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Impact des fongicides foliaires et des néonicotinoïdes sur le puceron du soya et ses ennemis naturelsGutman, Axel 01 1900 (has links)
No description available.
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Cellular biomarkers of exposure to the fungicide copper oxychloride, in the common garden snail Helix aspersa, in Western Cape vineyardsSnyman, Reinette Georgenie 03 1900 (has links)
Thesis (PhD(Agric)(Botany and Zoology))--University of Stellenbosch, 2001. / Copper oxychloride (Cu2CI(OH)3) is a broad-spectrum fungicide, intensively sprayed in many South
African vineyards and orchards. It is necessary to find accurate and effective methods of monitoring the
effects of this fungicide on the biota of the agricultural environment. The use of biomarkers may be a
possible method to employ for this purpose.
This study investigated the effects of copper, as a result of copper oxychloride exposure, on the biology
of the common garden snail Helix aspersa, as welI as a number of cellular responses to exposure to the
fungicide. The possible use ofthese responses as biomarkers was also investigated.
Two groups of snails were exposed to 80 and 240 tJg g-! copper oxychloride respectively, for six
weeks. A third group served as control. On a weekly basis, body mass, number of eggs produced,
neutral red retention (NNR) times of haemocytic lysosomes, and body copper concentrations were
determined for each individual. At the end of the experiment, the digestive glands, ovotestes and
hermaphrodite ducts of a number of snails were prepared for histological analysis. The following
parameters were investigated: tubule area, epithelium height and area in the digestive gland,
spermatozoan area in the vesicula seminalis and ovotestis, as wen as oocyte numbers in the ovotestis.
To test the validity of the laboratory results, a field survey was conducted. Snails were colIected from
an uncontaminated vineyard and on two occasions from a contaminated vineyard in the Western Cape.
The same cellular responses were investigated as in the laboratory study.
The results showed that growth, egg production and hatching success in Helix aspersa were affected by
experimental exposure to copper oxychloride. In both the laboratory study and field survey, copper in
the body of H. aspersa was shown to be compartmentalized and the digestive gland was the most
important site of copper accumulation. NNR times of haemocytic Iysosomes were shown to be affected
by copper oxychloride exposure, already during the first week of exposure. A time evolution of copper
accumulation and lysosomal damage existed. Epithelium height and area of digestive gland tubules,
and spermatozoan and oocyte densities in the ovotestis, were also affected by copper oxychloride
exposure and the concomitant copper burdens in the respective organs. Through the field survey it was
ascertained that these histopathological changes were largely dependent on exposure time. It was concluded that lysosomal response of H. aspersa haemocytes, as measured by the NNR time
assay, could be considered a useful biomarker of copper oxychloride exposure, since it provides an
early warning of stress induced by this fungicide. Changes in digestive gland epithelium cells, and
gametes in the ovotestis, can also possibly serve as biomarkers of copper oxychloride exposure.
However, these can not serve as an early warning. All of the cellular responses identified in the present
study can be used in combination with other cellular and physiological parameters and toxicological
endpoints in order to improve the reliability and accuracy of interpretations regarding cause and effect.
