
TY  - JOUR
A1  - Sobrado, M. A. 
A1  - Ball, M. C. 
T1  - Light use in relation to carbon gain in the mangrove, <emph type="2">Avicennia marina</emph>, under hypersaline conditions
JF  - Functional Plant Biology
JO  - Functional Plant Biol.
Y1  - 1999
VL  - 26
IS  - 3
SP  - 245
EP  - 251
KW  - Avicennia marina, fluorescence, mangroves, photoinhibition, photoprotection, photorespiration, photosynthesis, salinity, xanthophyll cycle.
UR  - https://doi.org/10.1071/PP98075 
N2  - Photosynthesis was studied in relation to light use in the mangrove, Avicennia marina (Forsk.) Vierh. var. australasica (Walp.) Moldenke, growing under soil salinities equivalent to one and two times seawater (i.e. 35 and 60&#8240;). Midday CO2 assimilation rates averaged 7.6 0.7 and 4.3 0.3 &#181;mol m&#8211;2 s&#8211;1 at the seawater and hypersaline sites, respectively. Despite this difference, xanthophyll pool sizes per Chl and epoxidation states were similar at both sites. Non-photochemical quenching also indicated comparable energy dissipation from pigment beds. Electron transport rates calculated from fluorescence characteristics were also similar and exceeded the requirements to sustain measured assimilation rates. However, cell wall conductance was low in seawater plants (75 mmol m2 s&#8211;1 ) and declined to 40 mmol m&#8211;2 s&#8211;1 in hypersaline plants. This would cause CO2 concentrations in chloroplasts (Cc ) to be lower than expected from measurements of intercellular CO2 concentrations (Ci ). In seawater plants, Cc was estimated to be 144 &#181;mol mol&#8211;1 when Ci was 245 mmol mol&#8211;1, while values for Cc and Ci in hypersaline plants were 78 and 212 mmol mol&#8211;1, respectively. Reductions in Cc would enhance rates of photorespiration relative to assimilation, with the higher photorespiratory rates being sufficient to account for apparent excess electron transport rates. 
ER  -

