Peanut Photosynthesis Under Drought and Re-Watering |
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Authors: | Lauriano JA Ramalho JC Lidon FC do Céu Matos M |
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Institution: | (1) Fac. Ciências Agrárias, Univ. Agostinho Neto, P.O. Box 236, Huambo, Angola;(2) Dept. Fisiologia Vegetal, Estação Agronómica Nacional, Quinta do Marquês, 2780 Oeiras, Portugal;(3) Centro de Estudos de Produção e Tecnologia Agrícolas - Inst. Inv. Científica Tropical, Tapada da Ajuda, Ap. 3014, 1301 Lisboa Codex, Portugal;(4) Sector de Biologia Vegetal, Fac, Ciências e Tecnologia - Univ. Nova de Lisboa, 2825 Monte-da-Caparica, Portugal;(5) Centro de Investigação das Ferrugens do Cafeeiro - Inst. Inv. Científica Tropical, Quinta do Marquês, 2780 Oeiras, Portugal |
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Abstract: | The photosynthetic response of three Arachis hypogaea L. cultivars (57-422, 73-30, and GC 8-35) grown for two months was measured under water available conditions, severe water stress, and 24, 72, and 93 h following re-watering. At the end of the drying cycle, all the cultivars reached dehydration, relative water content (RWC) ranging between 40 and 50 %. During dehydration, leaf stomatal conductance (g
s), transpiration rate (E), and net photosynthetic rate (P
N) decreased more in cvs. 57-422 and GC 8-35 than in 73-30. Instantaneous water use efficiency (WUEi) and photosynthetic capacity (P
max) decreased mostly in cv. GC 8-35. Except in cv. GC 8-35, the activity of photosystem 1 (PS1) was only slightly affected. PS2 and ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBPCO) were the main targets of water stress. After re-watering, cvs. 73-30 and GC 8-35 rapidly regained g
s, E, and P
N activities. Twenty-four hours after re-watering, the electron transport rates and RuBPCO activity strongly increased. P
N and P
max fully recovered later. Considering the different photosynthetic responses of the studied genotype, a general characterisation of the interaction between water stress and this metabolism is presented. |
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Keywords: | Arachis cultivar differences photosynthetic electron transport photosystems 1 and 2 ribulose-1 5-bisphosphate carboxylase/oxygenase stomatal conductance transpiration rate water stress |
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