CHANGES IN SOME PHOTOSYNTHETIC PARAMETERS IN PEA-PLANTS AFTER TREATMENT WITH COBALT

CO2 (40, 200, 400 muM) was added to the root system of 10-d-old pea pl ants (Pisum sativum L. cv. Ran). The Co2+-excess caused a reduction in the plant fresh and dry masses and water and chlorophyll contents. Th e rates of photosynthesis and transpiration decreased, while proline c ontent and stomata resistance increased. The dramatic effect of Co2+-t oxicity was expressed both in an inhibition of ribulose 1,5-bisphospha te (RuBP) carboxylase activity and a stimulation of RuBP-oxygenase and phosphoenolpyruvate carboxylase activities on the 4th day of cultivat ion of plants in a solution of 400 muM Co2+.