AGRONOMICAL AND PHYSIOLOGICAL CHARACTERIZATION OF SALINITY TOLERANCE IN A COMMERCIAL TOMATO HYBRID

The salt tolerance of the commercial Fl tomato hybrid (Lycopersicon es culentum Mill) Radja (GC-793) has been agronomically and physiological ly evaluated under greenhouse conditions, using a control (nutrient so lution), a moderate (70 mM NaCl added to the nutrient solution) and a high salt level (140 mM NaCl), applied for 130 days. The results show that Radja is a Na+-excluder genotype, tolerant to moderate salinity. Fruit yield was reduced by 16% and 60% and the shoot biomass by 30% an d more than 75% under moderate and high salinities, respectively. At 9 0 days of salt treatment (DST), the mature leaves feeding the 4th trus s at fruiting accumulated little Na+ (178 mmol kg(-1) DW). At this tim e, the sucrose concentration in these leaves even increased with moder ate salinity and the amino acid proline was not accumulated under salt conditions as compared to control. At 130 DST, Na+ was accumulated ma inly by the roots in proportion to the salt level applied, while in le aves appreciable amounts were found only at high salinity (452 mmol kg (-1) DW). In the leaves, Cl- was always accumulated in proportion to t he salt level and in a very much greater amounts than Na+ (until 1640 mmol kg(-1) DW). The sucrose content was reduced in all plants by sali nity, and was distributed preferentially toward the distal stem and pe duncle of a truss at fruiting under moderate salinity, and toward the basal stem and root at high salinity. Moreover, proline was accumulate d in different organs of the plant only at high salinity, coinciding w ith Na+ accumulation in leaves. Attempts are made to find a clear rela tionship between physiological behaviour triggered by stress and the a gronomical behaviour, in order to assess the validity of physiological traits used for salt-tolerance selection and breeding in tomato.