UFV - Teses

URI permanente para esta coleçãohttps://thoth.dti.ufv.br/handle/123456789/4

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Seasonal variation, spatial distribution and decision–making system to control of the Leucoptera coffeella in coffee arabica fields
(Universidade Federal de Viçosa, 2022-03-28) Walerius, Adriana Helena; Pallini, Angelo; Venzon, Madelaine; Picanço, Marcelo Coutinho
Coffee is the world's second-largest commodity and represented a global market of US$ 102.02 billion dollars in 2020. The Neotropical region is the main coffee producer globally, accounting for more than 56% of the world's production of Arabica coffee. In this region, the coffee leaf miner Leucoptera coffeella is one of key coffee pests. This pest can decrease productivity by around 50 to 87% at high densities. Several factors can influence the L. coffeella population dynamics in the field. Therefore, prior knowledge of the areas and seasons of higher incidence of L. coffeella is essential to field management. The objective of this study was to evaluate the seasonality of the L. coffeella population and the factors that regulate its dynamics in coffee crops located in the Atlantic Forest and the Cerrado biomes. We aim to determine the spatial distribution of Leucoptera coffeella in coffee crops in the Cerrado through geostatistical analyses and propose a decision-making control system based on management zones. L. coffeella densities were higher in the Cerrado area compared to the Atlantic Forest. In the Cerrado, air temperature and potential evapotranspiration were higher, while rainfall was lower. These data are correlated with the high densities of L. coffeella in the fields. The highest population densities were observed between July and October, when the coffee plants were in the fruiting and flowering phases. The minimum, optimum and maximum temperatures for the development of the pest were 16.59, 26.81, and 34.8°C, respectively. Therefore, the climatic elements in each biome influenced the spatio-temporal dynamics of L. coffeella. Geostatistical analysis showed an aggregated distribution of L. coffeella in the Cerrado field. Colonization generally started at the edges of the crop, except in the last year of evaluation. Pest outbreaks appeared at different pivots and different locations within the pivots. Due to isotropy, sampling must be done equidistantly, as the pest is evenly distributed in all directions. The programs that use sampling and level of control (30% of active mined leaves) in decision making were the most efficient and assertive in controlling L. coffeella. Management zones reduce insecticide use by 70% compared to conventional controlover the whole area. The information provided in this study is essential for designing and implementing efficient control strategies, thus reducing production costs and the harmful effects of pesticide use. Keywords: Coffea arabica. Coffe Leaf miner. Population Fluctuation. Climatic Elements. Geostatistics. Integrated Pest Management. Precision Agriculture.
Conservation biological control of coffee leaf miner: role of green lacewings and parasitoids
(Universidade Federal de Viçosa, 2021-10-29) Martins, Elem Fialho; Venzon, Madelaine; Schmidt, Jason M.; Perez, André Lage
Coffee leaf miner, Leucoptera coffeella, is a key coffee pest in the Neotropics. The larvae feed on the parenchyma between surfaces of coffee leaves causing decrease of the photosynthesis rate leading to significant losses in yield and in the longevity of coffee plant. Several natural enemies are involved in coffee leaf mine biological control, such as wasps, ants, parasitoids and green lacewings. However, normally their populations are not enough to decrease or to maintain the coffee leaf mine populations below threshold levels in coffee monocultures, due to their dependence on resources, such as pollen and nectar, which are scarce in conventional systems. The association of plant species to coffee crops might represent an effective strategy through the provision of alternative food and refuge for natural enemies. I investigate here whether the diversification of Coffea arabica crops with Inga edulis “erva-baleeira”, Varronia curassavica “inga”, Senna macranthera “fedegoso” and non-crop plants favors the biological control of coffee leaf miner by its predators and parasitoids. These plants can provide resources such as nectar and pollen constantly, shelter and oviposition and mating sites for natural enemies with either extrafloral nectaries (I. edulis and S. macranthera) and/or inflorescences (V. curassavica). Firstly, we performed laboratory experiments to evaluate whether the immature stages of the green lacewing Ceraeochrysa cubana are able to prey on the immature