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Diversité et adaptation aux fongicides des populations de Botrytis cinerea, agent de la pourriture grise / Diversity and adaptation to fungicides of Botrytis cinerea populations, the causal agent of grey mouldWalker, Anne-sophie 23 May 2013 (has links)
La sélection naturelle constitue un processus clé de l’adaptation des populations à leur environnement, favorisant les variants présentant les meilleures valeurs sélectives. Les champignons présentent généralement des traits biologiques (diversité des modes de reproduction, grandes tailles de populations, fortes capacités de dispersion, entre autres) qui favorisent leur adaptation à des environnements variés. La compréhension des mécanismes qui sous-tendent l’évolution de leurs populations sous les contraintes, naturelles et anthropiques, qu’elles subissent constituent donc un enjeu majeur pour la protection des plantes, en particulier dans le contexte actuel de durabilité des méthodes de lutte. Dans cette thèse, nous avons décrit la structure et la diversité des populations Botrytis cinerea à l’aide de marqueurs neutres et sélectionnés et d’un échantillonnage emboîté, et avons proposé des mécanismes pouvant expliquer les résultats observés. Puis nous avons analysé la réponse adaptative des populations de B. cinerea en Champagne, aux applications de fongicides. Premièrement, nous avons montré que la pourriture grise était causée par un complexe de deux espèces cryptiques, vivant en sympatrie sur des hôtes communs. De plus, les populations françaises de B. cinerea sont structurées en cinq dèmes, caractérisés par le système de culture (sélection directionnelle), la plante-hôte (adaptation écologique), et dans une moindre mesure, par la géographie. Sur vigne, nous avons mis en évidence une entité dont l’isolement génétique semble lié à un isolement temporel. Par ailleurs, nous avons montré que l’application de fongicides conduit à la sélection de phénotypes résistants spécifiquement à quasiment tous les modes d’action homologués, selon des proportions variant suivant les vignobles et les usages. Plus particulièrement, la résistance aux fongicides inhibiteurs de la succinate déshydrogénase (SDHI) est causée par au moins sept mutations affectant les gènes encodant la protéine cible de ces fongicides, déterminant ainsi une grande variété de phénotypes. Enfin, nous avons montré que les fongicides ne modifiaient pas la structure neutre des populations mais qu’ils pouvaient conduire à une perte de richesse allélique dans les populations traitées ainsi qu’à un équilibre sélection-migration détectable dans certaines situations sous forme de clines au loci sous pression de sélection contemporaine tels que ceux déterminant la résistance multidrogues. La modélisation de l’évolution des fréquences de résistance hivernale a permis d’estimer le coût de la résistance pour quatre loci déterminant la résistance aux fongicides. Cette thèse a permis d’appréhender le fonctionnement des populations de B. cinerea et de comprendre et quantifier partiellement les mécanismes sélectifs opérant in natura. Ces informations seront utilisées pour raisonner des stratégies anti-résistance adaptées localement et durables. / Natural selection is the most powerful force driving population adaptation to their environment, favoring the variants with the best fitness. Fungi generally exhibit biological traits (diversity of reproduction modes, large population sizes, and intense dispersion) that favor their adaptation to changing environments. Therefore, disentangling the mechanisms that explain their evolution under natural and anthropic constraints constitute a major challenge for plant protection, especially in the actual context of agriculture sustainability. In this thesis, we described Botrytis cinerea population structure and diversity, using neutral and selected markers and a hierarchical sampling, and proposed mechanisms that may explain these observations. We then analyzed the adaptive answer of this species towards fungicide applications. First, we showed that grey mold populations were caused by a complex of two cryptic species, living sympatrically on the same hosts. Second, B. cinerea populations are divided into five demes, according to the cropping system (directional selection), the host-plant (ecological adaptation), and to a lesser extent, by geography. On grapevine, we identified a specific populations exhibiting temporal isolation, as an evidence of extreme exploration of the viticultural conditions. Moreover, fungicide applications select resistance towards all unisite modes of action, with few exceptions, but at varying proportions according to vineyards and fungicide use. More specifically, resistance to succinate dehydrogenase inhibitors (SDHIs) is caused by at least seven mutations altering the target genes of these fungicides, and determines a large variety of phenotypes in the field. At last, we showed that fungicides did not shape population structure but that they could decrease allele richness in treated areas and lead to migration-selection equilibrium, detectable in some situation and for loci under contemporary selective pressures as clines. Modeling the evolution of resistance during winter allowed estimating fitness cost of four loci involved in contemporary fungicide resistance, such as multidrug resistance. As a conclusion, this thesis helped to understand how B. cinerea populations evolve and to detect and quantify selective mechanisms at work in natura. This information will be useful to deign sustainable and locally-adapted anti-resistance strategies.
