Species-specific smoke effects on seed germination of plants from different habitats from Sri Lanka

Abstract

Smoke and in particular karrikinolide (KAR1), a growth promoting compound found in smoke, have been shown to enhance seed germination in phylogenetically diverse plant families from both fire-prone and fire-free ecosystems. We tested the effects of water saturated with smoke, “smoke water” (SW), and KAR1 on seed germination of 18 native and exotic plant species from different habitats affected by anthropogenic fires in Sri Lanka. Seeds were tested with five concentrations of SW (5 %, 25 %, 50 %, 75 %, 100 %) and those that positively responded were tested with three different concentrations of KAR1 (10 nM, 100 nM and 1 μM). Germination percentage of three native (Flueggea leucopyrus, Maesa indica and Phyllanthus emblica) and two exotic (Chromolaena odorata and Hyptis suaveolens) species was significantly increased by both SW and KAR1 treatments. Seed germination percentage of the exotic species Euphorbia heterophylla was increased by SW treatments only. The time taken for 50 % germination (t50) of C. odorata, M. indica and P. emblica was decreased by both SW and KAR1, whilst t50 of E. heterophylla was decreased by SW only. Species-specific seed germination promotion response to SW and KAR1 was observed in both native and exotic plant species tested in the study confirming that the recruitment ecology of at least some species found in fire prone habitats of Sri Lanka is likely to be influenced by fire management practices.