Improving seed germination of four savanna-woodland species: effects of fire-related cues and prolonged soaking in sulphuric acid

A study was carried out to investigate the effects of fire related cues (heat and smoke) and sulphuric acid treatments on the germination of four woody savanna species, namely, Terminalia avicennioides, Piliostigma thonningii, Piliostigma reticulatum and Prosopis africana. The heat treatment consisted of putting seeds in a preheated oven at 100, 150 and 200 °C for 2.5 min. Seeds were then soaked in four concentrations of smoke solution (0 (tap water), 25, 50 and 100% smoke solutions). Parallel to smoke and heat treatment, seeds of the four species were each soaked in concentrated sulphuric acid for 2 hours and also according to the conventional soaking time of each species. Under experimental conditions, heat and smoke did not stimulate seed germination. For P. thonningii and P. africana, soaking seeds for 2 hours in sulphuric acid significantly increased germination capacity compared with conventional soaking time of 5 min. Longer soaking time reduced mean germination time. Results of this study will be useful in the establishment of these species