<?xml version="1.0" encoding="UTF-8"?><xml><records><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Oliveira, G</style></author><author><style face="normal" font="default" size="100%">Penuelas, J</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Effects of winter cold stress on photosynthesis and photochemical efficiency of PSII of the Mediterranean Cistus albidus L. and Quercus ilex L.</style></title><secondary-title><style face="normal" font="default" size="100%">Plant Ecology</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">evergreen</style></keyword><keyword><style  face="normal" font="default" size="100%">Fv/Fm</style></keyword><keyword><style  face="normal" font="default" size="100%">Mediterranean winter</style></keyword><keyword><style  face="normal" font="default" size="100%">photoinhibition</style></keyword><keyword><style  face="normal" font="default" size="100%">semi-deciduous</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2004</style></year><pub-dates><date><style  face="normal" font="default" size="100%">2004///</style></date></pub-dates></dates><urls><web-urls><url><style face="normal" font="default" size="100%">http://www.springerlink.com/index/GV5P7326829Q0GK6.pdf</style></url></web-urls></urls><volume><style face="normal" font="default" size="100%">175</style></volume><pages><style face="normal" font="default" size="100%">179 - 191</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">This study examined the photosynthetic and growth performances of potted plants of Cistus albidus L. and Quercus ilex L. submitted either to natural Mediterranean winter conditions or to mild greenhouse conditions. Plants grown outdoors exhibited lower light and CO2 -saturated CO2 assimilation rates Asat and apparent quantum yield i than those indoors. Until mid-winter, C. albidus had higher Asat than Q. ilex, but differences disappeared after a period of severe cold. Maximal photochemical efficiency of PSII Fv/Fm measured predawn was higher in C. albidus than in Q. ilex, and decreased throughout the season in outdoor plants. Fv/Fm also decreased at light saturation Asat in both species. Fv/Fm was correlated with photosynthetic capacity and efficiency quantum yield, but the resulting regression slopes were different between the two species. At the physiological level, C. albidus seemed to cope better with cold stress than Q. ilex. However, winter stress induced reduction of leaf absorptance, increased leaf mass per area, extensive leaf damage and high plant mortality in C. albidus. This suggests that the high performance of C. albidus leaves is not likely to be maintained for long periods of cold stress, and may therefore depend on continuous leaf replacement. Quercus ilex showed a conservative behaviour, with low net assimilation rates but greater leaf and plant survival than C. albidus.</style></abstract></record><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Oliveira, G</style></author><author><style face="normal" font="default" size="100%">Penuelas, J</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Comparative protective strategies of Cistus albidus and Quercus ilex facing photoinhibitory winter conditions</style></title><secondary-title><style face="normal" font="default" size="100%">Environmental and experimental botany</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">evergreen</style></keyword><keyword><style  face="normal" font="default" size="100%">leaf angle</style></keyword><keyword><style  face="normal" font="default" size="100%">manipulation</style></keyword><keyword><style  face="normal" font="default" size="100%">Mediterranean winter</style></keyword><keyword><style  face="normal" font="default" size="100%">photoprotection</style></keyword><keyword><style  face="normal" font="default" size="100%">semideciduous</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2002</style></year><pub-dates><date><style  face="normal" font="default" size="100%">2002///</style></date></pub-dates></dates><urls><web-urls><url><style face="normal" font="default" size="100%">http://www.sciencedirect.com/science/article/pii/S0098847202000035</style></url></web-urls></urls><volume><style face="normal" font="default" size="100%">47</style></volume><pages><style face="normal" font="default" size="100%">281 - 289</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">The role of structural photoprotection under photoinhibitory winter conditions was evaluated in two Mediterranean woody species: Cistus albidus (semideciduous) and Quercus ilex (evergreen). Shoots were manipulated in order to modify the light load naturally received by the leaves throughout the cold season, and monitored for changes in maximum photochemical efﬁciency of PSII, phenology, and leaf morphology. Naturally steep leaves of C. albidus were restrained to a horizontal position, and compared with control leaves (naturally horizontal, or steeply inclined). Fully exposed leaves of Q. ilex were artiﬁcially protected through partial shading, and compared with control leaves (not shaded). During the cold season, the most exposed (either naturally or artiﬁcially) leaves were always more photoinhibited (had lower maximal photochemical efﬁciency of PSII) than the photoprotected ones. The differences disappeared at the beginning of spring. Winter photoinhibition was not more pronounced in older than in younger leaves of C. albidus, indicating that inclination rather than age affected their photochemical efﬁciency. Leaf chlorophyll contents were not signiﬁcantly affected by the manipulations. Leaf thickness decreased slightly in the least exposed shoots of the evergreen species, but no changes were detected in leaf morphological traits of the semideciduous one. The increased photoinhibitory pressure led only to slight and non-signiﬁcant changes in phenology and growth</style></abstract></record></records></xml>