Influence of Growth Conditions on the Enhancement of Photophosphorylation by Carbon Dioxide.

In the earlier plublicationi concerninig the effect of CO., oni pliotophosphorylationi (3) a seasonal variationi in the CO, enhanicemiient w-as also described. The CO., enhanicenment wvas much greater w-hen determined wvith chloroplasts from wvinter-growvn oats thani stummlier grown oats. This variation in the response to CO. was a hinderance to further experimlenital stuidy of the effect, so a meanls of controllin-g it was sought. The 2 greatest changes in the elnvironmental conditionls found during the winter in the greenhouse were the reduced intensity of the light and the reduce(d amount of blue-violet light relative to the other spectral regions. The other conditionis, such as temperature and day length, were held fairly conlstalnt. The experiments described in this paper were performed in order to determine the effect of the formler 2 conditions on the CO, response.