Mecanismos de adaptação e fotoproteção em tomateiros submetidos ao estresse salino

• Ano de defesa: 2009
• Autor(a) principal: Azevedo, Leticia da Costa
• Orientador(a): Cano, Marco Antonio Oliva
• Banca de defesa: Kuki, Kacilda Naomi , Otoni, Wagner Campos
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Viçosa
• Programa de Pós-Graduação: Mestrado em Fisiologia Vegetal
• Departamento: Controle da maturação e senescência em órgãos perecíveis; Fisiologia molecular de plantas superiores
• País: BR
• Palavras-chave em Português: Estresse salino; Ajustamento osmótico; Fluorescência da clorofila a; Fotossíntese; Tomate
• Palavras-chave em Inglês: Water stress; Osmotic adjustment; Chlorophyll a fluorescence; Photosynthesis; Tomato
• Área do conhecimento CNPq: CNPQ::CIENCIAS BIOLOGICAS::BOTANICA::FISIOLOGIA VEGETAL::ECOFISIOLOGIA VEGETAL
• Link de acesso: http://locus.ufv.br/handle/123456789/4305

Tomato plants (Solanum lycopersicum Mill) c.v Santa Clara 5600 VF were submitted to increasing concentratíons of NaCl, up to 150 mM. In order were set up two experiments to evaluate the initial effects that affect the primary production and the mechanisms of adaptation to salinity under continuous stress. The plants were cultivated in Hoagland`s hidroponic solution, in the greenhouse. In condition the first experiment, the plants were grown in 0, 50, 100 and 150 mM NaCl solution obtained by gradually applied 50 mM of the salt. In the second experiment, the NaCl was add every 12 hours until the final concentration of 150 mM. It were evaluated the osmotic potential (Ψs) of leaves and roots, Na+, Cl-, K+, Ca2+ and Mg2+ íons concentratíons in roots, stem and leaves, proline concentration in leaves, gas exchange, estimative of photorespiration, chlorophyll a fluorescence, chlorophyll a fluorescence image and antioxidative activity in the leaves. The plants submitted to salt stress presented a decreased on ψs of leaves and roots. This decrease might be attributed to accumulation Na+, K+, Cl- and sugars in the cytoplasm, which also contributed to an osmotic adjustment. There was an increase in the proline synthesis, which is attributed the role as osmoprotectant osmolyte protection to salt stress. It was detected decrease in photosynthetic rate in response to stomatal and non-stomatal effects. The contents of chlorophyll a, chlorophyll b, carotenoids and the chlorophyll a/b ratio showed decrease. It was observed decrease in the quantum yield of linear electron flux through PSII. Increments in quantum yield of regulated non- photochemical energy loss in PS II Y(NPQ) and in non- photochemical quenching (NPQ) and high rates of Y(NPQ)/ Y (NO) in plants submitted to salt stress. There was increase of SODs and APXs enzymes activity that participate in water- water cycle. From these results, we can conclude that, tomato plants submitted to salt stress developed osmotic adjustment in order to assure water absorption. The plants also showed efficient mechanisms of photoprotection, through dissipation of excess energy in the electron transport chain. Such mechanisms involve the dissipation of energy as heat, by photorespiration and by water-water cycle. Furthermore, it was possible to monitor the extension of stress through the means of the chlorophyll a fluorescence image.