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Studies on Sclerotinia sclerotiorum (Sclerotinia stem rot) on soybeans.Visser, Dael Desiree. January 2007 (has links)
Soybeans, Glycine max, are an economically and strategically important crop in South
Africa (SA). In order to meet local demands, large imports of soybeans are required,
e.g., in the 2005/2006 soybean production period, 842 107 tonnes of oilcake were
imported. Due to an increase in soybean production throughout the world, diseases that
affect this crop have also increased in incidence and severity.
Sclerotinia sclerotiorum, the causal organism of sclerotinia stem rot (SSR), is an
important yield limiting disease of soybeans, as well as numerous other crops. The
pathogen was first reported in SA in 1979. However, it was only in 2002 that this fungus
was considered a major pathogen of soybeans in SA.
The research reported in this thesis was conducted to investigate the epidemiology of
S. sclerotiorum and examine numerous potential control methods for this pathogen, i.e.,
resistant cultivars, biocontrol, chemical control and seed treatments. A S. sclerotiorum
isolate was obtained from sunflowers in Delmas, Mpumulanga, SA, in the form of
sclerotia. This isolate was cultured and sent for identification and deposition in the Plant
Protection Research Institute collection. This isolate, in the form of mycelia, was used
for the duration of the study.
For epidemiology studies, the effect of temperature, leaf wetness duration (LWD) and
relative humidity (RH) were examined for their effect on rate of pathogen development.
Twenty four combinations of temperature (19°C, 22°C, 25°C and 28°C), LWD (24, 48
and 72 hr) and RH (85 and 95%) were investigated. No interaction between
temperature, LWD and RH was found. Temperature alone was the only factor that
affected disease development. At 22°C, the rate of pathogen development (0.45 per
unit per day) was significantly higher than all other temperatures, indicating that this
temperature is optimum for disease development.
Thirteen different soybean cultivars, i.e., LS6626RR, LS6710RR, LS666RR, LS555RR,
LS6514RR, LS678RR, Prima 2000, Pan 626, AG5601RR, AG5409RR, 95B33, 95B53
and 96B01B, commercially grown in SA were investigated for their reaction to
S. sclerotiorum. Prima 2000, 96B01B, 95B33 and AG5409RR were considered to be
the least susceptible as they showed a significantly low rate of pathogen development
(0.28, 0.28, 0.24, 0.23 per unit per day, respectively) and produced a significantly low
number of sclerotia (3.03, 3.42, 3.21, 2.38, respectively). LS6626R and LS666RR may
be considered most susceptible because of their significantly high rate of pathogen
development (0.45 and 0.42 per unit per day, respectively) and high sclerotia production
(8.16 and 7.50, respectively). Regression analysis showed a positive correlation
coefficient (R2=0.71) between rate of growth of the pathogen and number of sclerotia
produced, indicating that a higher rate is associated with a higher number of sclerotia.
In vitro dual culture bioassays were performed to identify the biocontrol mechanisms of
the biocontrol agents, EcoT® (a seed treatment) and Eco77® (a foliar treatment), against
hyphae and sclerotia of S. sclerotiorum. Ultrastructural studies revealed that
mycoparasitism is the probable mode of action as initial signs of hyphae of EcoT® and
Eco77® coiling around hyphae of S. sclerotiorum were observed. Surface colonization
of sclerotia by hyphae of EcoT® and Eco77® was also observed.
In vitro antagonism of EcoT® against S. sclerotiorum on soybean seed was performed to
determine pre-emergence and post-emergence disease. There was no significant
difference in percentage germination between seeds treated with EcoT® and plated with
the pathogen, untreated seeds and no S. sclerotiorum, and the control (i.e. no EcoT®
and no pathogen). However, percentage non infected seedlings from seeds not treated
with EcoT® was significantly lower, suggesting that EcoT® may be successfully used as
a seed treatment for the control of SSR. In vivo trials were performed to investigate the
effect of silicon (Si) alone, and in combination with Eco77®, on the effect of the rate of
disease development. Plants treated with Eco77® had a significantly lower rate of
disease development (0.19 per unit per day for plants treated with Eco77® and S.
