Performance of Forner-Alcaide 5 and Forner-Alcaide 13, hybrids of Cleopatra mandarin x Poncirus trifoliata, as Salinity-Tolerant Citrus Rootstocks

Abstract

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.