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NaCI and CaC12 are frequently used as deicing agents during the winter season. The present study compares the effect of these deicing salts on salt injury on spruce trees (Picea abies sp.). From two field experiments carried out for ten weeks during the winter period of 1986-1987, and a total dose of 1.5 kg m -2 NaC1, CaC12 or a 75/25 NaC1/CaC12 mixture, it was found that the presence of calcium clearly reduced the salt injury as was indicated by salt tolerance ratings. These ratings corresponded well to the CI concentrations found in needles and twigs. Though an equal dose of C1-was given, in the presence of CaCI2 the uptake of C1-was inhibited. Surely the role of calcium on ion permeability in salinized soil should have its effect, together with the regulatory role that calcium has on ion accumulation and transport. Furthermore it was found that the climatic conditions and the calcium status of the soil only have an effect on the time of appearance of the injury.

The influence of indol-3yl-acctic acid (IAA) and abscisic acid (ABA) on the capacities of the cytoplastn and vacuole and their elTects on unidirectiotial sodiutn fluxes across the plastnaletntna and the tonoplast of aged red beet storage tissue was investigated. After loading the tissue in a labelled NaCl solution the clllux of radio-activity was tneasured iti unlabelled NaCl. By tneatis of cotnparltncntal atialysis the capacities and fluxes were dctcrtnitied and cotnpated with those obtained after loading atid elution in the pteseticc of IAA or ABA.It was established thai both IAA and ABA alTect sodiutn transport across the principal cell tnetnbrancs. Both hormones inhibited the elUux across the plastnaletntna, possibly by alTecting a Na ' for H ' exchanging system. Elflux across the tonoplast was stitnttlatcd by IAA and influx across the satne tncmbtatic was enhanced by ABA. It was suggested that IAA stitnulated a proton putnp at this level while the influence of ABA tcmaitied diflicult to explain.