
TY  - JOUR
A1  - Henderson, S. 
A1  - Caemmerer, S. von 
A1  - Farquhar, G.D. 
A1  - Wade, L. 
A1  - Hammer, G. 
T1  - Correlation between carbon isotope discrimination and transpiration efficiency in lines of the C<emph tye="8">4</emph> species <emph type="2">Sorghum bicolor</emph> in the glasshouse and the field
JF  - Functional Plant Biology
JO  - Functional Plant Biol.
Y1  - 1998
VL  - 25
IS  - 1
SP  - 111
EP  - 123
KW  - 
UR  - https://doi.org/10.1071/PP95033 
N2  - Transpiration efficiency, W, the ratio of plant carbon produced to water transpired and carbon isotope discrimination of leaf dry matter, &#x394;d, were measured together on 30 lines of the C4 species, Sorghum bicolor, in the glasshouse and on eight lines grown in the field. In the glasshouse, the mean W observed was 4.9 mmol C mol-1 H2O and the range was 0.8 mmol C mol -1 H2O. The mean &#x394;d was 3.0 and the observed range was 0.4&#x2030;. In the field, the mean W was lower at 2.8 mmol C mol-1 H2O and the mean &#x394;d was 4.6&#x2030;. Significant positive correlations between W and &#x394;d were observed for plants grown in the glasshouse and in the field. The observed correlations were consistent with theory, opposite to those for C3 species, and showed that variation in &#x394;d was an integrated measure of long-term variation in the ratio of intercellular to ambient CO2 partial pressure, pi/pa. Detailed gas exchange measurements of carbon isotope discrimination during CO2 uptake, &#x394;A, and pi/pa were made on leaves of eight S. bicolorlines. The observed relationship between &#x394;A and pi/pa was linear with a negative slope of 3.7&#x2030; in &#x394;A for a unit change in pi/pa. The slope of this linear relationship between &#x394;A and pi/pa in C4 species is dependent on the leakiness of the CO2 concentrating mechanism of the C4 pathway. We estimated the leakiness (defined as the fraction of CO2 released in the bundle sheath by C4 acid decarboxylations, which is lost by leakage) to be 0.2. We conclude that, although variation in &#x394;d observed in the 30 lines of S. bicolor is smaller than that commonly observed in C3 species, it also reflects variation in transpiration efficiency, W. Among the eight lines examined in detail and in the environments used, there was considerable genotype &#xd7; environment interaction. 
ER  -

