Photomorphogenic and Chlorophyll Studies in the Bryophyte Marchantia polymorpha

Besides the standard rod (R) and far-red (FK) irradiations, a graded series of different R/FR ratios were tested as 10 min terminal exposures at the end of the daily 8-hour photoperiod of white fluorescent light. Water filtered incandescent light of 3780 lux during 10 min caused A rather weak hut reproducible effect. A superposition to the water layer of different filter combinations shifting the initial transmittance more towards the FR region, and thus gradually lowering the R/FB ratio, resulted in a parallel increase in orthotropic growth and a decrease in chlorophyll content. Our data show growth similarities with the results of other authors on light grown seedlings of higher plants. Rather high levels of the P_FR form of phytochrome seem to he required to maintain horizontal growth and optimal chlorophyll content in Marchantia thalli.