Ion accumulation and distribution in shoot components of salt-stressed Eucalyptus clones

Abstract

Four clones of Eucalyptus camaldulensis Dehn. (4543, 4544, 4573, and 4590) and one clone of E. rudis Endl. (4501) were grown in greenhouse sand cultures irrigated with waters designed to simulate saline drainage waters present in the San Joaquin Valley of California, and compositions that would result from further concentration of the waters. The drainage waters are typically high in Na+, SO4/2-, Cl-, and Mg2+. Electrical conductivities of the solutions were 2, 12, and 28 dS · m-1. Ion uptake and distribution patterns in above-ground components were studied in members of these clones grown under treatment for 7 weeks. Results indicated the clones could be separated into two distinct groups by significant differences in leaf-ion relations. Group 1 clones 4543, 4544, and 4573 accumulated less Na+ and more Ca2+ and Cl- in leaves than group 2 clones, 4501 and 4590. Group 2 clones accumulated Na+ under low salinity, but apparently possessed some mechanism for restricting Na+ accumulation by the leaves that was activated as salinity increased. Leaf and stem Cl- I concentrations tended to be lower in all clones grown at 28 dS · m-1 than at 2 dS · m-1, despite increases in Cl- concentration in the irrigation waters. Under saline conditions, K+ and P were preferentially accumulated in the youngest leaves in the upper portion of the canopy, whereas Na+, Ca2+, and Mg2+ were retained in the older leaves.