Effects of NaCl on seedling growth, biomass production and water status of Acacia nilotica and A. tortilis

The study reports on the salt tolerance of Acacia tortilis compared to A. nilotica. For the investigation, potted seedlings of both species were exposed to three levels of salt treatments (0, 150 and 300 mm NaCl) in a 1-month greenhouse experiment. In terms of biomass growth, both acacias responded similarly to salinity (i.e. insignificant species×treatment interaction) even though A. nilotica appears to be generally more productive than A. tortilis (i.e. significant effect of species). In terms of shoot water status, there was significant variation in the response to increased NaCl salinity between the two acacias. Furthermore, both acacias exposed to salt treatment shed their leaves, although at different time during the experiment. This suggests that both acacias are sensitive to the salt treatment applied here. Further screening tests involving various ssp. and genotypes of both species might be promising to find suitable trees for the afforestation on salt-affected soils in arid and semi-arid Africa.