Influência da espessura de embalagem de polietileno na deterioração fisiológica em raízes de mandioca

Cassava (Manihot esculenta Crantz) cv. Baiana roots were packed in 50 µ, 100 µ and 150 µ thickness poliethylene bags and stored in room conditions. At zero, three, six and nine days during the storage period, evaluations were made in five roots of each treatment. It was concluded that during the storage period a decrease was observed in total C vitamin, ascorbic and dehydroascorbic acid contents, while physiological deterioration values, peroxidase activity, total phenolics and their dimeric, oligomeric and polimeric forms (control and 50 µ package) of phenolics, were increased. The increase in the thickness of the poliethylene bags caused reductions in peroxidase activity, dehydroascorbic acid % C vitamin ration and physiological deterioration. Raízes de mandioca (Manihot esculenta Crantz) da cultivar Baiana foram embaladas em sacos de polietileno de 50 µ,100 µ e 150 µ de espessura, e raízes sem embalagem (testemunha) foram armazenadas em condições ambientais. Aos zero, três, seis, e nove dias de armazenamento foram retiradas cinco raízes/tratamento/repetição, das quais foram feitas as avaliações. Concluiu-se que o tempo de armazenamento provocou diminuições nos teores de vitamina C total, ácido deidroascórbico e ácido ascórbico e aumento no grau de deterioração fisiológica, atividade peroxidase, e nos teores de fenólicos totais e de suas frações diméricas, oligoméricas e poliméricas (testemunha e embalagem 50 µ). A espessura do saco de polietileno influencia nas reações oxidativas, fato evidenciado por redução da atividade peroxidase, percentagem de ácido deidroascórbico e grau de deterioração fisiológico.

Cyanogenic glycosides and graft compatibility of Asian pear grafted onto Pyrus calleryana and P. betulifolia

O objetivo deste trabalho foi avaliar os níveis dos glicosídeos cianogênicos amigdalina e prunasina em 13 cultivares de pereiras asiáticas (Pyrus pyrifolia) enxertadas sobre P. calleryana e P. betulifolia, bem como verificar os seus efeitos sobre a compatibilidade de enxertia. Utilizou-se o delineamento experimental inteiramente casualizado com três repetições. Foram avaliadas as cultivares: Ya li, Shinsui, Oku Sankichi, Hakucho, Nitaka, Shinseiki, Suisei, Choujuurou, Nijisseiki, Kousui, Housui, Kikusui e Hakkou. Os glicosídeos cianogênicos não tiveram influência na compatibilidade de enxertia e no teor de clorofila das combinações entre as cultivares e os porta‑enxertos. A concentração de glicosídeos cianogênicos não se mostra um marcador eficiente da incompatibilidade de enxertia entre as combinações estudadas.The objective of this work was to evaluate the levels of the cyanogenic glycosides amygdalin and prunasin in 13 Asian pear cultivars (Pyrus pyrifolia) grafted onto P. calleryana and P. betulifolia, as well as to verify their effects on graft compatibility. The experimental design was completely randomized with three replicates. The evaluated cultivars were: Ya li, Shinsui, Oku Sankichi, Hakucho, Nitaka, Shinseiki, Suisei, Choujuurou, Nijisseiki, Kousui, Housui, Kikusui, and Hakkou. The cyanogenic glycosides had no influence on graft compatibility and on the chlorophyll content of the combinations between cultivars and rootstocks. The concentration of cyanogenic glycosides is not an effective marker of graft incompatibility among the studied combinations

Induction of systemic resistance to anthracnose in common bean by the avirulent delta race of Colletotrichum lindemuthianum

