ABSTRACT
The aim of this study was to evaluate the effects of pre-treatment and post-treatment with ascorbic acid in reducing the damage caused by aging in cowpea seeds, which were aged in artificial accelerated aging chamber (45C, 99% relative humidity in the dark) for 72 h and it were subjected to four treatments: T1 non-aged seeds were not treated with ascorbic acid (AsA); T2 non-aged seeds treated with AsA; T3 seeds before aging were subjected to a treatment with AsA to 0.85 mM; T4 seeds after aging were subjected to a treatment with a 0.85 mM AsA. The aging of seeds for 72 h (T2) caused significant damage in the cell membranes of cowpea seeds, as evidenced by a increase in electrolyte leakage, higher level of lipid peroxidation and a lower germination percentage, when compared with the control (T1). T4 results were like the control treatment, with a lower electrolyte leakage and lipid peroxidation, well as a higher germination percentage, when compared with T2. The exogenous application of 0.85 mM ascorbic acid in cowpea seeds after artificial aging can mitigate its detrimental effects on the membranes integrity and seed physiological quality.
O objetivo desse estudo foi avaliar os efeitos do pré e pós-tratamento com ácido ascórbico na redução dos danos ocasionados pelo envelhecimento em sementes de feijão de corda, as quais foram envelhecidas em câmara de envelhecimento artificial (45 ºC, 99% U.R., no escuro) por 72 h, sendo submetidas a quatro tratamentos: T1 sementes não envelhecidas e não tratadas com ácido ascórbico (AsA); T2 sementes envelhecidas e não tratadas com AsA; T3 sementes que antes do envelhecimento foram submetidas a um tratamento com AsA a 0,85 mM; T4 sementes que após o envelhecimento foram submetidas a um tratamento com AsA a 0,85 mM. O envelhecimento das sementes por 72 h (T2) provocou danos significativos nas membranas celulares das sementes de feijão de corda, como foi evidenciado pelo aumento no vazamento de eletrólitos, maior nível de peroxidação de lipídios e menor porcentagem de germinação quando comparado com o controle (T1). O T4 conseguiu igualar aos resultados apresentados pelo controle, apresentando um menor vazamento de eletrólitos e peroxidação de lipídios, bem como maior germinação, quando comparado com o T2. A aplicação exógena de ácido ascórbico a 0,85 mM nas sementes de feijão de corda após o envelhecimento artificial pode atenuar efeitos deletérios na integridade de membranas e favorecer a qualidade fisiológica das sementes.
ABSTRACT
The aim of this study was to evaluate the effects of pre-treatment and post-treatment with ascorbic acid in reducing the damage caused by aging in cowpea seeds, which were aged in artificial accelerated aging chamber (45C, 99% relative humidity in the dark) for 72 h and it were subjected to four treatments: T1 non-aged seeds were not treated with ascorbic acid (AsA); T2 non-aged seeds treated with AsA; T3 seeds before aging were subjected to a treatment with AsA to 0.85 mM; T4 seeds after aging were subjected to a treatment with a 0.85 mM AsA. The aging of seeds for 72 h (T2) caused significant damage in the cell membranes of cowpea seeds, as evidenced by a increase in electrolyte leakage, higher level of lipid peroxidation and a lower germination percentage, when compared with the control (T1). T4 results were like the control treatment, with a lower electrolyte leakage and lipid peroxidation, well as a higher germination percentage, when compared with T2. The exogenous application of 0.85 mM ascorbic acid in cowpea seeds after artificial aging can mitigate its detrimental effects on the membranes integrity and seed physiological quality.
O objetivo desse estudo foi avaliar os efeitos do pré e pós-tratamento com ácido ascórbico na redução dos danos ocasionados pelo envelhecimento em sementes de feijão de corda, as quais foram envelhecidas em câmara de envelhecimento artificial (45 ºC, 99% U.R., no escuro) por 72 h, sendo submetidas a quatro tratamentos: T1 sementes não envelhecidas e não tratadas com ácido ascórbico (AsA); T2 sementes envelhecidas e não tratadas com AsA; T3 sementes que antes do envelhecimento foram submetidas a um tratamento com AsA a 0,85 mM; T4 sementes que após o envelhecimento foram submetidas a um tratamento com AsA a 0,85 mM. O envelhecimento das sementes por 72 h (T2) provocou danos significativos nas membranas celulares das sementes de feijão de corda, como foi evidenciado pelo aumento no vazamento de eletrólitos, maior nível de peroxidação de lipídios e menor porcentagem de germinação quando comparado com o controle (T1). O T4 conseguiu igualar aos resultados apresentados pelo controle, apresentando um menor vazamento de eletrólitos e peroxidação de lipídios, bem como maior germinação, quando comparado com o T2. A aplicação exógena de ácido ascórbico a 0,85 mM nas sementes de feijão de corda após o envelhecimento artificial pode atenuar efeitos deletérios na integridade de membranas e favorecer a qualidade fisiológica das sementes.
ABSTRACT
The effect of exogenously applied H2O2 on salt stress acclimation was studied with regard to plant growth, lipid peroxidation, and activity of antioxidative enzymes in leaves and roots of a salt-sensitive maize genotype. Pre-treatment by addition of 1 microM H2O2 to the hydroponic solution for 2 days induced an increase in salt tolerance during subsequent exposure to salt stress. This was evidenced by plant growth, lipid peroxidation and antioxidative enzymes measurements. In both leaves and roots the variations in lipid peroxidation and antioxidative enzymes (superoxide dismutase, ascorbate peroxidase, guaiacol peroxidase, glutathione reductase, and catalase) activities of both acclimated and unacclimated plants, suggest that differences in the antioxidative enzyme activities may, at least in part, explain the increased tolerance of acclimated plants to salt stress, and that H2O2 metabolism is involved as signal in the processes of maize salt acclimation.