Photosynthetic Rates of Sporophytes and Gametophytes of the Fern, Todea barbara

The photosynthetic rates of intact sporophytes or gametophytes of the fern Todea barbara grown in sterile culture were measured using an infrared gas analyzer. Sporophytes consisted of single whole plants with roots and leaves grown in tubes of agar. Gametophytes were grown as several plants covering the surface of the agar. Sporophytes had photosynthetic rates at light saturation of 8.50 microliters CO(2) per hour per milligram dry weight and 1,300 microliters CO(2) per hour per milligram chlorophyll, whereas rates for gametophytes were lower, 2.36 microliters CO(2) per hour per milligram dry weight and 236 microliters CO(2) per hour per milligram chlorophyll.O(2) inhibited the photosynthetic rates of both plants to a degree typical of C-3 plants. The light-saturated photosynthetic rates of sporophytes increased 42% and gametophytes increased 27% when the O(2) concentration was changed from 21 to 1%.