stages of coffee leaf miner (Chapter I). Larvae of C. cubana successfully prey on eggs and pupae of coffee leaf miner, being the first report about green lacewing predation on the pest eggs. We also investigate whether V. curassavica provides selective resources to C. cubana without benefiting coffee leaf miner adults (Chapter II). Larvae of C. cubana survived longer in the presence of V. curassavica inflorescences, and decrease the population growth rate of the pest. In the field, we evaluated the visitors of the inserted plants and whether the strategic diversification with I. edulis, S. macranthera and V. curassavica added to non-crop areas under management of no pesticide use influence the abundance and richness of predatory green lacewings and wasps, increase the parasitism and control coffee leaf miner compared to conventional coffee systems (Chapter III). I found that ants are the most abundant visiting insects of I. edulis, S. macranthera and V. curassavica. In addition, I found that although there was no significant difference in the abundance of green lacewings and wasps between systems, parasitism rate was higher in the diversified. Despite that, there was no difference in the pest infestation comparing to conventional coffee systems in 2019 and 2021, but in 2020 it was higher in the diversified. However, CLM populations did not reach threshold in any system. Our study demonstrates through laboratory and field experiments that it is possible to improve the biological control of coffee leaf miner with safe strategies to environment and humans, in addition to maintaining biodiversity in coffee agroecosystems. Keywords: Leucoptera cofeella. Conservation biological control. Ceraeochrysa cubana, Varronia curassavica
Varronia curassavica Jacq. (Boraginaceae) as an agroecological tool for coffee pest management
(Universidade Federal de Viçosa, 2022-08-04) Andrade, Fernanda Pereira; Venzon, Madelaine; Fonseca, Maira Christina Marques; Pallini Filho, Angelo
Coffee (Coffea sp.) is a crop of great relevance in agriculture. However, its productivity can be severely affected by the attack of pests, such as Leucoptera coffeella and Hypothenemus hampei. The coffee leaf miner, L. coffeella, is a key coffee pest in the Neotropics. The larvae feed on the parenchyma of coffee leaves decreasing the photosynthesis capacity and leading to significant losses in yield. The coffee berry borer, H. hampei, is the most damaging insect pest of coffee worldwide. This pest lives inside the coffee berry consuming the seeds thus reducing the quantity and quality of the coffee grains. The most common method of control to both pests is the use of synthetic pesticides, which have a low effectiveness due to the selection of resistant populations. Additionally, the excessive use of these products could have a severe impact in the environment and non-target individuals. An alternative for the management of these pests could be the use of specific plants and their secondary metabolites, such as the essential oils. Varronia curassavica is a medicinal species that produces an essential oil with a range of biological activities besides attracting natural enemies, such as the Chrysopidae. The specie Chrysoperla externa is an important biological control agent of a variety of pests, including L. coffeella and H. hampei. In this study, I investigate whether V. curassavica can be used in the management of L. coffeella and H. hampei and benefit their natural enemy C. externa. I performed a greenhouse experiment to evaluate if the association of V. curassavica plants with coffee plants would affect the oviposition of L. coffeella and its predator C. externa (Chapter I). The association of the V. curassavica plants with coffee plants didn’t affect L. coffeella oviposition, however, it increased the C. externa oviposition. I also investigate the effects of the V. curassavica essential oil in the oviposition and the development of eggs and mines of L. coffeella (Chapter II). The V. curassavica essential oil inhibited the oviposition of L. coffeella but did not affect the development of its eggs and mines. I evaluated the lethal and sublethal effects of V. curassavica essential oil on H. hampei, assessing the mortality rates, the mobility of H. hampei, and the repellence of the essential oil to this pest (Chapter III). The essential oil of V. curassavica is toxic to H. hampei and affects its mobility, but it wasn’t repellent to the pest in the concentration tested. This study demonstrates that V. curassavica plant and its essential oil could be a safer alternative in the management of the key coffee pests. Keywords: Coffea sp. Leucoptera coffeella. Hypothenemus hampei. Chrysoperla externa.
Potencial biocida de Jatropha curcas L.
