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1.
Braz. j. biol ; 83: e244718, 2023. graf
Artigo em Inglês | LILACS-Express | LILACS, VETINDEX | ID: biblio-1278533

RESUMO

Abstract The objective of this study was to evaluate the activity of antioxidant enzymes, the functioning of the photosystem II and quality of C. xanthocarpa seedlings cultivated under intermittent water deficit and shading levels and the influence of shading on recovery potential after suspension of the stress conditions. The seedlings were subjected to three levels of shading (0, 30, and 70%), six periods of evaluation (start: 0 days; 1st and 2nd photosynthesis zero: 1st and 2nd P0; 1st and 2nd recovery: 1stand 2nd REC; and END), and two forms of irrigation (control: periodically irrigated to maintain 70% substrate water retention capacity, and intermittent irrigation: suspension of irrigation). The plants subjected to intermittent irrigation conditions at 0% shading showed a reduction in water potential (Ψw) and potential quantum efficiency of photosystem II (Fv/Fm) and maximum efficiency of the photochemical process (Fv/F0) and an increase in basal quantum production of the non-photochemical processes (F0/Fm). Superoxide dismutase (SOD) activity was higher in the leaves than in the roots. The C. xanthocarpa is a species sensitive to water deficit but presents strategies to adapt to an environment under temporary water restriction, which are more temporary are most efficient under shading. The seedlings with water deficit at all levels of shading exhibited higher protective antioxidant activity and lower quality at 0% shading. The shading minimizes prevents permanent damage to the photosystem II and after the re-irrigation, the evaluated characteristics showed recovery with respect to the control group, except POD and SOD activities in the leaves.


Resumo O objetivo deste estudo foi avaliar a atividade de enzimas antioxidantes, o funcionamento do fotossistema II e a qualidade de mudas de C. xanthocarpa cultivadas sob déficit hídrico intermitente e níveis de sombreamento e a influência do sombreamento sobre o potencial de recuperação após suspensão das condições de estresse. As mudas foram submetidas a três níveis de sombreamento (0, 30 e 70%), seis períodos de avaliação (início: 0 dias; 1ª e 2ª fotossíntese zero: 1ª e 2ª P0; 1ª e 2ª recuperação: 1ª e 2ª REC; e final), e duas formas de irrigação (controle: periodicamente irrigado para manter 70% da capacidade de retenção de água do substrato, e irrigação intermitente: suspensão da irrigação). As plantas submetidas às condições de irrigação intermitente a 0% de sombreamento apresentaram redução do potencial hídrico (Ψw) e eficiência quântica potencial do fotossistema II (Fv/Fm) e máxima eficiência do processo fotoquímico (Fv/F0) e aumento da produção quantica basal dos processos não fotoquímicos (F0/Fm). A atividade da superóxido dismutase (SOD) foi maior nas folhas do que nas raízes. C. xanthocarpa é uma espécie sensível ao déficit hídrico, mas apresenta estratégias para se adaptar a um ambiente com restrição hídrica temporária, sendo mais eficientes sob sombreamento. As mudas com déficit hídrico em todos os níveis de sombreamento exibiram maior atividade antioxidante protetora e menor qualidade no sombreamento 0%. O sombreamento minimiza danos permanentes ao fotossistema II e após a re-irrigação, as características avaliadas apresentaram recuperação em relação ao grupo controle, exceto atividades de POD e SOD nas folhas.

2.
Braz. j. biol ; 82: e244331, 2022. graf
Artigo em Inglês | LILACS-Express | LILACS | ID: biblio-1249255

RESUMO

Abstract The aim of this research was to evaluate the effect of abscisic acid (ABA) on gas exchange and the activity of antioxidant enzymes of Ormosia arborea (Vell.) Harms seedlings under water deficit and its influence on the recovery potential of the seedlings. The experiment was conducted using four treatments, being daily irrigation or water restriction without and with 10 μM ABA. Seedlings under water deficit + ABA showed greater adjustment to drought, and when re-irrigated, they restored photosynthetic metabolism and water potential. ABA minimizes the reduction in the photosynthetic metabolism and water potential of the leaf, however, it does not increase the antioxidant activity of the O. arborea seedlings under water deficit. These results suggest that this species exhibits plasticity, which enables it to survive also in environments subjected to temporary water deficit regardless of the supplementation of ABA. We suggest that other doses of ABA be researched to expand the beneficial effect of ABA on this species.


