SALINE GROWING CONDITIONS INDUCE RIPENING OF THE NON-RIPENING MUTANTSNOR AND RIN TOMATO FRUITS BUT NOT OF NR FRUIT

Tomato (Lycopersicon esculentum Mill.) plants cv. 'Rutgers', and their three nearly isogenic ripening mutant derivative lines nor, rin and N r, were grown in sand culture irrigated with nutrient solution. Six-we ek-old plants were exposed to saline growing conditions (EC 15.5 mmohs /cm) by adding NaCL or NaCl + CaCl2 to the nutrient solution, Ripening was induced in nor fruit under both saline conditions as indicated by fruit softness, red colour development, induction of a climacteric pa ttern of C2H4 production and an increase in 1-aminocyclopropane-1-carb oxylic acid (ACC) content over that of the control. Similar stimulatio n of all ripening parameters was obtained in rin fruit, but only with NaCl treatment. It seems that the presence of Ca2+ in the saline solut ion blocked salt-induced rin fruit ripening. Neither saline treatment affected Nr fruit ripening. Furthermore, Nr fruit grown under non-sali ne conditions showed yellow colour development and produced C2H4 at a level comparable to that produced by 'Rutgers' fruit with no post-clim acteric decline. The ACC content of Nr fruit was significantly higher than that of post-climacteric 'Rutgers' fruit. These data are discusse d as to the possible role of saline treatment with or without Ca2+ in inducing ripening in the non-ripening mutants. (C) 1998 Elsevier Scien ce B.V. All rights reserved.