The effect of plant-derived smoke and smoke-isolated chemical karrikinolide on the germination and early seedling growth of some ornamental plant species

Smoke is produced by combustion of cellulose during a vegetation fire and includes thousands of chemical molecules. Some of seeds that have permeable seed coats perceive these chemicals as a signal and initiate germination. It is shown that one of these chemicals, karrikinolide, enhances germination in many species, therefore it has been considered as one of the active compounds in smoke. In addition to germination, smoke and chemicals found in smoke may also affect early seedling growth in plants. In this thesis, the effects of various concentrations of smoke solutions and smoke-isolated chemical karrikinolide were tested for the germination and early seedling growth of Hesperis matronalis and Lavandula stoechas species which are naturally found in Turkey and are grown as garden plants. In the early seedling growth experiments, the effects of smoke and karrikinolide chemical on root length, stem length, total seedling length and root/stem ratio were investigated. The results showed that smoke solution and karrikinolide chemical do not affect the germination of L. stoechas, while the germination of H. matronalis is negatively affected by smoke solution and karrikinolide. According to early seedling growth experiments, it was found that treatment and time of germination affect the root length, stem length, total seedling length and root/stem ratio in L. stoechas. Also, 100% smoke solution caused a decrease in root, stem and total seedling lengths in this species. Moreover, seedlings that germinate later had shorter stem length and total seedling length, but, their root lengths were increased. No effect of smoke treatments and karrikinolide treatment on seedling growth of H. matronalis was found. The results of this study showed that smoke and karrikinolid do not always have an improving effect on plants and the germination time may affect seedling growth. There is still need for further studies for a better understanding of the effect of smoke solutions and chemicals found in smoke on seedling growth of plants.