sclerotiorum and 0.20 per unit per day for plants treated with Eco77®, S. sclerotiorum
and Si), compared to plants not treated with Eco77® (0.29 per unit per day for plants
treated with S. sclerotiorum and 0.30 per unit per day for plants treated with S.
sclerotiorum and Si), regardless of the application of Si. Similarly, plants treated with
Eco77® had a significantly lower number of sclerotia (0.46 for plants treated with Eco77®
and S. sclerotiorum and 0.91 for plants treated with Eco77®, S. sclerotiorum and Si),
compared to plants not treated with Eco77® (3.31 for plants treated with S. sclerotiorum
and 3.64 for plants treated with S. sclerotiorum and Si). The significantly lower rate of
disease development coupled with a significant reduction in sclerotia showed that
Eco77®, and not Si, was responsible for reducing the severity of SSR. A strong positive
correlation between rate of disease development and the number of sclerotia produced
(R2=0.79) was observed.
For the investigation of various fungicides for the control of S. sclerotiorum, in vitro trials
to determine the potential of three different fungicides at different rates, i.e., BAS 516
04F (133 g a.i. ha-1), BAS 516 04F (266 g a.i. ha-1), BAS 512 06F (380 g a.i. ha-1) and
Sumisclex (760 g a.i. ha-1) were initially conducted. The control (non-amended PDA)
had a significantly higher area under mycelial growth curve (243.0) than all fungicides
tested. BAS 516 04F (at both concentrations) and BAS 512 06F completely inhibited
the mycelial growth of S. sclerotiorum. Sumisclex inhibited the fungus by 89.07%. For
in vivo trials, preventative treatments, i.e., BAS 516 04F (133 g a.i. ha-1), BAS 516 04F
(266 g a.i. ha-1), BAS 512 06F (380 g a.i. ha-1), curative treatment, i.e. Sumisclex (760 g
a.i. ha-1) and a combination preventative/curative treatment, i.e., BAS 512 06F (380 g
a.i. ha-1)/Sumisclex (570 g a.i. ha-1) were investigated. No significant difference in
disease severity index (DSI) was found between fungicide treatments and the inoculated
control. BAS 512 06F and BAS 512 06F/Sumisclex had significantly lower grain yields
(6.09 g and 5.96 g, respectively) compared to all other treatments. There was a positive
correlation coefficient (R2=0.76), between DSI and grain yield, indicating that a high DSI
is correlated with low grain yield.
Trials to evaluate the effect of commercially available and currently unregistered seed
treatments for the control of S. sclerotiorum on soybean seeds in vivo and in vitro were
performed. Seed germination tests were performed to determine if seed treatments had
any negative effects on seed germination in vitro. All seed treatments tested, i.e., BAS
516 03F (8, 16 and 32 ml a.i. 100 kg-1 seed), BAS 512 00F (7.5, 15 and 32 ml a.i. 100
kg-1 seed), Celest XL (100, 125, 200 and 250 ml a.i. 100 kg-1 seed), Sumisclex (5 and 10
ml a.i. 100 kg-1 seed), Benomyl (150 g a.i. 100 kg-1 seed), Captan (240 ml a.i. 100 kg-1
seed), Thiulin (180 g a.i. 100 kg-1 seed) and Anchor Red (300 ml a.i. 100 kg-1 seed),
showed no negative effect on seed germination. For in vivo trials, BAS 516 03F (16 and
32 ml a.i. 100 kg-1 seed), BAS 512 00F (7.5, 15 and 32 ml a.i. 100 kg-1 seed), Celest XL
(100, 125, 200 and 250 ml a.i. 100 kg-1 seed), Sumisclex (5 and 10 ml a.i. 100 kg-1
seed), Benomyl and Anchor Red had significantly similar percent germination and
percent seedling survival as the untreated/uninoculated control. These seed treatments
should be recommended for the control of S. sclerotiorum, as they protected seed
during germination and subsequent seedling development. BAS 516 03F (8 ml a.i. 100
kg-1 seed) should not be recommended for the control of SSR, as it gave the lowest
percent germination and percent seedling survival.
