Effect of interstock ('Salustiano' orange) on growth, leaf mineral composition and water relations of one year old citrus under saline conditions

We investigated the effects of salinity on the growth, mineral composition (leaf, stem and root) and water relations in one year old plants of 'Cleopatra' mandarin (Citrus reticulata Blanco) (CM), 'Salustiano' orange (Citrus sinensis (L.) Osbeck) grafted on 'Cleopatra' mandarin (CM/SAO), 'Valencia Late' orange (Citrus sinensis (L) Osbeck) on 'Cleopatra' mandarin (CMNLO) and 'Valencia Late' grafted on CM/SO (CM/SAO/VLO). Plants were grown in sand culture under greenhouse conditions and supplied with nutrient solution containing either 5 (control) or 50 mM NaCl. After ten weeks of salt treatment, the CM/SAO/VLO leaf growth was not affected, while CM/SAO showed the greatest leaf growth reduction. Root growth was less affected than leaf growth by salt treatment, and was similar for all four combinations. In the salt treatment, the leaf chloride concentration of CM/SAO/VLO was the lowest compared with the other plants and leaf Na concentration of CM/SAO/VLO was lower than CMNLO, suggesting that the interstock limited Cl and Na uptake and/or transport from roots to leaves. The high leaf growth reduction observed in CM/SAO could be related to a decrease in turgor, due to a decrease in leaf water potential caused by salt treatment not being compensated by a reduction in leaf osmotic potential.