(Universidade Federal de Viçosa, 2019-02-12) Silva, Dandara Rêgo Muniz da; Dias, Luiz Antônio dos Santos
Jatropha curcas L. é uma oleaginosa de múltiplos propósitos, por apresentar, além da importância do seu óleo para produção de biodiesel, uma grande diversidade de compostos bioativos com atributos medicinais e ação biocida no controle de pragas e doenças de diversos cultivos. Esta revisão aborda o estado da arte da ação biocida dos metabólitos secundários dessa espécie. Dentre esses compostos, os ésteres diterpênicos derivados do forbol são as moléculas mais estudadas, devido a toxicidade aos seres humanos e animais, e pela alta atividade fungicida e inseticida. Tais metabólitos, possivelmente, atuam na destruição do retículo endoplasmático e da parede celular das hifas. Nos insetos-praga, estes compostos, provavelmente, atuam sobre o metabolismo, ocasionando inibição alimentar, repelência, inibição do ato do acasalamento, ação inibitória ou supressora da oviposição e/ou indução da produção de ovos inférteis, além da inibição do desenvolvimento de larvas, ninfas e pupas. Vários estudos demonstram que embora todas as partes da planta sejam tóxicas, o grau de toxicidade pode variar de acordo com a forma de obtenção do extrato, dose e modo de administração, e sensibilidade do indivíduo. Sendo assim, J. curcas é destaque como espécie promissora por atender tanto o aspecto agroenergético, quanto o fitossanitário no controle de pragas e doenças que afetam a agricultura. Dessa forma, o presente estudo avaliou, no capítulo 2, a atividade fungicida e bactericida de extratos foliares e caulinares de 12 acessos, pré- selecionados em teste de progênies, sobre os fungos Hemileia vastatrix e Cercospora coffeicola, causadores de duas das mais importantes doenças do cafeeiro: ferrugem e cercosporiose, respectivamente, e sobre a bactéria Pseudomonas syringaepv. garcae, causadora da mancha aureolada. Amostras de folhas e caules de J. curcas foram submetidas a secagem e moagem e seus extratos clorofórmicos e etanólicos preparados com auxílio do aparato Soxhlet. As atividades fungicidas e bactericidas foram avaliadas, in vitro, a partir da inibição da germinação de esporos de H. vastatrix, da redução percentual do crescimento micelial de C. coffeicola e da diminuição da zona de crescimento de P. syringae pv. garcae. Todos os extratos foram capazes de inibir, em 100%, a germinação dos esporos de H. vastatrix. Todos os extratos reduziram significativamente o crescimento micelial de C. coffeicola, sendo as reduções mais expressivas de 16, 17, 12 e 20%, dos extratos EC04, EF04-clorofórmico e os EC08, EF08-etanólico, respectivamente. Alterações morfológicas também foram observadas nos micélios, indicando a possível variação na produção de melanina, metabólito secundário de importância no desenvolvimento fúngico. Os extratos não agiram sobre P. syringae pv. garcae. Esses resultados demonstram a importância dos estudos sobre as propriedades fungicidas dos extratos de J. curcas, bem como, na caracterização e identificação de seus componentes bioativos.
