Clomazone exposure-driven photosynthetic responses plasticity of Pontederia crassipes.

Clomazone is known to contaminate aquatic environments and have a negative impact on macrophytes. However, recent reports suggests that Pontederia crassipes Mart. can withstand clomazone exposure while maintaining growth rates. We hypothesized that this maintenance of growth is supported by photosynthetic plasticity of old leaves (developed before herbicide application), while new leaves (developed after application) exhibit phytotoxic symptoms. To investigate, two experiments were conducted with doses ranging from 0.1 mg L-1 to 0.5 mg L-1 plus untreated controls. Various parameters were measured in old and new leaves over 7, 12, and 15 d post-application, including visual symptoms, chlorophyll index, photosynthetic pigments, chlorophyll fluorescence, gas exchange, glycolate oxidase activity, carbohydrate content, leaf epidermis anatomy, and growth parameters. Clomazone exposure induced chlorosis, particularly in new leaves across all doses. These visual symptoms were accompanied by stomatal closure, restricting gas exchange and CO2 fixation, leading to reduced photosynthetic rates and carbohydrate synthesis. However, clomazone did not affect old leaves, which maintained photosynthetic activity, sustaining essential metabolic processes of the plant, including reproductive functions. By ensuring high reproductive rates and metabolic continuity, old leaves supported the species' persistence despite clomazone presence.

Alkaloids (emetine and cephalin) production - affected by full sunlight stress in Carapichea ipecacuanha.

This study evaluated the responses of Carapichea ipecacuanha to sunlight stress-induced changes in the electron transport chain and its extended effects on alkaloid production (emetine and cephalin). The treatments consisted of: (i). 50, 70, and 90% shading (controls) and their respective exposure to full sunlight; besides, full sunlight (55 days of direct sun exposure). Photosynthetic pigments, chlorophyll a fluorescence transient, antioxidant enzymatic system, and quantification of cephalin and emetine were analyzed. Several changes in the Chl a fluorescence induction were observed, such as a decline in the quantum yield of the conversion of photochemical energy and photosynthetic performance and; an increase in emetine production of plants exposed to full sunlight. These results demonstrated that ipecac plants are extremely sensitive to full exposure to solar radiation, especially in periods with high temperatures, such as in summer, however with increment in emetine production.

Herbicide weed control ­ induced differential tolerance and productivity in cowpea plants / Controle de ervas daninhas com herbicida - tolerância diferencial induzida e produtividade em plantas de feijão-caupi

The use of herbicides is a represents an efficient way to control the infesting plant population, since it is associated with low operational cost, and it does not demand large amounts of labour. An obstacle to growing cowpea (Vigna unguiculate) is the absence of herbicides registered for this crop. The objective of this work was to evaluate the tolerance of cowpea to herbicides. The experiment was carried out in a randomised block with treatment controls with and without weeding, Bentazon (720 g ha-1), Fluazifop-p-butyl (250 g ha-1), Fomesafen and a tank mix between Fluazifop-p-butyl + Fomesafen (250 + 187.5 g ha-1) with treatment replicates. The herbicides were applied on vegetative (V3 ­ stage) cowpea plants using a CO2-pressurised backpack sprayer with four spray tips TT 110.02 operating at a pressure of 2.5 bar and applying 240 litres of syrup per hectare. The cultivar BRS Guariba, with five planting lines per plot, was tested with the three central lines of the useful area, scoring 0.5 m of the ends. The species Oxalis latifolia was difficult to control. The Fluazifop-p-butyl + Fomesafen mixture presented better control of weeds. The herbicides caused phytotoxicity to cowpea and reduced leaf area and dry mass. The productivity of the crop was affected due to the low control of weeds. It was concluded that the cowpea presented differential tolerance to the herbicides tested doses.

O uso de herbicidas é uma alternativa promissora, pois permite um controle eficiente da população de plantas infestantes, associado a baixo custo operacional e sem exigir grandes quantidades de mão de obra. No entanto, um entrave no controle de plantas daninhas no feijão-caupi é a ausência de herbicidas registrados para essa cultura. Objetivou-se com este trabalho avaliar a tolerância do feijão-caupi cultivar BRS Guariba, a herbicidas. Um ensaio foi conduzido a campo em blocos casualizados composto dos tratamentos, testemunhas com e sem capina, Bentazon (720 g i.a. ha-1), Fluazifop-p-butyl (250 g i.a. ha-1), Fomesafen (187,5 g i.a. ha-1) e mistura de tanque entre Fluazifop-p-butyl + Fomesafen (250 + 187,5 g i.a. ha-1) com 4 repetições. Os herbicidas foram aplicados com plantas de caupi em estágio vegetativo V3 com pulverizador costal pressurizado por CO2 com quatro pontas de pulverização TT 110.02 operando a uma pressão de 2,5 Bar e aplicando 240 L ha-1 de calda. As parcelas foram compostas 5 linhas de plantio com cinco metros de comprimento, espaçadas de 0,5 m, com as 3 linhas centrais de área útil, desprezando 0,5 m das extremidades. Avaliou-se a comunidade infestante, a eficiência de controle de plantas daninhas, a tolerância e a produtividade do feijão-caupi. A espécie Oxalis latifolia foi encontrada em todos os tratamentos e apresentou difícil controle. A mistura Fluazifop-p-butyl + Fomesafen apresentou melhor controle das plantas daninhas. Os herbicidas ocasionaram fitotoxicidade ao feijão-caupi e redução de área foliar e massa seca de plantas. A produtividade da cultura foi reduzida nos tratamentos com baixo controle de plantas daninhas bem como nos tratamentos que provocaram toxicidade elevada. Conclui-se que o feijão-caupi apresentoutolerância diferencial aos herbicidas nas doses testadas.

