
TY  - JOUR
A1  - Matzner, Steven L. 
A1  - Rice, Kevin J. 
A1  - Richards, James H. 
T1  - Factors affecting the relationship between carbon isotope discrimination and transpiration efficiency in blue oak (<emph type="2">Quercus douglasii</emph>)
JF  - Functional Plant Biology
JO  - Functional Plant Biol.
Y1  - 2001
VL  - 28
IS  - 1
SP  - 49
EP  - 56
KW  - carbon isotope discrimination, intraspecificvariation, oaks, respiration, water-use-efficiency.
UR  - https://doi.org/10.1071/PP99088 
N2  - In a greenhouse study, variation in plant and leaf transpiration efficiency(W, A/E)and carbon isotope discrimination (D) were assessed forQuercus douglasii Hook &#38; Arn. (blue oak) from a&#8216;wet&#8217; (930 mm) and a &#8216;dry&#8217; (500 mm) site. Plants weregrown at 75&#8211;100% (wet) and 50&#8211;75% (dry) of fieldcapacity. Family variation masked population level differences, and twocontrasting patterns emerged. The expected pattern was observed with drytreatment plants having lower leaf internal CO 2concentration (c i ) and D, andhigher W andA/E. For families with verylarge increases in plant size from dry to wet treatments, however, wettreatment plants had lower c i andD, and higher W andA/E, reflecting a greaterinfluence of the maximum assimilation rate (Amax ) compared with stomatal conductance(g s ) on ci . In addition, large within-population variation inplant size appears to have affected both n (the vapor pressure deficit) and&oslash; c (a measure of respiredcarbon). Lower n for large plants may be due to the higher rates of stomatalconductance and greater leaf cooling. Values of &oslash;c appear to have increased for plants below 2.5 g (drymatter, DM). Variation in these factors would directly affect the relationshipbetween W and D. This study illustrates a case where significant within-population variation can occur in the relative effect ofg s and Amax on c i .In addition this study indicates that &oslash;c may not be a constant for a species. 
ER  -

