Utilize este identificador para referenciar este registo: http://hdl.handle.net/10400.1/3282
Título: The effects of drought on net CO2 uptake, chlorophyll fluorescence and photosynthetic pigments in mature and young leaves of sunflower
Autor: Osório, Maria Leonor
Barrote, Isabel
Osório, Júlio
David, Maria Manuela
Correia, Maria João
Palavras-chave: Drought
Chlorophyll fluorescence
Leaf age
Helianthus annuus
Photosynthetic pigments
Xanthophyll cycle
Water deficit
Stress recovery
Data: 2004
Editora: Sociedade Portuguesa de Fisiologia Vegetal
Citação: Osório M.L., Barrote I., Osório J., David M.M., Correia M.J. (2004). The effects of drought on net CO2 uptake, chlorophyll fluorescence and photosynthetic pigments in mature and young leaves of sunflower. VII Simposium Luso-Espanhol de Relações Hídricas das plantas, Universidade do Algarve, Faro, Portugal, p127-130
Resumo: Photosynthesis, photosystem II activity and photosynthetic pigments were analysed in mature and Young leaves of sunflower (Helianthus annuus L.) during dehydration and rehydration, in order to determine the influence of leaf age on the sensitivity to drought. Dehydration caused a more pronounced inhibition in photosynthetic rates in mature leaves compared to younger leaves, but 24 h after rewatering the recovery was complete in spite of leaf age. After exposure to drought, mature leaves showed a larger reduction in the actual PSII photochemical efficiency and a higher increase in nonradiative energy dissipation than young leaves. In well-watered plants the de-epoxidation level represented by the ratio A+Z/V+A+Z was higher in young leaves. However drought had opposite effects on both type of leaves: in young leaves A+Z/V+A+Z decreased with water deficit, while in mature leaves increased with soil drying. The results obtained suggest that leaf age influence the “strategy” to avoid irreversible damage of PSII activity under drought and that older leaves are more drought-sensitive than younger leaves of sunflower.
Peer review: yes
URI: http://hdl.handle.net/10400.1/3282
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