Caracterização molecular e resistência a doenças de genótipos de cafeeiros originários da América Central
(Universidade Federal de Viçosa, 2022-04-01) Granados Brenes, Eduardo; Zambolim, Laércio; Caixeta, Eveline Teixeira
A cultura do café tem apresentado uma série de doenças que provocam severos danos na cafeicultura de diversos países. Visando minimizar esses problemas, programas de melhoramento genético têm desenvolvido cultivares com resistência à fatores bióticos e abióticos. No entanto, o uso dessa cultivares associado a autogamia e origem do cafeeiro arábica tem resultado em estreita relação genética entre os genótipos e, consequentemente, maior vulnerabilidade a doenças e pragas. Técnicas tradicionais de inoculação do patógeno complementadas com a biologia molecular permitem verificar a presença de genes que conferem resistência a ferrugem (Hemileia vastatrix), principal doença da cultura, e ao Colletotrichum kahawae causador da antracnose verde dos grãos, além de auxiliar o estudo de diversidade das cultivares. Marcadores ligados a genes que conferem resistência a doenças, complementam os trabalhos clássicos de fenotipagem das plantas de café na determinação da resistência ou a susceptibilidade a patógenos. Diante desse panorama, esse trabalho teve como objetivo a verificação da diversidade genética das cultivares de café da América Central, utilizando 16 marcadores microssatélites distribuídos aleatoriamente no genoma de C. arabica. Além disso, a resistência dessas cultivares foi verificada por meio da fenotipagem com as raças II e XXXIII de H. vastatrix e genotipagem com marcadores moleculares ligados a genes de resistência a H. vastatrix e a C. kahawae. As análises moleculares com marcadores aleatórios revelaram diversidade entre e dentro das cultivares analisadas, sendo possível obter o padrão molecular da maioria delas. Essas análises permitiram também observar erros de identificação de cultivar, misturas ou hibridações nas cultivares. Das 36 cultivares fenotipadas para resistência, 30 foram resistentes a raça II e 26 a raça XXXIII de H. vastatrix. Na genotipagem, os cafeeiros apresentaram variabilidade e alelos que conferem resistência a H. vastatrix, complementado os resultados fenotípicos, sugerindo uma piramidação de genes de resistência nos cafeeiros da América Central. Palavras-chave: Coffea arabica. Hemileia vastatrix. Colletotrichum kahawae. Seleção assistida por marcadores moleculares. Diversidade genética.
Trichoderma spp. associated with coffee in Africa: taxonomy and potential uses for the biological control of coffee leaf rust and plant growth promotion
(Universidade Federal de Viçosa, 2019-03-11) Herrera Rodriguez, María del Carmen; Barreto, Robert Weingart; Abreu, Lucas Magalhães de; Evans, Harold Charles
Coffee leaf rust (CLR) caused by the fungus Hemileia vastatrix is the most important disease in coffee. Difficulties in obtaining long lasting resistance, the failure of the strategy of escaping the disease by highland coffee cultivation and the increasing restrictions to the use of fungicides prompted the search for alternative forms of management. Biological control is an alternative of major strategical importance in such a scenario. Although there are publications dealing with biological control of H. vastatrix, none of these studies involved fungi of the genus Trichoderma or the classical approach of biological control involving antagonists to H. vastatrix from its native range in Africa. The present work concentrated in the study of endophytic and mycoparasite Trichoderma – collected in Africa and obtained from coffee plants in wild or semi-wild conditions. Taxonomy of 94 isolates which were obtained, screening for potential antagonists to H. vastatrix and a preliminary evaluation of beneficial physiological effects of one selected isolate were performed. Among the isolates of Trichoderma obtained from Ethiopia, Cameroon and Kenya 16 distinct species Trichoderma were recognized. Twelve were known to science, namely: Trichoderma agressivum, T. andinense, T. atroviride, T. guizhouense, T. hamatum, T. koningiopsis, T. lentiforme, T. parareesei T. petersenii, T. spirale, T. theobromicola and T. virens. Four were described as new taxa: Trichoderma sp. nov.1, Trichoderma sp. nov.2, Trichoderma sp. nov.3 and Trichoderma sp. nov.4. All sporulating isolates were tested for their ability to reduce the germination of H. vastatrix urediniospores in vitro and of reducing CLR severity on leaf disc and plants. Additionally, to Trichoderma spp. some other taxa obtained as endophytes of coffee in Africa were also included in the screening. The ability of Trichoderma spp. to colonize coffee plants as endophytes after inoculation under controlled conditions was also investigated. Seventeen isolates of Trichoderma inhibited the germination of H. vastatrix urenidospores. Isolates COAD 2396 (T. atroviride), E48 (Cordyceps sp.) and E486 (Aspergillus sp.) reduced the severity of the disease to less than 50% of the levels observed in the controls when applied at 72h, 24h before or simultaneously with H. vastatrix on coffee leaf discs. Over 60% reduction of disease severity was obtained when E48 (Cordyceps sp.) was applied xiiion coffee plants 72h before inoculation with H. vastatrix. All species of Trichoderma were able to colonize coffee stems and leaves as endophytes except for COAD 2399 – Trichoderma sp. nov1. Additionally, to those studies one selected isolate (COAD 2482 - T. parareesei) was tested for growth stimulation in a model-plant species (tomato). This involved four tomato cultivars: Cereja, Italiano, Maça and Santa Cruz. The results showed that the application of the COAD 2482 isolate produced a beneficial effect which was only statistically significant for the cultivar "Santa Cruz". For that cultivar the significant effect was on the growth and development of the root system.
