A Comparison of Three Populations of Eucalyptus obliqua L'hérit. Growing on Acid and Calcareous Soils in Southern Victoria

Abstract

In the Otways district, Vic., Eucalyptus obliqua exhibits a wide edaphic tolerance and evidence is presented for the existence of ecotypes in this region.

A comparison of three populations from acidic loam, neutral sand and alkaline sand showed significant differences in yield response when grown under glasshouse conditions. A tall open- forest population, naturally occurring on fertile acidic loams (pH 4.6-5.2), showed a marked reduction in yield, was severely chlorotic and developed red and necrotic patches on leaves when grown on calcareous sands of pH 6.5 and 8.0. Open-forest and low open-forest populations native to the sands of pH 6.5 and 8.0 respectively also developed some chlorosis, but maintained greater yields, particularly on the soil of pH 6.5. Chlorosis in all populations was correlated with decreased levels of chlorophylls a and b, and carotenoids; on soil of pH 8.0, all populations showed increases in calcium, potassium, magnesium, sodium, phosphorus and the phosphorus/iron ratio in leaf tissue. Populations showed differing contents of iron in seedlings (but with no particular trends), and the low open-forest population developed a significantly low phosphorus/iron ratio when grown on Leached calcareous soil of pH 6.5.