approachFisher, Nadia Mitilda 04 1900 (has links)
Thesis (MSc)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: Global food security is hampered by a variety of insects/pest and plant diseases. In wheat, the Russian wheat aphid (RWA) is a significant pest problem in many areas of the world. Wheat has developed defensive mechanisms against the RWA over time which are activated upon feeding. One such mechanism is the hypersensitive response (HR) which is effective against phloem-feeding insects i.e. D. noxia (Diuraphis noxia, Kurdjumov, RWA). In this study, two genes associated with the hypersensitive response i.e. ascorbate peroxidase (APX) and glutathione S transferase (GSTF6b) were investigated to elucidate their function in the defensive mechanism of wheat using a reverse genetic approach i.e. particle bombardment. This study has succeeded in the established of a tissue culture and transformation system which generated three genetically modified wheat plants with decreased resistance to RWA feeding due to gene silencing. The establishment of this system enabled to test the association of defensive related genes in wheat to RWA resistance. Expression analysis performed on obtained transgenics before and after RWA infestation reavealed that the silenced plants were more susceptible to RWA feeding. Chlorosis was observed in the Gamtoos-S-APX transgenic plant which is an indicator of oxidative damage to the photosynthetic machinery of the plant. Decreased GSTF6b transcripts was found in the transgenic Gamtoos-S-GSTF6b and transgenic Gamtoos-R-GSTF6b transgenic plants but no visible symptoms of infestation was observed in these two plants. Resistance breeding could be strengthened by developing broad spectrum resistance plants by incorporating wheat defensive related genes with known function into the breeding programs. The use of this transformation system will allow rapid identification and introduction of agronomically important genes by upregulating these genes to enhance bread wheat against aphid infestation.
|
147 |
Efecto de la aplicación de ácido húmico sobre las propiedades físicas de un suelo cultivado con trigo en la Región de la Araucanía / Effect of the application of humic acid on the physical properties of a soil cultivated with wheat in the Region of Araucanía, ChileParra Vergara, Cristián Iván January 2016 (has links)
Memoria para optar al título profesional de Ingeniero Agrónomo / En el presente estudio se evaluó el efecto de un ácido húmico sobre algunas propiedades físicas de un suelo Andic Haplohumult cultivado con trigo en la Región de la Araucanía, IX región de Chile. Los tratamientos aplicados fueron un testigo sin enmienda (T0), aplicación de ácido húmico (T1) y una condición nativa en que no se ha intervenido el suelo en un período de tiempo superior a los 15 años (T2). Se realizaron muestreos a dos profundidades (0-10 y 30-40 cm) con cuatro repeticiones, evaluando algunas propiedades físicas del suelo a un mes de la aplicación de la enmienda y a los 6 meses después de ésta. Además, se midieron componentes de rendimiento relevantes para el cultivo del trigo, con el fin de evaluar si las mejoras estructurales que produce el ácido húmico en el suelo, se traducen en aumentos de la biomasa vegetal y el rendimiento de grano. En cuanto a las propiedades físicas de suelo, la aplicación de ácido húmico tuvo efectos positivos sobre la retención de agua, se produjo un aumento en la porosidad, hubo una disminución de la densidad aparente y se originó mayor estabilidad de macroagregados en profundidad (30-40 cm), alcanzando niveles similares al sitio nativo. También existió una mayor producción de biomasa en el tratamiento con aplicación de la enmienda respecto al control sin ella, acompañado por un aumento en el número de granos por metro cuadrado, sin modificar el peso de los granos, lo que se tradujo finalmente en un aumento sustancial, pero no significativo, en el rendimiento del trigo producto de una mejor condición del suelo.