Resistance of rice genotypes to Tibraca limbativentris (Hemiptera: Pentatomidae).

The Tibraca limbativentris is a pest that causes rice crop damage and may lead to grain yield reductions of up to 90%. The most commonly used tactic for T. limbativentris control is chemical, which causes adverse effects on the environment. This study was conducted to identify sources of antixenosis and antibiosis resistance to T. limbativentris mediated by the hardness and diameter of the stem of the rice plant. Antibiosis and antixenosis tests were carried out with 22 rice genotypes of Brazilian and Asian origin. The Canela de Ferro, BRS Esmeralda, and Desconhecido Branco genotypes had the lowest proportions of stems showing symptoms of the damage caused by T. limbativentris. Canela de Ferro, Primavera, and IR 22 genotypes had the lowest nymphs survivorship and the genotypes Marabá Branco, Marabá, Skirivimankoti, Pepita, BR IRGA 409, Curinga, IR 40, Bonança, Desconhecido Branco, Bico Ganga, Primavera, and BRS Esmeralda were the least attractive to the insects. The genotypes BRS Esmeralda, Primavera, Desconhecido Branco, and Canela de Ferro were resistant to the rice stalk stink bug by antibiosis and/or antixenosis. These genotypes can be used directly by rice farmers for T. limbativentris management. Molecular biology studies should be conducted to identify and characterize resistance genes in these genotypes so that they can be used in breeding programs.

Limited Diclosulam Herbicide Uptake and Translocation-Induced Tolerance in Crotalaria juncea.

The study was to identify the potential tolerance of Crotalaria juncea to diclosulam uptake and translocation and its effects on the physiological metabolism of plants. Two experiments were carried out; I-Evaluation of uptake and translocation of 14C-diclosulam (35 g a.i. ha-1) in C. juncea, at seven and 14 days after emergence. II-Evaluation of chlorophyll a transient fluorescence of dark-adapted C. juncea leaves when applied diclosulam in pre-emergence. Plants of C. juncea presented an anatomical/metabolic barrier to diclosulam translocation in the stem, which may confer tolerance to this herbicidal, besides reduced translocation due to low accumulation in the cotyledons. In addition, plants can maintain photosynthetic metabolism active when growing in soil with diclosulam by not changing the dynamics of energy dissipation. Thus, when cultivated in soil with residual of diclosulam, C. juncea can tolerate the herbicide to maintain plant growth.

Stink bug control at different stages of soybean development / Controle de percevejos em diferentes estádios de desenvolvimento da planta de soja

This study evaluates the effects of combinations of pyrethroids and neonicotinoids on the control of stink bugs at different stages of soybean crop development. The experiment was set up in a factorial randomized block design (4×6: 4 treatments and 6 stages) with 4 repetitions. The following treatments were tested during the V6/V7, R2, R4, R5.1, R5.5 and R 6 phenological stages: 1 ­ control (no application), 2 ­ thiamethoxam + λ-cyhalothrin, 3 ­ acetamiprid + α-cypermethrin, and 4 ­ dinotefuran + α-cypermethrin. Infestation, number of damaged seeds, number of pods, number of pods per plant, and yield (kg/ha) were evaluated. Stink bug infestations were smaller when applications commenced during the vegetative stages (V6-V8). Pod numbers and yields were highest in the dinotefuran + α-cypermethrin treatment with applications from V6/V8 to R4. The active ingredients dinotefuran + α-cypermethrin reduced stink bug populations and increased yields and could therefore be considered in integrated pest management (IPM) programs for soybean crops.(AU)

O objetivo deste trabalho foi avaliar o efeito de combinações de piretroides com neonicotinoides no controle de percevejos em diferentes estádios de desenvolvimento da cultura da soja. O delineamento experimental foi em blocos randomizados, em esquema fatorial 4×6 (4 tratamentos e 6 estádios) com 4 repetições. Os produtos utilizados foram: 1 ­ testemunha (sem aplicação), 2 ­ tiametoxam + λ-cialotrina, 3 ­ acetamiprida + α-cipermetrina, e 4 ­ dinotefuran + α-cipermetrina, e as aplicações foram realizadas a partir dos estádios fenológicos V6/V7,R2, R4, R5.1, R5.5 e R6. Avaliaram-se a infestação, número de grãos danificados, número de vagens, número de vagens por planta e produtividade (kg/ha). A infestação de percevejo foi menor quando se iniciou a aplicação precocemente nos estádios vegetativos (V6-V8).O número de vagens e produtividade foi superior no tratamento dinotefuran + α-cipermetrina nos estádios V6/V8 até R4. Os ingredientes ativos dinotefuran + α-cipermetrina apresentaram resultados positivos na redução da população de percevejo e proporcionaram incremento no rendimento de grão, podendo ser utilizado como opção em programa de manejo integrado de pragas (MIP) na cultura da soja.(AU)

The specific leaf area of forest species subjected to different degrees of shading did not differ when detached and full leaflets were compared / Folhas compostas de espécies florestais apresentam a mesma área foliar específica com folíolos destacados ou com folhas completas sob sombreamento

