EFFECTS OF SHORT-TERM SALINITY ON LEAF GAS-EXCHANGE OF THE FIG (FICUS-CARICA L)

The influence of short-term salinity (day 1-day 2: 50 mol m-3 NaCl, day 3-day 7: 100 Mol m-3 NaCl in the nutrient solution) on leaf gas exchange characteristics were studied in two fig clones (Ficus carica L.), whose root mass had been varied in relation to the leaf area. The stomatal conductance was diminished by NaCl in the first week of treatment. NaCl slightly reduced the calculated intercellular partial pressure of CO2. The net photosynthetic rate of plants with many roots was stimulated by NaCl on some days of the first week of treatment, whereas the net assimilation rate of the plants with few roots remained unaltered or decreased by NaCl. Only the assimilation of the salt-treated plants of one clone for some days during the first week of treatment seemed to be influenced by stomatal conductance. Nonstomatal factors were primarily responsible for the changes in CO, uptake in response to salt and/or root treatment. The water use efficiency increased during several days of the first week of NaCl treatment. Decreased stomatal conductance, increased water use efficiency and stimualtion of the net CO2 assimilation rate appear to enhance salt tolerance during the first few days of salinity.