Effects of CO2 and O2 on the Photosynthetic O2 Evolution of Spirodela polyrrhiza Turions

摘要

Net photosynthetic rates of Spirodela polyrrhiza turions, at low O2 levels, were 6.2 and 38.8 micromoles O2 per gram fresh weight per hour at 1 millimolar HCO3⁻ and CO2 saturation, respectively, and much lower in a regular low-pH growth solution. Air equilibration O2 concentrations decreased rates considerably, except at CO2 saturation. The surfacing rate of turions in various inorganic carbon surroundings correlated positively with their photosynthetic rates, but were the same at high and low O2 levels. The relevance of these findings in relation to environmental conditions conductive to germination of autotrophically growing turions is discussed.