Prospecting of endophytic fungi producing volatile organic compounds: taxonomy, identification of volatiles and potential uses for the biological control of postharvest diseases
(Universidade Federal de Viçosa, 2017-02-17) Gomes, André Angelo Medeiros; Pereira, Olinto Liparini; Lopes, Ueder Pedro; Queiroz, Marisa Vieira de
In the search for alternative strategies to control of postharvest diseases in fruits and vegetables aimed at reducing the use of fungicides, was conducted a prospection to endophytic fungi capable of emitting volatile compounds with antimicrobial properties. Through parallel growth technique, directed towards the isolation of fungi producing volatile antimicrobials, endophytic isolates of coffee and carqueja plants were obtained and in preliminary test inhibited the growth of Aspergillus ochraceus by the emission of volatile compounds. The presence of at least three distinct species of Muscodor was verified, and a new taxon of Simplicillium by clarifying the identity of the endophytic isolates obtained through comparative studies of morphological structures, BLAST of gene sequences and phylogenetic analyzes. M. yucatanensis, Muscodor sp. and M. coffeanum isolates were obtained from coffee branches, the latter also isolated in leaves of carqueja. The antimicrobial activity of these isolates was demonstrated against Aspergillus species frequently associated with coffee beans by in vitro mycofumigation. In addition, mycofumigation with M. coffeanum CDA 741 inhibited the growth of A. ochraceus inoculated in coffee beans. The compounds present in the volatile mixture emitted by each isolate were identified by solid-phase micro-extraction gas chromatography and mass spectroscopy. Simplicillium sp. CDA 734, a new species of endophytic Cordycipitaceae from coffee plants, will be proposed through comparative studies of its morphology combined with phylogenetic analyzes. Simplicillium sp. CDA 734 inhibited the growth of A. ochraceus, A. tubingensis, A. sydowii and A. niger by mycofumigation. Among the compounds identified in the volatile mixture emitted by Simplicillium sp. CDA 734, 1-Propanone, 1-(5-methyl-2-furanyl)-, Cyclopropane, 1- ethoxy-2,2-dimethyl-3-(2-phenylethynyl)-, and 2-Propenoic acid, 3-(2-formyl-4- methoxyphenyl)-, ethyl ester, (E)- were those with the highest percentage of peak per area. In mycofumigation of organic strawberries inoculated with Colletotrichum acutatum e Botrytis cinerea, M. coffeanum CDA 739 decreases 100 and 81% the incidence of anthracnose and gray mold in the fruits, respectively. Mycofumigation through sachets containing rye grains colonized by M. coffeanum CDA 739 significantly reduced the incidence of anthracnose in fruits inoculated with C. acutatum, making possible its use in large-scale to control postharvest strawberry diseases through mycofumigation.