The results presented in this thesis have helped to identify optimal environmental
conditions for the development of S. sclerotiorum, which is important for the
development of forecasting models for disease control. The least and most susceptible
cultivars of those tested have been identified. Biocontrol using Eco77® as a foliar
application showed great potential.
The effect of Si needs to be further investigated, including the testing of more frequent
applications and higher concentrations. The fungicides tested in this research did not
show any potential for the control of SSR. However, the spray programme tested is for
the control of soybean rust (Phakopsora pachyrhizi), and was investigated for its
potential for the control of SSR. The spray programme, fungicide application and rating
scale needs to be modified, to determine the true potential of these fungicides for the
control of SSR. Numerous seed treatments have shown potential for the control of seed
infection by SSR. Due to difficulties in producing ascospores, which are the primary
source of inoculum for this pathogen in the field, all studies in this research were
conducted with mycelia and not ascospores. The production, collection and storage of
ascospores needs to be thoroughly investigated, and research conducted with
ascospores. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2007.
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The effects of foliar diseases and irrigation on root development, yield and yield components of wheat (Triticum aestivum L.)Balasubramaniam, Rengasamy January 1985 (has links)
Studies were conducted on three field trials of wheat cv. Kopara to investigate the lack of compensation by later determined components of yield because of early disease constraints. The investigation was based on the hypothesis that early disease reduces root development and thus causes the plants to be water constrained at later growth stages when soil water deficits usually occur. The reduced root development and soil water deficits may reduce the ability of the plant to compensate for reductions in early determined components. The hypothesis was tested by the application of irrigation to alleviate water stress. In a disease free crop, the possible phytotonic effects of the fungicides benomyl and triadimefon on wheat were investigated. These fungicides had no phytotonic effects on shoot, root growth, or yield under the prevailing conditions. The effect of disease on root development was analysed by root length measurements. Disease present in the crop at any stage of growth affected root development. Root development in the upper zones of the soil profile was reduced more by disease compared to those zones below 35 cm. A full disease epidemic reduced root development more than an early or late disease epidemic. The early and late disease epidemics had similar effects on root length. Alleviation of early disease constraints enabled greater development of roots to offset any earlier reductions. Soil water deficits increased root development in the lower zones of the nil disease plants. The presence of adequate soil water from irrigation reduced the requirement for further root growth in all treatments. In the 1981-1982 field trial a full disease epidemic reduced yield by 14% whereas an early disease epidemic reduced yield by 7%. The reduction in yield was attributed to a lower grain number. With irrigation the yield reduction in the full disease plants was 12% whereas in the early disease plants the reduction was only 2.4%. This indicated that plants affected by the early disease epidemic were water constrained. In this study, the results suggested that, for conditions prevailing in Canterbury, the supply of water at later growth stages increased grain weight in plants which were subject to early disease epidemics. This suggests that reduced root development caused by early disease and soil water deficits may prevent compensation by grain weight. Water use was similar in all disease treatments. After irrigation the irrigated plants of all treatments used more water. Disease affected water use in relation to yield production however, and was better expressed by water use efficiency. Water use efficiency was reduced in the full disease plants. A stepwise regression analysis suggested that water use efficiency was affected directly by disease at later growth stages, and indirectly via an effect on total green leaf area at early growth stages. This study partially proves the hypothesis that reductions in root development caused by an early disease epidemic may constrain the plants at later growth stages when water deficits usually occur. It was shown that the reduction in root development caused by disease could be counteracted by irrigation. In this respect, water served as a tool to study the effect of disease constraints on the yield of wheat. A knowledge of cereal crop physiology, root growth and function is used to explain and discuss the observations made in this research programme. The results are discussed in relation to the way in which disease affects yield through its effect on root development. The possible reasons for the continued effects of disease even after the control of disease at later growth stages are discussed. The economic use of fungicides and water in diseased crops are also outlined. Suggestions for future studies on disease-yield loss relationships are provided. The repetition of these experiments in different sites and climatic regions could provide information which may be incorporated in disease-yield loss simulation models. This could then be used to predict root development and water requirements of diseased plants, and provide a basis for economic use of fungicides and water, and for better disease management programmes.
