Varietal Response of Acacia species to Salinity Stress During Germination and Seedling Growth

Abstract

Seeds and seedlings of Acacia bivenosa D.C. Prod, A. salicina Lindl., A. saligna (Labill.) H. Wendl. and A. tumida F.Muell. ex Benth were germinated and grown in NaCl solutions to investigate the relative salt tolerance among the diferent species,and to determine whether a relationship exists between salt tolerance at germination and seedling growth stages. In all the speciestested, the germination of the seeds decreased and mortality of the seedlings increased with increasing NaCl concentration. Speciesvaried considerably in salt tolerance at both seed germination and seedling stages. The ranking of species at the germination stagewas not identical to the seedling stage. The concentrations reducing A. saligna germination or survival to 50% of control valueswere 58 and 197 mol m-3 for seed germination and 2-6 weeks old seedlings, respectively, while the equivalent values for A. tumidawere 215 and 16 mol m-3. Considerable diferences were also found in the ranking of species for a range of seedling growthparameters. These results show that responses at germination could not be used to screen and select for plant salt tolerance and thatit may be unwise to rely on only one measurement of growth to estimate the salt tolerance of sedlings.