Seedling Tolerance of Three Eucalypt Species to Changes in Soil Alkalinity Due to Limestone Addition

The present research was implemented to analyses the seedling tolerance of three species Eucalyptus gomphocephala DC (Myrtaceae) (common name 'Tuart'), Eucalyptus marginata Sm. (common name 'Jarrah') and Corymbia calophylla (Lindl.) K.D. Hill & J. A. S. Johnson (common name 'Marri') to soil-induced stressor, namely soil alkalinity (limestone). Seeds germinated in shallow trays filled with white sand in a naturally lit glasshouse (control treatment). A liming treatment was conducted with 20% w/w crushed and sifted Tomala limestone adds to potting mix to increase soil pH. The experiment was conducted over 82 days. E. gomphocephala is restricted soils overlying limestone on study area and according to total seedling dry weight data and calculated relative growth rates coped best in a limestone-enriched soil. However, when examining all the growth and physiological data collected C. calophylla appeared to be the middling tolerant, with no significant difference in leaf allocation or leaf water loss between the well-watered controls and the limestone-enriched treatments whereas the E. marginata was the least tolerant with a 14% reduction in stomatal conductance.