Studies of forest species under different environmental conditions are essential for enhancing our understanding of plant-environment relationships. Different light conditions interfere with the production of seedlings within forests, and this interference can be verified by assessing leaf area. However, several species have leaf compound that often contain numerous leaflets, which makes the direct measurement of leaf area difficult. This leads researchers to question whether these types of leaves should be separated for analysis or measured whole. Thus, the aim of this study was to analyse specific leaf area in whole leaves and detached leaflets of six forest species subjected to different levels of shading. The forest species assessed all produced compound leaves and included Schinus terebinthifolius Raddi (aroeira), Schinopsis brasiliensis Engl. (braúna), Dalbergia nigra (Vell.) Fr. All. ex Benth. (jacaranda-da-bahia), Chorisia speciosa A. St.-Hil (paineira), Caesalpinia peltophoroides Benth (sibipiruna) and Plathymenia reticulata Benth (vinhático). Each species was subjected to six different degrees of shading: 0% (full sun); 20; 40; 60; 80 and 90%. Sombrite netting was used to shade plants. The analysis of the specific leaf area was performed using two different methods, which included the analysis of separate leaflets and whole leaves. To analyse leaflet area,50 leaflets per plant were assessed three times, and six plants per treatment were assessed. To assess whole leaves, data were obtained from the whole leaves of six plants per treatment. This process was repeated for all aforementioned species. Data obtained from both analysis methods indicated that all species assessed were similarly affected by shade, and leaf area varied according to the level of shading. This similarity of data demonstrates that, for these species, itis not necessary to use complex methods to obtain specific leaf area measurements. Thus, determining specific [...].(AU)

Estudos com espécies florestais, em diferentes condições ambientais são essenciais para o entendimento da relação planta-ambiente. Diferentes condições de luminosidade podem interferir na produção de mudas florestais e o reflexo dessa interferência pode ser verificado pela análise da área foliar. No entanto, muitas espécies apresentam folhas compostas, sendo muitas vezes com inúmeros folíolos, o que dificulta as análises com mensuração direta da área foliar, proporcionando dúvidas durante a análise, se devem ser separados para análise ou mensurados com a folha inteira. Assim, o objetivo desse estudo foi analisar a área foliar específica em folhas inteiras e folíolos destacados de folhas compostas de seis espécies florestais submetidas à diferentes níveis de sombreamento. As espécies florestais utilizadas foram Schinus terebinthifolius Raddi (aroeira), Schinopsis brasiliensis Engl. (braúna), Dalbergia nigra (Vell.) Fr. All. ex Benth. (jacarandá-da-bahia), Chorisia speciosa A.St.-Hil (paineira), Caesalpinia peltophoroides Benth (sibipiruna) e Plathymenia reticulata Benth (vinhático), todas com folhas compostas. Cada espécie foi submetida a seis tratamentos de sombreamento: 0% (pleno sol); 20;40; 60; 80 e 90%, com a utilização de "sombrites" para os tratamentos sombreados. A análise da área foliar específica foi realizada de duas maneiras: folíolos separados e folha inteira. Para a análise dos folíolos esses foram obtidos de três medidas (repetições) de 50 folíolos por planta, realizada em seis plantas por tratamento. Para a análise da folha inteira os dados foram obtidos de folhas inteiras de seis plantas por tratamento. Esse processo se repetiu em todas as espécies supramencionadas. Para todas as espécies, os dados indicaram um padrão de resposta semelhante em ambos os métodos de análise, [...].(AU)

Stink bug control at different stages of soybean development / Controle de percevejos em diferentes estádios de desenvolvimento da planta de soja

This study evaluates the effects of combinations of pyrethroids and neonicotinoids on the control of stink bugs at different stages of soybean crop development. The experiment was set up in a factorial randomized block design (4×6: 4 treatments and 6 stages) with 4 repetitions. The following treatments were tested during the V6/V7, R2, R4, R5.1, R5.5 and R 6 phenological stages: 1 ­ control (no application), 2 ­ thiamethoxam + λ-cyhalothrin, 3 ­ acetamiprid + α-cypermethrin, and 4 ­ dinotefuran + α-cypermethrin. Infestation, number of damaged seeds, number of pods, number of pods per plant, and yield (kg/ha) were evaluated. Stink bug infestations were smaller when applications commenced during the vegetative stages (V6-V8). Pod numbers and yields were highest in the dinotefuran + α-cypermethrin treatment with applications from V6/V8 to R4. The active ingredients dinotefuran + α-cypermethrin reduced stink bug populations and increased yields and could therefore be considered in integrated pest management (IPM) programs for soybean crops.(AU)

O objetivo deste trabalho foi avaliar o efeito de combinações de piretroides com neonicotinoides no controle de percevejos em diferentes estádios de desenvolvimento da cultura da soja. O delineamento experimental foi em blocos randomizados, em esquema fatorial 4×6 (4 tratamentos e 6 estádios) com 4 repetições. Os produtos utilizados foram: 1 ­ testemunha (sem aplicação), 2 ­ tiametoxam + λ-cialotrina, 3 ­ acetamiprida + α-cipermetrina, e 4 ­ dinotefuran + α-cipermetrina, e as aplicações foram realizadas a partir dos estádios fenológicos V6/V7,R2, R4, R5.1, R5.5 e R6. Avaliaram-se a infestação, número de grãos danificados, número de vagens, número de vagens por planta e produtividade (kg/ha). A infestação de percevejo foi menor quando se iniciou a aplicação precocemente nos estádios vegetativos (V6-V8).O número de vagens e produtividade foi superior no tratamento dinotefuran + α-cipermetrina nos estádios V6/V8 até R4. Os ingredientes ativos dinotefuran + α-cipermetrina apresentaram resultados positivos na redução da população de percevejo e proporcionaram incremento no rendimento de grão, podendo ser utilizado como opção em programa de manejo integrado de pragas (MIP) na cultura da soja.(AU)