Resumo O objetivo deste trabalho foi avaliar o efeito do ácido abscísico (ABA) nas trocas gasosas e na atividade de enzimas antioxidantes de mudas de Ormosia arborea (Vell.) Harms sob deficiência hídrica e sua influência no potencial de recuperação das mudas. O experimento foi conduzido com quatro tratamentos, sendo eles irrigação diária ou restrição hídrica sem e com 10 μM ABA. As mudas sob déficit hídrico + ABA apresentaram maior ajuste à seca e ao serem re-irrigadas restabeleceram o metabolismo fotossintético e o potencial hídrico. O ABA minimizou a redução do metabolismo fotossintético e do potencial da água na folha, porém, não aumentou a atividade antioxidante de mudas de O. arborea sob déficit hídrico. Esses resultados sugerem que esta espécie apresenta plasticidade fisiológica, o que lhe permite sobreviver em ambientes sujeitos a déficit hídrico temporário, independente da suplementação de ABA. Sugerimos que outras doses de ABA sejam avaliadas para ampliar os efeitos benéficos do ABA sobre esta espécie.

3.
Braz J Biol ; 83: e244718, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34161459

RESUMO

The objective of this study was to evaluate the activity of antioxidant enzymes, the functioning of the photosystem II and quality of C. xanthocarpa seedlings cultivated under intermittent water deficit and shading levels and the influence of shading on recovery potential after suspension of the stress conditions. The seedlings were subjected to three levels of shading (0, 30, and 70%), six periods of evaluation (start: 0 days; 1st and 2nd photosynthesis zero: 1st and 2nd P0; 1st and 2nd recovery: 1stand 2nd REC; and END), and two forms of irrigation (control: periodically irrigated to maintain 70% substrate water retention capacity, and intermittent irrigation: suspension of irrigation). The plants subjected to intermittent irrigation conditions at 0% shading showed a reduction in water potential (Ψw) and potential quantum efficiency of photosystem II (Fv/Fm) and maximum efficiency of the photochemical process (Fv/F0) and an increase in basal quantum production of the non-photochemical processes (F0/Fm). Superoxide dismutase (SOD) activity was higher in the leaves than in the roots. The C. xanthocarpa is a species sensitive to water deficit but presents strategies to adapt to an environment under temporary water restriction, which are more temporary are most efficient under shading. The seedlings with water deficit at all levels of shading exhibited higher protective antioxidant activity and lower quality at 0% shading. The shading minimizes prevents permanent damage to the photosystem II and after the re-irrigation, the evaluated characteristics showed recovery with respect to the control group, except POD and SOD activities in the leaves.


Assuntos
Plântula , Água , Antioxidantes , Fotossíntese , Folhas de Planta
4.
Braz J Biol ; 82: e244331, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34076168

RESUMO

The aim of this research was to evaluate the effect of abscisic acid (ABA) on gas exchange and the activity of antioxidant enzymes of Ormosia arborea (Vell.) Harms seedlings under water deficit and its influence on the recovery potential of the seedlings. The experiment was conducted using four treatments, being daily irrigation or water restriction without and with 10 µM ABA. Seedlings under water deficit + ABA showed greater adjustment to drought, and when re-irrigated, they restored photosynthetic metabolism and water potential. ABA minimizes the reduction in the photosynthetic metabolism and water potential of the leaf, however, it does not increase the antioxidant activity of the O. arborea seedlings under water deficit. These results suggest that this species exhibits plasticity, which enables it to survive also in environments subjected to temporary water deficit regardless of the supplementation of ABA. We suggest that other doses of ABA be researched to expand the beneficial effect of ABA on this species.