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Época de colheita, irrigação, fitoquímica e atividades carrapaticida e fungicida do óleo essencial de genótipos de Lippia gracilis SchauerCruz, Elizangela Mércia de Oliveira 15 March 2013 (has links)
The aim of this study was to determine the influence of harvesting time and water stress on the chemical composition of the essential oil and to test the activities against ticks and fungus of the essential oil of L. gracilis. For the analysis of harvest season the plant material was collected from seven genotypes of L. gracilis at the Research Farm "Campus Rural da UFS", in the rainy and dry seasons. The experiment testing water stress was conducted in the dry season. The extraction of essential oils was performed in the Laboratory of Phytotechnology of the UFS through hydrodistillation. Chemical analysis of the essential oil performed using GC-MS in the Laboratory of Chromatography of the UFS. For the activity tests against ticks package larvae and immersion of engorged tick Rhipicephalus microplus in different concentrations of essential oil, thymol or carvacrol. To test of fungicidal activity, the essential oil at different concentrations was added to PDA medium. Each plate was inoculated with mycelia culture of Thielaviopis paradoxa. The essential oil of L. gracilis presented two distinct chemotypes, one genotype LGRA-106 presenting as major compound thymol and the other genotypes presenting carvacrol as major compound. The leaves provided essential oil with an average grade of 1.55% in the rainy season and 2.09% in the dry season. In the rainy season there was no significant difference in both the yield and the content. The chemical composition of essential oils L. gracilis showed high levels of terpenes, 92% in the rainy season and 96% in the dry season. In the experiment with irrigation the values of content and yield of all genotypes were smaller when compared without irrigation. In general, the species L. gracilis, for the presence of water in the soil, provides stability in the chemical composition of the essential oil regardless of season, since plants subjected to irrigation, even in the dry season, the essential oil produced in quantity and quality similar to the rainy season. The essential oil of L. gracilis exhibits high activity against ticks, proven by lethal concentrations of genotypes LGRA-201 (1.31 mg.mL-1) and LGRA-106 (4.66 mg.mL-1), demonstrating efficiency in the control of this parasite. The tests showed that the concentrations 0.45; 0.91 and 2.75 mg.mL-1 of all genotypes of L. gracilis completely inhibited the development of the pathogen T. paradoxa, corresponding to a percentage of mycelium growth inhibition of 100%. The concentration of 0.18 mg.mL-1 of essential oil was sufficient to significantly reduce the number of spores of T. paradoxa. The minimal fungicidal concentration T. paradoxa was found between concentrations from 0.80 to 0.98 mg.mL-1 for the essential oils and 0.26 mg.mL-1 for carvacrol and 0.35 mg.mL-1 to thymol. / O presente trabalho teve como objetivo determinar a influencia da época de colheita e do estresse hídrico na composição química do óleo essencial e testar a atividade carrapaticida e fungicida do óleo essencial de L. gracilis. Para as análises de época de colheita o material vegetal foi colhido de sete genótipos de L. gracilis no Campus Rural da UFS , nas épocas chuvosa e seca. Já para o ensaio de estresse hídrico o experimento foi conduzido na época seca. A extração de óleos essenciais foi realizada no Laboratório de Fitotecnia da UFS, por meio de hidrodestilação. A análise química do óleo essencial foi realizada utilizando CG-EM, no Laboratório de Cromatografia da UFS. Para a atividade carrapaticida foram realizadas os testes de pacote de larvas e de imersão de fêmeas ingurgitadas do carrapato Rhipicephalus microplus em diversas concentrações de óleo essencial, timol ou carvacrol. Para o teste de atividade fungicida, o óleo essencial, em diferentes concentrações foi adicionado ao meio BDA. Cada placa foi inoculada com micélios da cultura monospórica de Thielaviopis paradoxa. O óleo essencial de L. gracilis apresentou dois