Antibiosis in soybean genotypes to Spodoptera cosmioides (Lepidoptera: Noctuidae)

Abstract The occurrence of the black caterpillar Spodoptera cosmioides (Lepidoptera: Noctuidae) has been increasing in soybean crops in Brazil leading to yield losses. The objective of this study was to evaluate antibiosis in soybean genotypes to S. cosmioides. The following parameters were evaluated: duration, viability and larval weight; duration and viability of the pre-pupal; duration, weight and viability of pupa; total cycle and sex ratio. The design was completely randomized with 18 treatments (genotypes) and 30 replicates. The genotypes PI 227687, PI227682, IAC 100 and BRS 7270 IPRO showed significant levels of antibiosis against S. cosmioides. These results will be useful for soybean producer or in breeding programs focusing on host plant resistance.

The specific leaf area of forest species subjected to different degrees of shading did not differ when detached and full leaflets were compared / Folhas compostas de espécies florestais apresentam a mesma área foliar específica com folíolos destacados ou com folhas completas sob sombreamento

Studies of forest species under different environmental conditions are essential for enhancing our understanding of plant-environment relationships. Different light conditions interfere with the production of seedlings within forests, and this interference can be verified by assessing leaf area. However, several species have leaf compound that often contain numerous leaflets, which makes the direct measurement of leaf area difficult. This leads researchers to question whether these types of leaves should be separated for analysis or measured whole. Thus, the aim of this study was to analyse specific leaf area in whole leaves and detached leaflets of six forest species subjected to different levels of shading. The forest species assessed all produced compound leaves and included Schinus terebinthifolius Raddi (aroeira), Schinopsis brasiliensis Engl. (braúna), Dalbergia nigra (Vell.) Fr. All. ex Benth. (jacaranda-da-bahia), Chorisia speciosa A. St.-Hil (paineira), Caesalpinia peltophoroides Benth (sibipiruna) and Plathymenia reticulata Benth (vinhático). Each species was subjected to six different degrees of shading: 0% (full sun); 20; 40; 60; 80 and 90%. Sombrite netting was used to shade plants. The analysis of the specific leaf area was performed using two different methods, which included the analysis of separate leaflets and whole leaves. To analyse leaflet area,50 leaflets per plant were assessed three times, and six plants per treatment were assessed. To assess whole leaves, data were obtained from the whole leaves of six plants per treatment. This process was repeated for all aforementioned species. Data obtained from both analysis methods indicated that all species assessed were similarly affected by shade, and leaf area varied according to the level of shading. This similarity of data demonstrates that, for these species, itis not necessary to use complex methods to obtain specific leaf area measurements. Thus, determining specific [...].

Estudos com espécies florestais, em diferentes condições ambientais são essenciais para o entendimento da relação planta-ambiente. Diferentes condições de luminosidade podem interferir na produção de mudas florestais e o reflexo dessa interferência pode ser verificado pela análise da área foliar. No entanto, muitas espécies apresentam folhas compostas, sendo muitas vezes com inúmeros folíolos, o que dificulta as análises com mensuração direta da área foliar, proporcionando dúvidas durante a análise, se devem ser separados para análise ou mensurados com a folha inteira. Assim, o objetivo desse estudo foi analisar a área foliar específica em folhas inteiras e folíolos destacados de folhas compostas de seis espécies florestais submetidas à diferentes níveis de sombreamento. As espécies florestais utilizadas foram Schinus terebinthifolius Raddi (aroeira), Schinopsis brasiliensis Engl. (braúna), Dalbergia nigra (Vell.) Fr. All. ex Benth. (jacarandá-da-bahia), Chorisia speciosa A.St.-Hil (paineira), Caesalpinia peltophoroides Benth (sibipiruna) e Plathymenia reticulata Benth (vinhático), todas com folhas compostas. Cada espécie foi submetida a seis tratamentos de sombreamento: 0% (pleno sol); 20;40; 60; 80 e 90%, com a utilização de "sombrites" para os tratamentos sombreados. A análise da área foliar específica foi realizada de duas maneiras: folíolos separados e folha inteira. Para a análise dos folíolos esses foram obtidos de três medidas (repetições) de 50 folíolos por planta, realizada em seis plantas por tratamento. Para a análise da folha inteira os dados foram obtidos de folhas inteiras de seis plantas por tratamento. Esse processo se repetiu em todas as espécies supramencionadas. Para todas as espécies, os dados indicaram um padrão de resposta semelhante em ambos os métodos de análise, [...].

Nitrogen source influences the antioxidative system of soybean plants under hypoxia and re-oxygenation

In this work, we compared nitrate-supplied plants (non-nodulated) with non-nitrate-supplied plants (nodulated) under oxygen privation of root system (hypoxia) and re-oxygenation (post-hypoxia; recovery) in order to verify whether N sources affect the antioxidant system during oxidative stress caused by hypoxia and post-hypoxia conditions. Antioxidant enzymatic activities, ascorbate redox state, and reactive oxygen species (ROS) levels were analyzed in roots and leaves of two soybean genotypes, Fundacep 53 RR and BRS Macota at reproductive stage R2, during hypoxia and post-hypoxia in an experiment carried out in a hydroponic system. The antioxidant system was strongly induced in roots of nitrate-supplied plants of both genotypes, with high activity of superoxide dismutase, ascorbate peroxidase, catalase, glutathione reductase and guayacol peroxidase. It also increased reduced ascorbate and ascorbate redox state and decreased ROS production under hypoxia and recovery, while in leaves of nodulated and non-nodulated plants, a slight increase on antioxidant system was observed. Nitrate may benefit soybean plants under hypoxic conditions and subsequent re-oxygenation by inducing the antioxidant system mainly in roots to cope with ROS production and reduce oxidative damage.

