Association of Marginal Leaf Scorch with Sodium Accumulation in Salt-stressed Peach

The effect of specific ion toxicity during salt stress was tested in the present study. The experiment was repeated twice, in 1996 and 1998, with `Nemaguard' peach seedlings and rooted cuttings grown in hydroponics under two NaCl concentrations (50 and 30 m m ). Foliage was separated in symptomatic and symptomless leaves and the amount of sodium (Na + ) and chloride (C1 – ) was determined. Significantly higher Na + content was found in symptomatic than in symptomless leaves in both experiments, whereas in only two of the six cases was Cl – content higher in symptomatic than in symptomless leaves. The Na + threshold for leaf scorch was somewhere between 4 and 6 mg·g –1 dry weight . Results indicated that Na + accumulation, rather than Cl – accumulation, was associated with the familiar marginal and interveinal scorch symptoms seen in salt-stressed peach leaves.