Photosynthetic apparatus inSelaginella. I. Morphology and photosynthesis under different light and temperature regimes

摘要

Several hydrophytic and umbrophilic species ofSelaginellawere grown in sterile culture and scrutinized for morphological and photosynthetic variability under light intensities between 0 and 500ensp;ft-c and temperatures of 9deg; and 22 deg;C. Bleaching was induced by raising light intensity; and for a particular light intensity was enhanced by lowering temperature. Regreening could be achieved by reversing conditions. Branching patterns, leaf symmetry, and orientation of leaves to axis were also light dependent. Light levels which produced normal green plants forS. uncinatainitiated only half-saturation photosynthetic rates. Photosaturating light intensities, if applied for several weeks, induced bleaching. Based on fresh or dry weight bleaching plants had lower photosynthetic rates than green plant's; but based on chlorophyll content the photosynthetic rates of green and bleaching plants were the same.