quimiotipos distintos um com o genótipo LGRA-106 apresentando o composto timol como majoritário e os demais o carvacrol. As folhas forneceram óleos essenciais amarelados com teor médio de 1,55% na época chuvosa e 2,09% na seca. Na época chuvosa não houve diferença significativa tanto no rendimento como no teor. A composição química dos óleos essenciais de L. gracilis apresentou altos níveis de terpenos, 92% na época chuvosa e 96% na época seca. No ensaio com irrigação os valores de teor e rendimento de todos os genótipos são menores quando comparado com o ensaio sem irrigação. De maneira geral a espécie L. gracilis, quanto à presença de água no solo, apresenta estabilidade na composição química do óleo essencial independente da época do ano, uma vez que as plantas submetidas à irrigação, mesmo no verão, produziram óleo essencial em quantidade e qualidade semelhantes à época do inverno. O óleo essencial de L. gracilis apresenta alta atividade carrapaticida, comprovados pelas concentrações letais dos genótipos LGRA-201 (1,31 mg.mL-1) e LGRA-106 (4,66 mg.mL-1), demonstrando eficiência no controle desse parasita. Os ensaios demonstraram que as concentrações 0,45; 0,91 e 2,75mg.mL-1 de todos os genótipos de L. gracilis inibiram completamente o desenvolvimento do patógeno T. paradoxa, correspondendo a uma porcentagem de inibição do crescimento micelial de 100%. A concentração de 0,18mg.mL-1 de óleo essencial foi suficiente para reduzir significativamente o número de esporos de T. paradoxa. A concentração fungicida mínima de T. paradoxa foi encontrada entre as concentrações de 0,80 a 0,98mg.mL-1 para os óleos essenciais e 0,26mg.mL-1 para o carvacrol, e 0,35mg.mL-1 para o timol.
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Época de colheita, irrigação, fitoquímica e atividades carrapaticida e fungicida do óleo essencial de genótipos de Lippia gracilis SchauerCruz, Elizangela Mércia de Oliveira 15 March 2013 (has links)
The aim of this study was to determine the influence of harvesting time and water stress on the chemical composition of the essential oil and to test the activities against ticks and fungus of the essential oil of L. gracilis. For the analysis of harvest season the plant material was collected from seven genotypes of L. gracilis at the Research Farm "Campus Rural da UFS", in the rainy and dry seasons. The experiment testing water stress was conducted in the dry season. The extraction of essential oils was performed in the Laboratory of Phytotechnology of the UFS through hydrodistillation. Chemical analysis of the essential oil performed using GC-MS in the Laboratory of Chromatography of the UFS. For the activity tests against ticks package larvae and immersion of engorged tick Rhipicephalus microplus in different concentrations of essential oil, thymol or carvacrol. To test of fungicidal activity, the essential oil at different concentrations was added to PDA medium. Each plate was inoculated with mycelia culture of Thielaviopis paradoxa. The essential oil of L. gracilis presented two distinct chemotypes, one genotype LGRA-106 presenting as major compound thymol and the other genotypes presenting carvacrol as major compound. The leaves provided essential oil with an average grade of 1.55% in the rainy season and 2.09% in the dry season. In the rainy season there was no significant difference in both the yield and the content. The chemical composition of essential oils L. gracilis showed high levels of terpenes, 92% in the rainy season and 96% in the dry season. In the experiment with irrigation the values of content and yield of all genotypes were smaller when compared without irrigation. In general, the species L. gracilis, for the presence of water in the soil, provides stability in the chemical composition of the essential oil regardless of season, since plants subjected to irrigation, even in the dry season, the essential oil produced in quantity and quality similar to the rainy season. The essential oil of L. gracilis exhibits high activity against ticks, proven by lethal concentrations of genotypes LGRA-201 (1.31 mg.mL-1) and LGRA-106 (4.66 mg.mL-1), demonstrating efficiency in the control of this parasite. The