Heuer, B., Institute of Soils and Water, ARO, Volcani Centre, PO Box 6, Bet Dagan 50-250, Israel, Contribution from the Agricultural Research Organization, The Volcani Centre, Bet Dagan, Israel
Plaut, Z., Institute of Soils and Water, ARO, Volcani Centre, PO Box 6, Bet Dagan 50-250, Israel, Contribution from the Agricultural Research Organization, The Volcani Centre, Bet Dagan, Israel

The response of photosynthesis in two sugarbeet cultivars exposed to 180 mol m-3 NaCl was investigated.An increase in photosynthesis was found in both cultivars during the initial 4 d after exposure to salinity. With longer time periods, CO2 fixation in one cultivar, Monriac, was not affected, while under the same conditions, photosynthesis of the other cultivar, Kawemegapoly, was significantly reduced. Full osmotic adjustment was obtained in both cultivars, and the sensitivity of Kawemegapoly to salinity was not due to loss of turgor. The possible mechanisms responsible for this phenomenon are discussed. Rubisco activity responded to salinity as CO2 fixation rate in both cultivars. © 1989 Oxford University Press.