| Summary: | Chloride and sodium concentrations and gas exchange parameters were measured on leaves of 'Valencia' orange scions grafted onto the rootstocks Cleopatra mandarin (CM), Poncirus trifoliato (PT) and their hybrids Forner-Alcaide 5 (FA-5) and Forner-Alcaide 13 (FA-13), grown in pots with different concentrations of NaCl in the external medium. Scions on CM accumulated less Cl(-) in their leaves than scions on PT. However, Na(+) concentrations were lower in scions on PT than on CM. Leaf Cl(-) exclusion appears to be transmitted to F1 hybrids FA-5 and FA-13. Also, the limited transport of Na(+) from rootstock to scions on PT was transmitted to FA-5. Leaf gas exchange parameters in salt-treated plants were reduced to different extents, depending on the rootstock. The decreases in net CO, assimilation and transpiration were more pronounced in CM, followed by PT and FA-13. The lowest reductions in both parameters occurred in scions on FA-5. The results indicate that, both in terms of saline ion exclusion and gas exchange parameters, FA-5 was the most tolerant genotype to salinity of the four studied, followed by FA-13.
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