tests showed that the concentrations 0.45; 0.91 and 2.75 mg.mL-1 of all genotypes of L. gracilis completely inhibited the development of the pathogen T. paradoxa, corresponding to a percentage of mycelium growth inhibition of 100%. The concentration of 0.18 mg.mL-1 of essential oil was sufficient to significantly reduce the number of spores of T. paradoxa. The minimal fungicidal concentration T. paradoxa was found between concentrations from 0.80 to 0.98 mg.mL-1 for the essential oils and 0.26 mg.mL-1 for carvacrol and 0.35 mg.mL-1 to thymol. / O presente trabalho teve como objetivo determinar a influencia da época de colheita e do estresse hídrico na composição química do óleo essencial e testar a atividade carrapaticida e fungicida do óleo essencial de L. gracilis. Para as análises de época de colheita o material vegetal foi colhido de sete genótipos de L. gracilis no Campus Rural da UFS , nas épocas chuvosa e seca. Já para o ensaio de estresse hídrico o experimento foi conduzido na época seca. A extração de óleos essenciais foi realizada no Laboratório de Fitotecnia da UFS, por meio de hidrodestilação. A análise química do óleo essencial foi realizada utilizando CG-EM, no Laboratório de Cromatografia da UFS. Para a atividade carrapaticida foram realizadas os testes de pacote de larvas e de imersão de fêmeas ingurgitadas do carrapato Rhipicephalus microplus em diversas concentrações de óleo essencial, timol ou carvacrol. Para o teste de atividade fungicida, o óleo essencial, em diferentes concentrações foi adicionado ao meio BDA. Cada placa foi inoculada com micélios da cultura monospórica de Thielaviopis paradoxa. O óleo essencial de L. gracilis apresentou dois quimiotipos distintos um com o genótipo LGRA-106 apresentando o composto timol como majoritário e os demais o carvacrol. As folhas forneceram óleos essenciais amarelados com teor médio de 1,55% na época chuvosa e 2,09% na seca. Na época chuvosa não houve diferença significativa tanto no rendimento como no teor. A composição química dos óleos essenciais de L. gracilis apresentou altos níveis de terpenos, 92% na época chuvosa e 96% na época seca. No ensaio com irrigação os valores de teor e rendimento de todos os genótipos são menores quando comparado com o ensaio sem irrigação. De maneira geral a espécie L. gracilis, quanto à presença de água no solo, apresenta estabilidade na composição química do óleo essencial independente da época do ano, uma vez que as plantas submetidas à irrigação, mesmo no verão, produziram óleo essencial em quantidade e qualidade semelhantes à época do inverno. O óleo essencial de L. gracilis apresenta alta atividade carrapaticida, comprovados pelas concentrações letais dos genótipos LGRA-201 (1,31 mg.mL-1) e LGRA-106 (4,66 mg.mL-1), demonstrando eficiência no controle desse parasita. Os ensaios demonstraram que as concentrações 0,45; 0,91 e 2,75mg.mL-1 de todos os genótipos de L. gracilis inibiram completamente o desenvolvimento do patógeno T. paradoxa, correspondendo a uma porcentagem de inibição do crescimento micelial de 100%. A concentração de 0,18mg.mL-1 de óleo essencial foi suficiente para reduzir significativamente o número de esporos de T. paradoxa. A concentração fungicida mínima de T. paradoxa foi encontrada entre as concentrações de 0,80 a 0,98mg.mL-1 para os óleos essenciais e 0,26mg.mL-1 para o carvacrol, e 0,35mg.mL-1 para o timol.
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Abiotischer Stress in Weizenblättern: Reaktionen im Photosynthese-Apparat in Relation zum Stressmetabolismus / Abiotic stress in wheat leaves: reactions in photosynthesis processes in relation to stress metabolismGrimme, Elke 25 January 2007 (has links)
No description available.
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Reduktion des Pflanzenschutzmitteleinsatzes - Konsequenzen für das Schaderregerauftreten und die Wirtschaftlichkeit in Getreide-Zuckerrübe-Fruchtfolgen / Reduction of plant protection products - economic and biological consequences for the pest and weed development in sugar beet-grain-croprotationsBusche, Stephan 22 May 2008 (has links)
No description available.
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