Influência do óxido nítrico na longevidade pós-colheita de inflorescências de Epidendrum ibaguense Kunth

• Autor(a) principal: Vieira, Luciana Marques
• Data de Publicação: 2013
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/998
• topic: Flores; Óxido nítrico; Conservação pós-colheita; Sistema antioxidante; Flowers; Nitric Oxide; Postharvest conservation; Antioxidant system; CNPQ::CIENCIAS BIOLOGICAS::BOTANICA::FISIOLOGIA VEGETAL

This work aimed to evaluate the effects of sodium nitroprusside (SNP) on postharvest longevity of inflorescences of Epidendrum ibaguense Kunth and its action on the antioxidative system. In the first chapter, the inflorescences were treated with a solution containing 5, 10, 50, 100 e 500 μM SNP by pulsing or by spraying with control in water. In the second and third chapters, the inflorescences were treated with 500 μM SNP by pulsing or by spraying with control in water. There were no differences in the longevity of the flowers treated with SNP solution to the concentrations of 100 μM, regardless of the mode of application. Inflorescences treated with 500 μM SNP by pulsing had increased abscission of flowers and showed toxicity symptoms such as labellum darkening, resulting in reduction of longevity from 5 to 2 days. The longevity of inflorescences sprayed with 500 μM SNP reduced from 6.8 to 5.1 days. There was inhibition of 47% compared to control, for superoxide dismutase (SOD) activity in flowers pulsed with 500 μM SNP, 48 hours after treatment. In flowers sprayed with SNP we observed inhibition of peroxidase (POD) activity. Catalase (CAT), ascorbate peroxidase (APX) and polyphenol oxidase (PPO) activities did not change, regardless of the mode of application. It was observed increased of phenylalanine ammonia lyase (PAL) activity in flowers pulsed with 500 μM SNP solution. However, flowers sprayed with SNP showed higher activity compared to control, 96 hours after treatment. The phenol content was not different in flowers kept in water or solution of SNP however, was higher in flowers sprayed with 500 μM SNP, compared to control, 48 hours after treatment. The electrolyte leakage did not differ among treatments, except in inflorescences sprayed with SNP which showed an increase of 4%, compared to control sprayed with water at the end of the study period. Lipid peroxidation, estimated by production malondialdehyde (MDA), was not changed in flowers kept in SNP solution, compared with the control kept in water. TBA-MDA content increased by 127% in inflorescences sprayed with 500 μM SNP, 72 hours after treatment. Thus, nitric oxide caused deleterious effect on E. ibaguense flowers, inhibiting the activity of enzymes of the antioxidative system and promoting lipid peroxidation.