Assuntos
Ácido Abscísico , Água , Antioxidantes , Secas , Fotossíntese , Folhas de Planta
5.
Neotrop Entomol ; 48(2): 323-331, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-30456722

RESUMO

The number of Tetrastischus howardi (Olliff) females to be released and their dispersion should be known, that way, used D. saccharalis pupae as sentinel host to measure parasitism as function of the release density of the parasitoid and its location in the field. Two sets of trials were run aiming first to define the number of parasitoids to be released and the dispersal of the parasitoid using plots in sugarcane commercial fields, respectively. Pieces of sugarcane stalk holding sentinel pupae were taken to the field and exposed to parasitism in both trials. The parasitoid was released at the rate of 20, 40, 80, and 160 females per sentinel pupa, except for the control plot without releasing. The parasitism rate was calculated based on the recovered pupae after 96 h of exposure time from releasing the parasitoids. The models estimated the best parasitism rate by releasing 102 parasitoids per pupa. In the second trial, sentinel pupae were arranged in five subsequent circles corresponding 4, 8, 12, 16, and 20 m around the central parasitoid releasing point at rate of 4, 8, 12, 16, and 18 pupae per circle. The mean estimated dispersal distance was 7.64 m, with a covering area of 80.07 m2. Based on these findings, release of T. howardi is recommended in 125 points per hectare of sugarcane at rate of 102 females per pupa of the pest aiming to achieve homogeneous distribution and parasitism.


Assuntos
Lepidópteros/parasitologia , Controle Biológico de Vetores/métodos , Saccharum , Vespas/fisiologia , Distribuição Animal , Animais , Feminino , Densidade Demográfica , Pupa/parasitologia
6.
Neotrop Entomol ; 43(5): 446-52, 2014 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-27193955

RESUMO

Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) causes significant losses in corn crops and necessitates the use of alternative control strategies, such as the application of bioinsecticides. We report the effect of methanolic leaf extracts of Annona dioica, Annona cacans, and Annona coriacea on the development and reproduction of S. frugiperda. A quantitative analysis was carried out to determine the total concentration of phenolics, flavonoids, and condensed tannin (CT) in leaf extracts. Corn leaves were immersed in a 1% methanolic leaf extract solution and fed to second instars of S. frugiperda. Leaf disks dipped in the synthetic insecticide Connect® (Bayer CropScience Ltda) composed of a neonicotinoid (imidacloprid) and a pyrethroid (ß-cyfluthrin), which are harmful to S. frugiperda, was used as positive control. Distilled water was used as a negative control treatment. The leaf extract of A. coriacea decreased larval survivorship, arrested pupal development, and affected the weight gain of S. frugiperda. A. dioica also affected larval survivorship, but its effects were more pronounced for the adult stage, as fecundity, fertility, egg hatchability, and embryonic development were severely affected. Leaf extracts from A. cacans had no effect on S. frugiperda. The leaf extracts of A. dioica and A. coriacea showed a higher content of flavonoids and phenols, respectively. Our results indicated that both A. dioica and A. coriacea have the potential for development as botanical insecticides.


Assuntos
Metanol/análise , Reprodução , Spodoptera/química , Animais , Annona , Larva , Nitrilas , Piretrinas , Spodoptera/crescimento & desenvolvimento
7.
Rev. bras. plantas med ; 15(4,supl.1): 655-663, 2013. graf, tab
Artigo em Português | LILACS | ID: lil-700004

RESUMO

Devido à devastação de áreas do Cerrado, muitas espécies nativas encontram-se ameaçadas de extinção e devido à ampla utilização de Anadenanthera falcata, estudos sobre a ecofisiologia da germinação e do crescimento das mudas tornam-se necessários. O presente trabalho objetivou avaliar o efeito do condicionamento osmótico e do sombreamento na germinação e no crescimento inicial de mudas de angico. As sementes foram pré-embebidas em soluções de diferentes concentrações de PEG e KNO3 e incubadas em temperatura de 10°C e 20°C durante 12 e 24 horas. Após estes períodos as sementes foram secas até atingirem os teores iniciais de umidade, sendo posteriormente colocadas para germinar em BOD na temperatura de 20-30°C em regime fotoperiódico de 8h luz e 16h de escuro. O tratamento testemunha e os pré-condicionamentos com KNO3 (-1,0 MPa) e PEG (-1,0 MPa) proporcionaram os melhores resultados de germinação em BOD. As sementes foram semeadas em bandejas e posteriormente transplantadas para embalagens plásticas, permanecendo sob telado coberto com sombrite de 50% e 70% de sombreamento e a pleno sol. Em BOD, os tratamentos de osmo-condicionamento, reduziram de forma negativa a germinação das sementes. Sob sombreamento, as doses avaliadas não influenciaram na emergência do angico, entretanto, sementes tratadas com KNO3 (-1,0 MPa) tiveram maior índice de velocidade de emergência sob pleno sol apresentando melhor desenvolvimento quando mantidas até os 145 dias de idade.


