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 mM). 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.