abstractthis study aimed to evaluate the effect of flooding and water restriction (drought) on the photosynthetic activity in plants of the hybrid rootstock 'GxN-9' (Prunus dulcis Mill. × Prunus persica l. Bastsch), grown in a greenhouse. chlorophyll fluorescence and gas exchange were analyzed in plants of approximately 12 months. the reduction of photosynthetic activity in both the stresses were associated with decreased carboxylation efficiency, but without affecting the internal concentration of carbon dioxide. the JiP-test parameters revealed changes in the energy flux processes demonstrating that in terms of flooding the rootstock GxN-9 the rate of photosynthetic performance significantly decreases, resulting in a considerable decrease in net assimilation rate. the JiP-test analysis was efficient in determining the thresholds mainly of the flood response, proving to be useful in exploration of the photosynthetic activity as a physiological marker of the stress tolerance.
-The objective of this work was to investigate the injuries caused to the photosynthetic apparatus of three types of rice exposed to application of imidazolinone group herbicides. Two experiments were conducted using herbicides Imazethapyr+imazapic and Imazapyr+imazapic, in a split-plot experimental design, and a 3 x 3 factorial, with six replications. The first factor (A) consisted of the herbicide rates 0, 100 e 200 g ha -1 of Imazethapyr+imazapic and 0, 140 e 280 g ha -1 of Imazapyr+imazapic; factor B consisted of type of rice (cv. Puitá Inta CL, sensitive red rice ecotype and red rice ecotype with suspected herbicide tolerance to Imidazolinone). Chlorophyll a fluorescence parameters were evaluated in plants at 30 days after herbicide application, using a portable fluorometer (HandyPEA, Hanstech). The photosynthetic metabolism of cv. Puitá Inta CL was found to tolerate commercial dosages of both herbicides. High sensitivity to the herbicides was observed for the sensitive red rice ecotype, while the photosynthetic apparatus of red rice ecotype with suspected herbicide tolerance showed high tolerance to both herbicides applied at rates higher than the commercial rate. The application of chemical herbicides of the imidazolinone group on rice plants causes changes in the photosynthetic metabolism of plants, detected by evaluating the emission of transient chlorophyll a fluorescence. This method can be useful in helping detect resistance and/or tolerance of red rice plants to herbicides of the imidazolinone group.Keywords: ALS-inhibitors, Oryza sativa, photosystems, JIP-test. SOUSA, C.P. et al. RESUMO -Este estudo objetivou avaliar as injúrias causadas ao aparelho fotossintético de três tipos de arroz, expostos a herbicidas do grupo das imidazolinonas. Foram conduzidos dois experimentos utilizando os herbicidas imazethapyr+imazapic e imazapyr+imazapic, ambos em delineamento experimental de parcelas subdivididas, em fatorial 3 x 3, com seis repetições. O fator A consistiu de doses dos herbicidas correspondentes a 0, 100 e 200 g ha -1 de imazethapyr+imazapic e a 0, 140 e 280 g ha -1 de imazapyr+imazapic, e o fator B, do tipo de arroz (cv. Puitá Inta CL, ecótipo de arroz-vermelho sensível e ecótipo de arroz-vermelho com suspeita de tolerância aos herbicidas imidazolinonas). Foram avaliados os parâmetros da fluorescência da clorofila a nas plantas aos 15 e 30 dias após a aplicação dos herbicidas, utilizando-se um fluorômetro portátil (HandyPEA
-The study aimed to evaluate the behavior of the chair of photosynthetic electron transport in the presence of DCMU and atrazine in detached leaves of pea through simultaneous measurements of the kinetics of fluorescence transient, fluorescence delayed and modulated reflection at 820 nm. The petioles of the leaves were immersed for two hours in solution of inhibitors at concentrations of 0 (control), 25, 50, 100, 250 and 500 M. Measurements of the kinetics of fluorescence transient and fluorescence delayed and modulated reflection at 820 nm were recorded simultaneously by the M-PEA fluorometer. Simultaneous measurement of fluorescence transient, fluorescence delayed and modulated 820 nm reflection is important for assessments of the photosynthetic electron transport chain activity tool. The use of specific inhibitors of the electron transport chain allows you to collect and correlate a lot of information about the effect of different inhibitors at specific points in the photosynthetic electron transport chain. DCMU and atrazine are inhibitors of photosystem II and the concentration of 500 mM affects more strongly the flow of photosynthetic electrons. RESUMO -O trabalho teve como objetivo avaliar o comportamento da cadeia de transporte de elétrons fotossintética na presença de DCMU e atrazina, em folhas destacadas de ervilha, através de medidas simultâneas das cinéticas da fluorescência transiente, decaída da fluorescência da clorofila a e reflexão modulada a 820 nm. O pecíolo das folhas foi imerso por duas horas em solução de inibidores nas concentrações de 0 (controle), 25, 50, 100, 250 e 500 µM. Medidas da cinética da fluorescência transiente, da decaída da fluorescência e reflexão modulada a 820 nm foram gravadas, simultaneamente, pelo fluorômetro M-PEA. A medida simultânea da fluorescência transiente, decaída da fluorescência e reflexão modulada a 820 nm é ferramenta importante para avaliações da atividade da cadeia de transporte de elétrons fotossintética. O uso de inibidores específicos da cadeia de transporte de elétrons permite coletar e correlacionar uma série de informações sobre o efeito de diferentes inibidores em pontos específicos na cadeia de transporte de elétrons fotossintético. DCMU e atrazina são inibidores do fotossistema II e a concentração de 500 µM afeta de maneira mais acentuada o fluxo de elétrons fotossintético. Palavras-chave:Pisum sativum L.. Fluorescência transiente. Decaída da fluorescência. DCMU. Atrazina.
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