Seed dormancy and germination in the Australian baobab, Adansonia gregorii F. Muell.

Abstract

Seeds of the iconic Australian baobab Adansonia gregorii display physical dormancy (PY) and germinate readily once they become water permeable, a trait found in most other species in this genus. Highest germination (100%) was observed when seeds were placed in concentrated sulphuric acid (H2SO4) for 24 h, although exposure to H2SO4 for 6-12 h also resulted in >85% germination. Exposure to boiling water for 1-5 min was far less effective in promoting germination (0-23%), although a high number of seeds were water permeable (67-99%) following boiling water treatment. However, the majority of these water-permeable seeds appeared to have been injured by boiling water exposure. Germination at warmer temperatures (30 or 35°C) was found to be optimal (81-83% germination) and proceeded rapidly, with maximum germination occurring after incubation for only 8 d. In comparison, germination at 15-25°C resulted in 3-67% germination over a longer time frame (up to 20 d). While seeds of A. gregorii display PY they are unusually sensitive to dipping in boiling water and are therefore atypical when compared to most other Adansonia species. © 2009 Cambridge University Press.