<?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%">Gratani, L</style></author><author><style face="normal" font="default" size="100%">Bombelli, A</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Leaf anatomy, inclination, and gas exchange relationships in evergreen sclerophyllous and drought semideciduous shrub species</style></title><secondary-title><style face="normal" font="default" size="100%">PHOTOSYNTHETICA</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">cistus incanus</style></keyword><keyword><style  face="normal" font="default" size="100%">leaf inclination</style></keyword><keyword><style  face="normal" font="default" size="100%">leaf life-span</style></keyword><keyword><style  face="normal" font="default" size="100%">leaf mass/area ratio</style></keyword><keyword><style  face="normal" font="default" size="100%">leaf thickness</style></keyword><keyword><style  face="normal" font="default" size="100%">net photosynthetic rate</style></keyword><keyword><style  face="normal" font="default" size="100%">phillyrea latifolia</style></keyword><keyword><style  face="normal" font="default" size="100%">Quercus ilex</style></keyword><keyword><style  face="normal" font="default" size="100%">transpiration rate</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">1999</style></year></dates><publisher><style face="normal" font="default" size="100%">INST EXPERIMENTAL BOTANY, ACAD SCI CZECH REPUBLIC</style></publisher><pub-location><style face="normal" font="default" size="100%">NA KARLOVCE 1A, PRAGUE 6 CS-160 00, CZECH REPUBLIC</style></pub-location><volume><style face="normal" font="default" size="100%">37</style></volume><pages><style face="normal" font="default" size="100%">573-585</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">There are significant differences in leaf life-span among evergreen sclerophyllous species and drought semideciduous species growing in the Mediterranean maquis. Cistus incanus, which has a leaf life-span of four-eight months, was characterised by the highest net photosynthetic rates (PN). while Quercus ilex and Phillyrea latifolia, which maintain their leaves two-three and two-four years, respectively, had a lower PN- The longer leaf life-span of the two evergreen sclerophyllous species may be justified to cover the high production costs of leaf protective structures such as cuticle, hairs, and sclereids: cuticle and hairs screen radiation penetrating into the more sensitive tissues, and sclereids have a light-guiding function. Q. ilex and P. latifolia have the highest leaf mass/area ratio (LMA = 209 g m(-2)) and a mesophyll leaf density (2065 cells per mm(2) of leaf cross section area) about two times higher than C. incanus. In the typical evergreen sclerophyllous species the steepest leaf inclination (alpha = 56 degrees) reduces 42% of radiation absorption, resulting in a reduced physiological stress at leaf level, particularly in summer. C. incanus, because of its low leaf life-span, requires a lower leaf investment in leaf protective structures. It exhibits a drastic reduction of winter leaves just before summer drought, replacing them with smaller folded leaves. The lower leaf inclination (alpha = 44 degrees) and the lower LMA (119 g m(-2)) of C. incanus complement photosynthetic performance. Water use efficiency (WUE) showed the same trend in Q. ilex, P. latifolia, and C. incanus, decreasing 60% from spring to summer, due to the combined effects of decreased CO2 uptake and increased transpirational water loss.</style></abstract></record></records></xml>