O objetivo deste trabalho foi avaliar o potencial da raça delta avirulenta do fungo Colletotrichum lindemuthianum, como protetora contra raças virulentas deste fungo e quanto à capacidade de induzir resistência sistêmica em feijoeiro-comum (Phaseolus vulgaris). Quatro cultivares de feijoeiro foram avaliadas quanto às alterações nas atividades de beta-1,3-glucanase e quitinase, em dois estádios de desenvolvimento (V2 e R6), três dias após a aplicação de suspensão de esporos de C. lindemuthianum raça delta avirulenta, em comparação com aplicações de água e ácido salicílico. As plantas foram, então, infectadas com o patótipo virulento 33/95 de C. lindemuthianum em suspensão e, depois de cinco dias, foram reavaliadas quanto à atividade das enzimas. Observaram-se acréscimos significativos nas atividades da beta-1,3-glucanase e quitinase, após inoculação do fungo indutivo, nas duas avaliações, nos dois estádios de desenvolvimento. As atividades da beta-1,3-glucanase e da quitinase variaram entre as cultivares e entre os estádios de desenvolvimento das plantas. A correlação entre o índice de severidade da doença e a atividade das enzimas foi altamente significativa. O uso de C. lindemuthianum raça delta avirulenta diminuiu a severidade da doença e pode ter potencial para controlar a antracnose do feijoeiro.The objectives of this work were to evaluate the potential of the avirulent delta race of Colletotrichum lindemuthianum as a protector against virulent races of this fungus and induce systemic resistance to anthracnose in common bean (Phaseolus vulgaris). Four common bean cultivars were evaluated for changes in the activities of beta-1,3-glucanase and chitinase at two common bean developmental stages, V2 and R6, three days after the infection with delta race of C. lindemuthianum, in comparison with control applications of water and salicylic acid. The plants were then infected with a spore suspension of 33/95, a virulent C. lindemuthianum patotype and reevaluated five days later for the enzyme activities. Significant increases in the activities of both beta-1,3-glucanase and chitinase were observed after inoculation of inductive fungus at the two evaluation periods, at both plant development stages. The activities of both beta-1,3-glucanase and chitinase varied among cultivars and among plant development stages. A significant correlation was observed between the disease severity and the enzyme activity. The avirulent delta race of C. lindemuthianum reduced the severity of anthracnose on common bean and may have the potential to control the disease

Potencial de rizobactérias no controle de Meloidogyne incognita em figueira

A figueira é economicamente importante pelo papel social que representa no contexto da agricultura familiar. No entanto, sua viabilidade econômica pode ser comprometida em áreas infestadas pelo nematoide das galhas (Meloidogyne incognita) devido à carência de medidas de controle efetivas e disponíveis. Assim, a inserção do controle biológico no manejo integrado dessa praga constitui-se como uma estratégia importante. As rizobactérias são consideradas biocontroladoras promissoras por promover o crescimento vegetal e/ou inibir a ação parasítica dos fitonematoides sobre as plantas hospedeiras. Dessa forma, objetivou-se com esse trabalho, avaliar o desempenho de 14 isolados bacterianos provenientes da rizosfera de figueira e de rochas de folhelhos betuminosos, no biocontrole de M. incognita em figueira. Mudas de figueira cv. ‘Roxo de Valinhos' microbiolizadas com os isolados bacterianos foram transplantadas em solo naturalmente infestado com M. incognita. Sete isolados (F08, F25, F71, F76, F78, FB34 e FB59), reduziram significativamente o fator de reprodução do nematoide das galhas (P<0,05) em valores que variaram entre 20 e 49%. Contudo, além de suprimir a multiplicação do patógeno, o isolado F78 (Streptomyces sp.) promoveu aumento do peso de raízes, maiores índices de clorofila e conteúdo das enzimas de resistência peroxidades e polifenol-oxidades, e, redução na concentração de fenóis das figueiras microbiolizadas. Nesse sentido, a condução de trabalhos adicionais nesse patossistema pode possibilitar a melhor compreensão dos mecanismos de atuação das bactérias testadas no biocontrole de M. incognita, além de fornecer informações adicionais para a implementação dessa técnica em um programa de manejo integrado do nematoide das galhas.The fig tree is economically important for the social role it plays in the context of family farming. However, its economic viability can be compromised in infested areas by root-knot nematode (Meloidogyne incognita) due to lack of effective and available control measures. Therefore, the insertion of the biological control on the integrated management of this pest constitutes an important strategy. The rhizobacteria are considered promising biocontrol agents for promoting plant growth and or inhibit the parasitic action of plant-parasitic nematodes in the host plants. So, the aim of this study was to evaluate the performance of 14 bacterial isolates from the rhizosphere of fig and shale rocks in biocontrol of M. incognita in fig. Seedlings of fig plants of cv. 'Roxo de Valinhos' were microbiolized with these bacterial isolates and they were transplanted in soil naturally infested with M. incognita subsequently. Seven isolates (F08, F25, F71, F76, F78, FB34 and FB59) reduced the reproduction factor of the root-knot nematode (P <0.05) at rate ranging between 20 and 49%. Besides to suppress the pathogen reproduction, the isolated F78 (Streptomyces sp.) promoting increasing of root weight, higher chlorophyll contents and content peroxidases and polyphenol oxidases resistance enzymes, and reduction of the phenol concentration of microbiolized fig plants. In this sense, conducting further studies in this pathosystem can enable a better understanding of the action mechanisms of the bacteria tested in the biocontrol of M. incognita, as well as providing additional information for the implementation of this technique in an integrated management program of root-knot nematode