Due to the devastation of the Cerrado areas, many native species are threatened with extinction, and due to the widespread use of Anadenanthera falcata, studies on the ecophysiology of seed germination and seedling growth are necessary. This study aimed to evaluate the priming and shading effects on the germination and early growth of angico seedlings. The seeds were pre-soaked in solutions with different concentrations of PEG and KNO3 and incubated at 10°C and 20°C for 12 and 24 hours. After these periods the seeds were dried until reaching the initial moisture levels, and subsequently incubated in BOD at the temperature of 20-30°C under photoperiods of 8h of light and 16h of dark. The control treatment and pre-conditioning with KNO3 (-1.0 MPa) and PEG (-1.0 MPa) presented the best germination results in BOD. The seeds were sown in trays and then transplanted to plastic packages, remaining in a greenhouse covered with 50% and 70% shading, in full sun. In BOD, the priming treatments decreased the germination of seeds. Under shade, the doses evaluated did not affect the emergence of angico, however, seeds treated with KNO3 (-1.0 MPa) had a greater EVI, in full sun and showed a better development when maintained up to 145 days of age.


Assuntos
Fabaceae/crescimento & desenvolvimento , Germinação , Métodos de Embebição , Sementes/crescimento & desenvolvimento
8.
Rev. bras. plantas med ; 14(1): 18-25, 2012. ilus, tab
Artigo em Português | LILACS | ID: lil-644609

RESUMO

Folhas de Glycine max (L.) Merril,infectadas pelo fungo Phakopsora pachyrhizi H. Sydow & Sydow e tratadas com extratos vegetais foram avaliadas, visando determinar in vivo as modificações anatômicas nas diferentes estruturas/tecidos foliares, além de reconhecer prováveis mecanismos de defesa. Folhas de soja cultivar 181 provenientes do quinto nó foram inoculadas com fungo e tratadas com diferentes extratos vegetais, água e álcool 70%. Para comparação foram analisadas a anatomia das folhas sadia e infectada e realizadas medidas nas estruturas/tecidos foliares. Na folha infectada, observou-se destruição da epiderme e parênquima lacunoso, visível proliferação de tricomas e cutícula espessada, principalmente na face abaxial. Observou-se a presença de compostos fenólicos nas células da epiderme quando rompida, em função do crescimento micelial. Nas folhas infectadas e tratadas com os extratos vegetais de Azadirachta indica, Maytenus ilicifolia e Allium sativum, as estruturas/tecidos vegetais apresentaram aumento de espessura por alongamento celular.


Glycine max (L.) Merril leaves, infected by the fungus Phakopsora pachyrhizi H. Sydow & Sydow and treated with plant extracts, were evaluated with the aim of determining in vivo the anatomical modifications in different leaf structures and of identifying probable defense mechanisms. Leaves from the 181 soybean cultivar originated from the fifth node were inoculated with the fungus and treated with different plant extracts, water and alcohol at 70%. For comparison, the anatomy of the healthy and infected leaves was analyzed and the leaf structures were measured. In the infected leaf, there was destruction of the epidermis and lacunar parenchyma, apparent trichome proliferation and denser cuticle, especially on the abaxial surface. There were also phenolic compounds in ruptured epidermis cells, due to mycelium growth. In the infected leaves treated with Azadirachta indica, Maytenus ilicifolia and Allium sativum extracts, the plant tissues had an increase in thickness due to cell elongation.


Assuntos
Phakopsora pachyrhizi/isolamento & purificação , Folhas de Planta/crescimento & desenvolvimento , Soja/classificação , Fungos/isolamento & purificação , Extratos Vegetais/administração & dosagem , Sementes
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