%0 Journal Article
%T Comparative Gas Exchange of <i>Ulmus crassifolia</i> (Cedar Elm, Ulmaceae) and <i>Ungnadia speciosa</i> (Mexican Buckey, Sapindaceae) at Ambient and Elevated Levels of Light, CO<sub>2</sub> and Temperature
%A Matthew B. Grunstra
%A Oscar W. Van Auken
%J American Journal of Plant Sciences
%P 691-709
%@ 2158-2750
%D 2023
%I Scientific Research Publishing
%R 10.4236/ajps.2023.146047
%X <i><span style=\"font-family:&quot;\">Ulmus
crassifolia</span></i><span style=\"font-family:&quot;\"> </span><span style=\"font-family:&quot;\">Nutt. (Cedar elm, Ulmaceae) </span><span style=\"font-family:&quot;\">is a tree found in central and east Texas, northern
Mexico, east to Florida, and north to southern Missouri and Oklahoma. <i>Ungnadia speciosa</i> Endl. (Mexican-buckeye,
Sapindaceae)<b> </b>is a shrub or small tree found in woodlands and savannas of
central and western <span>Texas, southern New
Mexico and northern Mexico. In central Texas, both</span> <span>species are found in <i>Juniperus ashei</i>/<i>Quercus
virginiana </i>woodlands or sa</span>vannas or also at low density in
inter-canopy grassland gaps or patches. Environmental conditions in this area
are stressful because of shallow soils, high summer temperatures, and
inconsistent low rainfall. Currently, both species have </span><span style=\"font-family:&quot;\">a </span><span style=\"font-family:&quot;\">low density in these areas, and <i>Ulmus crassifolia </i>is
usually a tree</span><span style=\"font-family:&quot;\">,</span><i><span style=\"font-family:&quot;\"> </span></i><span style=\"font-family:&quot;\">while<i> Ungnadia
speciosa</i> is a woody understory shrub. This study suggests <i>U. cras<span>sifolia
and U. speciosa </span></i><span>are</span><span> </span></span><span style=\"font-family:&quot;\">tolerant</span><span style=\"font-family:&quot;\"> or intermediate species</span><span style=\"font-family:&quot;\">,</span><span style=\"font-family:&quot;\"> with juveniles</span><span style=\"font-family:&quot;\"> starting
in shade. Maximum photosynthetic rate (<i>A</i><sub>max</sub>),
dark respiration (R<sub>d</sub>), intercellular CO<sub>2</sub>, light
saturation (<i>L</i><sub>sp</sub>) and water
use efficiency significantly increased when light levels and CO<sub>2</sub> concentrations were elevated for both spe<span>cies</span></span><span style=\"font-family:&quot;\">,</span><span style=\"font-family:&quot;\"> but not when temperatures were
elevated. Stomatal conductance de</span><span style=\"font-family:&quot;\">creased when the CO<sub>2</sub> concentration
doubled</span><span style=\"font-family:&quot;\">,</span><span style=\"font-family:&quot;\"> but there were </span><span style=\"font-family:&quot;\">few</span><span style=\"font-family:&quot;\"> </span><span style=\"font-family:&quot;\">e</span><span style=\"font-family:&quot;\">ffect</span><span style=\"font-family:&quot;\">s</span><span style=\"font-family:&quot;\"> from
elevated temperature. These findings
%K Light Response
%K Gas Exchange
%K Photosynthesis
%K Respiration
%K Water Use  Efficiency
%U http://www.scirp.org/journal/PaperInformation.aspx?PaperID=126079