Abstract:

Smoke and smoke-derived compounds can regulate physiological and developmental processes, such as seed germination, somatic embryogenesis, and flowering in plants. Smoke-related germination responses are highly complex due to the presence of stimulatory and inhibitory compounds, such as karrikins, glyceronitrile, syringaldehyde, catechol, and 3,4,5-trimethylfuran-2(5H)-one. In this study, the effects of smoke water, karrikinolide (KAR1), mandelonitrile (MAN), and catechol (CAT) treatments on seed germination of Liquidambar orientalis Mill. were investigated. Moreover, gibberellic acid (GA3) and reactive oxygen species (ROS), which are thought to play a role in KAR1- and cyanohydrin-induced seed germination, were also included in the experiments. Hydrogen peroxide and methyl viologen solutions were used for ROS treatments. Germination experiments were carried out under different light conditions in incubators set at 20 °C. The results of the study showed that L. orientalis seeds were sensitive to smoke. In addition, 0.01 and 0.1 µM KAR1 and 50 µM MAN solutions promoted the germination of the study species under both dark and light conditions (p < 0.05). On the other hand, CAT treatments did not have a positive or negative effect on germination. L. orientalis seeds sensitive to KAR1 and cyanohydrin gave a positive germination response to GA3 in the concentration range of 10-5 to 10-3 M. GA3 treatments also eliminated the requirement of light for high germination success. ROS-induced germination was only observed in the presence of light. The findings of this study can be used to increase the germination success of L. orientalis, a narrowly distributed species.

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