PARTITIONING OF PHOTOSYNTHETIC CARBOHYDRATES IN LEAVES OF SALT-STRESSED OLIVE PLANTS

Changes in photosynthetic carbon partitioning were determined, during (CO2)-C-14 pulse-chase experiments, in fully-expanded leaves of olive (Olea europaea L, cv. Frantoio) plants treated in containers with 100 mM NaCl for 5 weeks and compared with partitioning in leaves of untrea ted plants. Salt stress caused an increase in the radioactivity partit ioned into mannitol and a decrease of that recovered as glucose. The r adioactivity in sucrose was significantly reduced in salt-treated plan ts after 19.5 min of chase. There was no difference between the two tr eatments in the radioactivity found in fructose and galactose, whereas a significant decrease in the radioactivity found in stachyose and ra ffinose of salt-treated leaves was observed after 19.5 min chase. The radioactivity incorporated into starch was 11 and 16% of the total in control and salt-treated leaves respectively. There were no significan t differences in the leaf pools of soluble carbohydrates over the chas e period, except for mannitol which increased in the leaf tissue of sa lt-treated plants. Over the course of the diurnal period, and under hi gh irradiance conditions, the leaf mannitol content increased more mar kedly in salt-treated plants than in the controls.