Effect of photoperiod, potassium nitrate and gibberellic acid on dormancy breaking and germination of lavender (Lavandula angustifolia) seeds

Lavender (Lavandula angustifolia), widely used in health, cosmetics and perfumery fields, is a very valuable medicinal and aromatic plant, belonging to the Lamiaceae family. Low and poor germination in lavender seeds caused by dormancy significantly restrict generative propagation of lavender. This study was carried out to determine the effects of photoperiod (16/8 hours light/dark, 24 hours dark), GA3 (0, 125, 250, 375 and 500 ppm) and KNO3 (0, 1000, 2000, 3000 and 4000 ppm) applications on breaking dormancy and germination in lavender seeds. In lavender seeds germinated in the photoperiod environment, the germination rate and germination speed increased by 20% and 80.4%, respectively, compared to the seeds in the dark environment, and the average germination time was shortened by 16%. On the other hand, at the 375 ppm GA3 dose, compared to the control application, there was an increase of 31.3% and 54% in the germination rate and germination speed, respectively, and the average germination time was shortened by 29.3%. With the KNO3 application, a 12.3% increase was observed in the germination rate, which initially increased gradually, at the 3000 ppm KNO3 dose, compared to the control application, but the 4000 ppm KNO3 dose led to a lower germination rate than the control application. These research findings show that for the purpose of breaking dormancy and promoting germination in lavender seeds, the application of 375 ppm GA3 and/or 2000 ppm KNO3 applications in 16/8 hours light/dark photoperiod environment can be recommended.