<?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%">Gratani, L</style></author><author><style face="normal" font="default" size="100%">Crescente, M F</style></author><author><style face="normal" font="default" size="100%">Petruzzi, M</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Relationship between leaf life-span and photosynthetic activity of Quercus ilex in polluted urban areas (Rome).</style></title><secondary-title><style face="normal" font="default" size="100%">Environmental pollution (Barking, Essex : 1987)</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">chlorophyll content</style></keyword><keyword><style  face="normal" font="default" size="100%">leaf life-span</style></keyword><keyword><style  face="normal" font="default" size="100%">leaf thickness</style></keyword><keyword><style  face="normal" font="default" size="100%">Net photosynthesis</style></keyword><keyword><style  face="normal" font="default" size="100%">shoot production</style></keyword><keyword><style  face="normal" font="default" size="100%">traffic level</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2000</style></year></dates><volume><style face="normal" font="default" size="100%">110</style></volume><pages><style face="normal" font="default" size="100%">19-28</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">Anatomical, morphological and physiological leaf traits of Quercus ilex in response to different traffic levels (high traffic level, type A sites; average traffic level, type B sites; control sites, type C sites) were analysed in Rome. Superficial leaf deposits were analysed comparing unwashed and washed leaf samples. Washing lowered Pb 61% in A, 54% in B and 27% in C. Sr, Fe, Cu, Zn and Al showed the same trend as Pb. The higher photosynthetic activity of 1-year-old leaves (Pn=7.0+/-2.9 micromol m(-2 )s(-1), average value) in A sites with respect to B sites (6.7+/-2.4 micromol m(-2 )s(-1)) and C sites (6.7+/-1.8 micromol m(-2 )s(-1)) seems to be related to higher stomatal conductance (g(s)=0.13+/-0.06 mol m(-2 )s(-1)), higher total chlorophyll content (Chl=1.57 mg g(-1)) and higher leaf thickness (L(T)=218.9 microm), particularly palisade parenchyma thickness (109.4 microm). Q. ilex showed, on average, 95% of 1-year-old leaves and rarely 2-year-old leaves in A and B sites; 77% 1-year leaves, 20% previous-year leaves and sporadic 3-year leaves in C sites. The enhanced leaf senescence in A sites is compensated by a stimulated shoot production (18% higher with respect to C sites); 25% increased specific leaf area seems to be compensatory growth occurring in order to increase the size of the assimilatory area. The inverse trend of leaf life-span and Pn seems to be Q. ilex' adaptive strategy in polluted areas.</style></abstract><accession-num><style face="normal" font="default" size="100%">15092853</style></accession-num></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%">ASCASO, C</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Chioroplast-ultrastructure and chlorophyll contení in leaves from Quercus branches with and without epiphytic lichen thalli</style></title><secondary-title><style face="normal" font="default" size="100%">Plañí, Cell and Environment (1985)</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">chlorophyll content</style></keyword><keyword><style  face="normal" font="default" size="100%">chloroplast-ultrastructure of Quercus</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">1985</style></year></dates><volume><style face="normal" font="default" size="100%">8</style></volume><pages><style face="normal" font="default" size="100%">651-656</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">The effect that the massive presence of lichen thalli growing on the branches of Quercus pyrenaica and Q. rotundifolia leaves has on their chloroplasts been studied. In both species there were significant decreases in the amount of chlorophylls in the leaves of twigs with a dense cover of lichens in comparison with the leaves from thallus-free twigs. The áreas and perimeter of chloroplasts in leaves from twigs with epiphytes did not differ significantly from those in leaves without epiphytes. However, in leaves with epiphytes the percentage of chloroplast área occupied by starch was higher. In Q. pyrenaica the number of grana per chloroplast section and per //in2, the percentage of chloroplast stroma occupied by grana, the average number of thylakoids forming grana and the grana width was significantly smaller in leaves near lichen populations. These results are discussed and related to the great chelating capacity of the lichen's substances.</style></abstract></record></records></xml>