Nitrogen source influences the antioxidative system of soybean plants under hypoxia and re-oxygenation

In this work, we compared nitrate-supplied plants (non-nodulated) with non-nitrate-supplied plants (nodulated) under oxygen privation of root system (hypoxia) and re-oxygenation (post-hypoxia; recovery) in order to verify whether N sources affect the antioxidant system during oxidative stress caused by hypoxia and post-hypoxia conditions. Antioxidant enzymatic activities, ascorbate redox state, and reactive oxygen species (ROS) levels were analyzed in roots and leaves of two soybean genotypes, Fundacep 53 RR and BRS Macota at reproductive stage R2, during hypoxia and post-hypoxia in an experiment carried out in a hydroponic system. The antioxidant system was strongly induced in roots of nitrate-supplied plants of both genotypes, with high activity of superoxide dismutase, ascorbate peroxidase, catalase, glutathione reductase and guayacol peroxidase. It also increased reduced ascorbate and ascorbate redox state and decreased ROS production under hypoxia and recovery, while in leaves of nodulated and non-nodulated plants, a slight increase on antioxidant system was observed. Nitrate may benefit soybean plants under hypoxic conditions and subsequent re-oxygenation by inducing the antioxidant system mainly in roots to cope with ROS production and reduce oxidative damage.(AU)

Antioxidant activity and fermentative metabolism in the plant Erythrina crista-galli L. under flood conditions / Atividade antioxidante e metabolismo fermentativo em plantas de Erythrina crista-galli sob alagamento

This study aimed to evaluate the mechanisms of flood tolerance of the root system of Erythrina crista-galli L. plants by measuring the activity of antioxidant enzymes and oxidative stress components in the leaves and roots. Additionally, the activity of fermentation enzymes in the roots was measured. The following two treatments were used: plants with flooded roots, which were maintained at a given water level above the soil surface, and non-flooded plants, which were used as the control. The measurements were performed at 10, 20, 30, 40, and 50 days after treatment. The following parameters were evaluated at each time-point: the activities of superoxide dismutase, catalase and ascorbate peroxidase, the quantification of lipid peroxidation and hydrogen peroxide (H2O2) content in the leaves, roots, and adventitious roots, and the activities of lactate dehydrogenase, pyruvate decarboxylase and alcohol dehydrogenase in both the primary and adventitious roots. There was an increase in the activity of catalase and ascorbate peroxidase in the leaves to maintain stable H2O2 levels, which reduced lipid peroxidation. In the roots, higher activity of all antioxidant enzymes was observed at up to 30 days of flooding, which favoured both reduced H2O2 levels and lipid peroxidation. Activity of the fermentation enzymes was observed in the primary roots from the onset of the stress conditions; however, their activity was necessary only in the adventitious roots during the final periods of flooding. In conclusion, E. crista-galli L. depends on adventitious roots and particularly on the use of the fermentation pathway to tolerate flood conditions.(AU)

O objetivo deste trabalho foi determinar os mecanismos de tolerância ao alagamento de plantas de Erythrina crista-galli L., por meio da avaliação da atividade de enzimas antioxidantes e fermentativas, assim como dos componentes do estresse oxidativo em folhas e raízes. Plantas oriundas de sementes foram cultivadas em vasos com capacidade para 0,5 litros em casa de vegetação e transferidas para vasos de cinco litros. Foram utilizados dois tratamentos: plantas alagadas nas raízes com a manutenção de uma lâmina de água acima da superfície do solo e plantas não alagadas (controle). As avaliações foram realizadas aos 10, 20, 30, 40 e 50 dias após a indução dos tratamentos. O delineamento experimental utilizado foi em blocos ao acaso e os resultados obtidos submetidos à análise de variância e analisados por comparação de médias pelo Teste de Tukey. Em cada período foram avaliadas a atividade de superóxido dismutase, catalase, ascorbato peroxidase, quantificação da peroxidação lipídica e teores de peróxido de hidrogênio em folhas, raízes e raízes adventícias; a atividade das enzimas lactato desidrogenase, piruvato descarboxilase e álcool desidrogenase nas raízes principais e adventícias. Foi verificado um aumento na atividade das enzimas ascorbato peroxidase e catalase nas folhas para manter estáveis os níveis de H2O2, o que proporcionou redução na peroxidação lipídica. Nas raízes foi verificada uma atuação mais marcante de todas as enzimas antioxidantes até os 30 dias de alagamento, favorecendo a redução nos níveis de H2O2 e de peroxidação de lipídios. A atividade das enzimas fermentativas foi evidenciada nas raízes principais desde o início do estresse, porém nas raízes adventícias só foi requerida nos períodos finais. Pode-se concluir que a E. crista-galli L., depende das raízes adventícias e, em especial, da utilização da rota fermentativa para tolerar a condição de alagamento.(AU)

Antioxidant activity and fermentative metabolism in the plant Erythrina crista-galli L. under flood conditions / Atividade antioxidante e metabolismo fermentativo em plantas de Erythrina crista-galli sob alagamento

