Thermodormancy in Seedlings of Eucalyptus obliqua L'herit

Abstract

High (30°C) day and night temperatures reduced mainstem elongation in E. obliqua seedlings resulting in a temporary quiescence in height growth after 8 days of high temperature treatment; rapid stem elongation did not recommence when seedlings were returned to conditions usually favourable to growth. Associated with the onset of quiescence were: an increase in the respiratory quotient and a decrease in the respiration rate of upper terminal buds; an accumulation of inhibitory substances; and an increase in total polyphenols in the stem.