Palabras clave:
|
148 |
Atividade da nitrato redutase, composição mineral e caracteres da planta de trigo associados à aplicação de molibdênio, à peletização e à inoculação das sementes com Azospirillum brasilense / Activity of nitrate reductase, mineral composition and characteristics of wheat plant associated a molybdenum application, a pelletization and a seeds inoculation with Azospirillum brasilenseCoelho, Maurício Antônio de Oliveira 18 June 2001 (has links)
Submitted by Marco Antônio de Ramos Chagas (mchagas@ufv.br) on 2017-07-03T17:23:46Z
No. of bitstreams: 1
texto completo.pdf: 529263 bytes, checksum: 519329022e5e2f52db8e5958ffce55b7 (MD5) / Made available in DSpace on 2017-07-03T17:23:46Z (GMT). No. of bitstreams: 1
texto completo.pdf: 529263 bytes, checksum: 519329022e5e2f52db8e5958ffce55b7 (MD5)
Previous issue date: 2001-06-18 / Fundação de Amparo à Pesquisa do Estado de Minas Gerais / Este estudo objetivou avaliar, em dois cultivares de trigo irrigado, os efeitos da inoculação, peletização das sementes e aplicação de Mo em cobertura sobre a atividade da nitrato redutase (ANR), compo sição mineral e características agronômicas. Um experimento, em condições de campo, foi conduzido no Departamento de Fitotecnia (DFT) (Estação Experimental Diogo Alves de Melo), de junho a outubro de 1999, sendo outro experimento, em vasos, conduzido em casa de vegetação do DFT e na mesma época. O experimento de campo foi constituído de 16 tratamentos, dispostos num esquema fatorial 2 x 2 x 2 x 2 [dois -1 cultivares (EMBRAPA-22 e BR-26), Mo (0 e 90 g.ha ), peletização (presente e ausente) e inoculação com Azospirillum brasilense (presente e ausente)], no delineamento em blocos casualizados com quatro repetições. O experimento em vasos foi constituído de 18 tratamentos, num esquema fatorial, acrescidos de duas -1 parcelas [(EMBRAPA-22 + 90 g.ha de Mo + peletização + inoculação - P e - S) e -1 (BR-26 + 90 g.ha de Mo + peletização + inoculação - P e - S)], no delineamento em blocos casualizados com quatro repetições. Avaliaram-se a ANR em quatro estádios da cultura, o teor de macro e micronutrientes na parte aérea e nos grãos e -1 características radiculares e agronômicas. A aplicação de 90 g.ha de Mo e a inoculação das sementes aumentaram significativamente a ANR, nas quatro épocas avaliadas (28, 48, 68 e 88 dias após a emergência das plântulas). Ocorreu redução -1 na atividade da enzima com o avanço do ciclo da cultura. A aplicação de 90 g.ha de Mo e a inoculação das sementes com Azospirillum brasilense aumentaram a matéria seca, o comprimento e área radiculares e os teores de nutrientes das plantas, além de diminuírem o diâmetro radicular destas. A matéria seca e o comprimento e área radiculares e os teores de nutrientes foram superiores no -1 cultivar EMBRAPA-22. A aplicação de 90 g.ha de Mo, assim como a inoculação de Azospirillum brasilense, aumentou a altura das pl antas, a produção de grãos, a biomassa seca e o peso de mil grãos, nos dois experimentos realizados. / The objective of this study was to evaluate the effects from seed inoculation, seed pelletization and Mo application on the activity of nitrate reductase (ANR), the mineral composition and agronomic characteristics. An experiment was carried out under field conditions at the Estação Experimental Diogo Alves de Melo from June to October 1999, and at the same time another one was accomplished in pots under greenhouse conditions, both places pertaining to the Departmento de Fitotecnia-UFV. The field experiment consisted of 16 treatments arranged in a factorial scheme of 2 x 2 x 2 x 2 [two cultivars -1 (EMBRAPA-22 and BR-26), Mo (0 and 90 g.ha ), pelletization (present and absent) and inoculation with Azospirillum brasilense (present and absent)] on a randomized block experimental design with four replicates. The experiment in pots consisted of 18 treatments on a factorial scheme with two additional plots -1 [(EMBRAPA-22 + 90 g.ha of Mo + pelletization + inoculation - P and - S) and (BR-26 + 90 g.ha -1 of Mo + pelletization + inoculation - P and - S)] on a randomized block experimental design with four replicates. The ANR was evaluated at four crop stages, as well as the macronutrient and micronutrients in the aerial part and the grains, the agronomic and root characteristics were also evaluated. The -1 application of 90 g.ha Mo and seed