Diurnal and Seasonal Changes in Prunus Amygdalus Gas Exchanges |
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Authors: | Matos M.C. Matos A.A. Mantas A. Cordeiro V. Vieira Da Silva J.B. |
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Affiliation: | (1) Departamento de Fisiologia Vegetal, Estaçâo Agronómica Nacional, 2780 Oeiras, Portugal;(2) Direcçâo Regional de Agricultura de Trás-os-Montes, Rua da República 197, 5370 Mirandela, Portugal;(3) Laboratoire d'Ecologie Génerale et Appliquée, Université Denis Diderot, 2 Place Jussieu, 75251 Paris Cedex 05, France |
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Abstract: | Diurnal courses in net photosynthetic rate (PN), stomatal conductance (gs), leaf water potential (), internal CO2 concentration (ci), and water use efficiency (WUE) were studied as season progressed, in relation to environmental factors in field grown Prunus amygdalus. In sun leaves PN reached maximum between 09:00 to 11:00 h and subsequently declined when high temperature and low humidity occurred. An increase was observed late in the afternoon. A decrease in gs and was found as season progressed in both years of measurements. In periods of high evaporative demand, was very low, however, it did not explain the reductions of PN in all the three periods (spring, early and late summer). Midday depression of PN and gs seemed to be related with leaf temperature (Tl) and high irradiance. Increase in ci and F0 and decrease in Fv/Fm found between 12:00 and 14:00 h corresponded to the decrease in PN. Therefore, a transient modification of photosynthetic machinery might be considered. WUE was negatively correlated with vapour pressure difference of leaf to air, that decreased during the day. The September values, higher than in the previous months, were due to the lower seasonal decreases in PN than in gs. |
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Keywords: | diurnal course drought internal CO2 partial pressure irradiance net photosynthetic rate seasonal course temperature water relations water stress water use efficiency |
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