Peroxidase and polyphenol oxidase activity in bean anthracnose resistance

O objetivo deste trabalho foi avaliar a influência das enzimas peroxidase e polifenoloxidase na resistência à antracnose de quatro cultivares de feijão. Plântulas de feijão foram pulverizadas com ácido salicílico e com a raça delta de Colletotrichum lindemuthianum (fungo indutor) e submetidas à inoculação do patótipo virulento 33/95 de C. lindemuthianum três dias após a aplicação do fungo indutor e do ácido salicílico. Essas plantas foram avaliadas quanto à atividade enzimática e teores de fenóis, três dias após a aplicação do fungo indutor e cinco dias após a inoculação do patótipo virulento. Acréscimos nas atividades dessas enzimas foram maiores nos tratamentos com ácido salicílico e fungo indutor em todas as cultivares. Maiores estímulos nas atividades enzimáticas foram observados nas cultivares com maior resistência à doença. Constatou-se o aparecimento de uma isoperoxidase nos tratamentos com fungo indutor, ácido salicílico, após inoculação do patótipo virulento, e na testemunha, nas cultivares AB 136, Rio Tibagi e Macanudo. Houve correlação positiva entre as atividades da peroxidase e da polifenoloxidase, os teores de compostos fenólicos e a resistência à antracnose.The objective of this work was to evaluate the influence of peroxidase and polyphenol oxidase enzymes in anthracnose resistance of four bean cultivars. Seedlings were sprinkled with salicylic acid and delta race of Colletotrichum lindemuthianum (inducer fungus) and after three days they were inoculated with 33/95 virulent pathotype of C. lindemuthianum. Enzyme activity and phenol levels were evaluated three days afte rinducer fungus application and five days after inoculation with virulent pathotype. Plants treated with salicylic acid and inducer fungus presented higher activity increases of both enzymes, in all cultivars. Higher impulses in enzymatic activity were observed in cultivars with higher disease resistance. One isoperoxidase appeared in treatments with inducer fungus, salicylic acid, after inoculation with virulent pathotype, and in control plants, in AB 136, Rio Tibagi and Macanudo cultivars. Positive correlation was observed among peroxidase and polyphenol oxidase activity, phenolic compound levels and anthracnose resistance

Modeling the impact of child vaccination (5–11 y) on overall COVID-19 related hospitalizations and mortality in a context of omicron variant predominance and different vaccination coverage paces in Brazil

Background Developing countries have experienced significant COVID-19 disease burden. With the emergence of new variants, particularly omicron, the disease burden in children has increased. When the first COVID-19 vaccine was approved for use in children aged 5–11 years of age, very few countries recommended vaccination due to limited risk-benefit evidence for vaccination of this population. In Brazil, ranking second in the global COVID-19 death toll, the childhood COVID-19 disease burden increased significantly in early 2022. This prompted a risk-benefit assessment of the introduction and scaling-up of COVID-19 vaccination of children. Methods To estimate the potential impact of vaccinating children aged 5–11 years with mRNA-based COVID-19 vaccine in the context of omicron dominance, we developed a discrete-time SEIR-like model stratified in age groups, considering a three-month time horizon. We considered three scenarios: No vaccination, slow, and maximum vaccination paces. In each scenario, we estimated the potential reduction in total COVID-19 cases, hospitalizations, deaths, hospitalization costs, and potential years of life lost, considering the absence of vaccination as the base-case scenario. Findings We estimated that vaccinating at a maximum pace could prevent, between mid-January and April 2022, about 26,000 COVID-19 hospitalizations, and 4200 deaths in all age groups; of which 5400 hospitalizations and 410 deaths in children aged 5–11 years. Continuing vaccination at a slow/current pace would prevent 1450 deaths and 9700 COVID-19 hospitalizations in all age groups in this same time period; of which 180 deaths and 2390 hospitalizations in children only. Interpretation Maximum vaccination of children results in a significant reduction of COVID-19 hospitalizations and deaths and should be enforced in developing countries with significant disease incidence in children