inoculation significantly increased the ANR at the four appraised times (28, 48, 68 and 88 days after emergency of the seedlings). There was a reduction in enzyme activity as the crop cycle advanced. Either -1 application of 90 g.ha Mo and the seed inoculation with Azospirillum brasilense increased the root dry matter, root length, root area and the nutrient contents in plants, whereas the root diameter was reduced. The root dry matter, root length, root area and the nutrient contents in plants were superior in cultivar EMBRAPA- -1 22. The application of 90 g.ha Mo as well as the seed inoculation with Azospirillum brasilense increased the plant heights, grain yield, dry biomas s and the weight of a thousand grains in both experiments. / Tese importada do Alexandria
|
149 |
Giberela do trigo: resistência a fungicidas e metanálise da eficácia do controle químico / Fusarium head blight of wheat: resistance to fungicides and meta-analysis of control efficacyMachado, Franklin Jackson 23 February 2016 (has links)
Submitted by Marco Antônio de Ramos Chagas (mchagas@ufv.br) on 2016-08-22T11:29:51Z
No. of bitstreams: 1
texto completo.pdf: 956629 bytes, checksum: 1096a842439a74fe8b122975f58e42bd (MD5) / Made available in DSpace on 2016-08-22T11:29:51Z (GMT). No. of bitstreams: 1
texto completo.pdf: 956629 bytes, checksum: 1096a842439a74fe8b122975f58e42bd (MD5)
Previous issue date: 2016-02-23 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / Os fungicidas são normalmente aplicados para o manejo da giberela com o objetivo de garantir a produtividade e reduzir níveis de micotoxinas associadas à doença. Vários ingredientes ativos estão disponíveis no Brasil, sendo que os mais comumente recomendados pertencem ao grupo dos inibidores da demetilação (DMI) e benzimidazóis (MBC), ou usados em mistura com fungicidas do grupo das estrobilurinas (QoI). Dada a importância crescente de epidemias de giberela no Brasil, o uso de fungicidas vêm aumentando consideravelmente e, geralmente, duas aplicações têm sido recomendadas. Parcelas de campo em 16 municípios na região de Guarapuava, Sul do Paraná foram monitoradas durante quatro anos (2011 a 2014) e um total de 227 isolados semelhantes a espécies do complexo de espécies de Fusarium graminearum foram obtidos a partir de espigas de trigo sintomáticas. Uma amostra de 173 isolados foi identificada quanto ao genótipo tricoteceno com base em PCR. Entre eles, 67% foram identificados como 15- (A)cetil-desoxinivalenol(DON), 29% do nivalenol (NIV) e 4% como genótipo 3-ADON. Uma amostra de 35 isolados foi selecionada para determinar a concentração dos fungicidas tebuconazol e carbendazim que reduz em 50% do crescimento de micelial (EC 50 ), usando as seguintes doses (0; 0,5; 1,0; 2,0 e 4,0 μg / ml). As medias estimadas de EC 50 , independente do genótipo, foram 0,39 μg/ml (0,0004 a 3,0) e 1,25 μg/ml (0,91 a 2,65) para tebuconazol e carbendazim, respectivamente. As medias de EC 50 foram 1,32 μg/ml e 1,21 μg/ml para carbendazim e 0,58 μg/ml e 0,05 μg/ml para tebuconazol, para os isolados 15-ADON e NIV ou 3-ADON, respectivamente. O teste não paramétrico Kolmogorov-Smirnov mostrou diferença entre os isolados 15-ADON e os NIV+3-ADON quanto ao tebuconazol (P = 0,002), mas não para o carbendazim (P = 0,514). As doses discriminatórias de 1,4 μg/ml e 2,0 μg/ml foram usadas para identificar isolados menos sensíveis à carbendazim e tebuconazol, respectivamente, em toda coleção. Baseado nessas doses, dois isolados menos sensíveis ao tebuconazol e seis isolados menos sensíveis ao carbendazim foram encontrados, sendo todos originários do munícipio de Guarapuava ao longo de três safras e possuem o genótipo 15-ADON. Houve correlação significativa entre os valores de EC 50 dos dois fungicidas (r = 0,45; P = 0,007). Um único isolado apresentou os maiores valores de EC 50 para ambos fungicidas e apresentou uma mutação (R31K) no gene cyp51A. A presença da reduzida sensibilidade e um isolado resistente, reportado pela primeira vez no Brasil, sugerem que a seleção pode conduzir mudanças nas populações com consequências no manejo da doença. Estudos futuros devem se concentrar em atributos de fitness, competitividade e experimentos in vivo para verificar se a eficácia do fungicida é prejudicada na presença de isolados menos sensíveis. Em estudos de controle químico da giberela, resultados sobre a