PHOTOTACTIC MOVEMENTS OF CHLOROPLASTS AND THEIR RELATION TO PHOTOSYNTHETIC ACTIVITY IN VALLISNERIA-SPIRALIS L

The possible relation between chloroplast orientation and photosynthet ic activity is still a debated issue. It is known that chloroplast ori entation starts even with a very low irradiation energy. In the presen t communication we show how orientation is affected by white light irr adiation intensities in the cells of leaf segments of Vallisneria spir alis L. The relation of orientation to photosynthetic activity is expl ored by using the techniques of optical microscopy and morphometry to determine the area of chloroplasts coverage after irradiation of the s amples, and using C-14 incorporation in order to estimate photosynthet ic activity. The course of the phototactic movements of chloroplasts h ave been discussed on the basis of the results of C-14 fixed obtained.