RESUMO:Objetivou-se avaliar o potencial alelopático de extratos aquosos de braquiária, girassol e sorgo na germinabilidade e crescimento inicial de alface (Lactuca sativa L.) visando o uso destes extratos como herbicida natural. O estudo foi realizado no Laboratório de Fisiologia Vegetal da Universidade Federal do Recôncavo da Bahia. Foi instalado um experimento no delineamento inteiramente casualizado, com 4 tratamentos e 6 repetições. Os tratamentos foram extratos de braquiária, girassol, sorgo e como controle, água destilada. Os extratos foram obtidos, utilizando 200 g de material vegetal para 1000 mL de água destilada. Os aquênios de alface foram distribuídos em caixa gerbox contendo duas folhas de papel germitest umedecidas com os tratamentos e levadas para câmara de germinação. A germinação foi acompanhada diariamente. Foram avaliados o tempo médio de germinação e, após dez dias, o crescimento inicial, medindo-se o comprimento da parte aérea (CPA) e o comprimento do sistema radicular (CSR). Os dados gerados foram submetidos à análise de variância e as médias comparadas pelo teste de Tukey. Com base nos resultados, os extratos de braquiária, girassol e sorgo não afetaram a germinação da alface, mas os de braquiária e sorgo aumentaram o tempo médio de germinação. Os extratos causaram aumento na parte aérea, diminuíram o crescimento do sistema radicular e a formação de plântulas normais. Por causarem inibição no crescimento do sistema radicular da alface, apresentam potencial para serem utilizados como herbicidas naturais.Palavras-chave: alelopatia, compostos secundários, extratos vegetais, herbicidas naturais, Lactuca sativa L.ABSTRACT: Evaluation of extracts from Helianthus annuus, brizantha and Sorghum bicolor with allelopathic potential for use as a natural herbicide. This study aimed to evaluate the allelopathic potential of aqueous extracts of Brachiaria, sunflower, sorghum germination and early growth of lettuce (Lactuca sativa L.), in the attempt of employing these extracts as a natural herbicide. The study was conducted at the Laboratory of Plant Physiology of the Universidade Federal do Recôncavo da Bahia. A trial was arranged in a completely randomized design with 4 treatments and 6 replications. The treatments were extracts of Brachiaria, sunflower, sorghum, and, as a control, distilled water. The extracts were obtained by using 200 g of plant material in 1000 mL of distilled water. First, the lettuce seeds were distributed in a seedling box containing two sheets of germitest moistened paper with treatments, and then were taken to a germination chamber. The germination was daily monitored. The average germination time and the initial growth were evaluated after ten days, through the measuring of the aerial part length (APL) and the root system length (RSL). The data generated were subjected to analysis of variance and the means were compared by the Tukey test. Based on the results, the extracts of Brachiaria, sunflower and sorghum did not affect the germination of lettuce, but, on the other hand, ...

Resumo -O objetivo deste trabalho foi determinar as características químicas do óleo essencial de alecrim e o seu efeito na produtividade, no controle da mancha da folha e do míldio, e na indução de resistência em videira 'Isabel'. O experimento foi realizado em vinhedo comercial, em dois ciclos consecutivos. Os tratamentos consistiram das doses do óleo essencial: 0, 500, 1.000, 2.000 e 4.000 µL L -1 , além dos tratamentos Tween 80%, calda bordalesa, acibenzolar-S-metil e mancozebe. Foram avaliados a severidade da mancha da folha e do míldio, a atividade das enzimas quitinase e catalase, a massa e o número de cachos e as características químicas das uvas. Houve efeito quadrático das doses do óleo essencial de alecrim, para severidade da mancha da folha e do míldio da videira, nos dois ciclos, com resultados semelhantes aos dos tratamentos com calda bordalesa, acibenzolar-S-metil e mancozeb. Também houve aumento no número e na massa dos cachos, bem como na produtividade. O óleo essencial não interferiu nas características químicas das uvas. Observaram-se aumento na atividade da enzima quitinase e redução na atividade da catalase nas folhas. O óleo essencial nas doses de 500, 1.000 e 2.000 μL L -1 é uma alternativa para o controle de doenças da videira 'Isabel'.Termos para indexação: Rosmarinus officinalis, Vitis labrusca, sustentabilidade, viticultura. Rosemary essential oil in the control of diseases and induction of resistance in grapevineAbstract -The objective of this work was to determine the chemical qualities of rosemary essential oil and its effect on productivity, on the control of leaf spot and mildew, and on the induction of resistance in 'Isabel' grapevine. The experiment was carried out in a commercial vineyard, in two consecutive cycles. The treatments consisted of the essential oil doses: 0, 500, 1,000, 2,000, and 4,000 µL L -1 , besides the Tween 80%, bordeaux mixture, acibenzolar-S-methyl, and mancozeb treatments. Severity of leaf blight and mildew, the activity of chitinase and catalase enzymes, and mass and number of clusters and chemical characteristics of grapes were evaluated. There was a quadratic effect as affected by the doses of essential rosemary oil, for severity of leaf spot and mildew in grapevine, in both cycles, with results similar to those of bordeaux mixture, acibenzolar-S-methyl, and mancozeb. There was also an increase in the number and mass of clusters, as well as in productivity. The essential oil did not affect the chemical characteristics of grapes. An increase in the activity of the chitinase enzyme and a decrease in the catalase activity were observed in leaves. Essential oil at the doses of 500, 1,000, and 2,000 µL L -1 is an alternative for the control of diseases in 'Isabel' grapevine.