eficácia têm sido inconsistentes e variáveis para um mesmo fungicida. Uma revisão sistemática de estudos de eficácia dos fungicidas pode ser útil para apontar para os produtos mais eficazes e cenários onde a eficácia pode ser melhorada. Os objetivos deste trabalho foram a) revisar sistematicamente estudos de controle químico para o manejo da giberela realizados no Brasil durante os últimos 15 anos (2000-2015), publicados em revistas com e sem corpo editorial e b) conduzir uma metanálise da eficácia de controle e retorno em produtividade de fungicidas selecionados. Uma busca na literatura identificou 18 estudos que relataram a severidade da giberela (o mesmo que índice giberela) para pelo menos um tratamento com fungicida em comparação com um tratamento controle sem o fungicida, e também uma medida da variância amostral do ensaio. Apenas três e dois estudos relataram valores médios de grãos giberelados e deoxinivalenol (DON), respectivamente. Os estudos foram analisados e oito tratamentos com fungicidas, com pelo menos dez entradas foram selecionados para o estudo de metanálise. Foram incluídos os tratamentos com os fungicidas dos grupos: DMI (tebuconazol, metconazol e propiconazol) e MBC (carbendazim) formulados individualmente e uma pré-mistura de DMI + QoI (azoxistrobina + tebuconazol, piraclostrobina + metconazol, trifloxistrobina + prothioconazol e trifloxistrobina + tebuconazol). Foram testadas uma aplicação (×1) e duas aplicações (×2), sendo a primeira na floração plena e a segunda dez dias após. Um modelo metanalítico multivariado foi ajustado para o log das médias para cada fungicida e o tratamento controle de cada ensaio. A diferença nas estimativas médias do log da severidade entre um tratamento com fungicida e o controle foram usadas para calcular a razão de resposta média (R) e então transformadas para porcentagem de controle (C) e porcentagem de retorno em produtividade (P). A média de C e P variou de 48,94 a 70,39% e de 7,41 a 21,29%, respectivamente. Metconazol (×2) teve o melhor desempenho para reduzir a severidade da doença (C = 70,39%) e tebuconazol (×1) em retorno em produtividade (P = 21,29%). Propiconazol foi o menos eficaz entre os DMIs (C = 48,94%), seguido de carbendazim (C = 53,90%). Em geral, os fungicidas mais eficazes resultaram em maior retorno de rendimento. Quando os grupos de fungicidas foram comparados, em geral, os DMIs e as misturas tiveram o melhor desempenho, especialmente em ensaios conduzidos sob elevada pressão da doença (> 7% no tratamento controle). Os resultados mostraram que a eficácia de controle média em estudos brasileiros quando se utiliza duas aplicações são mais elevadas do que quando se utiliza apenas uma aplicação, como relatado em outro estudo de metanálise na América do Norte. Estudos futuros deverão centrar-se no efeito sobre os níveis de DON, especialmente para as misturas, que estão estrategicamente utilizadas para o controle de doenças foliares. / Fungicides are commonly applied for managing Fusarium head blight (FHB) with the aim of protecting yield and improving grain quality, but especially targeting mycotoxin reduction. Several active ingredients are available in Brazil and the most common belong to the demethylation-inhibitor (DMI) and benzimidazoles (MBC) groups, with the former commonly used in mixture with fungicides of the quinone-outside inhibitor (QoI) group. Given the increasing importance of FHB epidemics in Brazil, the use of fungicides is increasing considerably and usually two sprays are recommended. Experimental trials where fungicides have been applied for FHB control were monitored in 16 municipalities at the Guarapuava region, Southern Paraná, during four years (2011 to 2014). A total of 227 isolates resembling those of the Fusarium graminearum species complex were obtained from wheat heads with FHB symptoms. Of those, 173 isolates were assigned to trichothecene genotypes based on PCR assays. A random sample of 35 isolates from 2011 to 2013 was selected to determine the concentration of tebuconazole and carbendazim fungicides that reduces 50% of the mycelial growth (EC 50 ). The following doses were used: 0, 0.5, 1.0, 2.0 and 4.0 μg/ml. In the PCR assays, most isolates (67%) were of the 15-(A)cetyl-deoxynivalenol (DON), 29% of the nivalenol (NIV) and 4% of the 3-ADON genotype. The estimated means of the EC 50 , irrespectively of the genotype, were 0.39 μg/ml (0.0004 to 3.0) and 1.25 μg/ml (0.91 to 2.65) for tebuconazole and carbendazim, respectively. The mean EC 50 were 1.32 μg/ml and 1.21 μg/ml for carbendazim and 0.58 μg/ml and 0.05 μg/ml for tebuconazole, for isolates of the 15-ADON and NIV + 3-ADON isolates, respectively. A Kolmogorov-Smirnov non-parametric test suggested that the sensitivity to tebuconazole of the 15-ADON and NIV+3-ADON isolates were sampled from populations with different distributions (P = 0.002), but not for carbendazim (P = 0,514). Discriminatory doses of the 1.4 μg/ml and 2.0 μg/ml were used to screen for less- sensitive isolates in the whole sample. Based on those doses, two tebuconazole-less sensitive and six carbendazim-less sensitive isolates were found, all were originated from Guarapuava municipality across three growing seasons and possessed the 15-ADON genotype. There was as significant correlation between the EC 50 values of tebuconazole and carbendazim (r = 0.45; P = 0,007). One isolate exhibited the highest EC 50 values for both fungicides and showed a mutation (R31K) in the cyp51A gene. The presence of less sensitive and a resistant isolate reported for the first time in Brazil suggest that selection may drive changes in the populations with impact in disease management. Future studies should focus on the attributes of fitness, competitiveness and in vivo assays to check whether fungicide efficacy is hindered in the presence of resistant isolates. Furthermore, results on fungicide efficacy have been inconsistent and variable for a same fungicide. Quantitative summary of fungicide data available in the country is lacking and could be useful to point to the most efficacious products and scenarios where efficacy can be improved. The objectives of this work were to a) systematically review the peer- and non- peer reviewed literature on chemical control studies for FHB management conducted in Brazil during the last 15 years and b) conduct a meta-analysis of the control efficacy and yield return of selected fungicides. A search in the literature identified 18 studies that reported FHB severity (same as FHB index) for least one fungicide treatment compared to a non-treated check, and also a measure of sampling variance in the trial. Only three and two studies reported mean values of Fusarium-damaged kernels (FDK) and deoxyninvalenol (DON), respectively. Studies were scrutinized and eight fungicide treatments with at least 10 entries were selected for the meta-analysis study. They included DMI (tebuconazole, metconazole and propiconazole) and MBC (carbendazim) fungicide treatments formulated solo and a pre-mix of DMI+QoI (azoxystrobin + tebuconazole, pyraclostrobin + metconazole, trifloxystrobin + prothioconazole and trifloxystrobin + tebuconazole). One (×1) and two applications (×2) were tested, the first at full flowering and the second 10 days later. A multivariate meta-analytic model was fitted to the log of the means for each fungicide and check treatment of the trial. The difference in the mean estimates of the log of severity between a fungicide treatment and the check were used to calculate the mean response ratio represented by percentage control efficacy (C) and percentage yield return (P). Mean C and P ranged from 48.94 to 70.39% and from 7.41 to 21.29%, respectively. Metconazole (×2) performed best to reduce disease severity (C = 70.39%) and tebuconazole (×1) to increase yield (P = 21.29%). Propiconazole was the least efficacious among the DMIs (48.94%), followed by carbendazim (53.9%). In general, the most efficacious fungicides resulted in higher yield return. When fungicide groups were compared, the DMIs and the mixtures performed best in general, especially in trials conducted under high disease pressure (>7% in the check treatment). Results showed that mean control efficacy in Brazilian studies when using two sprays are higher one spray, as reported in other meta-analysis study in North America. Future studies should focus on the effect on DON levels, especially for the mixtures, which are strategically used for the control foliar diseases.
|
150 |
Využití bílkovinných signálních genů pro hodnocení účinnosti gametocidu GENESIS u pšeniceTriticum aestivum L./Vyhnánek, Tomáš January 2001 (has links)
No description available.
|
Page generated in 0.0713 seconds