This study aimed to evaluate the mechanisms of flood tolerance of the root system of Erythrina crista-galli L. plants by measuring the activity of antioxidant enzymes and oxidative stress components in the leaves and roots. Additionally, the activity of fermentation enzymes in the roots was measured. The following two treatments were used: plants with flooded roots, which were maintained at a given water level above the soil surface, and non-flooded plants, which were used as the control. The measurements were performed at 10, 20, 30, 40, and 50 days after treatment. The following parameters were evaluated at each time-point: the activities of superoxide dismutase, catalase and ascorbate peroxidase, the quantification of lipid peroxidation and hydrogen peroxide (H2O2) content in the leaves, roots, and adventitious roots, and the activities of lactate dehydrogenase, pyruvate decarboxylase and alcohol dehydrogenase in both the primary and adventitious roots. There was an increase in the activity of catalase and ascorbate peroxidase in the leaves to maintain stable H2O2 levels, which reduced lipid peroxidation. In the roots, higher activity of all antioxidant enzymes was observed at up to 30 days of flooding, which favoured both reduced H2O2 levels and lipid peroxidation. Activity of the fermentation enzymes was observed in the primary roots from the onset of the stress conditions; however, their activity was necessary only in the adventitious roots during the final periods of flooding. In conclusion, E. crista-galli L. depends on adventitious roots and particularly on the use of the fermentation pathway to tolerate flood conditions.

O objetivo deste trabalho foi determinar os mecanismos de tolerância ao alagamento de plantas de Erythrina crista-galli L., por meio da avaliação da atividade de enzimas antioxidantes e fermentativas, assim como dos componentes do estresse oxidativo em folhas e raízes. Plantas oriundas de sementes foram cultivadas em vasos com capacidade para 0,5 litros em casa de vegetação e transferidas para vasos de cinco litros. Foram utilizados dois tratamentos: plantas alagadas nas raízes com a manutenção de uma lâmina de água acima da superfície do solo e plantas não alagadas (controle). As avaliações foram realizadas aos 10, 20, 30, 40 e 50 dias após a indução dos tratamentos. O delineamento experimental utilizado foi em blocos ao acaso e os resultados obtidos submetidos à análise de variância e analisados por comparação de médias pelo Teste de Tukey. Em cada período foram avaliadas a atividade de superóxido dismutase, catalase, ascorbato peroxidase, quantificação da peroxidação lipídica e teores de peróxido de hidrogênio em folhas, raízes e raízes adventícias; a atividade das enzimas lactato desidrogenase, piruvato descarboxilase e álcool desidrogenase nas raízes principais e adventícias. Foi verificado um aumento na atividade das enzimas ascorbato peroxidase e catalase nas folhas para manter estáveis os níveis de H2O2, o que proporcionou redução na peroxidação lipídica. Nas raízes foi verificada uma atuação mais marcante de todas as enzimas antioxidantes até os 30 dias de alagamento, favorecendo a redução nos níveis de H2O2 e de peroxidação de lipídios. A atividade das enzimas fermentativas foi evidenciada nas raízes principais desde o início do estresse, porém nas raízes adventícias só foi requerida nos períodos finais. Pode-se concluir que a E. crista-galli L., depende das raízes adventícias e, em especial, da utilização da rota fermentativa para tolerar a condição de alagamento.

Waterlogging-induced changes in fermentative metabolism in roots and nodules of soybean genotypes

Waterlogging blocks the oxygen supply to the root system which inhibits respiration, and greatly reduces the energy status of cells that affect important metabolic processes. This study evaluated fermentative metabolism and carbohydrate contents in the root system of two soybean (Glycine max L. Merril) genotypes under hypoxic and post-hypoxic conditions. Nodulated plants (genotypes Fundacep 53 RR and BRS Macota) were grown in vermiculite and transferred to a hydroponic system at the reproductive stage. The root system was submitted to hypoxia by flowing N2 (nitrogen) gas in a solution for 24 and 72 h. For recovery, plants returned to normoxia condition by transfer to vermiculite for 24 and 72 h. Fermentative enzyme activity, levels of anaerobic metabolites and carbohydrate content were all quantified in roots and nodules. The activity of alcohol dehydrogenase, pyruvate decarboxylase and lactate dehydrogenase enzymes, as well as the content of ethanol and lactate, increased with hypoxia in roots and nodules, and subsequently returned to pre-hypoxic levels in the recovery phase in both genotypes. Pyruvate content increased in nodules and decreased in roots. Sugar and sucrose levels increased in roots and decreased in nodules under hypoxia in both genotypes. Fundacep RR 53 was more responsive to the metabolic effects caused by hypoxia and post-hypoxia than BRS Macota, and it is likely that these characteristics contribute positively to improving adaptation to oxygen deficiency.(AU)

Waterlogging-induced changes in fermentative metabolism in roots and nodules of soybean genotypes

Waterlogging blocks the oxygen supply to the root system which inhibits respiration, and greatly reduces the energy status of cells that affect important metabolic processes. This study evaluated fermentative metabolism and carbohydrate contents in the root system of two soybean (Glycine max L. Merril) genotypes under hypoxic and post-hypoxic conditions. Nodulated plants (genotypes Fundacep 53 RR and BRS Macota) were grown in vermiculite and transferred to a hydroponic system at the reproductive stage. The root system was submitted to hypoxia by flowing N2 (nitrogen) gas in a solution for 24 and 72 h. For recovery, plants returned to normoxia condition by transfer to vermiculite for 24 and 72 h. Fermentative enzyme activity, levels of anaerobic metabolites and carbohydrate content were all quantified in roots and nodules. The activity of alcohol dehydrogenase, pyruvate decarboxylase and lactate dehydrogenase enzymes, as well as the content of ethanol and lactate, increased with hypoxia in roots and nodules, and subsequently returned to pre-hypoxic levels in the recovery phase in both genotypes. Pyruvate content increased in nodules and decreased in roots. Sugar and sucrose levels increased in roots and decreased in nodules under hypoxia in both genotypes. Fundacep RR 53 was more responsive to the metabolic effects caused by hypoxia and post-hypoxia than BRS Macota, and it is likely that these characteristics contribute positively to improving adaptation to oxygen deficiency.