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2RESUMO -A homeopatização de óleos essenciais revela-se como uma alternativa para o controle de fitopatógenos e na indução de compostos de defesa em plantas, como as fitoalexinas. Neste sentido, o objetivo do trabalho foi de avaliar o efeito de soluções dinamizadas de Eucalyptus citriodora (EC) e Cymbopogon citratus (CC) na germinação de conídios de Alternaria solani e Corynespora cassiicola e na produção de fitoalexinas em soja. Para os testes foram utilizados os tratamentos homeopáticos: 6CH, 12CH, 30CH, 60CH, 100CH e 200CH de ambos os óleos. A porcentagem de germinação foi determinada 4 horas após incubação dos patógenos na presença dos tratamentos, em placas tipo Elisa a 25 ºC, e feita contagem de esporos em microscópio óptico. Para fitoalexinas, cotilédones de soja oriundos de sementes cultivadas em areia estéril foram cortados na superfície inferior e submetido aos tratamentos, permanecendo no escuro por 20 horas. A gliceolina formada foi extraída e determinada em espectrofotômetro. Todas as dinamizações aplicadas reduziram a germinação de ambos patógenos, chegando à redução de 59% em A. solani e 42% em C. cassiicola por CC 30CH. As dinamizações testadas não foram eficientes para indução de gliceolina, indicando maior potencial dos tratamentos sobre os patógenos em comparação a elicitação destes compostos de defesa. Baseando-se nestes resultados, é possível evidenciar o potencial de tratamentos homeopáticos no controle de A. solani e C. cassiicola. O processo de homeopatização manteve as propriedades antimicrobianas dos óleos testados. Palavras-chave: Eucalyptus citriodora. Cymbopogon citratus. Alternaria solani. Corynespora cassiicola. Controle alternativo de patógenos.ABSTRACT -The homeopathic use of essential oils is seen as an alternative in the control of plant pathogens and in the induction of such defensive plant compounds as phytoalexins. The aim of this study therefore, was to evaluate the effect of dynamised solutions of Eucalyptus citriodora (EC) and Cymbopogon citratus (CC) on conidial germination in Alternaria solani and Corynespora cassiicola, and on the production of phytoalexins in the soybean. The following homeopathic treatments from both oils were used in the tests: 6CH, 12CH, 30CH, 60CH, 100CH and 200CH. Germination percentage was determined four hours after incubation of the pathogens in the presence of the treatments using Elisa plates at 25 °C; spore counts were made by optical microscope. For the phytoalexins, soybean cotyledons from seeds grown in sterile sand were cut on their lower surface and subjected to the treatments, remaining in the dark for 20 hours. The gliceolin formed was extracted and determined by spectrophotometer. All the levels of dynamisation applied reduced germination in both pathogens, reaching 59% for A. solani and 42% for C. cassiicola with CC 30CH. The dynamisations under test were not efficient in gliceolin induction, demonstrating a greater potential of the treatments for pathogens, when compared to induction of these defensive compounds. Based on the resu...

The use of elicitors in plants for disease control is demonstrated by the accumulation of phytoalexins. Among these elicitors, metabolic products from fungi have been shown to be effective in the activation of mechanisms of induced resistance. Thus, this study aimed to evaluate the effects of filtrates from the saprobic fungi Curvularia inaequalis, Pseudobotrytis terrestris, Memnoniella echinata and Curvularia eragrostidis in inducing phaseolin, glyceolin and deoxyanthocyanidins. For this, fungal mycelial disks were liquid-subcultured in potato dextrose (BD) media and maintained in BOD at 25 °C and 12 h of light and darkness. After 20 days, the cultures were filtered and, the filtrates were used in the experiments. Phaseolin was measured in etiolated hypocotyls of bean. For glyceolin evaluation, cotyledons of soybean were used. The deoxyanthocyanidin accumulation was evaluated in etiolated mesocotyls of sorghum. The results were subjected to analysis of variance and compared by regression tests (p < 0.05). The filtrates of the saprobic fungi C. eragrostidis, C. inaequalis, P. terrestris and M. echinata promoted 9, 8, 9 and 7% greater increases in the concentration of phaseolin accumulations, respectively. The glyceolin accumulation varied with the concentration of C. eragrostidis, C. inaequalis and P. terrestris by adjusting the behavior to a cubic model. The deoxyanthocyanidin accumulation increased with concentration, while the filtrates of M. echinata and C. eragrostidis promoted 2 to 3 times more increases than the application of water. The filtrates of P. terrestris, C. eragrostidis, C. inaequalis and M. echinata induced accumulations of phytoalexins in soybean, beans and sorghum.