Abstract
Rapid changes (CFI) in intensity of chlorophyll a fluorescence during dark-light transient reflect the various reactions of photosynthesis. The image analysis of CFI gives information not only about the localized differences in photosynthetic activity on whole leaves in situ but also on the development of photosynthetic system.
Development of the photosynthetic system in cultured tissues is very complex. Therefore, the development of carrot (Daucus carota L. cv US-Harumakigosun) tissues was studied by the image analysis of CFI. The nodular callus, which had been formed by culturing 1-weekold hypocotyl segments on MS agar medium containing 2, 4-D (1 mg⋅l-1), was used for the experiments. After the nodular callus was transplanted to MS agar medium without 2, 4-D, the embryogenic cells appeared within 2 to 3 weeks. The tissues grew under 25°C air temperature and 80 μmol photons⋅ m-2. sec-1. At 3 days after the transplanting, the appearance of chlorophyll a in the nodular callus was detected by the CFI images. The CFI patterns changed in the development of photosynthetic apparatus of developing leaves. The changes in each developing stage were very complex but the progress in the photosynthetic system was diagnosed by the CFI curves. The CFI pattern of the developing leaves at 60 days after the transplanting were similar to the typical pattern of mature leaves.