Ação de extratos de Zantedeschia aethiopica na qualidade fisiológica de sementes, pigmentos fotossintéticos e metabolismo antioxidativo de plântulas de arroz vermelho / Action of Zantedeschia Aethiopica extracts in seed physiological quality, photosynthetic pigments and antioxidative metabolism of red rice seedlings

Objetivou-se com este trabalho avaliar a influência da concentração do extrato de folhas maduras de Zantesdeschia aethiopica sobre atributos fisiológicos de sementes e plântulas de arroz vermelho. Os tratamentos foram extratos nas concentrações 0; 12; 25; 50 e 75%. Foram avaliados germinação, primeira contagem, comprimento de parte aérea e raiz, massa seca total de plântulas, condutividade elétrica, teores de clorofila a, b e total, atividade das enzimas superóxido-dismutase, catalase e ascorbarto peroxidase, peroxidação lipídica e teor de peróxido de hidrogênio, emergência de plântulas, comprimento de parte aérea e de raiz e massa seca total das plântulas emergidas. Os teores de clorofila foram alterados quanti-qualitativamente, a emergência de plântulas, o comprimento de raiz e a massa seca total de plântulas emergidas foram reduzidos pelo aumento da concentração do extrato. A peroxidação de lipídeos, a atividade das enzimas superóxido-dismutase, ascorbato-peroxidase e catalase aumentaram com a concentração. Os resultados encontrados no trabalho demonstraram que o extrato de folhas maduras de Z. aethiopica altera diferentes atributos fisiológicos e apresenta toxidez a sementes e a plântulas de arroz vermelho.

The work aimed to evaluate the leaves extract concentration influence Zantedeschia aethiopica on physiological attributes of red rice seeds and seedlings. Treatments were mature leaf extracts at concentrations of 0; 12; 25; 50 and 75%. Were evaluated the germination, first count germination, length of shoot and root, seedling total dry mass, chlorophyll content, electrical conductivity, activity of the enzymes superoxide dismutase, catalase and ascorbarto peroxidase, lipid peroxidation, content of hydrogen peroxide and seedling emergence, length of organs and total dry mass of seedlings emerged. Chlorophyll contents were changed quantitavely and qualitatively, seedling emergence, the root lenght and total dry mass of seedlings was reduced by increasing the concentration of the extract. There was increase in lipid peroxidation, the activity increase of enzymes superoxide dismutase, ascorbate peroxidase and catalase with the concentration of the extract. The results of the work demonstrated that extract of mature leaves of Z. aethiopica alters different physiological attributes and features toxicity of red rice seeds and seedlings.

Desempenho de sementes e plântulas de rabanete sob ação de extrato aquoso de folhas de Trema micrantha (Ulmaceae) / Performance of radish seeds and seedlings under action of aqueous extract of leaves of Trema micrantha (Ulmaceae)

O trabalho objetivou avaliar o efeito alelopático de extrato aquoso de folhas de Trema micrantha sobre germinação de sementes e crescimento inicial de plântulas de rabanete. Para os extratos foram utilizadas folhas maduras e frescas nas concentrações 2, 4 e 8% (p/v), com aferição do pH e potencial osmótico. No bioensaio de germinação, foram empregadas cinco repetições de 25 sementes distribuídas em placas de petri forradas com papel Germitest, umedecido com 7 mL de extrato ou água e mantidos a 25 ºC em B.O.D., por cinco dias. Foram determinados a porcentagem de germinação (PG), velocidade de germinação (VG), índice de velocidade de germinação (IVG) e índice de efeito alelopático (RI). No bioensaio de crescimento inicial, foram avaliados o comprimento da radícula e do hipocótilo, a biomassa fresca e seca, o conteúdo de água e os teores de clorofila a, b e total. Todos os atributos de germinação, PG, VG, IVG e RI, foram afetados negativamente pelos extratos de T. micrantha. O crescimento inicial foi influenciado pelos extratos, ocorrendo redução do comprimento da radícula e aumento do hipocótilo. O extrato não alterou a biomassa fresca e seca e os teores de clorofila. Extratos aquosos de folhas de Trema micrantha exerceram ação alelopática sobre a germinação e crescimento inicial do rabanete, não influenciando na inibição da síntese de pigmentos fotossintéticos.

This study aimed to evaluate the allelopathic effects of aqueous extracts of Trema micrantha leaves on seed germination and early growth of seedlings of radish (Raphanus sativus L.). Leaf extracts were prepared at concentrations of 2, 4 and 8%. pH and osmotic potential were also performed from the extracts. Germination bioassay consisted of five replicates of 25 seeds of radish distributed in Petri dishes with germitest paper and 7 mL of extract or water and kept at 25°C in B.O.D. for five days. Germination percentage (PG), germination speed (VG), germination speed index (IVG) and index of allelopathic effect (RI) were determined. For bioassay initial growth, seeds were germinated until they reach 2 mm protrusion radicle and transferred to Gerbox containing germitest paper and 15 mL of extract or water, kept seven days at 25°C in B.O.D. for evaluating length of the radicle and hypocotyl, fresh and dry mass, water content and content of chlorophyll (a, b and total). Leaf extracts from T. micrantha affected negatively all parameters examined for germination (PG, VG, IVG and RI). The extracts affected the initial growth, causing reduction of the radicle length and stimulating the growth of hypocotyls, but not interfered on fresh and dry weight and content of chlorophyll. Aqueous extracts of T. micrantha leaves exerted allelopathic action on germination and early growth of radish, but not caused inhibition of synthesis of photosynthetic pigments.

