Spiegel-Roy, P., Institute of Horticulture, Agricultural Research Organization, The Volcani Center, Bet-Dagan, Israel
Ben-Hayyim, G., Institute of Horticulture, Agricultural Research Organization, The Volcani Center, Bet-Dagan, Israel

Selection for tolerance to NaCl in Citrus sinensis and C. aurantium has been carried out in agar and suspension cultures. Callus was subjected to culture media containing up to 0.17 M NaCl for ten passages. Selected cell lines were grown for three passages on media without salt before further tests on saline media. Four stable tolerant cell lines, differing in degree of tolerance, have been selected from C. sinensis. Four lines of similar tolerance have been selected from C. aurantium. The stability of most lines was very satisfactory. Most C. sinensis lines grew well in media containing up to 0.2 M NaCl, and C. aurantium lines in media of up to 0.15 M NaCl. Embryos were regenerated in most selected cell lines from C. sinensis and, more sporadically, from C. aurantium. Addition of 0.5-0.6% NaCl to the media often enhanced embryogenesis. Embryos from a selected line of C. sinensis showed higher tolerance to NaCl in the medium than comparable embryos from an unselected line. Single embryos derived from both selected and unselected cell lines of C. sinensis were successfully cloned. A limited comparison of plantlets from one tolerant line (R14) with plantlets from unselected control lines showed better adaptation of the former to salt (0.085 to 0.12 M NaCl in the medium), and a lesser degree of leaf burn symptoms. © 1985 Martinus Nijhoff Publishers.