WATER RELATIONS, PHOTOSYNTHESIS AND ASSIMILATE PARTITIONING IN LEAVES OF PEPPER (CAPSICUM-ANNUUM) TRANSPLANTS - EFFECT OF WATER-STRESS AFTER TRANSPLANTING

When pepper (Capsicum annuum L., cv. Maor) transplants, grown in Speedling type trays, were transplanted into wet soil but not watered for up to 48 h (day/night temperature 30/25-degrees-C), their leaf water potential was reduced from -0.5 to nearly -2.0 MPa. This decrease was mainly due to loss of leaf tugor. At such low water potential, photosynthesis of the source leaves was completely inhibited. The leaf water potential returned to the control values 24 h after rewatering but the photosynthetic rate of the stressed plants did not fully recover and was dependent on the extent to which the water potential had decreased during the stress. Translocation of C-14-assimilates, following (CO2)-C-14 feeding, was inhibited in stressed transplants with the upward flow towards the young leaves being more affected that the downward flow towards the roots. after rewatering, transport of C-14-assimilates from the source leaf of the stressed transplants to the root was recovered but transport to the young developing leaves remained inhibited. The different capacity of the root and the top to recover the import of assimilates after rewatering was also manifested in their different growth responses during ten days following recovery from the stress.