Atividade de enzimas fermentativas em raízes e nódulos de soja sob condições de hipóxia e pós-hipóxia / Fermentative enzymes activity in soybean roots and nodules under hypoxia and post-hypoxia conditions

O objetivo deste trabalho foi avaliar a atividade de enzimas fermentativas em raízes e nódulos de soja (Glycine max) sob condições de hipóxia e pós-hipóxia. Os genótipos Fundacep 53 RR e BRS Macota foram cultivados em vasos de 3L contendo vermiculita como substrato em associação com Bradyrhizobium elkanii em casa de vegetação. No estádio R2, o sistema radicular das plantas foi submetido à hipóxia pelo encaixe de um segundo vaso sem perfurações e inundado com solução nutritiva diluída a 1/3 da concentração original, por 8 dias. Posteriormente, foram retirados os vasos sem perfurações para avaliação da recuperação. O material vegetal foi coletado no 2º, 4º, 6º e 8º dias após a inundação ou recuperação, juntamente com os controles para a dosagem da atividade das enzimas álcool desidrogenase (ADH), piruvato descarboxilase (PDC) e lactato desidrogenase (LDH) em raízes e nódulos. Os dados foram submetidos à ANOVA e comparados pelo teste de Tukey a 5% de probabilidade. As atividades da ADH, PDC e LDH foram fortemente estimuladas com a inundação, especialmente em nódulos, e diminuíram com a recuperação, em ambos os genótipos. Fundacep 53 RR respondeu de forma mais efetiva aos efeitos dos tratamentos.

This study aimed to evaluate the activity of fermentative enzymes in soybean (Glycine max) roots and nodules under hypoxia and post-hypoxia conditions. The soybean genotypes Fundacep 53 RR and BRS Macota associated with Bradyrhizobium elkanii were grown in 3L pots containing vermiculite as substrate under greenhouse conditions. Root system of plants at the R2 stage was subjected to hypoxia by blocking drainage of the pot, by fitting a second one without holes and flooded with nutrient solution diluted one-third of the original. The flooding of the plants was carried out for eight days and after, the pot without drilling was removed for recovery assessment. Non-waterlogged plants were kept as control. Activities of the fermentation enzymes alcohol dehydrogenase (ADH), pyruvate decarboxylase (PDC) and lactate dehydrogenase (LDH) were quantified in roots and nodules collected at 2, 4, 6 and 8 days after flooding or recovery. Data were analyzed by ANOVA and compared by the Tukey test (P ≤ 0,05). Activities of ADH, PDC and LDH were hardly stimulated during flooding, especially in nodules, in both genotypes and decreased with recovery. Fundacep 53 RR responded more effectively to treatment effects.

Atividade de enzimas fermentativas em raízes e nódulos de soja sob condições de hipóxia e pós-hipóxia

This study aimed to evaluate the activity of fermentative enzymes in soybean (Glycine max) roots and nodules under hypoxia and post-hypoxia conditions. The soybean genotypes Fundacep 53 RR and BRS Macota associated with Bradyrhizobium elkanii were grown in 3L pots containing vermiculite as substrate under greenhouse conditions. Root system of plants at the R2 stage was subjected to hypoxia by blocking drainage of the pot, by fitting a second one without holes and flooded with nutrient solution diluted one-third of the original. The flooding of the plants was carried out for eight days and after, the pot without drilling was removed for recovery assessment. Non-waterlogged plants were kept as control. Activities of the fermentation enzymes alcohol dehydrogenase (ADH), pyruvate decarboxylase (PDC) and lactate dehydrogenase (LDH) were quantified in roots and nodules collected at 2, 4, 6 and 8 days after flooding or recovery. Data were analyzed by ANOVA and compared by the Tukey test (P 0,05). Activities of ADH, PDC and LDH were hardly stimulated during flooding, especially in nodules, in both genotypes and decreased with recovery. Fundacep 53 RR responded more effectively to treatment effects.

O objetivo deste trabalho foi avaliar a atividade de enzimas fermentativas em raízes e nódulos de soja (Glycine max) sob condições de hipóxia e pós-hipóxia. Os genótipos Fundacep 53 RR e BRS Macota foram cultivados em vasos de 3L contendo vermiculita como substrato em associação com Bradyrhizobium elkanii em casa de vegetação. No estádio R2, o sistema radicular das plantas foi submetido à hipóxia pelo encaixe de um segundo vaso sem perfurações e inundado com solução nutritiva diluída a 1/3 da concentração original, por 8 dias. Posteriormente, foram retirados os vasos sem perfurações para avaliação da recuperação. O material vegetal foi coletado no 2º, 4º, 6º e 8º dias após a inundação ou recuperação, juntamente com os controles para a dosagem da atividade das enzimas álcool desidrogenase (ADH), piruvato descarboxilase (PDC) e lactato desidrogenase (LDH) em raízes e nódulos. Os dados foram submetidos à ANOVA e comparados pelo teste de Tukey a 5% de probabilidade. As atividades da ADH, PDC e LDH foram fortemente estimuladas com a inundação, especialmente em nódulos, e diminuíram com a recuperação, em ambos os genótipos. Fundacep 53 RR respondeu de forma mais efetiva aos efeitos dos tratamentos.