Isolates of Aspergillus, Clonostachys and Trichoderma from Africa as potential biocontrol agents against coffee leaf rust
(Universidade Federal de Viçosa, 2022-03-14) Kapeua Ndacnou, Miraine; Barreto, Robert Weingart
Hemileia vastatrix – the coffee leaf rust (CLR) fungus – is native from Africa and an exotic invasive species in all other areas of the world where coffee is grown. It causes the worst disease of coffee, but in Africa, it is not regarded as the worst pathogen of the crop. Management of CLR has relied on escaping the disease through the highland plantation, using resistant coffee varieties and fungicide applications. There are limitations for each of these strategies and novel approaches for CRL management are necessary. It has been conjectured that natural enemies of H. vastatrix endemic to Africa might have been overlooked and that such antagonists might have the potential for CLR management. Surveys conducted since 2015 in Cameroon, Ethiopia and Kenya, have revealed numerous mycoparasitic fungi attacking CLR in the field as well as endophytic fungi growing inside healthy coffee plants (several of which were, or are being, described as new to science), which might play a bodyguard role, protecting the plants against the disease. Results of previous studies and of the present research seem to confirm this hypothesis. A series of taxonomic and polyphasic studies allowed to identify isolates of Aspergillus and Clonostachys as belonging to Aspergillus flavus, Clonostachys byssicola, C. rhizophaga and C. rosea f. rosea. All the selected endophytic isolates (confirmed here regardless of the genus, to grow as endophytes in coffee), including Trichoderma strains were demonstrated to inhibit the germination of H. vastatrix in vitro. The isolate of A. flavus was shown not to produce aflatoxin. Beforehand applications of a series of isolates, of Clonostachys, Trichoderma and also of A. flavus, on young C. arabica plants (a combination of soil and foliar applications) followed by inoculation with H. vastatrix led to the significant reductions in CLR severity. Two Clonostachys rhizophaga isolates (COAD 2981 and COAD 2982), and one C. rosea isolate (COAD 2984) yielded the best highly significant (p < 0.001) results for reduction of CLR severity among the Clonostachys isolates. Trichoderma guizhouense (COAD 2398), T. virens (COAD 2400) and T. theobromicola (COAD 2406) also produced highly significant (p < 0.001) levels of CLR severity reduction. This is the first study reporting anti-CLR biocontrol potential for African isolates of A.flavus, Clonostachys and Trichoderma. And, they may pave the way towards preventive treatment of coffee plants with ‘bodyguard’ endophytes antagonistic to H. vastatrix as well as their use for control of CLR in the field. A continuation of this work is required to better assess this possibility. Keywords: Classical biocontrol. Coffee rust. Endophytes. Phylogeny. Taxonomy.
Sistemas conservacionistas de manejo integrado de plantas daninhas na cultura do café
(Universidade Federal de Viçosa, 2020-11-06) Zaidan, Ursula Ramos; Freitas, Francisco C. L. de; Costa, Maurício Dutra; Santos, Ricardo H. Silva
O manejo de plantas daninhas é um aspecto de suma importância no cultivo de café, pois trata- se de uma cultura sensível à competição por água, luz e nutrientes. As plantas daninhas usualmente são controladas de forma intensiva e sem rotação de métodos de controle, o que vem causando a depauperação das lavouras, esgotamento dos solos e seleção de espécies de difícil controle. Fato que vem causando a depauperação das lavouras, esgotamento dos solos e seleção de espécies de difícil controle. O objetivo deste estudo foi avaliar o efeito de diferentes estratégias de controle de plantas daninhas sobre a composição florística, a produtividade e a qualidade do solo de lavoura cafeeira mensurada por meio de indicadores microbiológicos, ao longo de três anos. O experimento foi conduzido em lavoura de café (Coffea arabica L.) estabelecida, onde foram avaliadas cinco estratégias de manejo de plantas daninhas na entrelinha do cafeeiro: cultivo de Urochloa ruziziensis, Pueraria phaseoloides e vegetação espontânea mantidos por roçada, para formação de cobertura vegetal sobre o solo; controle da vegetação espontânea com duas aplicações de herbicidas ao longo do ano e solo mantido “no limpo” por meio de capinas manuais. O primeiro capítulo aborda o estudo fitossociológico nas unidades experimentais e demonstra que estratégias de manejo de plantas daninhas modificam a composição florística, a diversidade e a densidade destas. A capina manual selecionou e aumentou a densidade das espécies Cyperus rotundus e C. esculentus nas unidades experimentais. Este estudo remete à compreensão de que estratégias de manejo com produção e manutenção de cobertura vegetal viva ou morta sobre o solo, como no cultivo de U. ruziziensis e P. phaseoloides na entrelinha, são alternativas para reduzir a infestação de plantas daninhas e que a adoção de roçadas, controle químico e capinas devem ser intercalados no intuito de evitar pressão de seleção de espécies adaptadas aos respectivos métodos de controle. O segundo capítulo avalia a produtividade e granulometria dos grãos de café, também em função das estratégias de manejo. No período avaliado a produtividade não foi afetada pelos métodos de controle. Nas unidades experimentais em que o solo foi mantido descoberto os grãos de café apresentaram maior granulometria. Embora os métodos de manejo com manutenção de palhada sobre o solo não tenham apresentado benefícios em termos de produtividade no período avaliado, deve-se considerar os beneficios relacionados à proteção e qualidade do solo à médio e longo prazos. No terceiro capítulo, avaliou-se a qualidade e a sustentabilidade do sistema solo-planta por meio da análise de indicadores microbiológicos sensíveis à distúrbios ocorridos no solo relacionados as estratégias de manejo de plantas daninhas. Neste estudo verificou-se que os indicadores microbiológicos utilizados não indicaram diferenças entre as estratégias de manejo de plantas daninhas quando em condição de estresse hídrico por baixa disponibilidade de água no solo. Entretanto, observou-se diferença nos valores de gC0O> com tendência de melhoria da qualidade do solo e da sustentabilidade do sistema nas estratégias de manejo em que houve acúmulo de matéria seca sobre o solo quando as avaliações foram realizadas na época do ano com alto índice pluviométrico. O manejo de plantas daninhas no cafeeiro deve ser realizado integrando diferentes métodos de controle, procurando manter a cobertura do solo com material vegetal de modo a evitar a seleção de espécies de plantas daninhas de dificil controle, preservando a microbiota do solo e mantendo a produtividade e qualidade dos grãos, em um sistema de produção sustentável. Palavras-chave: Composição florística no cafeeiro. Atividade microbiana no solo. Manejo conservacionista de plantas daninhas. Cobertura vegetal.
Análise de elementos transponíveis em Hemileia vastatrix e Coffea spp
(Universidade Federal de Viçosa, 2022-11-28) Silva, Lucas Fagundes da; Zambolim, Laércio; Caixeta, Eveline Teixeira
A ferrugem do cafeeiro é causada pelo fungo Hemileia vastatrix Berk. & Broome, um parasita obrigatório que infecta folhas de plantas do gênero botânico Coffea. Entre as espécies cultivadas deste gênero, Coffea arabica é a mais suscetível. A desfolha precoce pode levar à morte de ramos, seguido de perdas da produtividade no ano subsequente. Os danos podem alcançar índices de 50% quando as condições são favoráveis. Há um consenso que existe grande variabilidade genética na população de H. vastatrix e o surgimento de novas raças são um grande desafio para o manejo da doença. A raça II de H. vastatrix é a mais prevalente e a raça XXXIII suplantou a resistência de algumas cultivares comerciais de C. canephora no Brasil. No entanto, como o ciclo sexual ainda é parcialmente descrito, não são claros quais são mecanismos-chave de variabilidade genética ligados ao surgimento de raças em H. vastatrix. Nesse contexto, os elementos transponíveis (ETs) podem ser uma abordagem promissora, porém, pouco explorada nos estudos que visam a compreender a variabilidade genética em raças de H. vastatrix. Este trabalho teve como objetivo verificar o impacto de retrotransposons e elementos transponíveis de DNA nos genomas de H. vastatrix, C. arabica, C. canephora e C. eugenioides. Foram desenvolvidos scripts de bioinformáticas para identificação, caracterização e analise da divergência genética. No capitulo I, foram identificados ETs expressos nas interações de compatibilidade entre H. vastratrix e o cafeeiro. No capítulo II, as populações dos ETs foram estruturadas de acordo com as espécies de café analisadas. No capítulo III, genótipos de café arábica foram agrupadas em função do padrão de resistência às raças II e XXXIII de H. vastatrix. Este trabalho relata novos ETs e apresenta novas informações sobre seus os impactos na coevolução entre o H. vastatrix e cafeeiro. Palavras-chave: Transcriptoma. Hemileia. Coffea. Transposons.

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